Need For Additional Filters Research Articles

Single‐stage ZVS boost integrated push–pull power factor correction converter

AbstractThis study proposes a cutting‐edge AC/DC converter designed for medium‐power PFC applications. The converter is a single‐phase, single‐stage boost‐push–pull model. It consists of three key components: an interleaved boost, a push–pull, and a resonant tank circuit. The interleaved boost operates in DCM mode and serves as power factor correction. The push–pull converter includes a resonant tank on the secondary side of the transformer to achieve ZVS. The two switches control the boost and the push–pull circuits to create a single‐stage converter. The converter in question provides an array of advantages, such as zero voltage switching (ZVS), an intermediate bus voltage that is independent of the load, and a low‐ripple input current, all of which can be achieved without the need for additional filtering. The present article provides a comprehensive overview of the design procedure, simulation and experimental results, and separate operating modes analysis. To verify the design and simulation results, a 200‐W interleaved boost push–pull converter (IBPPC) prototype is implemented. Finally, because it is crucial to maintain the voltage of the bus capacitor within an acceptable range, this study investigated the impact of load variation on the bus voltage.

Inviscid water-waves and interface modeling

We present a rigorous mathematical analysis of the modeling of inviscid water waves. The free-surface is described as a parametrized curve. We introduce a numerically stable algorithm which accounts for its evolution with time. The method is shown to converge using approximate solutions, such as Stokes waves and Green-Naghdi solitary waves. It is finally tested on a wave breaking problem, for which an odd-even coupling suffices to achieve numerical convergence up to the splash without the need for additional filtering.

Parametric generative schemes with geometric constraints for encoding and synthesizing airfoils

The modern aerodynamic optimization has a strong demand for parametric methods with high levels of intuitiveness, flexibility, and representative accuracy, which cannot be fully achieved through traditional airfoil parametric techniques. In this paper, two deep learning-based generative schemes are proposed to effectively capture the complexity of the design space while satisfying specific constraints. 1. Soft-constrained scheme: a Conditional Variational Autoencoder-based model that directly incorporates geometric constraints as part of the network. 2. Hard-constrained scheme: a Variational Autoencoder-based model for generating diverse airfoils, with projection onto given constraints using Free Form Deformation-based techniques. According to the statistical results, the reconstructed airfoils are both accurate and smooth, without any need for additional filters. The soft-constrained scheme generates airfoils that exhibit slight deviations from the expected geometric constraints, yet still converge to the reference airfoil in both geometry space and objective space with some degree of distribution bias. In contrast, the hard-constrained scheme produces airfoils with a wider range of geometric diversity while strictly adhering to the geometric constraints. The corresponding distribution in the objective space is also more diverse, with isotropic uniformity around the reference point and no significant bias. These proposed airfoil parametric methods can break through the boundaries of training data in the objective space, providing higher quality samples for random sampling and improving the efficiency of optimization design.

Duplex Phenotype Detection and Targeting of Breast Cancer Cells Using Nanotube Nanoprobes and Raman Imaging.

We designed, synthesized, and characterized a Raman nanoprobe made of dye-sensitized single-walled carbon nanotubes (SWCNTs) that can selectively target biomarkers of breast cancer cells. The nanoprobe is composed of Raman-active dyes encapsulated inside a SWCNT, whose surface is covalently grafted with poly(ethylene glycol) (PEG) at a density of ∼0.7% per carbon. Using α-sexithiophene- and β-carotene-derived nanoprobes covalently bound to an antibody, either anti-E-cadherin (E-cad) or anti-keratin-19 (KRT19), we prepared two distinct nanoprobes that specifically recognize biomarkers on breast cancer cells. Immunogold experiments and transmission electron microscopy (TEM) images are first used to guide the synthesis protocol for higher PEG-antibody attachment and biomolecule loading capacity. The duplex of nanoprobes was then applied to target E-cad and KRT19 biomarkers in T47D and MDA-MB-231 breast cancer cell lines. Hyperspectral imaging of specific Raman bands allows for simultaneous detection of this nanoprobe duplex on target cells without the need for additional filters or subsequent incubation steps. Our results confirm the high reproducibility of the nanoprobe design for duplex detection and highlight the potential of Raman imaging for advanced biomedical applications in oncology.

Tunable Multiband Halide Perovskite Tandem Photodetectors with Switchable Response.

Photodetectors with multiple spectral response bands have shown promise to improve imaging and communications through the switchable detection of different photon energies. However, demonstrations to date have been limited to only two bands and lack capability for fast switching in situ. Here, we exploit the band gap tunability and capability of all-perovskite tandem solar cells to demonstrate a new device concept realizing four spectral bands of response from a single multijunction device, with fast, optically controlled switching between the bands. The response to monochromatic light is highly selective and narrowband without the need for additional filters and switches to broader response bands on applying bias light. Sensitive photodetection above 6 × 1011 Jones is demonstrated in all modes, with rapid switching response times of <250 ns. We demonstrate proof of principle on how the manipulation of the modular multiband detector response through light conditions enables diverse applications in optical communications with secure encryption.

High-Efficiency Coupled-Inductor Switched-Capacitor Boost Converter With Improved Input Current Ripple

A novel single-switch coupled-inductor switched-capacitor (CISC) high step-up converter is proposed which has a boost-type input structure allowing an improved input current ripple compared to other leading CISC converters. This is important for sustainable energy applications, such as photovoltaic (PV) cells and fuel cells where high current ripple can degrade performance or lifetime. Though large input filters can be added between the energy source and the boost converter to smooth a pulsed converter input current, the proposed converter naturally has a more moderate current ripple, reducing the need for additional filtering. With regards to the coupled inductor, the leakage inductor energy is recycled without using an extra clamped circuit, and core utilization is high. The detailed theoretical operation is presented and an experimental prototype (200 W, 36 V to 48 input, 400 V output) achieves a maximum efficiency of 97.1%.

Sinusoidal pulse width modulation for a photovoltaic-based single-stage inverter

The work proposed in this paper focuses on providing an effective solution to the shortage of power in rural areas with an effective technique implemented in an economically feasible way. The traditional inverters used for either residential or commercial purposes consume electrical energy from the grid to fulfill the charging and discharging of the battery, which may lead to overloading. The shortcomings of the traditional inverters such as the nonrenewable nature of power sources increased cost of manufacturing, and multistage conversion complexity is considered by the researchers for improvement. As a result, an attempt has been made to provide a cost-effective renewable energy system with a single-stage topology for ac power applications. Single-stage power conversion with an allowed shoot through the state is used here to avoid additional components and reduce the switching losses. Unlike the traditional inverters, the quasi-impedance source inverter (QZSI) that is brought forward can be utilized as a standalone system or a capable backup at the time of power outages. Sinusoidal pulse width modulation (SPWM) is applied to attain reduced harmonics which are measured by observing the harmonic pattern in the total harmonic distortion (THD) curve. The lab results obtained through MATLAB simulation confirm the noteworthy diminution of the THD level in the proposed system compared to the reported one. Usage of photovoltaic (PV) panels to tap energy with reduced stochastic fluctuations due to the high filtering capacity of the proposed circuit, eliminating the need for additional filters, is the uniqueness of this technique.

In-Fiber Mach–Zehnder Interferometer Sensor Based on Er Doped Fiber Peanut Structure in Fiber Ring Laser

A novel temperature sensor based on rare earth fiber peanut (REFP) shape structure in fiber ring laser (FRL) is proposed and demonstrated. A single-mode rare earth doped fiber is used to fabricate a peanut structure to produce Mach-Zehnder interferometer (MZI). Benefited from the strong thermo-optic effect of rare earth ions in fiber, high sensitivity measurement of temperature is exploited to realize. More importantly, there is no need for additional filters compared to traditional fiber laser sensors. The sensitivity of refractive index (RI) was measured to further verify the sensing performance of MZI. The experimental results show that compared with the external sensing unit, the Er-doped fiber peanut (EDFP) structure has higher thermo-optic effect coefficient and superior temperature sensitivity. The temperature and RI sensitivity of the EDFP is 0.158 nm/°C and -19.55 nm/RIU, respectively. The optical fiber MZI sensor based on the EDFP has the advantages of high sensitivity, good repeatability, simple fabrication, and compact structure. It has good application prospects in biomedicine, aerospace, and marine development.

Magnet-Less Circulator Using AlN MEMS Filters and CMOS RF Switches

A circulator with three ports allows unidirectional (or non-reciprocal) power transmission and facilitates the development of in-band full duplexers for simultaneous transmit and receive radio frequency (RF) applications. The use of ferromagnetic materials is the dominant approach for the implementation of circulators despite they are bulky and non-integrable with semiconductor electronics. Here, we present a novel magnetic-free electrical circulator using CMOS-integrable filters based on AlN MEMS resonators and CMOS RF switches. This paper describes a compact approach for a circulator that could be used in handheld devices. To break reciprocity, the AlN MEMS filter network is parametrically modulated via a switching matrix. The modulation frequency and duty cycle of the switching matrix were optimized experimentally so that the circulator can provide up to 15dB of isolation over the entire filter bandwidth. This prototype is a very compact solution for the implementation of magnetic-free circulators, which also intrinsically offer sharp pass-band filtering, thus eliminating the need for additional filters. The discussion highlights how possible paths to reduce the circulator insertion loss would make this approach more appealing for a broad range of applications.

Symmetries and entanglement features of inner-mode-resolved correlations of interfering nonidentical photons

Multiphoton quantum interference underpins fundamental tests of quantum mechanics and quantum technologies. Consequently, the detrimental effect of photon distinguishability in multiphoton interference experiments can be catastrophic. Here, we employ correlation measurements in the photonic inner modes, time or frequency, to restore quantum interference between photons differing in their colors or injection times in arbitrary linear optical networks, without the need for additional filtering or post selection. Interestingly, we demonstrate how harnessing the multiphoton inner-mode quantum information enables to unravel symmetries of multiphoton networks and states and the generation of an entire class of multipartite entangled states with a fixed interferometer. These results are therefore of profound interest for future applications of universal inner-mode resolved linear optics across fundamental science and quantum technologies with photons with experimentally different spectral properties.

Design of reconfigurable active integrated microstrip antenna with switchable low‐noise amplifier/power amplifier performances for wireless local area network and WiMAX applications

A novel design of reconfigurable monopole microstrip active integrated antenna (AIA) for wireless local area network (WLAN) and Worldwide Interoperability for Microwave Access (WiMAX) applications is presented and discussed in this study. The primary designed reconfigurable passive antenna is capable of supporting switchable single/dual band performances while having a compact dimension of 12 × 18 mm2. The proposed reconfigurable passive antenna is integrated with an interdigital filter and a reconfigurable switchable power/low-noise amplifier (LNA) (power amplifier – PA, LNA) forming a single-port microstrip AIA which can be used as a full-duplex switchable transceiver in which the need for additional filters is eliminated because of its reconfigurable structure. A 2.3–2.56 GHz (WLAN) with 12.3 dB (PA) gain improvement and 3.3–3.59 GHz (WiMAX) with 8.5 dB (LNA) gain improvement are supported at switchable performances of the fabricated reconfigurable AIA. Measured results show that the designed passive and active antennas have proper almost omnidirectional radiation characteristics at their desired operation frequencies which is suitable for WLAN and WiMAX applications.

A Large-Power Voltage Source Converter for FACTS Applications Combining Three-Level Neutral-Point-Clamped Power Electronic Building Blocks

This paper presents a novel large-power voltage source converter (VSC) arrangement suitable for flexible alternating current transmission system applications, achieved by combining four three-level three-phase neutral-point-clamped inverters by means of intermediate magnetic elements with lower VA rating and size than those of similar existing installations. The 12 inverter poles forming the VSC share a common dc bus and are implemented using standard power electronic building blocks of well-proven reliability. The output voltage is doubled by using an H-bridge configuration, and only a single-secondary grid coupling transformer is required. In addition, the intermediate magnetic elements ensure an equal power sharing between the four inverters. Since they also allow for the harmonic cancellation between the inverter poles and eliminate any third harmonic component created by the modulation, the output voltage waveform has a high quality, often eliminating the need for additional filtering. In this paper, the converter components and its operation are explained, and experimental results for several modulation strategies are provided.

Effects of Common-Mode Active Filtering in Induction Motor Drives for Electric Vehicles

This paper deals with the active common-mode (CM) voltage compensation in an induction motor drive where the inverter is supplied by a dc source, which is typical of vehicle applications. The CM voltage at motor terminals, creating a shaft voltage through the motor air gap with possible rise in bearing current, can endanger motor reliability and reduce its lifetime. Therefore, CM voltage filtering is desirable. On the other hand, the operation of an active filter has an impact on drive efficiency due to its specific losses and can affect the electromagnetic interference (EMI) emissions that are generated by the drive. Such effects are investigated in this paper. A detailed description of a CM active filter (CMAF) is presented. An analysis of the CM voltage and current on the motor ground connection before and after the introduction of the CMAF is performed. The power losses due to the CMAF operation are analyzed and experimentally evaluated. Furthermore, the EMI toward the vehicle dc power supply line is investigated. All phenomena are studied by simulation and experimentally. The simulated results “are obtained developing” a high-frequency circuit model of the drive system, including the CMAF, which is implemented using the PSpice software. To accurately perform the experimental tests, a new dedicated high voltage dual dc line impedance stabilization network (LISN) is designed and set up on purpose. The CMAF is found to be an effective solution for the increase in motor reliability and drive electromagnetic compatibility, and its operation does not significantly reduce drive efficiency. Moreover, the CMAF does not worsen the EMI toward the dc supply line. Therefore, its presence does not imply the need for additional filters with respect to the case where no CMAF is used. Simulated results are in good agreement with the experimental ones, confirming the validity of the proposed modeling of the drive system.

A 4.75-GHz Fractional Frequency Divider-by-1.25 With TDC-Based All-Digital Spur Calibration in 45-nm CMOS

This paper presents a fractional frequency divider-by-1.25 and associated all-digital calibration circuitry. The divider can be used in a wireless transceiver to prevent direct or harmonic pulling of the VCO by the power amplifier. Timing errors between the quadrature phases used in the phase-rotating divider introduce fractional spurs at the output. In this design, the timing errors are measured with a stochastic time-to-digital converter with 20 fs resolution, and corrected to suppress output spurs. The fractional divider has been implemented in a 45 nm CMOS LP process and its core dissipates an estimated 17 mA current from a 1.1 V supply. After calibration, fractional spurs are on average below -59 dBc and -50 dBc (¿ ~ 2 dB over 10 samples) with a 2.5 and 3.8 GHz output frequency respectively. Calibration performance has been confirmed for temperatures from -20°C up to 85°C. The low spur level facilitates radio co-existence with no need for additional filtering. This makes this divider a good candidate for WiFi and WiMAX radios up to 3.8 GHz.

Energy-Efficient Low-Complexity CMOS Pulse Generator for Multiband UWB Impulse Radio

This paper presents an energy-efficient low-complexity pulse-generator design technique for multiband impulse-radio ultrawide-band (IR-UWB) system in 0.18-mum CMOS technology. The short pulses are generated based on the on/off switching operation of an oscillator with subband switching functionality, which is mandatory for multiband IR-UWB systems. The relation between the oscillator switching operation and the resulting output pulse envelope, which determines pulse spectral characteristics, is analyzed, and the design guidelines for topology and component values are presented. Measurements show the output pulses with the duration of 3.5 ns, which corresponds to 520-MHz bandwidth. The output pulse spectrum centered at 3.8 GHz fully complies with the Federal Communication Commission spectral mask with more than 25 dB of sidelobe suppression without the need for additional filtering. Thus, the low-complexity pulse generator can maintain its simplicity for low cost with core chip size of 0.3 mm2. The pulse generator shows an excellent energy efficiency with average energy dissipation of 16.8 pJ per pulse from 1.5-V supply. The proposed pulse generator is best suited for energy-detection IR-UWB systems.