Search Results (234)

This paper introduces an electrocardiogram (ECG) noise removal front-end amplifier circuit based on a current-feedback operational amplifier (CFOA) that uses the current feedback to detect error signals and control the output. This ECG circuit focuses on denoising the ECG noise to accentuate the ECG electrical signals from the heart. Noises in ECG refer to baseline wander (BW), powerline interference (PLI) and motion artifacts. We proposed a CFOA-based ECG pre-amplifier using the AD844 commercial operational amplifier built inside with a positive second-generation current conveyor (CCII+) and a voltage follower circuit. This work introduces an ECG noise removal front-end amplifier based on a CFOA. The primary innovation lies in the balancing instrumentation amplifier architecture that utilizes the high-speed and robust properties of the AD844 commercial operational amplifier to achieve superior noise rejection. To protect against high-frequency interference, we introduce a novel cascaded low-pass filter (LPF) stage that ensures a sharper cut-off compared to traditional single-stage designs. Experimental results validate the design’s effectiveness, achieving a high common-mode rejection ratio (CMRR) of 75.4 dB and a mid-band gain of 46.5 dB. These performance metrics, combined with the circuit’s ability to eliminate BW and PLI, confirm its robust suitability for high-fidelity wearable ECG monitoring. Full article

Accurate liquid level regulation is critical for ensuring printing quality and process stability in stereolithography (SLA) 3D printing. However, traditional liquid level control methods often suffer from insufficient prediction accuracy, poor disturbance rejection capability, and limited adaptability under dynamic printing conditions. To address these challenges, this paper proposes an enhanced Transformer-based time series prediction model integrated with an xLSTM module for SLA liquid level prediction and adaptive control. By embedding the xLSTM structure into the Transformer encoder, the proposed model combines the global dependency modeling capability of self-attention mechanisms with the local temporal feature extraction capability of recurrent memory units, thereby improving the prediction accuracy and robustness of liquid level sequences. Experimental datasets were collected from an actual SLA printing platform, including multiple process-related features such as layer height, laser power, platform position, and vacuum pressure. Comparative experiments were conducted against conventional Transformer, LSTM, xLSTM, GRU, TCN, and PID-based methods. The results demonstrate that the proposed model achieves the best prediction performance, with an MAE of 0.174, RMSE of 0.222, and R² of 0.9903. Compared with the original Transformer model, the proposed approach significantly reduces prediction error and improves fitting stability. In disturbance rejection experiments, the proposed strategy effectively suppresses liquid level fluctuations under sudden pulse interference conditions, exhibiting superior robustness and dynamic response capability compared with traditional PID control. Furthermore, physical printing experiments verify that the proposed method can improve surface quality, contour accuracy, and structural stability of printed parts. Overall, the proposed Transformer–xLSTM framework provides an effective intelligent prediction and control solution for SLA liquid level regulation, offering significant potential for high-precision and intelligent additive manufacturing applications. Full article

As intelligent systems become decision-support tools in the architecture, engineering, and construction (AEC) industry, establishing human–AI trust is critical. However, in engineering consulting, the psychological mechanisms underlying trust formation remain unclear. Grounded in Self-Determination Theory and the Stereotype Content Model, this study utilized multi-wave survey data from Chinese engineering consulting employees to investigate these mechanisms. We examined how perceived autonomy influences human–AI trust through the competitive dual-mediation of warmth perception and competence perception, alongside the asymmetric moderating role of critical thinking. Results reveal that perceived autonomy directly enhances trust. However, social cognition acts as a competitive mechanism: autonomy positively impacts trust via warmth perception but generates a negative indirect effect via competence perception. Furthermore, critical thinking exerts an asymmetric boundary effect; it does not interfere with the intuitive warmth pathway but significantly intensifies the negative indirect effect through the competence pathway. Ultimately, these findings highlight that perceived autonomy exerts a double-edged sword effect in the context of human–AI collaboration. To mitigate professional defensive rejection and calibrate trust, AEC firms should prioritize human-in-the-loop deployment strategies, objective interface designs, and the cultivation of AI collaborative literacy. Full article

A single-band-notched ultra-wideband (UWB) low-sidelobe planar array antenna for millimeter-wave (mmWave) applications is presented. The antenna element employs a planar dipole excited through an H-shaped coupling slot to achieve broadband impedance matching, while a centrally loaded parasitic patch acts as a half-wavelength resonator to generate a controllable notch band. Additional parasitic patches are introduced to recover the high-frequency matching without degrading the notch response. An $8\times 8$ array is then developed using a Taylor-weighted feed network implemented with three classes of 1-to-4 microstrip power dividers. Measured results show that the array operates from 19.0 to 45.0 GHz with $\mathrm{VSWR}<2$, while providing a rejection band from 35.0 to 38.5 GHz. The notch suppresses the realized gain by about 5 dB around 37.0 GHz, the peak gain reaches 20.5 dBi in the passband, and average sidelobe levels better than $-17$ dB are obtained. The proposed design provides a practical approach for combining ultra-wide bandwidth, in-band interference rejection, and low-sidelobe radiation in a compact mmWave planar array. Full article

This paper proposes a generalized high-order linear active disturbance rejection control (GHO-LADRC) method to suppress non-stationary disturbances in VICTS antenna direct-drive motors during high-dynamic scanning. First, a fourth-order generalized extended state observer is constructed, in which the derivative of the total disturbance is explicitly modeled as an extended state. This configuration enables real-time observation of the disturbance rate of change and suppresses the phase lag inherent in traditional ADRC during rapid disturbance variations through disturbance feedforward compensation. Secondly, drawing on singular perturbation theory and the motor’s dual-time-scale characteristics, this work precisely decouples and explicitly extracts the nonlinear friction and electromagnetic damping terms during the modeling stage. By integrating the extracted electromagnetic damping terms and the disturbance variation rate, an improved model-assisted control law is formulated, enabling active compensation for intense dynamic interference. Theoretical analysis and experimental results demonstrate that the proposed method significantly enhances disturbance rejection capability and satellite communication accuracy. As the first application of GHO-LADRC in the field of direct-drive VICTS antenna control, this work validates its effectiveness in improving system robustness within complex dynamic environments. Full article

In order to solve the coupling problem of the six-pole hybrid magnetic bearing (SHMB), an active disturbance rejection control based on modified particle swarm optimization is proposed. Firstly, the active disturbance rejection control (ADRC) for the six-pole hybrid magnetic bearing is introduced, which is a second-order system. Secondly, the modified particle swarm optimization (MPSO) is used for the ADRC, which can decouple the SHMB. Then, simulations of SHMBs are performed under different disturbance signals, and floating simulations and anti-interference simulations of ADRC-MPSO and ADRC are compared. Finally, an experimental platform is established that verifies feasibility and reliability. Full article

Precise manipulation and directed transport of micro- and nano-particles are cornerstones of emerging lab-on-a-chip technologies. Traditional optofluidic systems that combine optical tweezers with microfluidic channels enable long-range transport. However, they rely on fixed physical boundaries that lack reconfigurability. To bridge this gap, we propose a reconfigurable virtual optical waveguide (VOW) based on a discretized beam-shaping strategy. By superposing two orthogonally polarized shaped beams, we construct interference-free optical channels without physical boundaries. This platform enables programmable transport along complex trajectories, including space-filling Hilbert curves that maximize interaction path length, and shields the transport channel from perturbations induced by surrounding particles. Crucially, the VOW offers multi-dimensional sorting capabilities: (i) it performs precise size-dependent sieving via tunable channel widths, and (ii) it functions as an intrinsic material filter by stably guiding scattering-dominated particles (e.g., gold) while rejecting gradient-dominated dielectric ones. This work establishes a versatile, contactless strategy for adaptive optical logistics and on-chip material purification. Full article

Coherent optical communication serves as the backbone of long-haul, high-capacity optical networks, where polarization-insensitive 90° optical hybrids (OHs) are crucial for system simplification and robustness. This work presents a polarization-insensitive 90° OH based on asymmetric double-strip silicon nitride waveguides, designed for dual-polarization quadrature phase-shift keying (DP-QPSK) systems. The device consists of a cascaded polarization-insensitive structure incorporating one 1 × 2 and three 2 × 2 multimode interference (MMI) couplers, interconnected by four 90° bent waveguides. Optimized via 3D finite-difference time-domain (FDTD) simulations, the 1 × 2 MMI coupler exhibits insertion losses below 0.06 dB (TE) and 0.09 dB (TM), while each 2 × 2 MMI coupler shows insertion losses under 0.2/0.4 dB, amplitude imbalance below 0.05/0.18 dB, and phase error within ±0.5°/±1.5° for the TE/TM modes, respectively. Based on these components, the full device achieves polarization-insensitive operation across a 100 nm bandwidth (1500–1600 nm), with a phase error within ±1°, insertion loss below 0.3 dB (TE) and 0.5 dB (TM), and common-mode rejection ratio better than −40 dB (TE) and −30 dB (TM). Furthermore, the design demonstrates high fabrication tolerance, maintaining performance under manufacturing deviations of ±2 μm in MMI length and ±20 nm in waveguide spacing. This work provides a promising polarization-insensitive OH design and a viable route toward cost-effective mass production of next-generation high-speed coherent systems. Full article

This article examines the Americanization of television news in post-communist media systems through an in-depth case study of bTV, Bulgaria’s first national commercial television broadcaster, launched by News Corporation in 2000. Drawing on original in-depth qualitative interviews with founding executives, journalists, regulators, and consultants, alongside archival materials and documentary analysis, the study traces how U.S. journalistic norms were introduced, negotiated, and ultimately hybridized within a fragile post-socialist media environment. Building on Gabriel Tarde’s theory of imitation, the article proposes a three-stage analytical model—transmission, transnationalization, and appropriation—to capture the dynamics of media transformation beyond simple adoption or rejection. The findings show that Americanization initially operated as a professionalizing force, reshaping visual storytelling, newsroom routines, and narrative structures, while also functioning as a symbolic and structural shield against overt political interference. Foreign ownership, particularly American ownership, was widely perceived by media actors as a buffer separating newsrooms from local power networks and enabling a degree of editorial autonomy. At the appropriation stage, however, the analysis reveals a more ambivalent outcome. While American formats and aesthetics were rapidly internalized at the surface level, deeper journalistic identities and democratic functions (most notably the Fourth Estate ideal) were only partially and unevenly appropriated. The result was a hybrid media model characterized by format mixing, depoliticization, and selective adaptation to local cultural and institutional legacies. The article conceptualizes this outcome as a Copycat Fourth Estate: a media system that appears American in form yet remains shaped by post-communist legacies of control, accommodation, and limited civic engagement. By offering a historically grounded, outlet-level analysis, the study contributes to debates on media Americanization, hybridization, and media capture, and advances understanding of how imported journalistic models are reshaped in transitional democracies. Full article

This paper proposes a Cascode phase compensation network structure for controlling Buck–Boost converters to achieve wide-bandwidth and high-speed operation. The proposed scheme relocates the compensation capacitor (C_C) from the traditional position “across the first-stage output and the second-stage output” to a new position “between the source of the first-stage Cascode common-gate transistor and the second-stage output.” By integrating their high common-mode rejection ratio and power supply rejection ratio, a global system loop with robust interference immunity is constructed. The results indicate that a dominant-pole frequency of 10 kHz is achieved with our proposed structure compared to the circuit without Cascode compensation, representing a tenfold increase. As a result, a phase margin (PM) of up to 58.36° is achieved, which is improved by 9.1%. This work can provide an effective reference for achieving stable and rapidly responsive power conversion. Full article

Immune checkpoint inhibitors (ICIs) have transformed the therapeutic landscape of advanced hepatocellular carcinoma (HCC), establishing immunotherapy-based combinations as the standard of care. Improved treatment responses have expanded liver transplant eligibility for selected patients with advanced HCC through downstaging or bridging strategies. Such advances have directly influenced transplant candidacy and post-transplant outcomes. However, accumulating evidence indicates that pretransplant exposure to ICIs may disrupt post-transplant immune homeostasis, increasing the risk of acute allograft rejection and graft failure requiring retransplantation. From an immunological perspective, rejection following pretransplant ICI therapy predominantly manifests as T cell-mediated rejection and is characterized by the sustained activation of effector T cells and impairment of regulatory immune pathways. Blockade of immune checkpoint signaling interferes with mechanisms critical for allograft tolerance, including T cell apoptosis and regulatory T cell induction. Recent studies further underscore the importance of the washout period between ICI discontinuation and LT, with longer washout intervals being associated with lower rejection rates. Importantly, timely recognition and appropriate immunosuppressive management can often resolve acute rejection without adversely affecting long-term graft outcomes. This review integrates current immunological insights with emerging clinical evidence to inform optimal transplant timing and management strategies for liver transplant candidates receiving ICIs. Full article

In this paper, a notch bandpass filter based on spoof surface plasmon polaritons (SSPPs) is presented and systematically analyzed. The bandpass response is realized by a momentum-matched SSPP transition section and two SSPP resonant units. An annular slot defected ground structure (DGS), evolved from the conventional dumbbell DGS is etched on the ground plane to introduce an in-band notch. The notch frequency can be controlled independently by the DGS geometric parameters while the passband edges remain nearly unchanged. A prototype is fabricated and measured. The measured results agree well with the simulations. Two passbands are obtained from 0.67 to 3.40 GHz and from 3.67 to 4.77 GHz. The insertion loss is 0.48 dB at 2.00 GHz and 1.11 dB at 4.22 GHz. The return loss on both sides of the notch is better than −10 dB. A notch centered at 3.50 GHz provides −25 dB rejection. The compact structure and the independently controllable notch frequency make the proposed filter suitable for narrowband interference suppression in microwave and millimeter-wave front ends. Full article

Flexible-joint manipulators suffer from severe performance degradation due to the coupling of joint elasticity and varying loads. To address this, we propose a composite finite-time active disturbance rejection control (CFT-ADRC) strategy utilizing a frequency-domain separation architecture. A recursive least squares (RLS) algorithm identifies slow-varying load parameters, while an extended state observer (ESO) compensates for high-frequency unmodeled dynamics and external disturbances, effectively preventing loop interference. A finite-time control law guarantees rapid tracking error convergence. Comprehensive simulations confirm that this approach significantly outperforms standard ADRC and neural network-based methods (RBFNN-ASMC). Under 50% load variations, it achieves an RMS tracking error of $2\times {10}^{-3}$ rad and maintains robust stability during 200% instantaneous load mutations. The strategy presents a strong theoretical framework for future hardware implementation while maintaining an optimal balance of precision, robustness, and computational simplicity. Full article

Optically pumped magnetometers (OPMs) provide a non-cryogenic alternative to superconducting quantum interference devices (SQUIDs) for detecting weak biomagnetic fields. We report the design, construction, and characterization of a single-cell intrinsic OPM gradiometer. The gradiometer employs a rubidium-87 vapor cell in an orthogonal pump and probe beam configuration. The pump beam was split to illuminate two parallel sensing regions of the cell, separated by a baseline of 3 cm, with opposing circular polarization. A linearly polarized probe beam propagated through both regions and was captured by a balanced polarimeter whose output directly measured the spatial magnetic gradient. This prototype achieved a common-mode rejection ratio exceeding 50 dB and a sensitivity of 267 pT/cm/√Hz without passive magnetic shielding, using active ambient-field coils. As a proof of concept, we recorded preliminary cardiac-synchronous magnetic measurements using an optical pulse sensor for beat segmentation. After bandpass filtering and ensemble averaging, a cardiac-synchronous waveform was observed, consistent with cardiac timing. Unlike many multi-cell gradiometers that require complex calibration, modulation, and passive shielding, this single-cell design reduces cost and complexity. Full article

Practical robotic systems require control methods that remain reliable under limited computational resources, uncertain environments, and frequent changes in operating conditions. Although model-based control forms the foundation of high-performance robotics, real-world deployment is often hindered by model uncertainty, time-varying dynamics, and costly identification. As a result, low-order and intuitive control schemes remain dominant, yet such approaches often fail to sustain consistent performance under disturbances and parameter variations. Robust and adaptive control provide representative paradigms to address this gap, where a Disturbance Observer (DOB) suppresses uncertainty through disturbance rejection and a Parameter Adaptation Algorithm (PAA) improves model fidelity through online identification. However, direct integration of a DOB and a PAA often introduces functional interference, including mutual masking between disturbance compensation and parameter estimation, which compromises closed-loop stability. This paper proposes an Adaptive Disturbance Observer (ADOB) that integrates a DOB with online parameter adaptation. The ADOB updates the nominal model of the DOB in real time using a Recursive Least Squares (RLS)-based PAA, while a dual-filtering structure separates disturbance rejection and parameter identification. Stability is analyzed using hyperstability theory, where a smoothing mechanism enforces the slowly varying parameter assumption. Experiments on a one-Degree-of-Freedom (DOF) electromagnetic actuator and a three-DOF robotic manipulator demonstrate reductions in model uncertainty and tracking error compared with a conventional DOB. Full article