Search Results (56)

Permanent Magnet Synchronous Motors (PMSMs) have been widely applied across various electrical systems due to their significant advantages, including high power density, high-efficiency conversion, and easy controllability. However, the issue of ‘parameter asymmetry’ (a mismatch between the controller’s preset parameters and the actual system parameters) in PMSMs can lead to performance problems, such as delayed speed response and increased overshoot. The destruction of symmetry, including the asymmetric weight distribution between new and old data in the moment-of-inertia identification algorithm and the asymmetry between “measured values and true values” caused by sampling delay, is the core factor limiting the system’s control performance. All these factors significantly affect the accuracy of parameter identification and the system’s stability. To address this, this study focuses on the mechanical parameter identification of PMSMs with the core goal of “symmetric matching between set values and true values”. Firstly, a current-speed dual closed-loop vector control system model is constructed. The PI parameters are tuned to meet the symmetric tracking requirements of “set value-feedback” in the dual loops, and the influence of the PMSM’s moment of inertia on the loop symmetry is analyzed. Secondly, the symmetry defects of traditional algorithms are highlighted, such as the imbalance between “data weight and working condition characteristics” in the least-squares method and the mismatch between “set inertia and true inertia” caused by data saturation. Finally, a Forgetting Factor Recursive Least Squares (FFRLS) scheme is proposed: the timing asymmetry of signals is corrected via a first-order inertial link, a forgetting factor λ is introduced to balance data weights, and a recursive structure is adopted to avoid data saturation. Simulation results show that when λ = 0.92, the identification accuracy reaches +5% with a convergence time of 0.39 s. Moreover, dynamic symmetry can still be maintained under multiple multiples of inertia, thereby improving identification performance and ensuring symmetry in servo control. Full article

In order to solve the problem of the IEEE 1588 (precise time protocol, PTP) path delay asymmetry caused by network congestion in data center time synchronization, this paper proposes a novel PTP time synchronization mechanism based on the original path return method and minimum delay packet screening (MDPS) algorithm. The original path return method utilizes the routing record and source station routing function of the IP protocol to enable the PTP packet to return along the original path, ensuring sufficient conditions for delay symmetry of the forth and back paths. The MDPS algorithm is proposed to select the packets on the same path whose delay is not affected by network congestion, thereby fundamentally eliminating the problem of delay asymmetry of forth and back paths in the case of network congestion. To verify the performance of the proposed mechanism, a simulation of the PTP packet queuing model and PTP time synchronization is conducted. The simulation results show that the uncongested packet can be obtained within 2.2 s. Moreover, the maximum absolute time deviation between the slave and master clocks is reduced by approximately 50 times, and the standard deviation of the time deviation is reduced by about 2 orders of magnitude. Full article

We conducted a comprehensive experimental investigation of dual-wavelength switching of 1560 nm, 75 fs pulses (referred to as signal) driven by 1030 nm, 270 fs pulses (referred to as control) using two dual-core fibers with high refractive index contrast and different levels of asymmetry. The study explores the influence of fiber length, control pulse energy, and control-signal pulse delay on switching performance. For the fiber with higher dual-core asymmetry, we achieved an exceptional switching contrast of 41.6 dB at a 14 mm fiber length, exhibiting a homogeneous character within the spectral range of 1450–1650 nm. In contrast, the study of the weaker dual-core asymmetry fiber revealed a maximum switching contrast of 10.7 dB at a 22 mm fiber length, albeit under lower control pulse energy. These observations confirm that the switching mechanism is based on the nonlinear balancing of dual-core asymmetry, wherein the control pulse induces an enhancement of the effective refractive index in the fast fiber core, facilitating the switching of the signal pulse. This work demonstrates high switching contrasts with only a 0.4–0.6 nJ control pulse energy requirement, providing experimental confirmation of a previously reported theoretical model. For the first time, the dual-wavelength switching performance of dual-core fibers with varying levels of asymmetry is compared. The results reveal key directions for the further development of dual-core fibers in view of their potential applications. Full article

This work investigates feedback control systems with first order plus dead time (FOPDT) plants, which are characterized by asymmetric dynamics. The term asymmetric dynamics is understood to mean that the dynamics of the response of the controlled parameter of the plant to the rise and fall of the plant control signal are different. The novelty of the current work is that it analyzes a case where the asymmetry is introduced by both dynamic parameters of the FOPDT plant: by the asymmetry of the time constant and by the asymmetry of the response delay. Another novelty is that in the proposed asymmetrical PI (aPI) controller, the change in the plant control signal time derivative sign is used to determine the moments for the switching of controller parameters. The use of an aPI controller instead of a conventional PI controller allows us to improve the quality of the control of plants with asymmetric dynamics. It is also important that the problem is solved using a PI type controller, which automation engineers are well aware of and know how to tune its parameters to the dynamics of the plant. Therefore, an aPI controller can be attractive in practical applications. All investigations were performed using Matlab/Simulink software (version R2021b). Full article

Differentiating genuine hemiplegic gait (HG) in stroke survivors from hemiplegic-like gait voluntarily imitated by healthy adults (MHG) is essential for reliable assessment and intervention planning. Treadmill-based gait data were obtained from 79 participants—39 stroke patients (HG) and 40 healthy adults—instructed to mimic HG (MHG). Forty-eight spatiotemporal and force-related variables were extracted. Random Forest, support vector machine (SVM), and logistic regression classifiers were trained with (i) the full feature set and (ii) the 10 most important features selected via Random Forest Gini importance. Performance was assessed with 5-fold stratified cross-validation and an 80/20 hold-out test, using accuracy, F1-score, and the area under the receiver operating characteristic curve (AUC). All models achieved high discrimination (AUC > 0.93). The SVM attained perfect discrimination (AUC = 1.000, test set) with the full feature set and maintained excellent accuracy (AUC = 0.983) with only the top 10 features. Temporal asymmetries, delayed vertical ground reaction force peaks, and mediolateral spatial instability ranked highest in importance. Reduced-feature models showed negligible performance loss, highlighting their parsimony and interpretability. Supervised machine learning algorithms can accurately distinguish true hemiplegic gait from mimicked patterns using a compact subset of gait features. The findings support data-driven, time-efficient gait assessments for clinical neurorehabilitation and for validating experimental protocols that rely on gait imitation. Full article

Background. Sex-based disparities in chronic obstructive pulmonary disease (COPD) diagnosis remain underexplored, particularly in primary care settings. This study assessed sex differences in clinical burden, diagnostic delay, and missed diagnostic opportunities using conventional and composite metrics. Methods. A cross-sectional analysis was conducted in 166 newly diagnosed COPD patients (76 women, 90 men) from Spanish primary care. Clinical severity, healthcare use, and diagnostic timing were compared using Mann–Whitney and chi-squared tests. Composite indices included the Symptom Intensity Score, Diagnostic Inertia Indices, DOSE Index, and Diagnosis Complexity Score. Multivariable regressions evaluated independent associations. Results. At diagnosis, women showed a greater clinical and functional burden (FEV₁ % predicted: 50.4% vs. 61.4%, p < 0.001; symptom intensity z-score: 0.13 vs. −0.67, p < 0.001), higher diagnostic complexity (Diagnosis Complexity Score: 403.5 vs. 272.0, p < 0.001), and longer diagnostic delay (median: 133.0 vs. 66.5 days, p < 0.001). Stratified and composite analyses confirmed consistent sex-based asymmetries. In adjusted models, being female independently predicted a longer diagnostic delay (β = 0.888, p = 0.005), but was not significantly associated with the burden of missed diagnostic opportunities (MDOs) (β = 0.112, p = 0.395). Conclusions. Women with newly diagnosed COPD experience greater symptom burden and longer diagnostic delays. Composite metrics may improve the identification of diagnostic disparities in routine clinical settings. Full article

Sharing bottleneck bandwidth among TCP flows with diverse round-trip times (RTTs) remains a persistent challenge. This study investigates RTT unfairness and evaluates the behavior of two widely deployed congestion control algorithms, TCP Cubic and TCP BBR, under a variety of scenarios. The main objective is to better understand the underlying causes of RTT-based throughput disparity and to identify network configurations that promote fair bandwidth sharing. Using the Mininet emulation platform, extensive experiments were conducted to examine the effects of buffer size, sender distribution, and delay asymmetry on transmission performance metrics. The results show that while TCP BBR achieves high utilization with minimal buffering, its fairness depends on the interaction between RTT and buffer size. On the other hand, TCP Cubic achieves better fairness when moderate buffer sizes are provisioned and bandwidth imbalance is driven mostly by RTT ratio. These findings suggest that careful buffer sizing can reduce RTT unfairness and highlight the broader impact of queuing strategies on network performance. Full article

Background/Objectives: Diabetic foot ulcers (DFUs) remain a critical complication of diabetes, with high rates of amputation when not diagnosed early. Despite advancements in medical imaging, current DFU detection methods are often limited by their computational complexity, poor generalizability, and delayed diagnostic performance. This study presents a novel hybrid diagnostic framework that integrates traditional feature extraction methods with deep learning (DL) to improve the early real-time computer-aided detection (CAD) of DFUs. Methods: The proposed model leverages plantar thermograms to detect early thermal asymmetries associated with DFUs. It uniquely combines the oriented FAST and rotated BRIEF (ORB) algorithm with the Bag of Features (BOF) method to extract robust handcrafted features while also incorporating deep features from pretrained convolutional neural networks (ResNet50, AlexNet, and EfficientNet). These features were fused and input into a lightweight deep neural network (DNN) classifier designed for binary classification. Results: Our model demonstrated an accuracy of 98.51%, precision of 100%, sensitivity of 98.98%, and AUC of 1.00 in a publicly available plantar thermogram dataset (n = 1670 images). An ablation study confirmed the superiority of ORB + DL fusion over standalone approaches. Unlike previous DFU detection models that rely solely on either handcrafted or deep features, our study presents the first lightweight hybrid framework that integrates ORB-based descriptors with deep CNN representations (e.g., ResNet50 and EfficientNet). Compared with recent state-of-the-art models, such as DFU_VIRNet and DFU_QUTNet, our approach achieved a higher diagnostic performance (accuracy = 98.51%, AUC = 1.00) while maintaining real-time capability and a lower computational overhead, making it highly suitable for clinical deployment. Conclusions: This study proposes the first integration of ORB-based handcrafted features with deep neural representations for DFU detection from thermal images. The model delivers high accuracy, robustness to noise, and real-time capabilities, outperforming existing state-of-the-art approaches and demonstrating strong potential for clinical deployment. Full article

School-aged children are routinely exposed to additional physical stress due to carrying school backpacks. These backpacks often exceed recommended limits and can contain not only books and notebooks but also laptops, water bottles, and other personal items. The present study aimed to evaluate the impact of different backpack loads (10%, 15%, and 20% of body weight) on dynamic gait parameters in 7-year-old girls and boys. Twenty-six children (13 girls, 13 boys) participated in the study. Gait analysis was performed using the Footscan® system (RSscan International, Olen, Belgium; 2 m × 0.4 m × 0.02 m, 16,384 sensors) equipped with Footscan software version 7 (Gait 2nd generation), examining peak force (FMAX), peak pressure (PMAX), contact area (CA), and time to peak force (Time to FMAX) across five anatomical foot zones. The study revealed significant changes in all parameters, particularly at loads of 15% and 20% of body weight. Increases in plantar pressure, contact area, and asymmetry were observed, along with delays in time to peak force. These findings support the recommendation that children’s backpack loads should not exceed 10% of their body weight to prevent potential adverse effects on postural and musculoskeletal development. Full article

Background: Hyaluronic acid (HA) has emerged as a favored adjunct to restore volume after blepharoplasty and is very effective in the treatment of postoperative hollowness, sagging, and asymmetry. Its efficacy, rate of complications, and optimal injection technique are different in different clinical studies. Hyaluronidase has been studied by diverse methods in the treatment of HA complications, including chronic edema and surgical distortion. This study critically evaluated the efficacy, safety, and technical aspects of HA in the context of blepharoplasty outcomes. Methods: A systematic review was performed to evaluate the use of HA and hyaluronidase for post-blepharoplasty volume rejuvenation and the treatment of complications. Studies describing HA injection technique, time interval between blepharoplasty and injection, volumetric maintenance, complication rates, esthetic and functional results, and patient satisfaction scores were considered. Risk of bias was estimated with the ROBINS-I tool. Results: Sample sizes across the five included studies ranged from 5 to 109 patients, and follow-up intervals ranged from 1 month to 7 years. The age of patients ranged from 31 to 76 years, and females accounted for 86% of the participants in some studies. Injection of HA successfully restored meaningful volume, with retention persisting for over 12 months in the majority of cases. HA preoperative injection caused significant patient satisfaction in a short duration and was not associated with severe complications; delayed injection caused slight distortions in some revision operations. Lipofilling showed a reduced rate of complications (12%) compared with isolated blepharoplasty (20%), suggesting its utility as an adjuvant procedure of volume restoration. Hyaluronidase successfully treated recalcitrant edema, with improvements ranging from 50% to 100%, while the application of adjuvant RF microneedling caused complete remission (100%) in subjects with multiple treatments. The application of ultrasound imaging made measurements more precise, although methods of clinical assessment were significantly heterogeneous among the studies. Conclusions: HA displayed efficacy in terms of efficient volume restoration after blepharoplasty, especially when technique, time, and filler selection are meticulously optimized. In comparison to lipofilling, HA is seen as somewhat safer because of its reversibility and lower likelihood of adverse vascular events. Nonetheless, considerable variability in filler type, amount, timing of administration, and result evaluation constrains conclusive clinical recommendations. The use of hyaluronidase is an effective remedial approach for overcorrection or ongoing edema. Full article

Background: This study aimed to evaluate the functional status of the biceps and triceps brachii muscles using tensiomyography in individuals diagnosed with multiple sclerosis. Methods: The study involved 19 patients with multiple sclerosis (MS) aged 19–46 years and 24 healthy individuals aged 20–25 years. Each person underwent a tensiomyographic examination of the biceps and triceps brachii muscles in both upper limbs. The following indices were analysed: contraction time (Tc), delay time (Td), muscle displacement (Dm), and bilateral and antagonist functional asymmetry index. Results: For the biceps brachii muscle, a statistically significant difference in muscle stiffness was observed between the MS and healthy groups. These differences were noted on both the left and right sides (p < 0.0001). Conclusions: The results of the tensiomyographic examination of the arm muscles in the group of patients with MS showed increased stiffness of the biceps brachii muscle. The functional asymmetry index in the triceps brachii muscle showed a significant difference between the sides, but no differences were noted in the functional asymmetry index between the antagonist muscles. Full article

Due to the unbalanced temporal and spatial distribution of the passenger flow on metro lines during peak hours, the implementation of passenger flow control strategies effectively ensures operational safety and travel efficiency for passengers. In this study, we analyze the coupling relationship between trains and passengers, introduce train-stopping state variables, and synergistically optimize both train operation schedules and station passenger flow control. Aiming to minimize the total passenger delay time and maximize the number of boarding passengers, we consider four constraints: the train operation process, the passenger entry process, the passenger–train interaction process, and system constraints. This framework enables us to construct a cooperative passenger flow control optimization model for oversaturated metro lines. Subsequently, we propose an improved artificial bee colony algorithm to solve this model. We utilize evolutionary operators and an enhanced tabu search to create new food sources for employed bees and enhance their local search capabilities during the employed phase. Finally, Shanghai Metro Line 9 is used as a case study for the model validation. The computational results indicate that the proposed Collaborative passenger flow control strategy significantly reduces the number of stranded passengers on platforms and decreases the total passenger delay time by 36.26% compared to the existing passenger flow control strategy. The findings demonstrate that the cooperative control strategy proposed in this paper can effectively alleviate the pressure from passenger flow on oversaturated lines, balance the asymmetry between supply and demand, and markedly improve both safety and efficiency in the metro system during peak hours. Full article

Existing studies on ontology evolution lack automated mechanisms to balance semantic coherence and adaptability under real-time uncertainties, particularly in resolving spatiotemporal asymmetry and multidimensional coupling imbalances in dam-break scenarios. Traditional methods such as WordNet’s tree symmetry and FrameNet’s frame symmetry fail to formalize dynamic adjustments through quantitative metrics, leading to path dependency and delayed responses. This study addresses this gap by introducing a novel symmetry-entropy-constrained matrix fusion algorithm, which integrates algebraic direct sum operations and Hadamard product with entropy-driven adaptive weighting. The original contribution lies in the symmetry entropy metric, which quantifies structural deviations during fusion to systematically balance semantic stability and adaptability. This work formalizes ontology evolution as a symmetry-driven optimization process. Experimental results demonstrate that shared concepts between ontologies (s = 3) reduce structural asymmetry by 25% compared to ontologies (s = 1), while case studies validate the algorithm’s ability to reconcile discrepancies between theoretical models and practical challenges in evacuation efficiency and crowd dynamics. This advancement promotes the evolution of traditional emergency management systems towards an adaptive intelligent form. Full article

In the research and practice of integrated scheduling problems, the tree structure of complex products usually presents an asymmetric and complex form. This asymmetry is mainly reflected in the hierarchical relationship between the various components of the product, the degree of dependence, and the sequence of production processes. Existing studies often neglect that leaf nodes with the lowest layer priority can be scheduled at any moment, leading to underutilization of parallelism potential under symmetric structures and exacerbation of critical path delays under asymmetric structures. Aiming at solving this kind of problem, an integrated scheduling algorithm based on the improved Floyd algorithm (ISA-IFA) is proposed. According to the improved Floyd algorithm, the algorithm proposed a path-weighted strategy, which constructs the vertical path value according to the processing time of the process itself. Combined with the proposed process scheduling advantage strategy, the leaf node process is especially emphasized as the priority scheduling object, which makes the connection between the processes more closely, and then significantly reduces the idle time of the equipment. The empirical results show that the ISA-IFA algorithm shortens the completion time of complex products and simultaneously improves the equipment utilization rate to 55.9%, verifying its effectiveness in dynamic scheduling and resource co-optimization. Full article

Background: Healthcare restrictions on non-urgent services during the COVID-19 pandemic led to limited access to rehabilitation and delayed treatment, potentially affecting early and mid-term recovery following anterior cruciate ligament reconstruction (ACLR). However, little is known about its specific consequences on muscle strength recovery in recreational and amateur athletes. Objectives: This study aimed to compare short-term clinical outcomes in ACLR patients before, during, and after the pandemic, spanning from 2020 to 2022. Methods: We conducted a retrospective review of 126 patients who underwent ACLR using a hamstring tendon autograft. Patients were grouped based on the timing of surgery and matched for gender. Clinical outcomes and muscle strength parameters were evaluated using an isokinetic dynamometer. Results: Male patients exhibited no significant differences in muscle strength across all time frames (control, 2020, 2021, and 2022). In contrast, female patients who underwent surgery in 2020 and 2021 showed higher extension asymmetry index deficits (Q-AI: 34.09 ± 14.59% and 36.47 ± 16.36%, respectively) and increased flexion deficits in 2021 (H-AI: 25.14 ± 11.41%). Significant differences were observed in quadriceps and hamstring peak torque values, both absolute and normalized. By 2022, the female group exhibited a reduced extension deficit (Q-AI: 18.64 ± 14.49%) comparable to pre-pandemic levels (Q-AI: 19.84 ± 12.37%), indicating a recovery of knee extensor strength. Conclusion: Our study showed gender-specific differences in muscle strength recovery after ACLR during the COVID-19 pandemic, with females showing poorer outcomes than males at 5 months post-operation. Larger studies with extended follow-up are needed to clarify the pandemic’s impact and gender-specific responses. Full article