Low-pass Filter Function Research Articles

Output-mask-based adaptive NN control for stochastic time-delayed multi-agent systems with a unified event-triggered approach

This paper investigates a class of output-mask-based adaptive neural network (NN) tracking control for nonlinear stochastic time-delayed multi-agent systems (STMASs) based on a unified event-triggered approach. The output signal relies on an output mapping acted as a mask, defined as a privacy-protection-like method, so that the internal state of one agent cannot be identified by other distrustful eavesdroppers or attackers. Moreover, the construction of a unified event-triggered control scheme retains the advantages of the saturation threshold triggering strategy, incorporates distributed errors, and increases the flexibility of thresholds. Furthermore, for stochastic time-delay multi-agent systems, the initial value limitation of the conventional first-order filter is removed by a first-order Levant differentiator, and a new estimation term in the fuzzy observer is established to solve the nonlinear fault. The unknown function in pure-feedback form is addressed via combining Butterworth low-pass filter and radial basis function neural networks (RBF NNs). Finally, the boundedness of all signals in the closed-loop systems is demonstrated, and the effectiveness of the proposed algorithm is verified by some simulation results.

Power-to-Frequency Conversion in Cryogenic Sapphire Resonators

We studied how the cryogenic sapphire resonator responds to fast variations in the dissipated microwave power. The experiments were carried out with sapphire resonators cooled to 6 K at frequencies around 11 GHz. We found that the power-to-frequency conversion of the resonator depends on Fourier frequency as the transfer function of the first-order low-pass filter with corner frequency close to the resonator’s loaded half-bandwidth. Having measured the power-to-frequency conversion of the cryogenic sapphire resonator, we predicted the phase noise of the microwave oscillator based on such a resonator.

Improved Electronically-Tunable Current-Mode Square-Root-Domain First-Order Multifunction Filter

Some time back, Kircay reported an electronically-tunable current-mode square-root-domain first-order filter capable of realizing low-pass (LP), high-pass (HP) and all-pass (AP) filter functions. When simulated in SPICE, Kircay’s circuit has been found to exhibit DC offsets in case of LP and AP responses and incorrect transient response in case of HP response. In this paper, an improved circuit overcoming these difficulties/deficiencies has been suggested and its workability of the improved circuit as well as its capability in meeting the intended objectives has been demonstrated by SPICE simulation results.

Tuning the synaptic behaviors of biocompatible synaptic transistor through ion-doping

Biodegradable and environmentally friendly artificial synapse devices are essential for the future development of neuromorphic computing. The emergence of synaptic transistors based on biocompatible polymer materials provides an ideal approach to achieve green electronics. However, modulating the synaptic properties in a wide range in a fixed biocompatible synaptic transistor is still challengeable, while it is vitally important for improving the adaptability of the synaptic device to achieve neuro-prosthetics in the future. Here, we reported the regulation of the synaptic behavior of biocompatible synaptic transistor through ion-doping, which allows to adjusting the response of the synaptic device according to a specific function. The ions doped into the insulating layer strengthen the formation of electric double layers (EDLs), which enables a remarkable regulation effect on post-synaptic current. Moreover, basic synaptic properties, including excitatory/inhibitory post-synaptic current (EPCS/IPSC), paired-pulse facilitation/depression (PPF/PPD), short-term/long-term memory (STM/LTM) are successfully demonstrated. In addition, high-pass and low-pass filtering functions are also implemented in a single synaptic device, indicating that the synapse attenuation can be effectively transformed according to the needs of the function. More importantly, this is the first work to demonstrate that the accuracy of pattern recognition of synaptic transistors, an important indicator of neuromorphic calculations, can be significantly improved via ion doping (as high as 75.96% relative to undoped devices of 41.68%). Our research provides a feasible strategy for precisely controlling synaptic behaviors, which has a profound impact on improving the adaptability of artificial synaptic devices in the field of neuromorphic computing. • A biocompatible synaptic transistor with tunable synaptic properties base on ion-doped polymer electrolyte material. • Basic synaptic behaviors are demonstrated, such as PPF/D, and STM to LTM. • First work to show the accuracy of pattern recognition of synaptic transistors can be improved via ion-doping.

A new MOS-C multifunction filter and its third order oscillator application

This paper introduces a novel multifunction filter employing single current operational amplifier (COA) with MOS-C implementation and a third order sinusoidal oscillator as its application. The proposed topology provides voltage-mode high-pass, low-pass, all-pass, band-pass and band-stop filter functions by modifying four passive components. The workability of the circuit is confirmed by PSPICE simulation software using MOSIS 0.18 μm CMOS model parameters and a good consistency observed between theoretical analysis and simulation results. The circuit is supplied by symmetrical voltage of ±0.9 V. Considering the number of input and output terminals, the proposed circuit can be classified as single input single output (SISO) filter. An experimental study using commercially available 844 CE as sub-circuit of COA which verify the workability of the proposed topology is also included. Electronic tunability of the central frequency, MOS-C implementation which is a requirement for integration, simple circuitry, low distortion and operability at low voltage are the considerable features of the introduced circuit.

Design of an Isolated Bidirectional DC–DC Converter With Built-in Filters for High Power Density

This article aims to realize an isolated dc-dc converter with high power density, high power efficiency, and low noise performance. Although a dual-active-half-bridge (DAHB) converter can achieve high efficiency, it requires input and output low-pass filters to suppress the operational ripple current and switching noise. Owing to the volume of the filters, a DAHB converter cannot be implemented with high power density. This article presents a design theory for a novel isolated bidirectional dc-dc converter with built-in filters. The proposed converter is derived from a DAHB converter and can eliminate the input and output filters via split windings and tank capacitors; the principle of elimination is based on LC low-pass filter function and zero-ripple-current operation. As the number of transistors, capacitors, and magnetic cores of the proposed converter are equal to those of the DAHB converter, the application of the proposed converter allows volume reduction by eliminating the filter components at the input and output ports. Theoretical equations are derived to design a power flow control function and a filter function simultaneously. Finally, prototypes of a DAHB converter and the proposed converter are constructed for comparison. The results demonstrate that the input port noise of the proposed prototype is lower than that of the DAHB prototype by 10 dB (peak) over 1 MHz, and the proposed approach can achieve a significant improvement in efficiency.

Unitary Representations of the Baumslag–Solitar Group on the Cantor Set

The Cantor Set supports a Borel probability measure known as the Hutchinson measure which satisfies a well known fixed point relationship (Hutchinson in Indiana University Math J 30(5):713–747, 1981). Previously it has been shown by Jorgensen and Dutkay that the Cantor set can be extended to an inflated Cantor set, $${\mathcal {R}}$$, on a subset of the real line, which supports an extended Hutchinson measure $${\bar{\mu }}$$ (Dutkay and Jorgensen in Rev. Mat. Iberoamericana 22(1):131–180, 2006). Unitary dilation and translation operators can be defined on $$L^2({\mathcal {R}}, {\bar{\mu }})$$ which satisfy the Baumslag–Solitar group relation, and give rise to a filtration of the Hilbert space $$L^2({\mathcal {R}}, {\bar{\mu }})$$ called a multi-resolution analysis (Dutkay and Jorgensen 2006). The low pass filter function corresponding to this construction can be used to produce a measure, m, on a compact topological group called the 3-solenoid, denoted $${\mathcal {S}}_3$$ (Dutkay in Trans Am Math Soc 358(12):5271–5291, 2006). The Hilbert space $$L^2({\mathcal {S}}_3, m)$$ also admits a unitary representation of the Baumslag–Solitar group, and there exists a generalized Fourier transform between $$L^2({\mathcal {R}}, {\bar{\mu }})$$ and $$L^2({\mathcal {S}}_3,m)$$ (Dutkay 2006). In this paper, we build off of Jorgensen and Dutkay’s work to show that the unitary operators on $$L^2({\mathcal {S}}_3,m)$$ mentioned above are related to each other via a family of partial isometries, which satisfy properties resembling the Cuntz relations.

CSI-HC: A WiFi-Based Indoor Complex Human Motion Recognition Method

WiFi indoor personnel behavior recognition has become the core technology of wireless network perception. However, the existing human behavior recognition methods have great challenges in terms of detection accuracy, intrusion, and complexity of operations. In this paper, we firstly analyze and summarize the existing human motion recognition schemes, and due to the existence of the problems in them, we propose a noninvasive, highly robust complex human motion recognition scheme based on Channel State Information (CSI), that is, CSI-HC, and the traditional Chinese martial art XingYiQuan is verified as a complex motion background. CSI-HC is divided into two phases: offline and online. In the offline phase, the human motion data are collected on the commercial Atheros NIC and a powerful denoising method is constructed by using the Butterworth low-pass filter and wavelet function to filter the outliers in the motion data. Then, through Restricted Boltzmann Machine (RBM) training and classification, we establish offline fingerprint information. In the online phase, SoftMax regression is used to correct the RBM classification to process the motion data collected in real time and the processed real-time data are matched with the offline fingerprint information. On this basis, the recognition of a complex human motion is realized. Finally, through repeated experiments in three classical indoor scenes, the parameter setting and user diversity affecting the accuracy of motion recognition are analyzed and the robustness of CSI-HC is detected. In addition, the performance of the proposed method is compared with that of the existing motion recognition methods. The experimental results show that the average motion recognition rate of CSI-HC in three classic indoor scenes reaches 85.4%, in terms of motion complexity and indoor recognition accuracy. Compared with other algorithms, it has higher stability and robustness.

Bandwidth-Limited and Noisy Pulse Sequences for Single Qubit Operations in Semiconductor Spin Qubits

Spin qubits are very valuable and scalable candidates in the area of quantum computation and simulation applications. In the last decades, they have been deeply investigated from a theoretical point of view and realized on the scale of few devices in the laboratories. In semiconductors, spin qubits can be built confining the spin of electrons in electrostatically defined quantum dots. Through this approach, it is possible to create different implementations: single electron spin qubit, singlet–triplet spin qubit, or a three-electron architecture, e.g., the hybrid qubit. For each qubit type, we study the single qubit rotations along the principal axis of Bloch sphere including the mandatory non-idealities of the control signals that realize the gate operations. The realistic transient of the control signal pulses are obtained by adopting an appropriate low-pass filter function. In addition. the effect of disturbances on the input signals is taken into account by using a Gaussian noise model.

Detection of Mo geochemical anomaly in depth using a new scenario based on spectrum–area fractal analysis

Detection of deep and hidden mineralization using the surface geochemical data is a challenging subject in the mineral exploration. In this work, a novel scenario based on the spectrum–area fractal analysis (SAFA) and the principal component analysis (PCA) has been applied to distinguish and delineate the blind and deep Mo anomaly in the Dalli Cu–Au porphyry mineralization area. The Dalli mineral deposit is located on the volcanic–plutonic belt of Sahand–Bazman in the central part of Iran. The geochemical data was transformed to the frequency domain using the Fourier transformation, and SAFA was applied for classification of geochemical frequencies and detection of geochemical populations. The very low-frequency signals in the fractal method were separated using the low-pass filter function and were interpreted using PCA. This scenario demonstrates that the Mo element has an important role in the mineralization phase in the very low-frequency signals that are related to the deep mineralization; it is an important innovation in this work. Then the Mo geochemical anomaly has been mapped using the inverse Fourier transformation. This research work shows that the high-power spectrum values in SAFA are related to the background elements and the deep mineralization. Two exploratory boreholes drilled inside and outside the deep Mo anomaly area properly confirm the results of the proposed approach.

Voltage Differencing Transconductance Amplifier-Based Quadrature Oscillator and Biquadratic Filter Realization with All Grounded Passive Elements

The work realizes the sinusoidal quadrature oscillator and biquadratic filter with the same configuration using merely two voltage differencing transconductance amplifiers (VDTAs) as active devices and one grounded resistor and two grounded capacitor as passive elements. Performing the quadrature oscillator, the realized circuit is capable of producing two quadrature voltage outputs with almost equal amplitudes, and an independent electronic control of oscillation condition and oscillation frequency. Operating in voltage-mode biquadratic filter, the circuit can simultaneously generate the bandpass and lowpass filtering functions without any matching constraints. The natural angular frequency and the quality factor of the filter are independently and electronically adjustable. The effects of the VDTA non-idealities are also investigated in detail. Simulation results with TSMC 0.25 μm CMOS technology validate both working functions of the proposed circuit.

CFD–CHT calculation method using Buckingham Pi-Theorem for complex fluid–solid heat transfer problems with scattering boundary conditions

A three-dimensional CFD–CHT simulation method is presented and validated with a turbocharged single cylinder SI engine. Various ignition time and lambda strategies as well as variations of boost pressure are investigated with regard to cycle averaged component temperatures. This complements existing published works which experimentally studied crank angle resolved heat fluxes or temperature swings rather than averaged temperatures. Cyclical fluctuations in the pressure curves were measured and processed statistically using probability density functions for the heat transfer coefficient and the cylinder gas temperature. The corresponding joint probability density function considers their strong correlation. The interpretation as random variables enables a time-scale separation with a low-pass filter function. The thermomechanical problem of heat transfer is addressed with simplified models according to Woschni, Eichelberg, and Hohenberg. Previous investigations primarily focused on their predictive quality of instantaneous in-cylinder heat fluxes. In this paper, their effect on cycle averaged component temperatures is investigated and the corresponding different sensitivities to specific engine settings are presented and compared with measurements. It is shown that, by choosing the right model, the suggested simulation approach is an alternative to prevailing experimental methods in temperature analysis: all thermodynamic variations examined are in good agreement with theoretical predictions.

Sliding-Mode Observer-Based Mechanical Parameter Estimation for Permanent Magnet Synchronous Motor

A mechanical parameter estimation algorithm for permanent magnet synchronous motor (PMSM) drive systems based on sliding-mode observer is proposed in this paper. First, an extended sliding-mode mechanical parameter observer (ESMMPO) is presented to track system disturbances in real time, which include the information of mechanical parameters. Based on this ESMMPO, the mechanical parameter can be extracted from the estimated system disturbance. Therefore, a simple algorithm for mechanical parameter estimation of the PMSM control system is presented. The parameter choice guidelines of ESMMPO are designed to guarantee the global stability of the observer. Then, the equivalent low-pass filter function of the ESMMPO is presented to suppress the sliding-mode chattering, which allows softening the output signal of observer while maintaining no phase lag incurring. Therefore, the smooth output of the ESMMPO can be directly used for the parameter estimation. Experimental results show the validity of the proposed parameter estimation approach.

Single VDTA Based Dual Mode Single Input Multioutput Biquad Filter

This paper presents a dual mode, single input multioutput (SIMO) biquad filter configuration using single voltage differencing transconductance amplifier (VDTA), three capacitors, and a grounded resistor. The proposed topology can be used to synthesize low pass (LP), high pass (HP), and band pass (BP) filter functions. It can be configured as voltage mode (VM) or current mode (CM) structure with appropriate input excitation choice. The angular frequency (ω0) of the proposed structure can be controlled independently of quality factor (Q0). Workability of the proposed biquad configuration is demonstrated through PSPICE simulations using 0.18 μm TSMC CMOS process parameters.

Research on Improved Control Strategy for STATCOM Based on Virtual Matrix Method

Fast and accurate detection of reactive current is the precondition for the realization of static synchronous compensator (STATCOM) reactive power compensation and harmonic suppression. Aiming at deviation and delay of the traditional reactive current detection algorithm with phase-locked loop (PLL) and low-pass filter (LPF) of STATCOM, a novel improved reactive current detection algorithm without PLL is proposed, in which the virtual matrix (VM) is built to replace the original PLL, and improved current average value filter is used to realize the function of LPF, so as to improve the real-time performance and robustness of reactive current detection. The realization process of VM detection method is derived in this paper, and improved control strategy for STATCOM is designed based on the VM detection method. Simulation analysis of the proposed detection algorithm and control strategy is conducted in Matlab platform so as to verify the correctness and effectiveness of the control strategy. The VM detection has the advantages of simple structure, fast response and easy for digital realization, which provides reference for the improvement of reactive power compensation precision for STATCOM.

A New Class of Low Complexity Low-Pass Multiplierless Linear-Phase Special CIC FIR Filters

This letter presents a new class of selective low-pass multiplierless linear-phase special CIC FIR filter functions of low complexity given in an explicit cascaded compact form. Several examples of the proposed filters are illustrated. They are compared in a fair way with conventional CIC FIR filters for the equal values of group delay and the same number of cascade sections. An example of the new class of the proposed seventh order filter with nine cascades is presented, where its stopband attenuation has high value of 143.82 dB, while corresponding conventional CIC FIR filter with the same filter order and the number of cascades has only 115.18 dB.

Transadmittance Type Universal Current-Mode Biquad Filter Using VDTAs.

A new resistorless single-input-multi-output (SIMO) universal transadmittance (TA) type filter employing two voltage differencing transconductance amplifiers (VDTA) and two grounded capacitors is proposed. The proposed topology realizes simultaneously low pass (LP), high pass (HP), and band pass (BP) filter functions. Band rejects (BR) and all pass (AP) filters are also realizable through appropriate connections of currents. The proposed configuration also offers independent control of natural angular frequency (ω 0) and bandwidth (BW) and low active and passive sensitivities. The workability of proposed configuration has been demonstrated through PSPICE simulations with TSMC CMOS 0.18 μm process parameters.

A low power current controllable single-input three-output current-mode filter using MOS transistors only

A novel circuit configuration for the realization of low power single-input three-output (SITO) current mode (CM) filters employing only MOS transistors are presented. The proposed circuit can realize low-pass (LP), band-pass (BP) and high-pass (HP) filter functions simultaneously at three high impedance outputs without changing configuration. Despite the other previously reported works, the proposed circuit is free from resistors and passive capacitors. Instead of passive capacitors; the gate-source capacitor of MOS transistor is used making the proposed circuit ideally suitable for integration. Compared to other works, the proposed filter has also the lowest number of transistors and lowest power consumption. The proposed circuit exhibits low-input and high-output impedances, which is highly desirable for cascading in CM signal processing. Moreover, it is center frequency can be electronically adjusted using a control current without a significant effect on quality factor (Q) granting it the highly desirable capability of electronic tunability. Transfer functions of the LP, BP and HP outputs are derived and the performance of the proposed circuit is proved through pre layout and post layout simulations at supply voltage of 1.8V and using 0.18μm CMOS process parameters. The power consumption and the required chip area are only 0.5mW and 77.4μm×70.2μm, respectively.

Transitional Selective Linear Phase 1D FIR Filter Function Generated by Christoffel-Darboux Formula for Chebyshev Polynomials

In this paper we propose a new economical selective low-pass finite impulse response filter function. First, we describe the two types of already developed filters, and then we obtain three new different types of filters, by combining the previous ones. Also, the general form of the proposed filter is given. In order to verify the effectiveness of the proposed filter function, the cut-off frequencies of the stop-band and pass-band of the filter, for equal constant group delay, are analysed and compared with classical first and second type of filters. It is shown that proposed filter is efficient related to high selectivity and high values of attenuation in the stop-band of the filter. DOI: http://dx.doi.org/10.5755/j01.eee.20.4.2783

Phase Locked Loop based on adaptive observer

A phase Locked Loop is a control system that generates an alternating signal with a bounded phase respect to an input signal, a feedback loop makes a comparison between these two signals and modifies its output signal frequency. This paper presents a PLL scheme which is aimed to estimate the angular frequency of the input voltage as well as a low pass filter function for cleaning this distorted signal. A prototype based on operational amplifiers has been built and simulations and experimental results are presented to prove its performance