Search Results (41)

In recent years, industrial systems and power electronic equipment have imposed increasingly stringent requirements on power quality, and therefore, the realization of a high-quality power supply has garnered extensive research attention. Selective harmonic elimination pulse width modulation (SHEPWM) features superior harmonic suppression performance and can effectively attenuate specific sub-harmonics; however, solving the associated system of nonlinear transcendental equations remains a critical challenge, primarily due to its inherent computational complexity and the risk of convergence to local optima. To address these limitations, we propose a multi-strategy enhanced chaotic black-winged kite algorithm (CMBKA). The proposed CMBKA integrates three synergistic optimization strategies: logistic–tent chaotic mapping for uniform population initialization, golden sine strategy to balance global exploration and local exploitation, and Monte Carlo perturbation to avoid convergence to local optima. In contrast to BKA, the proposed CMBKA achieves markedly higher calculation accuracy for switching angles, which is systematically validated on a five-level modified packed U-cell (MPUC) inverter platform. Experimental results verify that the proposed CMBKA achieves a lower total harmonic distortion (THD) than does the BKA, while the targeted specific sub-order harmonics are effectively suppressed to below 0.05%, with a maximum voltage deviation of 2.3% between the simulation results and experimental hardware tests. This work provides a high-precision SHEPWM solution for multilevel inverters, offering significant potential for renewable energy systems requiring minimal harmonic pollution and high power density. Full article

The integration of solar energy into smart grids requires high-efficiency power conversion to support grid stability. However, Partial Shading Conditions (PSCs) remain a primary obstacle by inducing multiple local maxima on P–V characteristic curves. This paper presents a hardware-aware and memory-enhanced Maximum Power Point Tracking (MPPT) approach based on a modified Dragonfly Algorithm (DA) for grid-connected microinverter-based photovoltaic (PV) systems. The proposed method utilizes a quasi-switched Boost-Switched Capacitor (qSB-SC) topology, where the DA is specifically tailored by combining Lévy-flight exploration with a dynamic damping factor to suppress steady-state oscillations within the qSB-SC ripple constraints. Coupling the MPPT stage to a seven-level Packed-U-Cell (PUC) microinverter ensures that each PV module operates at its independent Global Maximum Power Point (GMPP). A ZigBee-based Wireless Sensor Network (WSN) facilitates rapid data exchange and supports ‘swarm-memory’ initialization, matching current shading patterns with historical data to seed the population near the most probable GMPP region. This integration reduces the overall response time to 0.026 s. Hardware-in-the-loop experiments validated the approach, attaining a tracking accuracy of 99.32%. Compared to current state-of-the-art benchmarks, the proposed model demonstrated a significant improvement in tracking speed, outperforming the most recent 2025 GWO implementation (0.0603 s) by approximately 56% and conventional metaheuristic variants such as GWO-Beta (0.46 s) by over 94%.These results confirmed that the modified DA-based MPPT substantially enhanced the microinverter efficiency under PSC through cross-layer parameter adaptation. Full article

Parasitic infection is a major cause of infertility in small ruminants. This study aimed to assess the association between bioelectrical impedance analysis (BIA) measurements, testicular morphometrics, and sperm quality in parasitized goats. Thirty-eight intact mature Spanish bucks were allowed to graze on a naturally parasitically infected pasture for 3 months. Nineteen bucks were dewormed regularly (healthy group), while the other 19 bucks did not receive any anthelmintics (parasitized group). Fecal and blood samples were collected weekly to assess fecal egg count (FEC) and packed cell volume (PCV), respectively. Based on the size and morphology of the parasite eggs, they were presumptively identified as Haemonchus contortus. At the end of the grazing period, bucks were slaughtered, and testicles and epididymis were collected for analysis. In addition, BIA was applied to each testicle to measure series resistance (Rs) and reactance (Xc). Epididymal spermatozoa were retrieved and evaluated for motility, viability, morphology, and membrane and acrosome integrities. Data was analyzed using the Mann–Whitney U and Pearson Correlation Coefficient tests. The results showed that Rs (169.41 ± 1.76 Ω vs. 235.21 ± 20.21 Ω), Xc (37.55 ± 0.48 Ω vs. 52.08 ± 4.68 Ω), testicular and epididymis weights and lengths, sperm motility, viability, and membrane and acrosome integrities were lower (p < 0.0001) in parasitized than in healthy goats. Strong correlations (p < 0.001) were observed between Rs, sperm viability (r = 0.20), membrane integrity (r = 0.15), and acrosome integrity (r = 0.14), as well as between Xc and the same sperm parameters (r = 0.21, 0.18, and 0.16, respectively). In conclusion, our findings demonstrate that parasitic infection is associated with testicular health and subsequent epididymal sperm quality of goats. BIA can be utilized as an efficient tool to predict the impact of parasitic infection on testicular function in goats. Full article

In the high-performance environment of Formula Student Car racing, effective battery thermal management is crucial for safety, reliability, and performance. This work presents the design and validation of a lightweight, air-based Battery Cooling System (BCS) developed for a Formula Student vehicle. The system addresses the significant thermal loads generated by 528 Molicel P45B lithium-ion cells, arranged in a constrained U-shaped module layout. Using Computational Fluid Dynamics (CFD), the airflow geometry was optimized to deliver uniform cooling across all modules while minimizing aerodynamic drag. Simulations evaluated the system’s performance under various ambient temperatures (25 °C and 30 °C) and airflow velocities (from 16 m/s to 18 m/s), identifying the impact of duct geometry, internal air guides, and airflow distribution on thermal regulation. Results showed that, at nominal ambient temperature (25 °C), all monitored cells stayed below the 60 °C threshold required by FS regulations. At elevated ambient conditions (30 °C), regions above 60 °C appeared within the pack, revealing non-uniform cooling and reduced safety margin. These findings suggest that, while the system complies with current rules, additional design refinements are needed to enhance robustness under harsher conditions. Additionally, these results are specific to a Formula Student application under competition constraints and are not intended to be generalized to production EVs. Full article

In this study, a novel comparison between single phase 7-Level Packed U—Cell (PUC) inverter and single phase 9-Level Cross Switches Cell (CSC) inverter with Model Predictive Controller (MPC) for solar grid-tied applications is presented. Our innovation introduces a unique approach by integrating PV solar panels in PUC and CSC inverters in their two DC links rather than just one which increases power density of the system. Another key benefit for the proposed models lies in their simplified design, offering improved power quality and reduced complexity relative to traditional configurations. Moreover, both models feature streamlined control architectures that eliminate the need for additional controllers such as PI controllers for grid reference current extraction. Furthermore, the implementation of Maximum Power Point Tracking (MPPT) technology directly optimizes power output from the PV panels, negating the necessity for a DC-DC booster converter during integration. To validate the proposed concept’s performance for both inverters, extensive simulations were conducted using MATLAB/Simulink, assessing both inverters under steady-state conditions as well as various disturbances to evaluate its robustness and dynamic response. Both inverters exhibit robustness against variations in grid voltage, phase shift, and irradiation. By comparing both inverters, results demonstrate that the CSC inverter exhibits superior performance due to its booster feature which relies on generating voltage level greater than the DC input source. This primary advantage makes CSC a booster inverter. Full article

With the continuous development and innovation of thermal management technology for lithium-ion batteries, the advantages of direct immersion liquid cooling technology have become increasingly prominent. However, at present, there is relatively little research on immersion liquid cooling systems, and current research is still mainly focused on small-capacity battery systems. Therefore, taking a large-capacity battery pack as the research object, a new type of single-phase immersion liquid cooling system was designed. The battery pack has a charge and discharge rate of 1C, consists of 52 cells, and has a total capacity of 52.249 kWh. It was compared with traditional liquid cooling and static immersion liquid cooling. Then, the effects of the aperture of the flow distributor, the inlet flow rate of the cooling liquid, and the type of cooling liquid on the cooling performance of the dynamic immersion battery pack were discussed. The holes on the flow distribution plate are primarily designed to facilitate a relatively uniform distribution of incoming liquid flow. Our research found that compared with traditional liquid cooling and static immersion liquid cooling, the overall cooling performance of the dynamic immersion cooling system was significantly improved, with the maximum temperature T_max decreasing by 7.8 °C and 6.6 °C, the maximum temperature difference ΔT_max of the entire pack decreasing by 5.5 °C and 5.8 °C, and the maximum temperature difference U-DΔT_max between the top and bottom surfaces of the battery pack decreasing by 10.1 °C and 8.96 °C. An appropriate aperture had a positive impact on the cooling effect of the battery pack, with the best effect at a aperture of 4 mm. T_max and ΔT_max gradually decreased with an increase in the flow rate of the cooling liquid, with T_max decreasing from 42.3 °C to 31 °C and ΔT_max decreasing from 14.8 °C to 7.9 °C, but the rate of the temperature decrease gradually decreased. Deionized water in the cooling liquid had the best cooling effect, while ethyl silicone oil had the worst cooling effect. The novel single-phase immersion cooling system developed in this study serves as a valuable reference for the design of immersion liquid cooling systems in large-capacity battery packs, contributing to enhanced temperature uniformity and improved system safety. Full article

Accurate segmentation of cellular structures in whole slide images (WSIs) is essential for quantitative analysis in computational pathology. However, the complexity and scale of WSIs present significant challenges for conventional segmentation methods. In this study, we propose a novel hybrid deep learning framework that integrates three complementary approaches, YOLOv11, StarDist, and Segment Anything Model v2 (SAM2), to achieve robust and precise cell segmentation. The proposed pipeline utilizes YOLOv11 as an object detector to localize regions of interest, generating bounding boxes or preliminary masks that are subsequently used either as prompts to guide SAM2 or to filter segmentation outputs. StarDist is employed to model cell and nuclear boundaries with high geometric precision using star-convex polygon representations, which are particularly effective in densely packed cellular regions. The framework was evaluated on a unique WSI dataset comprising 256 × 256 image tiles annotated with high-resolution cell-level masks. Quantitative evaluations using the Dice coefficient, intersection over union (IoU), F1-score, precision, and recall demonstrated that the proposed method significantly outperformed individual baseline models. The integration of object detection and prompt-based segmentation led to enhanced boundary accuracy, improved localization, and greater robustness across varied tissue types. This work contributes a scalable and modular solution for advancing automated histopathological image analysis. Full article

The growing demand for high-power battery output in the ever-evolving electric vehicle and energy storage sectors necessitates the development of efficient thermal management systems. High-power lithium-ion batteries (LIBs), known for their outstanding performance, are widely used across various applications. However, effectively managing the thermal conditions of high-power battery packs remains a critical challenge that limits the operational efficiency and hinders broader market acceptance. The high charge and discharge rates in LIBs generate significant heat, and, as a result, inadequate heat dissipation adversely impacts battery performance, lifespan, and safety. This study utilized theoretical analysis, numerical simulations, and experimental methodologies to address these issues. Considering the anisotropic heat transfer characteristics of laminated pouch cells, this study developed a fluid–solid coupling simulation model tailored to the liquid-cooled structure of pouch battery modules, supported by an experimental test setup. A U-shaped “bathtub-type” cooling structure was designed for a 48 V/8 Ah high-power-density battery pack intended for start–stop power supply applications. This design aimed to resolve heat dissipation challenges, optimize the cooling efficiency, and ensure stable operation under varying conditions. During the performance assessments of the cooling structure conducted through simulations and experiments, extreme discharge conditions (320 A) and pulse charging/discharging cycles (80 A) at ambient temperatures of up to 45 °C were simulated. An analysis of the temperature distribution and its temporal evolution led to critical insights. The results showed that, under these severe conditions, the maximum temperature of the battery module remained below 60 °C, with temperature uniformity maintained within a 5 °C range and cell uniformity within 2 °C. Consequently, the battery pack meets the operational requirements for start–stop power supply applications and provides an effective solution for thermal management in high-power-density environments. Full article

Multilevel inverters have gained importance in modern power systems during the last few years because of their high power quality with lower THD. Various topologies developed include the packed U-cell inverter and its different modified versions that have emerged as a compact and efficient solution to distributed energy systems. Most of the available harmonic mitigation techniques, that is, passive filtering and individual optimization techniques, which include GA and PSO, are susceptible to a variety of shortcomings regarding their inherent complexity and inefficiency; hence, finding an appropriate convergence may be quite hard. This paper proposes a hybrid version of the GA-PSO algorithm that exploits the exploratory strengths of GA and the convergence efficiencies of PSO in determining the optimized switching angles for SHM techniques applied to modified five-level and seven-level PUC inverters. By utilizing the multi-objective optimization method, the approach minimizes THD while keeping voltage and efficiency constraints. Simulated in MATLAB/Simulink, the results were experimentally verified using hardware-in-the-loop testing on OP5700. A large THD reduction in both MPUC7 (11.68%) and MPUC5 (17.61%) was obtained. The proposed hybrid algorithm outperformed the standalone approaches of GA and PSO with respect to robustness and with precise harmonic suppression. Other appealing features are reduced computational complexity and improved waveform quality; hence, the method is highly suitable for both grid-tied and standalone renewable energy applications. This work lays a basis for efficient inverter designs that can adapt well under dynamic load conditions. Full article

Background: Trauma has a profound impact on mortality as well as short- and long-term health outcomes. For trauma patients to receive medical care in a timely manner, early identification and risk assessment are essential. The Geriatric Trauma Outcome Score (GTOS), which was created by combining age, the Injury Severity Score (ISS), and the requirement for packed red blood cell transfusion, has proven to be a valuable prognostic tool for elderly trauma patients, though its applicability to general trauma patients is still understudied. Methods: This retrospective study analyzed data from the Trauma Registry System at a Level I trauma center in southern Taiwan, covering the period from 1 January 2009 to 31 December 2021. This study included 40,068 trauma patients aged 20 years and older. Statistical analyses included chi-square tests, ANOVA, Mann–Whitney U tests, and multivariate analyses to identify independent risk factors for mortality. The predictive performance of the GTOS was assessed using the area under the curve (AUC) of the receiver operating characteristic curve. Results: The final study population included 40,068 patients, with 818 deaths and 39,250 survivors. Deceased patients had higher GTOS scores (mean 132.8 vs. 76.1, p < 0.001) and required more blood transfusions (mean 4.0 vs. 0.3 units, p < 0.001) compared to survivors. The optimal GTOS cut-off value for predicting mortality was 104.5, with a sensitivity of 82.6% and a specificity of 84.3% (AUC = 0.917). A high GTOS score was associated with increased mortality (9.6 vs. 0.4%, p < 0.001) compared with a low GTOS score, even after adjusting for confounding factors (adjusted mortality rate of 2.86, p < 0.001), and a longer hospital stay (14.0 vs. 7.7 days, p < 0.001). Conclusions: The GTOS is a valuable prognostic tool for predicting mortality in trauma patients, providing a simple and rapid assessment method. Its high predictive accuracy supports its use in broader trauma patient populations beyond the elderly. Further studies are recommended to refine and validate the GTOS in diverse trauma settings to enhance its clinical utility. Full article

Background/Objectives: The demographic shift towards an aging population necessitates a reevaluation of surgical interventions like coronary artery bypass grafting (CABG) in octogenarians. This study aims to elucidate the outcomes of CABG in octogenarians with heart failure and reduced ejection fraction (HFrEF), a group traditionally considered at high risk for such procedures. Methods: Conducted across four academic hospitals in Germany from 2017 to 2023, this retrospective multicenter study assessed 100 patients (50 octogenarians ≥80 years and 50 non-octogenarians <80 years) with HFrEF undergoing isolated CABG. Through propensity score matching, the study aimed to compare the incidence of major adverse cardiac and cerebrovascular events (MACCEs), as well as other clinical endpoints, between the two groups. Statistical analyses included chi-square, ANOVA, Mann–Whitney U test, Cox regression, and logistic regression, aiming to identify significant differences in outcomes. Results: The study revealed no significant difference in the combined incidence of MACCEs between octogenarians and non-octogenarians (OR: 0.790, 95% CI: 0.174–3.576, p = 0.759). Mortality rates were similar across groups (7% each, p = 1.000), as were occurrences of postoperative myocardial infarction (2% each, p = 1.000) and stroke (3% total). Secondary outcomes like delirium (17% total, no significant age group difference, p = 0.755), acute kidney injury (18% total, p = 0.664), and the need for dialysis (14% total, p = 1.000) also showed no differences between age groups. Interestingly, non-octogenarians required more packed red blood cells during their stay (p = 0.008), while other postoperative care metrics, such as hospital and ICU length of stay and ventilation hours, were comparable across groups. Conclusion: This multicenter study highlights that CABG is a viable and safe surgical option for octogenarians with HFrEF, challenging prior assumptions about the elevated risks associated with performing this procedure in older patients. The absence of significant differences in the incidence of MACCEs and other postoperative complications across age groups emphasizes the importance of careful patient selection and perioperative management. These findings advocate for a more inclusive approach to surgical treatment for octogenarians with HFrEF, suggesting that age alone should not be a determinant for CABG eligibility. This study contributes critical insights into optimizing care for a high-risk demographic, indicating a need for tailored guidelines that accommodate the aging population with complex cardiac conditions. Full article

This article presents a novel hybrid three-phase multilevel topology with a hybrid modulation and a control strategy for lower-medium voltage front-end converters. The proposed topology consists of a series arrangement of a three-phase full bridge and a packed U-cell. Each phase leg of the circuit comprises eight active switches and two DC link sources, which are connected to a shared DC bus voltage source, thus generating seven levels of output voltage. The active switches of the proposed topology are categorized based on voltage stresses and controlled using a low-frequency space vector PWM and high-frequency alternative phase opposition disposition PWM techniques. To validate the proposed topology and demonstrate the performance and effectiveness of the hybrid modulation and control schemes, simulations in MATLAB/Simulink and experiments on a custom-designed laboratory prototype have been carried out, and the results are discussed in detail. Moreover, a comprehensive comparison has been conducted among the relevant topologies, which reveals several advantages that include a reduced voltage and a current total harmonic distortion (THD) of 11.28% and 1.76%, respectively, minimized switch loss by 10.3 kW, improved efficiency by 0.26%, and decreased the component count with two levels increased in the output voltage. Full article

The Modular Multilevel Converter (MMC) is a promising converter for medium-/high voltage applications due to its various features. The waveform quality could be enhanced further by expanding the number of generated voltage levels, which increases the number of submodules (SMs); however, this improvement enlarges the size and cost of the converter, posing a persistent challenge. Hence, there exists a trade-off between power quality and the size and complexity of the converter. To verify the performance of such a complex converter and to validate the effectiveness of the control system, especially in the absence of a physical system, Real-Time (RT) simulation becomes crucial. However, the large number of components of a MMC creates important numerical challenges and computational difficulties in RT simulation. This paper proposes a grid-connected MMC employing a Z Packed U-Cell converter as a SM to generate a higher number of voltage levels while minimizing the required number of SMs. The ZPUC-MMC is implemented on an FPGA-based RT simulation platform using Electric Hardware Solver to reduce computational burden and simulation time, while improving the accuracy of the obtained results. Conventional controllers of MMCs are applied to assess the effectiveness and robustness of the proposed system during steady-state and dynamic operations. Full article

In this study, a wind energy conversion system is designed using a three-phase permanent magnet synchronous generator, a six-diode bridge rectifier, a DC–DC boost converter, an inverter, and a load. The proposed inverter is a Packed U-Cell-based multilevel inverter having five or seven voltage levels at the output. It is also a topology that is not widely used in wind energy applications. Furthermore, a dual-mode PI-PI control technique is proposed to regulate the auxiliary capacitor voltage in the PUC MLI. The inverter is designed and simulated for a permanent magnet synchronous generator-based variable speed wind energy conversion system. Additionally, the design and experimental application of the proposed system is carried out in a laboratory environment. In the experimental application, the rated voltage of the Packed U-Cell multilevel inverter is chosen as 45 V. The switching frequency of the multilevel inverter is set to 4 kHz, and a generator with rated power of 700 W is selected. The output voltage of the generator is varied between 25 V and 35 V through an induction motor. This varying voltage is increased to 45 V using a DC–DC boost converter. Finally, it is observed that the power generated by the permanent magnet synchronous generator is successfully transferred to the load and the designed system operates with low harmonic content. Full article

In this study, a model predictive control (MPC) technique is applied to a packed-u-cell (PUC)-based dual-output bidirectional electric vehicle (EV) battery charger. The investigated topology is a 5-level PUC-based power factor correction (PFC) rectifier allowing the generation of two levels of DC output voltages. The optimization of the MPC cost function is performed by reducing the errors on the capacitors’ voltages (DC output voltages) and the grid (input) current. Moreover, the desired capacitors’ voltages and peak value of the input current are considered within the designed cost function to normalize the errors. In addition, an external PI controller is used to generate the amplitude of the grid current reference based on the computed errors on the capacitors’ voltages. The presented simulation and experimental results recorded using a 1 kW laboratory prototype demonstrate the high performance of the proposed approach in rectifying the AC source at different levels (dual rectifier), while drawing a sinusoidal current from the grid with low THD (around 4%) and ensuring a unity power factor operation. Full article