Parallel Induction Research Articles

Component value calculations in a mixed element ladder network containing series capacitors separated by unit elements

SummaryLossless LC ladder networks have many applications. But at high frequencies, inductor‐free designs are preferred since inductors are heavy and have limited values. An additional reason for not using the inductors (at high frequencies) consists in that the values of very small inductors could be quite imprecise. If LC ladder network is high‐pass type, then parallel inductors must be removed. The resulting network will have only series capacitors, which can be combined as a single series capacitor. But if commensurate transmission lines separate the series capacitors, a high‐pass mixed element network is obtained. In this paper, a procedure is proposed to compute the values of series capacitors and characteristic impedances of the transmission lines in the mixed element ladder network. The usage of the procedure is explained by means of the given example.

Investigation of the Possibility of Applying a Genetic Algorithm for Electroacoustics Problems

This paper considers the adaptation and application of a genetic algorithm to find the parameters of the electrodynamic transducer model. The advantages and disadvantages of this method in comparison with the classical method of identification using added mass are considered. The derivation of the suitability function for estimating the identified parameters is presented, which can also be used to identify other types of electroacoustic transducers. The theory underlying genetic algorithms has been examined and shown how genetic algorithms work by assembling the best solutions from small structural elements with excellent qualities. Next, the differences between genetic and traditional algorithms were analyzed, including population population support and the use of genetic representation of solutions. After that, the strengths of genetic algorithms were described, including the possibility of global optimization and applicability to problems with complex mathematical representation or without representation at all, and noise resistance. Disadvantages were also highlighted: the need for special definitions and settings of hyperparameters, the danger of premature convergence. In conclusion, the situations when the use of genetic algorithms are listed This algorithm is not tied to a specific engineering or scientific field, which makes it universal, it is equally used in genetics and computer science. The parameters were determined using a genetic algorithm and compared with the more classical method of added mass for acoustics. The comparative table in the work illustrates the high accuracy of the genetic algorithm in comparison with the method of added mass. During the work on the practical part, also to improve the behavior of the model at frequencies higher than the resonant, it was decided to complicate the model of the electrical subsystem of the tranducer and introduce additional parameters: parallel resistance and parallel inductance. As a result, the complicated model began to correspond better to the measured values in the entire frequency domain, and is therefore more accurate. This is an example of the convenience of using a genetic algorithm in the transition from identification of one model with specific parameters to another. The results of this work prove that the use of a genetic algorithm is appropriate for solving electroacoustic problems because its application allows to quickly experiment and identify more complex models for which the added mass method can not be applied. Also, in the future, genetic algorithm can be used to identify transducer models of in time domain, for example, nonlinear models of electrodynamic transducers or models in a state space, which is the subject of future research.This paper considers the adaptation and application of a genetic algorithm to find the parameters of the electrodynamic transducer model. The advantages and disadvantages of this method in comparison with the classical method of identification using added mass and the method of parameter selection BL are considered. The derivation of the fitness function for assessing the quality of the identified parameters is presented, which can also be used to identify other types of electroacoustic transducers. The directly measured values ​​for the application of the algorithm are the voltage at the terminals of the converter, the current through the coil of the converter and the displacement of the moving part of the converter. The undoubted advantage of the genetic algorithm compared to classical identification methods is its versatility and the ability to quickly adapt and configure for research and experimentation with different models and different types of transducers used in acoustics. This article describes the adaptation and application of a genetic algorithm to find parameters of an electrodynamic transducer model. The advantages and disadvantages of this method in comparison with the classical identification method using added mass are considered. The derivation of the fitness function for assessing quality of the identified parameters is presented, which can also be used to identify other types of electroacoustic transducer models.

Design and analysis of a high-performance 90-101 GHz CMOS power amplifier

ABSTRACT A three-stage four–way 90–101 GHz power amplifier (PA) on 90 nm CMOS is reported. The PA consists of a meandrous four-way Wilkinson power divider, and common-source (CS) input and gain stages with inductive shunt-shunt feedback, followed by four-way CS output stage using a compact four-way current combiner. Wideband π-match inter-stage networks are used for broadband impedance and power matching. An LC input network (constituting a series capacitor, a parallel inductor, and an inductive shunt-shunt feedback) is used to convert the input impedance of the input-stage transistors to 50 Ω. This is the way to attain impedance matching at the outputs of the four-way Wilkinson power divider. Besides, an LC output network (constituting a series LC and a parallel inductor) is used to convert the 50 Ω load to the needed series RL load of the four-way current combiner. As a whole, the output-stage transistors operated at the maximal output power (Pout) and power-added efficiency (PAE). At 94 GHz, the PA attains gain of 20.1 dB, saturated Pout (Psat) of 17.5 dBm, and maximal PAE (PAEmax) of 17.7%, one of the best results ever reported for W-band CMOS PAs. The remarkable performance of the CMOS PA reveals its potential for 94 GHz radar systems.

Encapsulation of Recombinant MOMP in Extended-Releasing PLGA 85:15 Nanoparticles Confer Protective Immunity Against a Chlamydia muridarum Genital Challenge and Re-Challenge.

Recently we reported the immune-potentiating capacity of a Chlamydia nanovaccine (PLGA-rMOMP) comprising rMOMP (recombinant major outer membrane protein) encapsulated in extended-releasing PLGA [poly (D, L-lactide-co-glycolide) (85:15)] nanoparticles. Here we hypothesized that PLGA-rMOMP would bolster immune-effector mechanisms to confer protective efficacy in mice against a Chlamydia muridarum genital challenge and re-challenge. Female BALB/c mice received three immunizations, either subcutaneously (SC) or intranasally (IN), before receiving an intravaginal challenge with C. muridarum on day 49 and a re-challenge on day 170. Both the SC and IN immunization routes protected mice against genital challenge with enhanced protection after a re-challenge, especially in the SC mice. The nanovaccine induced robust antigen-specific Th1 (IFN-γ, IL-2) and IL-17 cytokines plus CD4+ proliferating T-cells and memory (CD44high CD62Lhigh) and effector (CD44high CD62Llow) phenotypes in immunized mice. Parallel induction of antigen-specific systemic and mucosal Th1 (IgG2a, IgG2b), Th2 (IgG1), and IgA antibodies were also noted. Importantly, immunized mice produced highly functional Th1 avidity and serum antibodies that neutralized C. muridarum infectivity of McCoy fibroblasts in-vitro that correlated with their respective protection levels. The SC, rather than the IN immunization route, triggered higher cellular and humoral immune effectors that improved mice protection against genital C. muridarum. We report for the first time that the extended-releasing PLGA 85:15 encapsulated rMOMP nanovaccine confers protective immunity in mice against genital Chlamydia and advances the potential towards acquiring a nano-based Chlamydia vaccine.

CD40 signaling augments IL-10 expression and the tolerogenicity of IL-10-induced regulatory dendritic cells.

CD40 expressed on stimulatory dendritic cells (DC) provides an important accessory signal for induction of effector T cell responses. It is also expressed at lower levels on regulatory DC (DCreg), but there is little evidence that CD40 signaling contributes to the tolerogenic activity of these cells. Indeed, CD40 silencing within DCreg has been reported to induce T cell tolerance in multiple disease models, suggesting that CD40 is superfluous to DC-induced tolerance. We critically assessed whether CD40 does have a role in tolerance induced by IL-10-differentiated DC (DC10) by using DC10 generating from the bone marrow of wild-type (w.t.) or CD40-/- donor mice, or IL-10-complemented CD40-/- DC10 to treat asthmatic mice. Wild-type DC10 ablated the OVA-asthma phenotype via induction of Foxp3+ Treg responses, but CD40-/- DC10 had no discernible effects on primary facets of the phenotype (e.g., IL-5, IL-9, IL-13 levels, IgE & IgG1 antibodies; p>0.05) and were ≤40% effective in reversal of others. Foxp3+ T cells from the lungs of CD40-/- DC10-treated mice expressed reduced levels of a panel of six Treg-specific activation markers relative to Treg from w.t. DC10-treated mice. Coculture with effector T cells from asthmatic mice induced a marked upregulation of cell surface CD40 on w.t. DC10. While untreated CD40-/- and w.t. DC10 secreted equally low levels of IL-10, stimulation of w.t. DC10 with anti-CD40 for 72 h increased their expression of IL-10 by ≈250%, with no parallel induction of IL-12. Complementing IL-10 expression in CD40-/- DC10 by IL-10 mRNA transfection fully restored the cells’ abilities to suppress the asthma phenotype. In summary, CD40 signaling in DC10 contributes importantly to their expression of IL-10 and to a robust induction of tolerance, including activation of induced Treg.

ІМІТАЦІЙНА МОДЕЛЬ ТА ДОСЛІДЖЕННЯ КВАЗІУСТАЛЕНИХ І ДИНАМІЧНИХ РЕЖИМІВ РОБОТИ АВТОНОМНОЇ ЕНЕРГОСИСТЕМИ ПОСТІЙНОГО СТРУМУ З ПАРАЛЕЛЬНО ПРАЦЮЮЧИМИ АСИНХРОННИМИ ГЕНЕРАТОРАМИ З ВЕНТИЛЬНИМ ЗБУДЖЕННЯМ

Purpose. The development of theory and research of autonomous DC power systems based on contactless electrical machines is an important element in ensuring the improvement of the reliability and energy efficiency of autonomous power supply of remote from centralized networks facilities, ship equipment, critical to power outages consumers. Originality. The use of induction generators with squirrel-cage rotor and an electronic converter in stator circuits in the design of autonomous DC power systems is advisable due to presence of a DC power output in these generators and the possibility of stabilizing the output voltage at variable speed. One of the scientific issues needed to be solved at creating induction generators-based DC power systems with inverter-assisted self-excitation of the generators is the determination of means and as well as development and verification of algorithms for regulating the generators load. Solving this issue requires the creation of appropriate simulation models. Methodology. In this work, a simulation dynamic model of an autonomous DC power system with two parallel operated induction generators with inverterassisted self-excitation and the six-step switching control algorithm has been developed. Results. A study of quasisteady-state and dynamic operating modes of the system was carried out. The duration of the initial excitation of the generators was determined for different values of the capacitance of the filter. Practical value. The results obtained showed the compliance of the parameters of electrical energy in the system with the standards established by the relevant regulatory documents and stable operation of the system with load changing from idle to rated. Further work is planned to focus on improving control algorithms for autonomous DC power systems with parallel operating induction generators and inverter-assisted self-excitation, studying the energy performance of such systems and developing recommendations for their design.

Developmental maturation of the colonic uptake process of the microbiota-generated thiamin pyrophosphate.

The water-soluble vitamin B1 is essential for normal human health and physiology. In its main biologically active form, i.e., thiamin pyrophosphate (TPP), the vitamin plays many critical roles in cell metabolism; thus, its deficiency leads to a variety of adverse effects. Humans/mammals obtain vitamin B1 from two exogenous sources: diet and gut microbiota. Considerable amount of the microbiota-generated vitamin B1 exists in the form of TPP, and colonocytes can efficiently absorb this TPP via a high-affinity and specific carrier-mediated mechanism that involves the recently cloned colonic TPP transporter (cTPPT; product of SLC44A4 gene). There is nothing currently known about colonic uptake of TPP during early stages of life and whether the process undergoes developmental regulation. We addressed this issue using the mouse as animal model. Our results showed that colonic uptake of TPP undergoes developmental upregulation as the animal moves from the suckling period to weanling and adulthood. This upregulation in uptake was found to be associated with a parallel induction in level of expression of the cTPPT protein, mRNA, and heterogeneous nuclear RNA, suggesting possible involvement of transcriptional mechanism(s). We also found a parallel upregulation in the level of expression of the two nuclear factors that drive activity of the SLC44A4 promoter (i.e., CREB-1 and Elf-3) with maturation. These results demonstrate, for the first time, to our knowledge, that colonic TPP uptake process and cTPPT expression are developmentally upregulated and that this upregulation is likely driven via transcriptional mechanism(s).NEW & NOTEWORTHY The colonic carrier-mediated uptake process of the microbiota-generated and phosphorylated form of vitamin B1, i.e., thiamin pyrophosphate, undergoes ontogenic changes that parallel the development of the gut microbiota (and their ability to generate vitamins) during early stages of life.

Simulation-based evaluation of operating room management policies

BackgroundSince operating rooms are a major bottleneck resource and an important revenue driver in hospitals, it is important to use these resources efficiently. Studies estimate that between 60 and 70% of hospital admissions are due to surgeries. Furthermore, staffing cannot be changed daily to respond to changing demands. The resulting high complexity in operating room management necessitates perpetual process evaluation and the use of decision support tools. In this study, we evaluate several management policies and their consequences for the operating theater of the University Hospital Augsburg.MethodsBased on a data set with 12,946 surgeries, we evaluate management policies such as parallel induction of anesthesia with varying levels of staff support, the use of a dedicated emergency room, extending operating room hours reserved as buffer capacity, and different elective patient sequencing policies. We develop a detailed simulation model that serves to capture the process flow in the entire operating theater: scheduling surgeries from a dynamically managed waiting list, handling various types of schedule disruptions, rescheduling and prioritizing postponed and deferred surgeries, and reallocating operating room capacity. The system performance is measured by indicators such as patient waiting time, idle time, staff overtime, and the number of deferred surgeries.ResultsWe identify significant trade-offs between expected waiting times for different patient urgency categories when operating rooms are opened longer to serve as end-of-day buffers. The introduction of parallel induction of anesthesia allows for additional patients to be scheduled and operated on during regular hours. However, this comes with a higher number of expected deferrals, which can be partially mitigated by employing additional anesthesia teams. Changes to the sequencing of elective patients according to their expected surgery duration cause expectable outcomes for a multitude of performance indicators.ConclusionsOur simulation-based approach allows operating theater managers to test a multitude of potential changes in operating room management without disrupting the ongoing workflow. The close collaboration between management and researchers in the design of the simulation framework and the data analysis has yielded immediate benefits for the scheduling policies and data collection efforts at our practice partner.

Ltspice Simulation of Non Linear Technique SSHI Serial and SSHI Parallel of Piezoelectric Vibration Energy Harvesting

in this paper, a simple but effective proposal for piezoelectric energy collectors. synchronized switching harvesting in the SSIH technique (synchronized switch harvesting on parallel inductor consists in placing a switch which will be commanded on closing at the instant when the amplitude of the vibrations passes through the extreme this technique makes it possible to increase the power harvested from a ratio of 8 compared to the power of a harvester based on ac dc converter similarly the SSIH command (synchronized switch harvesting on inductor for LT SPICEs-based simulations of the two techniques is carried out finally a comparison with respect to the standard structure of energy harvesting is made in order to validate theoretical concepts

Capacitance sensor for measuring void fraction in small channels

The paper presents a method for the measurement of void fraction in two-phase flow of liquid and gas phases in small channels by means of capacitance sensor. It was assumed arbitrarily that the small channels are those of diameter less than 10 mm. The capacitance sensor investigated in this paper consisted of two electrodes mounted on the outer wall of a glass pipe, and an electronic circuit for signal detection. The capacitance of two electrodes depends on the mean electric permittivity of the medium between them. The mean permittivity is a function of permittivity of the channel material and the percentage of both phases of different dielectric constants: liquid and gas. In this paper, the void fraction in two-phase flow was determined from frequency deviation of a high-frequency oscillator, in which the capacitance sensor was connected to a resonant circuit with an inductance in parallel. The advantage of this method over other methods based on the direct capacitance measurement (for example, LCR bridge) is that the intermediate steps for the determination of void fraction from the capacitance changes are omitted, and the void fraction can be directly determined from the calibration curve. Changes in the capacitance of electrodes for various void fractions have been determined numerically from the distribution of electric field in this geometry.

Design of Compact Reconfigurable Antenna Array for WLAN Applications

In this communication, a compact design of a reconfigurable antenna array operating in the band IEEE 802.11a is presented. The proposed antenna array contains four radiating elements excited by a hybrid parallel-series-feed network. The hybrid feed technique is used to avoid the main beam squint due to frequency changes compared to series and parallel array feed topologies. Each of the four radiating elements consists of straight narrow strip inductor in parallel with an interdigital capacitor. The antenna resonant frequency is electronically controlled by placing PIN diodes switches at the resonant element's inputs. The antenna permits reconfigurable switching frequency bands between 5.25 and 5.82 GHz. The results of the return loss and pattern radiation are shown. The size of the whole antenna structure is about 64 × 18 mm2 and can potentially be used in wireless systems.

A Novel Stress Reduction Technique Using Switched Capacitor with Coupled Inductor Based High Gain Converter for Electric Green Transport Scheme

This article develops a newly unique high gain step up DC / DC converter which is the future for interfacing to initiate rear bone of the fully green electric vehicle scheme. This technique optimally integrates four diodes, three capacitors and a modified coupled inductor connected to electric vehicle motor, which is three –phase Brushless DC motor. With this structure, reduced conduction losses, high conversion range and functionality with switched capacitor method and reduced voltage stress will occur during the switching period of the converter. Due to utilization of energy from leakage inductance, mutually joined inductor will support to kick efficiency and power concentration of the developed topology. Herein, the circuit configuration of DC/DC converter accommodating for electric green drive claims for even operation. A grouping of parallel inductor and diode L–D in series with the power switch is developed in this work . The converter suits extra beneficial conservative one by decreasing the switching stress current through the usage of new topology. The new topology results to increase the output voltage to 505V for an input DC voltage of 30V with voltage gain of 24.28, output power 525W achieving the efficiency of 97.74% by means of lossless power electronic semiconductor components. The stress voltage on switch, diode and capacitor is 170 V, which is 34 % of the converter output voltage. The designed converter is simulated using MATLAB/Simulink and the performance of the new topology is compared with different converter topologies. https://dorl.net/dor/20.1001.1.13090127.2021.11.2.8.7

Converter Compensation of Reactive Power Consumed by the Induction Generato

Purpose: The purpose of the article is to present a reactive power compensation for small hydropower plants with an induction generator. The classic compensation with capacitors is discussed and its improvement is proposed. Instead of capacitors, a three level power electronic converter connected in parallel to the induction generator can be used to provide reactive power compensation. The purpose of the paper is to present the developed structure of an active compensator and its control method. The developed control method was verified on a laboratory stand. The project and the methods: As part of research, an active compensator was built as a three-level power electronic converter in topology with Neutral Point Clamped. Laboratory tests of a converter compensator were carried out on a stand equipped with an induction generator with a power of 7.5 kW. Laboratory system measurements were made using a power analyzer and an oscilloscope. Results: A control structure of an active compensator based on a voltage-oriented method was presented and discussed. The operation of the con- verter compensator has been verified on a laboratory stand equipped with a 7.5 kW induction generator. The compensator current reduces the reactive (inductive) component of the current consumed from a power grid to a value equal to zero. The reactive power compensator ensures that the tgφ power factor is maintained at a set value of zero, which corresponds to the total compensation of inductive reactive power consumed by an induction generator working in a hydropower plant. Operation of the active compensator did not cause a significant increase in the harmonic content in the current consumed from the power grid. Conclusions: The paper presents the issues regarding reactive power compensation in hydropower plants with induction generators. Commonly used capacitor compensation has been covered and as a result, it is proposed to replace it with power electronics converter compensation of reactive power connected in parallel induction generators. Active compensator provides compensation for the entire reactive power consumed by the induction generator. The use of the converter compensator of reactive power significantly contributes to the reduction of costs for reactive power incurred by the owners of hydropower plants. The reactive power compensator also has a positive impact on the operation of the entire power grid, power losses from the reactive component of the current on the impedances of power grid components are limited. Keywords: renewable source of electricity, reactive power, active compensator, induction generator Type of article: original scientific article

Characterization of the 5′-flanking region of the human and mouse CHAC1 genes

The Unfolded Protein Response pathway is a conserved signaling mechanism having important roles in cellular physiology and is perturbed accompanying disease. We previously identified the novel UPR target gene CHAC1, a direct target of ATF4, downstream of PERK-EIF2A and activated by the UPR pathway. CHAC1 enzyme directs catalysis of γ-linked glutamate bonds within specific molecular targets. CHAC1 is the first enzyme characterized that can catalyze intracellular glutathione degradation in eukaryotes, having implications for regulation of oxidative stress. DDIT3 (CHOP) is a terminal UPR transcription factor, regulated by ATF4 and an output promoting cell death signaling. Herein we examine the relationship of CHOP controlling CHAC1 transcription in humans and mice. We note parallel induction of CHOP and CHAC1 in human cells after agonist induced UPR. Expanding upon previous reports, we define transcriptional induction of CHAC1 in humans and mice driven by ATF4 through a synergistic relationship with conserved ATF/CRE and CARE DNA sequences of the CHAC1 promoter. Using this system, we also tested effects of CHOP on CHAC1 transcription, and binding at the CHAC1 ATF/CRE using IM-EMSA. These data indicate a novel inhibitory effect of CHOP on CHAC1 transcription, which was ablated in the absence of the ATF/CRE control element. While direct binding of ATF4 to CHAC1 promoter sequences was confirmed, binding of CHOP to the CHAC1 ATF/CRE was not evident at baseline or after UPR induction. These data reveal CHAC1 as a novel CHOP inhibited target gene, acting through an upstream ATF/CRE motif via an indirect mechanism.

Considerations for Harmonics Distribution in Aperture-Tuned Inverted-F Antenna for Cellular Handheld Devices

An analysis of the harmonics distribution in the aperture-tuned inverted-F antenna (IFA) using the first-order transmission line model is presented. The analysis allows identifying local minimums for the second and third harmonics for a given use case, providing the mechanism for optimization of the nonlinear performance of an antenna system. The theoretical findings are verified on a hardware demonstrator, comprising a mechanically reconfigurable IFA and a single-pole single-throw (SPST)-based aperture tuning network. The aperture tuning network comprises a radio frequency (RF) high-voltage switch, including a voltage detector with low-harmonic feedback and a parallel inductor. The integrated circuit (IC) was fabricated in Infineon 130-nm dedicated RF switch technology. The hardware demonstrator enables the measurements of the impedance at the feed, harmonics, RF voltage along the radiating element, and impedance at aperture tuning port. The latter provides a mechanism for optimization of load impedance at integer multiplies of transmitted frequencies, which allows minimization of harmonic content generated by the tuning IC.

COVID19 Infection and Vascular Rearrangement/ Controlled Angiogenesis - A New Supportive Therapeutic Approach in Patients with Pre-existing Ischemic and High-Shear Vascular Conditions

This is an indicative mini-review on possible new therapeutics for COVID-19 with preexisting ischemic morbidities. The review highlights a new supportive therapeutic approach where lysine-induced controlled vascular organization (angiogenesis) has been demonstrated in reversal of cerebrovascular ischemic stroke which appears to be one of the few final fatal clinical outcomes of current COVID-19 infections. Further, a parallel supportive time-bound induction of fresh exchange beds, by way of rapid collateral formation, is proposed in all comorbid ischemic patients with the low-molecular-weight angiogen(s), with an objective of mitigation of tissue/organ ischemia.

A nondestructive testing method for soluble solid content in Korla fragrant pears based on electrical properties and artificial neural network.

The detection of soluble solid content in Korla fragrant pear is a destructive and time‐consuming endeavor. In effort to remedy this, a nondestructive testing method based on electrical properties and artificial neural network was established in this study. Specifically, variations of electrical properties (e.g., equivalent parallel capacitance, quality factor, loss factor, equivalent parallel resistance, complex impedance, and equivalent parallel inductance) of Korla fragrant pears with accumulated temperature were tested using a workbench developed by ourselves. After that the characteristic variables of electrical properties were constructed by principal component analysis (PCA). In addition, three models were constructed to predict SSC in Korla fragrant pears based on the characteristic variables: general regression neural network (GRNN), back‐propagation neural network (BPNN), and adaptive network fuzzy inference system (ANFIS). The results indicated that the GRNN model has the best prediction effects of SSC (R 2 = 0.9743, RMSE = 0.2584), superior to that of the BPNN and ANFIS models. Results facilitate a successful, alternative application for rapid assessment of SSC of the maturation stage Korla fragrant pear.

Detection of oxygen starvation during carbon corrosion in proton exchange membrane fuel cells using low-frequency electrochemical impedance spectroscopy

Proton exchange membrane fuel cells (PEMFCs) are considered a significant player in the hydrogen economy. However, before mass production is possible, significant improvements in durability are necessary. Monitoring the changes in the electrode structure is challenging without a complex measurement apparatus. Precisely, the changes in electrode properties during carbon corrosion (increase in the porosity and electrode collapse) cannot be quantified using conventional electrochemical methods. Here, we report capturing the oxygen diffusivity in the PEMFC cathode catalyst layer using low-frequency electrochemical impedance spectroscopy (0.3-0.01 Hz). The low-frequency arc is fitted with resistance, inductance, and capacitance in parallel to represent the resistance to oxygen supply, inertia to oxygen diffusion, and oxygen storage capacity in the catalyst layer, respectively. Over 600 cycles of accelerated stress test (ASTs) of carbon corrosion, the capacitance increases by 25–45% (0–150 ASTs), indicating an increase in oxygen storage capacity and electrode porosity. Then, (150–600 ASTs) the resistance and inductance increase while the capacitance decreases by 80%, highlighting a decrease of the oxygen diffusivity and storage in the catalyst layer as the electrode collapses, which causes oxygen starvation. Altogether, this low-frequency approach correlates electrochemical impedance measurements with the changes in electrode structure during carbon corrosion.

Double‐layer metasurface‐based low profile broadband X‐band microstrip antenna

In this paper, a novel technology based on double-layer metasurfaces is proposed in order to broaden the bandwidth of microstrip antennas, which has been verified in X-band linearly polarised and circularly polarised antennas. Referring to the conventional metasurface antenna that employs slot-coupled feeding, these designs add an extra metasurface between the radiation patch and the ground plane so as to establish dual resonance modes, TM10 and TM20. Following the adoption of the composite right/left-handed transmission lines principle, this technique aims to adjust the propagation constant in the right-hand region by introducing parallel inductors and capacitors to widen the dual resonant frequencies' interval, thereby realising a broadband antenna. In addition, the interlayer metasurface may also be utilised as a director to balance the E-field of the radiation patch. A linearly polarised double-layer metasurface antenna with a size of 0.8 0.8 0.058 (wavelength in free space at the centre frequency) is filled with F4B substrate with a dielectric constant of 2.2. It finally realises an impedance matching bandwidth (VSWR 2) from 8.41 to 11.67 GHz, occupying about 32.47 of the centre frequency. This circularly polarised antenna attains both an impedance matching bandwidth of 32.44 (i.e. 8.29–11.5 GHz) and an axial-ratio bandwidth of 19.72 (i.e. 9.6–11.7 GHz).

A novel simple chaotic circuit based on memristor–memcapacitor

In this paper, we focus on a novel simple chaotic circuit with a memristor, a memcapacitor and a linear inductor in parallel. Then we establish the circuit’s dimensionless mathematical model. Nineteen types of different chaotic attractors are found in the circuit. The chaotic system’s equilibrium point and stability are analyzed by using the traditional dynamic analysis methods, and the dynamical behaviors with three varying parameters of this circuit are analyzed in detail. Furthermore, some special phenomena such as state transition, chaos degradation and the multiple coexisting attractors are discovered. Finally, we implement this circuit through the DSP platform and the results illustrate the validity of the theoretical analysis. Theoretical analysis and simulation results indicate that the simple chaotic circuit has very rich dynamical characteristics.