Search Results (2,934)

The decoupling properties and low-inertia characteristics of large-scale wind power have heightened concerns regarding power grid frequency stability, particularly as modern power systems impose stringent frequency regulation requirements on wind integration, leading to an increased complexity of frequency response characteristics under fault conditions. To address this challenge in high-wind-penetration grids, this paper proposes a post-fault frequency dynamics analysis method capable of concurrently accommodating multi-wind-speed scenarios through three key innovations: the linearization of traditional AC system components (including network equations, composite load models, and generator prime mover-governor systems) to establish nodal power increment equations; the development of wind turbine frequency regulation models under diverse wind conditions using small-signal analysis, incorporating regional operational disparities and refined by information entropy-based reliability quantification for adaptive parameter adjustment; and the derivation of the system state equation for post-fault frequency response using wide-area measurement system (WAMS) data, yielding an analytical model that captures region-specific regulation characteristic disparities for physically faithful frequency analysis. Validation via tailored IEEE 39-node simulations convincingly demonstrates the method’s effectiveness and superiority in handling fault-induced transients and wind variability. Full article

Background: Male infertility is evaluated using standard semen parameters. However, these criteria offer limited insight into sperm functionality and poorly predict natural fertility or assisted reproductive technology (ART) outcomes. Methods: In this study, the expression levels of three genes (AURKA, HDAC4, and CARHSP1) involved in mitosis regulation, epigenetic modulation and early embryonic development, were measured by RT-qPCR in sperm samples (training dataset). For each gene, thresholds of normal and reduced expression were established by biostatistical modeling and combined with the number of motile spermatozoa to develop the Spermatozoa Function Index (SFI). Results: The ROC analysis was used to interpret the SFI values: SFI > 320 (normal), 290–320 (intermediate), and <290 (low). Then, this index was validated using 627 fresh semen samples from 25- to 60-year-old men at our ART center. Based on the World Health Organization criteria, 54.5% of the 627 sperm samples were normospermic, 8.8% showed oligo-astheno-teratospermia, and 36.6% had one or two abnormal parameters. According to the SFI values, 41% of sperm samples displayed normal expression, 55.9% low expression, and 4.1% intermediate expression. Only 57% of the 342 normospermic samples had normal SFI values and 37% had low SFI values. Among the 81 samples with stringent normal criteria (≥50 million/mL, ≥50% total motility, ≥14% normal morphology), 67.9% displayed normal SFI and 22.2% low SFI values. These findings suggest that even sperm with normal parameters may harbor dysfunctions. Conclusions: Our data highlight a gene signature with strong discriminatory power and promising diagnostic value for detecting subclinical sperm defects and improving male infertility assessment. Full article

This paper presents a Vibration-based Track Anomaly Detection (VTAD) system designed for real-time monitoring of urban tram infrastructure. The novelty of VTAD is that it converts existing public transport vehicles into distributed mobile sensor platforms, eliminating the need for specialized diagnostic trains. The system integrates low-cost micro-electro-mechanical system (MEMS) accelerometers, Global Positioning System (GPS) modules, and Espressif 32-bit microcontrollers (ESP32) with wireless data transmission via Message Queuing Telemetry Transport (MQTT), enabling scalable and continuous condition monitoring. A stringent ±6σ statistical threshold was applied to vertical vibration signals, minimizing false alarms while preserving sensitivity to critical faults. Field tests conducted on multiple tram routes in Zagreb, Croatia, confirmed that the VTAD system can reliably detect and locate anomalies with meter-level accuracy, validated by repeated measurements. These results show that VTAD provides a cost-effective, scalable, and operationally validated predictive maintenance solution that supports integration into intelligent transportation systems and smart city infrastructure. Full article

The Intact Proviral DNA Assay (IPDA) is widely used to quantify genome-intact HIV proviruses in people living with HIV, but viral sequence diversity has been observed to cause assay failures due to primer/probe mismatches. Adapted for subtype C, IPDA-BC is a modified version of the IPDA validated on South African HIV-1 subtype C. India is also impacted by subtype C, but IPDA performance within-subtype across geographical regions is not well studied. We analyzed Indian (IN) and South African (ZA) subtype C sequences in silico, hypothesizing that IPDA-BC may underperform with IN viruses. Primer/probe binding was predicted using three increasingly stringent nucleotide mismatch criteria, whose sensitivity and specificity were evaluated against experimental IPDA outcomes. Phylogenetic analyses confirmed that IN and ZA subtype C sequences form distinct clusters with significant compartmentalization (p < 0.003). Across criteria, up to 6–10% decreases in primer/probe binding were observed in IN versus ZA, with the env forward primer being the most affected. These criteria showed low sensitivity (18–53%) and variable specificity (67–100%) in predicting experimental outcomes. In conclusion, even within subtype, HIV-1 variation across geographical regions may impact IPDA performance, underscoring the need for improved predictive models to guide assay design for global HIV cure research. Full article

Synthetic Aperture Radar (SAR) three-dimensional (3D) imaging has considerable potential in disaster monitoring and topographic mapping. Conventional 3D SAR imaging techniques for unmanned aerial vehicle (UAV) formations require rigorously regulated vertical or linear flight trajectories to maintain signal coherence. In practice, however, restricted collaboration precision among UAVs frequently prevents adherence to these trajectories, resulting in blurred scattering characteristics and degraded 3D localization accuracy. To address this, a 3D reconstruction technique based on horizontal-cross configurations is proposed, which establishes a new theoretical framework. This approach reduces stringent flight restrictions by transforming the requirement for vertical baselines into geometric flexibility in the horizontal plane. For dual-UAV subsystems, a geometric inversion algorithm is developed for initial scattering center localization. For multi-UAV systems, a multi-aspect fusion algorithm is proposed; it extends the dual-UAV inversion method and incorporates basis transformation theory to achieve coherent integration of multi-platform radar observations. Numerical simulations demonstrate an 80% reduction in implementation costs compared to tomographic SAR (TomoSAR), along with a 1.7-fold improvement in elevation resolution over conventional beamforming (CBF), confirming the framework’s effectiveness. This work presents a systematic horizontal-cross framework for SAR 3D reconstruction, offering a practical solution for UAV-based imaging in complex environments. Full article

Increasingly stringent energy directives of the European Union, combined with rising cooling demands due to climate change, urge the investigation of energy-efficient cooling solutions. Free cooling offers a viable approach to reducing energy consumption. However, its effectiveness and applicability across different building types remain insufficiently established. This study aims to minimise mechanical cooling energy demand through the implementation of enhanced free cooling (EFC) as an operational control strategy in office, residential, and small commercial buildings. The introduction of the efficiency of EFC (η_fc) supports this analysis by quantifying how effectively EFC exploits free cooling potential in defined thermal and mechanical conditions based on an analytical approach supported by simplified simulations (in Microsoft Excel). The case study indicates that the east-oriented office building with a 40% glazing ratio achieves the highest cooling energy savings (49.63%) on the target summer day. For the residential building, savings are lower (37.78%) but more stable across the hot and the extremely hot days. The results further show that the influence of building orientation diminishes as external temperature increases, while higher glazing ratios stabilise η_fc across the examined thermal conditions. Analysis of the connection between air exchange rate and mechanical cooling energy savings identifies a critical resistance point (n_opt), defined as the ventilation rate beyond which no further cooling energy savings occur. The results enable practical applications in building operation and support both improved energy efficiency and the advancement of sustainable HVAC design. Full article

A segment of the machine tool industry in Taiwan specializes in manufacturing equipment tailored to the semiconductor sector. Due to the stringent quality requirements inherent in semiconductor manufacturing processes, the machine tools employed in these processes are also subject to correspondingly rigorous quality standards. In fact, a machine tool is assembled from hundreds of individual components, each of which must meet the required standards to ensure that the final product adheres to overall quality requirements. Similarly, each component possesses multiple quality characteristics, all of which must individually satisfy the specified criteria to guarantee that the component achieves the required quality level. Clearly, without a comprehensive evaluation model, ensuring final product quality is difficult. To address this practical issue, this study employed the Process Capability Index (PCI), the most widely used process capability index in the industry, and based on statistical verification principles, constructed a quality assessment and analysis model applicable to products with multiple quality characteristics. This approach enables process engineers to simultaneously evaluate all product quality characteristics and determine whether they meet the desired quality standards. For products that do not meet the expected quality standards, improvement directions are proposed, and improvement decisions are made based on cost and economic benefits, thereby ensuring final product quality. This study concludes with a real-world case study to illustrate the application of the proposed model, making it easier for relevant industries to apply the model. Full article

Advances in motor technology and the application of distributed electric propulsion systems have greatly promoted the development of electric vertical take-off and landing aircraft. As a critical safety component of eVTOL aircraft, the motor system design must satisfy both performance requirements and stringent airworthiness standards. This paper studies the lift–thrust unit drive motor system of an eVTOL aircraft and proposes an architecture that utilizes analytical redundancy to enhance system-level reliability. This paper focuses on threshold optimization in analytical redundancy systems. Through simulations and reliability analyses, the performance of the analytical redundancy system is quantified, with false alarm and missed detection probabilities evaluated, fault detection thresholds optimized, and overall system reliability enhanced analytical redundancy systems is improved. Simulation and calculation results demonstrate that the proposed fault detection method can effectively meet the requirements for rapid detection and achieve optimal reliability at the given optimal threshold. Full article

Background/Objectives: The role of daratumumab, lenalidomide, and dexamethasone (DRd) in autologous stem cell transplantation (ASCT)-eligible patients with multiple myeloma (MM) after first-line bortezomib, cyclophosphamide, and dexamethasone (VCd) treatment is not yet established. Methods: We retrospectively evaluated ASCT-eligible patients with MM who received second-line therapy with DRd after initial induction therapy with VCd between 2017 and 2023 (salvage group). For comparison, patients who successfully underwent per-protocol treatment with VCd induction, followed by ASCT during the same period, were selected (control group). Results: Eight patients with a median age of 61 years (range, 36–68 years) were included in the salvage group. After a median of 5 DRd cycles, the best response was partial response (PR) in two patients (25%) and a very good partial response (VGPR) in six (75%). All patients underwent ASCT, resulting in PR in one (13%), VGPR in four (50%), and stringent complete response in three (38%). Measurable residual disease (MRD) assessed using multicolor flow cytometry was negative in four patients (50%). The controls included thirteen patients with a median age of 60 years (range, 44–64 years). While most patients in both groups received various post-ASCT therapies, the post-ASCT 2-year time to the next treatment rate was slightly better in the salvage group than in the control group (88% vs. 49%, p = 0.089). However, hypogammaglobulinemia was more common in the salvage group (75% vs. 15%, p = 0.018). Conclusions: This small case series suggests that DRd is promising for ASCT-eligible patients with MM after VCd failure. Full article

Object detection in Unmanned Aerial Vehicle (UAV) imagery remains challenging due to the prevalence of small targets, complex backgrounds, and the stringent requirement for real-time processing on computationally constrained platforms. Existing methods often struggle to balance detection accuracy, particularly for small objects, with operational efficiency. To address these challenges, this paper proposes YOLO-CAM, an enhanced object detector based on YOLOv5n. First, a novel Combined Attention Mechanism (CAM) is integrated to synergistically recalibrate features across both channel and spatial dimensions, enhancing the network’s focus on small targets while suppressing background clutter. Second, the detection head is strategically optimized by introducing a dedicated high-resolution head for tiny targets and removing a redundant head, thereby expanding the detectable size spectrum down to small pixels with reduced parameters. Finally, the CIoU loss is replaced with the inner-Focal-EIoU loss to improve bounding box regression accuracy, especially for low-quality examples and small objects. Extensive experiments on the challenging VisDrone2019 benchmark demonstrate the effectiveness of our method. YOLO-CAM achieves a mean Average Precision (mAP0.5) of 31.0%, which represents a significant 7.5% improvement over the baseline YOLOv5n, while maintaining a real-time inference speed of 128 frames per second. Comparative studies show that our approach achieves a superior balance between accuracy and efficiency compared to other state-of-the-art detectors. The results indicate that the proposed YOLO-CAM establishes a new way for accuracy–efficiency trade-offs in UAV-based detection. Due to its lightweight design and high performance, it is particularly suitable for deployment on resource-limited UAV platforms for applications requiring reliable real-time small object detection. Full article

To meet the requirements of integrated accelerometers for a high-precision reference voltage under wide supply voltage range, high current drive capability, and low power consumption, this paper presents a bandgap reference operational amplifier (op-amp) circuit implemented in CMOS/BiCMOS technology. The proposed design employs a folded-cascode input stage, a push–pull Class-AB output stage, an adaptive output switching mechanism, and a composite frequency compensation scheme. In addition, overcurrent protection and low-frequency noise suppression techniques are incorporated to balance low static power consumption with high load-driving capability. Simulation results show that, under the typical process corner (TT), with VDD = 3 V and T = 25 °C, the op-amp achieves an output swing of 0.2 V~2.8 V, a low-frequency gain of 102~118 dB, a PSRR of 90 dB at 60 Hz, overcurrent protection of ±25 mA, and a phase margin exceeding 48.8° with a 10 μF capacitive load. Across the entire supply voltage range, the static current remains below 150 μA, while maintaining a line regulation better than 150 μV/V and a load regulation better than 150 μV/mA. These results verify the feasibility of achieving both high drive capability and high stability under stringent power constraints, making the proposed design well-suited as a bandgap reference buffer stage for integrated accelerometers, with strong engineering practicality and potential for broad application. Full article

Suaeda salsa, an annual herb belonging to the genus Suaeda within the Chenopodiaceae family, is highly salt-tolerant and can thrive in large quantities on saline and alkaline soils. This study presents a novel fermentation technique to produce Suaeda tea, utilizing a synergistic blend of microbial agents: Kluyveromyces marxianus, Komagataeibacter europaeus, and Acetobacter schutzenbachii. The resulting tea demonstrates a potent antioxidant capacity, with a hydroxyl radical scavenging rate of 64.2% and an exceptional 1,1-diphenyl-2-picrylhydrazyl radical scavenging capacity of 83.3%, along with increased ferric ion reduction/antioxidant power (FRAP) reducing power (1.82), indicating its superior antioxidant profile. Through the comparison of different microbial strain combinations under varying process parameters such as fermentation temperature and duration, the experiment revealed that fermentation at 37 °C for 24 h results in the highest concentrations of tea polyphenols (TPs) (≥10.87 mg/mL) and free amino acids (26.32 mg/100 mL). The quality of the fermented Suaeda tea meets the stringent GB/T 21733-2008 standards for tea beverages, exhibiting excellent physicochemical indices and sensory attributes. The antioxidant efficacy of the fermented Suaeda tea persists significantly throughout a 180-day duration. The optimization of the fermentation process for Suaeda tea not only provides a theoretical framework for large-scale production but also establishes a foundation for Suaeda salsa in the tea beverage sector. This innovation enriches the market with a diverse range of health-promoting teas, catering to the growing consumer demand for nutritious and beneficial beverages. Full article

Cannabis plants are susceptible to microbial contamination, including fungi capable of producing harmful mycotoxins. The presence of these toxins in cannabis products poses serious health risks, especially when used for medical purposes in immunocompromised people. This study evaluated the presence of fungi and mycotoxins in dried cannabis buds following gamma irradiation, using culture-based techniques, PCR/qPCR, and ELISA. Irradiation significantly reduced fungal and bacterial loads, eliminating culturable bacteria but did not achieve complete sterilization. Viable spores of toxigenic fungal genera, such as Aspergillus, Penicillium, and Fusarium, persisted. Sequencing of ITS amplicons revealed dominant mycotoxigenic fungi in non-irradiated (NR), irradiated (IR) and licensed producer (LP) samples, while next-generation sequencing (NGS) revealed additional non-culturable toxigenic species. PCR/qPCR detected biosynthetic genes for aflatoxins, trichothecenes, ochratoxins, and deoxynivalenol across all samples, with gene copy numbers remaining stable post-irradiation, suggesting DNA damage without full degradation. ELISA confirmed aflatoxin, ochratoxin, DON, and T2 toxins in both IR and LP samples at variable concentrations. While LP samples showed lower microbial counts and gene abundance, residual DNA and toxins were still detected. Our study shows that while irradiation decreases microbial loads, it does not completely remove toxigenic fungi or their metabolites. Ensuring the safety of cannabis products necessitates a multifaceted assessment that incorporates cultural, molecular, and immunological techniques, in parallel with more stringent microbial standards during production stage. Full article

Advanced manufacturing places stringent demands on measurement technologies, requiring ultra-high precision, non-contact operation, high throughput, and real-time adaptability. Optical metrology, with its distinct advantages, has become a key enabler in this context. This paper reviews optical metrology techniques from the perspective of precision manufacturing applications, emphasizing precision positioning and surface topography measurement while noting the limitations of traditional contact-based methods. For positioning, interferometers, optical encoders, and time-of-flight methods enable accurate linear and angular measurements. For surface characterization, techniques such as interferometry, structured light profilometry, and confocal microscopy provide reliable evaluation across scales, from large structures to micro- and nano-scale features. By integrating these approaches, optical metrology is shown to play a central role in bridging macroscopic and nano-scale characterization, supporting both structural assessment and process optimization. This review highlights its essential contribution to advanced manufacturing, and offers a concise reference for future progress in high-precision and intelligent production. Full article

Are environmental regulations the primary driver of rising electricity prices? Evidence from the Regional Greenhouse Gas Initiative (RGGI) suggests a more nuanced reality. This paper examines the impact of RGGI on wholesale and retail electricity prices using a difference-in-differences framework. We analyze three key policy events—the 2005 announcement, the 2009 implementation, and the 2014 adjustment of the emissions cap—drawing on detailed panel data from power plants in both RGGI and non-RGGI states. Our results indicate that wholesale electricity prices in RGGI states did not increase following the 2005 announcement relative to non-RGGI states. By contrast, retail electricity prices rose by about 11% in the short run, coinciding with electricity market restructuring, though this retail price gap declined over time. Over the subsequent decade, RGGI states achieved substantial reductions in CO₂ emissions alongside a transition to cleaner generation technologies. Importantly, the industry’s response to environmental regulation did not immediately affect electricity prices. However, as the emissions cap tightened, price effects became more pronounced: following the 2014 adjustment that reduced the cap to roughly 50% of its 2008 level, wholesale prices increased by 0.68 to 5.57 cents/kWh. These findings suggest that while the short-run effects of environmental regulation on electricity prices are limited, more stringent caps over time can lead to measurable price impacts. Full article