Search Results (196)

Cantonese Automatic Speech Recognition (ASR) is hindered by tonal complexity, acoustic diversity, and a lack of labelled data. This study proposes a phoneme-aware hierarchical augmentation framework that enhances performance without additional annotation. A Phoneme Substitution Matrix (PSM), built from Montreal Forced Aligner alignments and Tacotron-2 synthesis, injects adversarial phoneme variants into both transcripts and their aligned audio segments, enlarging pronunciation diversity. Concurrently, a semantic-aware SpecAugment scheme exploits wav2vec 2.0 attention heat maps and keyword boundaries to adaptively mask informative time–frequency regions; a reinforcement-learning controller tunes the masking schedule online, forcing the model to rely on a wider context. On the Common Voice Cantonese 50 h subset, the combined strategy reduces the character error rate (CER) from 26.17% to 16.88% with wav2vec 2.0 and from 38.83% to 23.55% with Zipformer. At 100 h, the CER further drops to 4.27% and 2.32%, yielding relative gains of 32–44%. Ablation studies confirm that phoneme-level and masking components provide complementary benefits. The framework offers a practical, model-independent path toward accurate ASR for Cantonese and other low-resource tonal languages. This paper presents an intelligent sensing-oriented modeling framework for speech signals, which is suitable for deployment on edge or embedded systems to process input from audio sensors (e.g., microphones) and shows promising potential for voice-interactive terminal applications. Full article

This research introduces a novel, high-performance multiple-input–multiple-output (MIMO) antenna designed to operate in allocated millimeter-wave (mmWave) 5G wireless communications. Operating in the tri-band, 28, 35, and 38 GHz, the four-port MIMO antenna possesses a compact size—measuring just 50 × 50 × 0.787 mm³ (4.67λ_o × 4.67λ_o × 0.73λ_o). The antenna delivers a remarkable performance, achieving peak gains of 9.6, 7.8, and 13.7 dBi in the tri-band, respectively. The realized bandwidths are 1.1, 2.2, and 3.7 GHz, at the tri-band frequencies. The antenna’s performance was significantly improved by carefully spacing the elements and employing a decoupling technique using metamaterial cells. This minimized interference between the antenna elements, resulting in efficient MIMO operation with a low envelope correlation coefficient of 0.00015 and a high diversity gain approaching 10 dB, and high isolation of 34.5, 22, and 30 dB, in the tri-band. This proposed design is confirmed with experimental measurements and offers a promising candidate for multi-band use of mmWave communication systems. Full article

The growing demand for high-speed and high-capacity wireless communication has intensified the need for compact, wideband, and efficient MIMO antenna systems, particularly for 5G mid-band and UWB applications. This article presents a miniaturized dual and quad port MIMO antenna design optimized for 5G mid-band (n77/n78/n79/n96/n102) and Ultra-Wideband (UWB) applications without employing any decoupling structures between the radiating elements. The 2-port configuration features two closely spaced symmetric monopole elements (spacing < λ_max/2), promoting efficient use of space without degrading performance. An FR4 substrate (εr = 4.4) is used for fabrication with a compact size of 30 × 41 × 1.6 mm³. This layout is extended orthogonally and symmetrically to form a compact quad-port variant with dimensions of 60 × 41 × 1.6 mm³. Both designs offer a broad operational bandwidth from 2.6 GHz to 10.8 GHz (8.2 GHz), retaining return loss (S_XX) below −10 dB and strong isolation (S_XY < −20 dB at high frequencies, <−15 dB at low frequencies). The proposed MIMO antennas demonstrate strong performance and excellent diversity characteristics. The two-port antenna achieves an average envelope correlation coefficient (ECC) of 0.00204, diversity gain (DG) of 9.98 dB, and a mean effective gain difference (MEG_ij) of 0.3 dB, with a total active reflection coefficient (TARC) below −10 dB and signal delay variation under 0.25 ns, ensuring minimal pulse distortion. Similarly, the four-port design reports an average ECC of 0.01432, DG of 9.65 dB, MEG_ij difference below 0.3 dB, and TARC below −10 dB, confirming robust diversity and MIMO performance across both configurations. Full article

Computer-Aided Design (CAD) plays a critical role in modern engineering education by supporting technical accuracy and fostering innovation in design. This study compares the performance of beginner CAD users employing general-purpose AutoCAD 2025 with those using the specialized AutoCAD Mechanical 2025. Fifty undergraduate mechanical engineering students, all with less than one year of CAD experience and no prior exposure to AutoCAD Mechanical, were randomly assigned to complete six mechanical drawing tasks using one of the two software environments. Efficiency was evaluated through command usage, frequency, and task completion time, while creativity was assessed using a rubric covering originality, functionality, tool proficiency, and graphical quality. Results show that AutoCAD Mechanical significantly improved workflow efficiency, reducing task execution time by approximately 50%. Creativity scores were also notably higher among users of AutoCAD Mechanical, particularly in functionality and tool usage. These gains are attributed to automation features such as parametric constraints, standard part libraries, and automated dimensioning, which lower cognitive load and support iterative design. The findings suggest that integrating specialized CAD tools into engineering curricula can enhance both technical and creative outcomes. Limitations and future research directions include longitudinal studies, diverse user populations, and exploration of student feedback and tool adaptation. Full article

Integrated Reporting (IR) has gained prominence as a comprehensive approach to corporate disclosure, yet theoretical clarity is still developing regarding how governance mechanisms shape IR quality and its relation to ESG risk ratings. Addressing this gap, this study explores the influence of board and audit committee characteristics on IR quality and whether an improved IR quality is associated with a lower ESG risk. Drawing on different theories, this research examines how governance structures enhance transparency and accountability in line with societal expectations. Based on panel data from 158 firms across four years (2019–2022), a random effects Panel EGLS regression model is employed along with an endogeneity check. Findings show that board independence and the presence of women members significantly enhance the IR quality, while board size is not a determining factor. Similarly, audit committee independence and meeting frequency positively influence the IR quality, whereas committee size does not. Furthermore, firms with a higher IR quality demonstrate significantly lower ESG risk scores. These results underscore the theoretical proposition that effective governance improves disclosure credibility and reduces information asymmetry. This study suggests that reinforcing board independence and diversity can enhance reporting quality and stakeholder trust, offering a strategic path toward more sustainable and transparent corporate behavior. Full article

Hydropower’s ability to start up and shut down quickly, combined with its flexible regulation characteristics, effectively alleviates frequency fluctuations caused by new energy sources, ensuring the safe and stable operation of the power system. However, during peak-frequency regulation tasks, the transition processes associated with the startup, shutdown, and load changes introduce frequent shocks to subsystems such as the hydro-turbine, governor, and diversion systems. These shocks pose significant challenges to the safe and stable operation of hydropower plants. Therefore, this study constructs a coupled hydraulic–mechanical–electrical model that incorporates the diversion system, hydro-turbine, governor, generator, and load, based on operational data from a real-world hydropower plant in China. The load increase transition process is selected for parameter sensitivity analysis to evaluate the influence of various structural, operational, and control parameters on unit stability and to identify key parameters affecting stability. The results indicate that the initial load exhibits the highest sensitivity to inversion power peak and rotational speed overshoot, with sensitivity values of 0.14 and 0.0038, respectively. The characteristic water head shows the greatest sensitivity to the inversion power peak time and rotational speed peak time, with values of 0.31 and 0.43, respectively. Additionally, the integration gain significantly influences the rotational speed rise time, with a sensitivity value of 0.30. These findings provide a theoretical basis for optimizing the parameter selection in hydropower plants. Full article

Implant–prosthetic rehabilitation of the posterior edentulous maxilla is challenging due to inadequate bone volume resulting from alveolar ridge resorption and maxillary sinus pneumatization. This study explores the use of hyaluronic acid (HA) as a biomaterial in maxillary sinus elevation, particularly in combination with a fluid dynamic approach, as an alternative to traditional lateral approaches and granular biomaterials. Methods: A prospective study was conducted on 58 patients with posterior maxillary edentulism. Preoperative CBCT scans assessed residual bone height and sinus width. A minimally invasive surgical protocol utilizing a device for fluid-dynamic membrane elevation and injection of 2% cross-linked hyaluronic acid was employed, followed by simultaneous implant placement. Postoperative follow-up included a CBCT scan at 12 months to evaluate new bone height, measured mesially and distally. Implant stability was assessed using resonance frequency analysis at second-stage surgery. Results: A significant increase in bone height was observed at 12 months post-surgery, with an average bone gain of 7.5 mm. All 58 implants achieved primary stability, and no implant failures or signs of peri-implantitis were noted during the follow-up period. Higher bone gain was observed in wider sinuses. Conclusions: The fluid-dynamic transcrestal sinus floor elevation technique combined with hyaluronic acid appears to be a minimally invasive and effective method for achieving significant bone regeneration in the posterior maxilla, facilitating implant–prosthetic rehabilitation with potentially low risks and morbidity. Further large-scale studies are warranted to validate these findings across diverse clinical scenarios. Full article

This paper put forward a hybrid energy harvester for collecting RF and solar energy in quad-band (GSM-900/1800, ISM-2400 and WiMAX-3500). By introducing diverse parasitic structures, good impedance matching with unidirectional radiation is achieved in the multi-band. Below the solar antenna, a low-power rectifier circuit is employed to achieve broadband rectification. Under the input power of 0 dBm, and maximum RF-DC conversion efficiency of 56.94% is realized. Accordingly, the hybrid energy harvester collects RF and solar energy individually or simultaneously, and then converts it into DC for power supply. With a light intensity of 1500 lux, the solar cell obtains 1.732 mW, and the rectenna can harvest additional 0.37–0.405 mW power. The proposed RF–Solar energy harvester has the advantages of multi-frequency operation, high gain, and high energy harvesting conversion efficiency. Full article

To achieve multi-band coverage within limited space, reduce antenna types, and enhance communication capabilities, an eight-unit dual-band 5G MIMO antenna array is proposed based on a monopole structure. The antenna operates in two frequency bands (3.23–4.14 GHz and 4.31–5.3 GHz), covering the n78 and n79 bands for 5G applications. The dual-band and miniaturized design of the antenna elements is achieved through the slotting and branch-loading techniques. The orthogonal placement of corner antenna elements is implemented to reduce coupling and optimize spatial utilization, achieving isolation of over 16 dB between elements. The introduction of a metasurface structure further improved isolation by 2 dB and increased the peak gain of the antenna array to 11.95 dBi. A prototype is fabricated and tested, demonstrating the following performance metrics: isolation exceeding 18 dB, gain ranging from 6 to 12 dBi, envelope correlation coefficient below 0.05, channel capacity greater than 41 bps/Hz, diversity gain of approximately 10 dB, total active reflection coefficient below −24 dB, and radiation efficiency exceeding 72%. These results confirm the superior performance of the proposed antenna design. Full article

A wideband antenna with a relatively compact size along with a multiple input and multiple output (MIMO) configuration for millimeter wave applications is proposed in this work. The antenna offers a low profile and simple structure. First of all, an antenna is designed using Rogers RT/duroid 6002 (Rogers Corporation, Chandler, AZ, USA) with a thickness of 0.79 mm, offering wideband ranges from 21 to 35 GHz. Subsequently, the unit element is converted into a four-port MIMO antenna to improve the capacity of the system, resulting in a high data rate, which is critical for 5G as well as for devices operating in the mm wave spectrum. The proposed work exhibits total dimensions of 24 × 24 mm² and offers a peak gain of 8.5 dBi, with an efficiency of more than 80%. The MIMO performance parameters are also studied, and the antenna offers exceptional performance in terms of mutual coupling (S_ij) without inserting a decoupling structure, envelop correlation coefficient (ECC), and diversity parameters. The proposed MIMO antenna offers a minimum isolation of −25 dBi and an ECC of less than 0.018. All the other MIMO parameter values lie below the acceptable range. The High Frequency Structure Simulator (HFSS) EM software (v.19) tool is used to analyze the antenna and study its performance. The simulated outcomes are verified by fabricating a prototype, where the result offers a good comparison among both results. Moreover, the contrast in terms of different performance parameters is carried out amongst recent research articles, highlighting the key contribution of the presented design. A compact size antenna with a wideband, simplified structure, and stable performance throughout the working band is achieved; thus, it is a solid contender for mm wave applications and 5G devices. Full article

The simultaneous analysis of electrophysiological signals from various physiological systems, such as the brain, skeletal muscles, and cardiac muscles, has become increasingly necessary in both clinical and research settings. However, acquiring multiple modalities of electrophysiological data often necessitates the use of diverse, specialized technological tools, which can complicate the establishment of a comprehensive multimodal experimental setup. This paper introduces a prototype system, named the Multimodal–Multichannel Acquisition Module—MADQ, designed for the simultaneous acquisition of multimodal and multichannel electrophysiological and general-purpose signals. The MADQ comprises three distinct capturing blocks, each equipped with separate reference circuits, supporting a total of up to 40 electrophysiological input channels, alongside 4 channels of analog input and 4 channels of digital input signal. The system is capable of sampling frequencies up to 16 kHz. Key features of the MADQ include individually configurable bipolar recording, lead-off detection capability, and real-time online filtering. The system’s functional performance was characterized through metrics such as Input-Referred Noise (IRN), Noise-Free Bits (NFB), and Effective Number of Bits (ENOB) across varying gain and sampling frequencies. Preliminary experiments, conducted in a setup emulating a sleep study with auditory evoked potential detection, demonstrate the system’s potential for integration into multimodal experimental scenarios. Full article

Massive multi-input multi-output (massive MIMO) technology offers significant multiplexing gains and enhances transmission rates by efficiently utilizing available airspace resources. However, it requires each antenna to be paired with a separate radio frequency (RF) chain, which leads to the need for numerous RF chains in the system, resulting in high hardware costs, increased computational complexity, and elevated power consumption. To address this, antenna selection technology reduces the number of RF chains required, activating only the antennas that correspond to the available RF chains. Moreover, user scheduling provides multi-user diversity in multi-user massive MIMO systems. Therefore, this paper introduces a joint antenna selection and orthogonality-based user scheduling (JAS-OUS) algorithm aimed at maximizing the system sum rate. Furthermore, to tackle the issue of fairness, which is often overlooked by traditional user scheduling algorithms, a proportional fairness user scheduling (PFUS) approach is proposed. In this scheme, user weights are updated based on proportional fairness, ensuring a fair selection of users for communication in each time slot. Simulation results demonstrate that the JAS-OUS algorithm achieves robust performance across various configurations of transmitting antennas and users. Additionally, when combined with PFUS, the joint algorithm ensures more equitable user participation in communication without compromising the system sum rate. Full article

This paper presents Waveshift Augmentation 2.0 (WS 2.0), an enhanced version of the previously proposed Waveshift Augmentation (WS 1.0), a novel data augmentation technique inspired by light propagation dynamics in optical systems. While WS 1.0 introduced phase-based wavefront transformations under the assumption of an infinitesimally small aperture, WS 2.0 incorporates an additional aperture-dependent hyperparameter that models real-world optical attenuation. This refinement enables broader frequency modulation and greater diversity in image transformations while preserving compatibility with well-established data augmentation pipelines such as CLAHE, AugMix, and RandAugment. Evaluated across a wide range of tasks, including medical imaging, fine-grained object recognition, and grayscale image classification, WS 2.0 consistently outperformed both WS 1.0 and standard geometric augmentation. Notably, when benchmarked against geometric augmentation alone, it achieved average macro-F1 improvements of +1.48 (EfficientNetV2), +0.65 (ConvNeXt), and +0.73 (Swin Transformer), with gains of up to +9.32 points in medical datasets. These results demonstrate that WS 2.0 advances physics-based augmentation by enhancing generalization without sacrificing modularity or preprocessing efficiency, offering a scalable and realistic augmentation strategy for complex imaging domains. Full article

With the acceleration of urbanization process, the number of elevators in China has surged. Concurrently, the prevalence of older elevators has increased, leading to a rise in frequent malfunctions. In recent years, there has been a troubling frequency of elevator accidents resulting in casualties, which has had a negative social impact. The elevator braking system is crucial for ensuring the safe operation of the elevator, and brake failure is a significant contributor to elevator accidents. The failure modes of elevator brakes are complex and diverse, and the failure risk factors are mixed, correlated and unknown. Therefore, this paper is based on the Failure Mode and Effects Analysis (FMEA), focusing on the structural characteristics of the elevator brake to determine the equipment failure risk factors. Based on the accident prevention theory model (24Model) for comprehensive analysis of internal and external causes, this study identifies the comprehensive failure risk factors for elevator brakes. The study employs affiliation function to build the failure risk factor indicator system, the use of the Decision-making Trial and Evaluation Laboratory (DEMATEL) and Interpretative Structural Modeling (ISM) methods to analyze the hierarchical structure and internal relationship between the factors. Based on the research results, the factors contributing to the failure of elevator drum brakes can be identified and the interrelationships among these factors can be systematically elucidated. This analysis can serve as a valuable tool in pinpointing critical areas for routine elevator maintenance and upkeep, with the aim of minimizing the likelihood of drum brake malfunctions. Furthermore, the insights gained can inform the design and implementation of elevator monitoring and management systems, enabling a clearer focus on pertinent factors. Ultimately, this study furnishes a theoretical framework for the prevention and mitigation of such accidents. Full article

This work presents a compact four-port MIMO antenna with each radiator consisting of a conventional two-monopole array fed at a single point by a coplanar line and reactively loaded with a stub. The incorporation of a T-stub-loaded tuning technique significantly improves the radiating element’s impedance, leading to deeper port coupling, a broader bandwidth, and an increased electrical length. Consequently, the operating frequency is substantially lower compared to a standalone radiator. By implementing this configuration with two monopoles of different lengths fed at the same end, an ultra-wideband effect is achieved. By placing four of these stub-loaded monopole arrays in an axial symmetric configuration, a MIMO antenna array is formed. The proposed MIMO array operates from 2.89 GHz to 12 GHz, exhibiting a TARC of less than −10 dB, an ECC of less than 0.002, an average diversity gain of 9.999, and port isolations are within a threshold from −18 dB to −50 dB over the entire bandwidth. The array’s footprint is 32 × 32 mm², equivalent to 0.083${\lambda }_0^2$ at the lower cutoff frequency. Full article