Search Results (172)

Background and Objectives: This study aimed to evaluate postoperative changes in voice quality and glottic function following early injection laryngoplasty with hyaluronic acid performed using a modified general anesthesia approach without airway instrumentation in patients with unilateral vocal fold paralysis. Materials and Methods: Thirty-two patients (19 females, 13 males; mean age 51.8 years, range 21–70) who underwent injection laryngoplasty within the first three months after the onset of paralysis were included in this retrospective study. All procedures were performed under general anesthesia without endotracheal intubation, using endoscopic visualization. Objective acoustic and aerodynamic analyses and videostroboscopic examinations were performed preoperatively and postoperatively. Data were analyzed using the Wilcoxon signed-rank test, with p < 0.05 considered statistically significant. Results: Significant postoperative improvement was observed in acoustic and aerodynamic parameters. Shimmer, jitter, and noise-to-harmonic ratio (NHR) values significantly decreased (p < 0.001, p < 0.001, and p = 0.001, respectively), while maximum phonation time (MFT) increased markedly (p < 0.001) and the S/Z ratio decreased (p = 0.006). The mean fundamental frequency (F0) decreased slightly but not significantly (p = 0.085). Videostroboscopic findings demonstrated improved glottic closure and vocal fold vibration. No major complications occurred. Conclusions: Early injection laryngoplasty with hyaluronic acid performed under general anesthesia and endoscopic guidance provides significant improvement in objective voice parameters and glottic efficiency in unilateral vocal fold paralysis. Early intervention appears to enhance phonatory stability and may prevent maladaptive laryngeal changes. Full article

This paper proposes a sub-sampling phase-locked loop (SSPLL) that combines a time-to-digital converter (TDC)-free digital coarse loop with a high-gain analog SSPD fine loop. The coarse loop follows a counter-assisted, frequency-domain DPLL framework with an auxiliary FLL, enabling wide capture range and fast initial acquisition. Precise fractional-N operation without a TDC is achieved by reusing the fine loop delta–sigma modulator (DSM) and digital-to-time converter (DTC) in the coarse loop: the DSM maps the frequency control word (FCW) fraction to a variable integer sequence for integer-domain fractional synthesis, while the DTC aligns reference clock to the nearest oscillator edge to cancel DSM-induced quantization error. An LMS-based DTC gain calibration is enabled in the coarse loop, and its calibrated gain is handed off to the fine loop, stabilizing loop switching despite the narrow locking range of the SSPD. Constraining arithmetic to the integer path eliminates a need of TDC and simplifies hardware, improving area efficiency while preserving accurate frequency/phase alignment. Simulations in 28 nm CMOS over 4–5 GHz with a 104 MHz reference demonstrate 177-fs RMS jitter, −245.6 dB FoM, 0.146-mm² active area, and 8.94 mW power, validating wide capture, low in-band phase noise, and robust coarse-to-fine handover. Full article

Spectral measurement technology has found extensive applications across a diverse range of fields, including chemical analysis, environmental monitoring, precise measurement, and laser frequency stabilization. However, the accuracy of spectral measurement results is often constrained by the power noise and frequency jitter inherent in the light source. In contrast to the traditional differential amplification method for acquiring spectral signals, our study introduces a novel approach. By employing a power correction quotient, we effectively suppress common-mode noise. Additionally, we introduce a novel composite differential method that, in theory, is capable of performing closed-loop processing on spectral signals to stabilize the laser frequency. This innovative method not only constructs a stable laser source but also yields high-quality spectral signals simultaneously. In an experiment involving iodine molecule absorption spectroscopy, the algorithm we propose demonstrated remarkable efficacy in mitigating distortions caused by modulated signals and significantly enhanced the signal-to-noise ratio. This algorithm is versatile and can be applied to the signal processing of any spectral signal sensor that employs dual-path light. Full article

Traditional zero-compensation techniques employed to improve sub-sampling phase-locked loop (SSPLL) stability often exacerbate spur degradation or incur excessive area overhead, rendering them unsuitable for high-resolution image sensor applications. This paper proposes a novel SSPLL based on capacitor multiplication technology. This capacitor multiplication technology employs dual charge pumps (CP1 and CP2) in a coordinated operational scheme where their charge/discharge states are inversely synchronized. The effective capacitance of the loop filter is thereby amplified without expanding the physical layout area dedicated to capacitive components. Meanwhile, the continued use of zero-compensation technology ensures the stability of the SSPLL. The proposed SSPLL is designed and verified in a 55 nm CMOS process. At a 1.2 GHz output frequency, simulation results show a spot phase noise of −131.5 dBc/Hz at 1 MHz offset, accompanied by an integrated RMS jitter of 549 fs across the 10 kHz to 40 MHz spectrum, spurs suppressed to −51.3 dB, while maintaining a power efficiency of 3.81 mW and a compact layout area of 0.064 mm². All the above results show that by introducing the novel dual-CP charge multiplication technology, the SSPLL can achieve low jitter and low power consumption performance while reducing the layout area, providing a new technical approach for its application in high-resolution image sensors. Full article

Surface electromyographic (sEMG) signals result from the interaction between motor unit action potentials (MUAPs) and neural spike trains, yet how specific features of spike timing shape the sEMG spectrum is not fully understood. Using a simplified convolutional model, we simulated sEMG by combining synthetic spike trains with MUAP templates, varying firing rate, temporal jitter, and motor unit synchronization to examine their effects on spectral characteristics. Rather than addressing a particular experimental condition such as fatigue or workload, the main goal of this study is to provide a framework that clarifies how variability in neural timing and muscle properties affects the observed sEMG spectrum. We introduce extractability indices to measure how clearly neural activity appears in the spectrum. Results show that MUAPs act as spectral filters, reducing components outside their bandwidth and limiting the detection of high firing rates. Temporal jitter spreads spectral energy and blunts frequency peaks, while moderate synchronization improves spectral visibility, partially countering jitter effects. These findings offer a reference for interpreting how neural and muscular factors shape sEMG signals, supporting a more informed use of spectral analysis in both experimental and applied neuromuscular studies. Full article

This paper presents the design of a Delay-Locked Loop (DLL) with a simple architecture and a wide input clock duty cycle range. The design is tailored to meet the increasing data rate and stringent clock requirements of modern semiconductor chips, with particular applicability to dynamic random-access memory (DRAM) systems. The structure features two Bang-Bang Phase Detectors (BBPDs) to adjust the rising and falling edges of the divided clock. Implemented using a 65 nm CMOS process, the design was verified through simulation. At a working frequency of 3.2 GHz, the input clock duty cycle range spans from 18% to 72%, with a maximum output clock duty cycle error of just 0.6%, a peak-to-peak jitter of 15.73 ps, and a power consumption of 12.7 mW. Full article

The Lomb–Scargle method (LSM) constitutes a robust method for frequency and amplitude estimation in cases where data exhibit irregular or sparse sampling. Conventional spectral analysis techniques, such as the discrete Fourier transform (FT) and wavelet transform, rely on orthogonal mode decomposition and are inherently constrained when applied to non-equidistant or fragmented datasets, leading to significant estimation biases. The classical LSM, originally formulated for univariate time series, provides a statistical estimator that does not assume a Fourier series representation. In this work, we extend the LSM to multivariate datasets by redefining the shifting parameter $\tau$ to preserve the orthogonality of trigonometric basis functions in ${\mathbb{R}}^n$. This generalization enables simultaneous estimation of the frequency, phase, and amplitude vectors while maintaining the statistical advantages of the LSM, including consistency and noise robustness. We demonstrate its application to solar activity data, where sunspots serve as intrinsic markers of the solar dynamo process. These observations constitute a randomly sampled two-dimensional binary dataset, whose characteristic frequencies are identified and compared with the results of solar research. Additionally, the proposed method is applied to an ultrasound velocity profile measurement setup, yielding a three-dimensional velocity dataset with correlated missing values and significant temporal jitter. We derive confidence intervals for parameter estimation and conduct a comparative analysis with FT-based approaches. Full article

This paper proposed an adaptive bandwidth Phase-Locked Loop (PLL) that integrates integer-N and fractional-N switching for energy-efficient RF synthesis in IoT and mobile applications. The architecture exploits wide-bandwidth integer-N mode for rapid lock acquisition, then seamlessly transitions to narrow-bandwidth fractional-N mode for high-resolution synthesis and noise optimization. The architecture features a bandwidth-reconfigurable loop filter with intelligent switching control that monitors phase error dynamics. A novel adaptive digital noise filter mitigates $\Delta \Sigma$ quantization noise, replacing conventional synchronous delay lines. The multi-loop structure incorporates a high-resolution digital phase detector to enhance frequency accuracy and minimize jitter across both operating modes. With 180 nm CMOS technology, the PLL consumes 13.2 mW, while achieving $-119$ dBc/Hz in-band phase noise and 1 $p{s}_{rms}$ integrated jitter. With an operating frequency range at 2.9–3.2 GHz from a 1.8 V supply, the circuit achieves a worst case fractional spur of −62.7 dBc, which corresponds to a figure of merit (FOM) of −228.8 dB. Lock time improvements of 70% are demonstrated compared to single-mode implementations, making it suitable for high-precision, low-power wireless communication systems requiring agile frequency synthesis. Full article

Objectives: The aim of the study was to gauge the clinical usefulness of the Derkay scale in assessing the severity of voice dysfunction in patients with recurrent respiratory papillomatosis (RRP). Material and Methods: The study included 29 patients (8 women and 21 men) with a mean age of 40.2 years. To subjectively assess each patient’s voice, the Polish version of the Voice Handicap Index questionnaire was used. Acoustic parameters were calculated using the Multidimensional Voice Program, which included mean fundamental frequency (F0), frequency changes (% Jitter), amplitude changes (% Shimmer), noise-to-harmonic ratios (NHRs), and the soft phonation Index (SPI). The stage of RRP was assessed using the Derkay scale, together with the anatomical location of the lesion (from laryngeal endoscopy) and the impact RRP had on the general condition of the patient. Results: In women, Derkay clinical and total scores showed significant, positive, and strong correlations with almost all VHI-30 subscales (rho = 0.73–0.76). In men, the correlations were weaker (rho = 0.38–0.55) but were strong between the Derkay total score and F0 and total score and Jitter (rho = 0.63–0.65). Patients with human papilloma virus HPV-6 had significantly higher soft phonation index values (M = 11.97) compared to patients with HPV-11 (M = 6.91, U = 34.0; p = 0.019). Conclusions: The Derkay classification system correlates well with objective acoustic frequency measures and patient-reported voice outcomes. The system may be helpful in identifying patients at increased risk of voice dysfunction. It could be used to guide decisions about voice assessment and rehabilitation. Full article

In automated orchard operations, the straight-line locomotion stability of ground-based weeding robots is critical for ensuring path coverage efficiency and operational reliability. To address the response lag and high-frequency oscillations often observed in conventional PID and fixed-lookahead Pure Pursuit controllers, this study proposes an adaptive lookahead Pure Pursuit method incorporating angular velocity feedback. By dynamically adjusting the lookahead distance according to real-time attitude changes, the method enhances coordination between path curvature and robot stability. To enable systematic evaluation, three time-series-based metrics are introduced: mean absolute yaw error (MAYE), peak-to-peak fluctuation amplitude, and the standard deviation of angular velocity, with overshoot occurrences included as an additional indicator. Field experiments demonstrate that the proposed method outperforms baseline algorithms, achieving lower yaw errors (0.61–0.66°), reduced maximum deviation (≤3.7°), and smaller steady-state variance (<0.44°²), thereby suppressing high-frequency jitter and improving turning convergence. Under typical working conditions, the method achieved a mean yaw deviation of 0.6602°, a fluctuation of 5.59°, an angular velocity standard deviation of 10.79°/s, and 155 overshoot instances. The yaw angle remained concentrated around the target orientation, while angular velocity responses stayed stable without loss-of-control events, indicating a favorable balance between responsiveness and smoothness. Overall, the study validates the robustness and adaptability of the proposed strategy in complex orchard scenarios and establishes a reusable evaluation framework, offering theoretical insights and practical guidance for intelligent agricultural machinery optimization. Full article

Background/Objectives: The post-COVID-19 condition frequently includes dysphonia. We aimed to assess objective and subjective voice disorders and short-term responses to multimodal therapy in patients with isolated post-COVID-19 dysphonia. Methods: This retrospective, single-center pre–post study screened 244 post-COVID-19 patients; a subset of 14 with isolated dysphonia underwent standardized assessment at baseline and at 1-month follow-up. Patient-reported outcomes (Voice Handicap Index, VHI; Voice-Related Quality of Life, V-RQOL) and endoscopic evaluation were performed using videolaryngostroboscopy (LVS) and high-speed videoendoscopy (HSV) with kymographic analysis to quantify parameters describing vocal fold oscillations. The treatment included short-term systemic corticosteroids, inhaled corticosteroids, hyaluronic-acid inhalations, and structured voice therapy. Results: At baseline, HSV revealed signs of glottal insufficiency—irregular and asymmetric vocal fold motion, reduced amplitude and pliability, a disrupted mucosal wave, and an increased open quotient. At follow-up, HSV showed increased oscillation, amplitude, and cycle regularity with reduced left–right asymmetry and phase differences; phonovibrograms displayed clearer and more structured patterns. Perturbation indices decreased across jitter and shimmer measures, and the mean fundamental frequency was lower. Improvements in instrumental measures aligned with better VHI and V-RQOL scores. Conclusions: In patients with persistent dysphonia after acute SARS-CoV-2 infection, comprehensive ENT evaluation with instrumental laryngeal assessment is warranted. Short-term multimodal management was associated with improvements in both HSV-derived measures and patient-reported outcomes; confirmation in controlled studies is needed. Full article

To address the problems of insufficient trajectory tracking accuracy, pronounced jitter over undulating terrain, and limited disturbance rejection in orchard mobile robots, this paper proposes a trajectory tracking control strategy based on a double-loop adaptive sliding mode. Firstly, a kinematic model of the orchard robot is constructed and a time-varying integral terminal sliding surface is designed to achieve global fast finite-time convergence. Secondly, a sinusoidal saturation switching function with a variable boundary is employed to suppress the high-frequency chattering inherent in sliding mode control. Thirdly, an improved double-power reaching law (Improved DPRL) is introduced to enhance disturbance rejection in the inner loop while ensuring continuity of the outer-loop output. Finally, Lyapunov stability theory is used to prove the asymptotic stability of the double-loop system. The experimental results show that attitude angle error settles within 0.01 rad after 0.144 s, while the position errors in both the x-axis and y-axis directions settle within 0.01 m after 0.966 s and 0.753 s, respectively. Regarding position error convergence, the Integral of Absolute Error (IAE)/Integral of Squared Error (ISE)/Integral of Time-Weighted Absolute Error (ITAE) are 0.7629 m, 0.7698 m, and 0.2754 m, respectively; for the attitude angle error, the IAE/ISE/ITAE are 0.0484 rad, 0.0229 rad, and 0.1545 rad, respectively. These results indicate faster convergence of both position and attitude errors, smoother control inputs, and markedly reduced chattering. Overall, the findings satisfy the real-time and accuracy requirements of fast trajectory tracking for orchard mobile robots. Full article

Speech Emotion Recognition (SER) plays a vital role in supporting applications such as healthcare, human–computer interaction, and security. However, many existing approaches still face challenges in achieving robust generalization and maintaining high recall, particularly for emotions related to stress and anxiety. This study proposes a dual-stream hybrid model that combines prosodic features with spatio-temporal representations derived from the Multitaper Mel-Frequency Spectrogram (MTMFS) and the Constant-Q Transform Spectrogram (CQTS). Prosodic cues, including pitch, intensity, jitter, shimmer, HNR, pause rate, and speech rate, were processed using dense layers, while MTMFS and CQTS features were encoded with CNN and BiGRU. A Multi-Head Attention mechanism was then applied to adaptively fuse the two feature streams, allowing the model to focus on the most relevant emotional cues. Evaluations conducted on the RAVDESS dataset with subject-independent 5-fold cross-validation demonstrated an accuracy of 97.64% and a macro F1-score of 0.9745. These results confirm that combining prosodic and advanced spectrogram features with attention-based fusion improves precision, recall, and overall robustness, offering a promising framework for more reliable SER systems. Full article

Femtosecond lasers have evolved continuously over the past three decades, enabling the transition of research from fundamental studies in atomic and molecular physics to the realm of practical applications. In femtosecond laser amplifiers, to ensure strict synchronization between the seed laser pulse and the pump laser, enabling their precise overlap during the amplification process and avoiding a decline in pulse amplification efficiency and the generation of undesired phase noise, this study designed a synchronous timing signal generation system based on the combination of FPGA and analog delay. This system was investigated from three aspects: delay pulse width adjustment within a certain range, precise delay resolution, and external trigger jitter compensation. By using a FPGA digital counter to achieve coarse-delay control over a wide range and combining it with the method of passive precise fine delay, the system can generate synchronous delay signals with a large delay range, high precision, and multiple channels. Regarding the problem of asynchronous phase between the external trigger and the internal clock, a jitter compensation circuit was proposed, consisting of an active gated integrator and an output comparator, which compensates for the uncertainty of trigger timing through analog delay. The verification of this study shows that the system operates stably under an external trigger with a repetition frequency of 80 MHz. The output delay range is from 10 ns to 100 $\mu$s, the coarse-delay resolution is 10 ns, the fine-delay adjustment step is 1.25 ns, and the pulse jitter is reduced from a maximum of 10 ns to the hundred-picosecond level. This meets the requirements of femtosecond laser amplifiers for synchronous trigger signals and offers essential technical support and fundamental assurance for the high-power and high-efficiency amplification of Ti:sapphire ultrashort laser pulses. Full article

The ultrasonic power supply constitutes the core component of an ultrasonic welding system, and its main function is to convert the industrial frequency electricity into resonant high-frequency electricity in order to achieve mechanical energy conversion. However, factors such as changes in ambient temperature or component aging may cause the resonant frequency of the transducer to drift, thus detuning the resonant system and seriously affecting system performance. Therefore, an ultrasonic welding system requires high-frequency tracking in real time. Traditional frequency tracking methods (such as acoustic tracking, PID control, etc.) have defects such as poor stability, narrow bandwidth, or cumbersome parameter setting, making it difficult to meet the demand for fast tracking. To address these problems, this study adopts a T-matching network and utilizes sliding mode control for frequency tracking. In order to solve the problems of slow convergence and obvious jitter in sliding mode control (SMC), a Hippopotamus Optimization (HO) algorithm is introduced to simulate hippopotamuses’ group behavior and predation mechanisms, thereby optimizing the control parameters. It is verified through simulation that the SMC algorithm optimized by the HO algorithm (HO-SMC) is able to suppress frequency drift more effectively and demonstrates the advantages of fast response, high accuracy, and strong robustness in the scenario of sudden load changes. Full article