Search Results (45)

Soluble cutting fluids (SCFs) from metalworking processes pose significant treatment challenges. Here, SCFs were treated using a monopolar electrochemical (EC) system, using turning scrap generated from metalworking operations as the anode. The system was operated for 60 min under various conditions, including different anode materials, electrolyte addition, aeration, and initial pH. Treatment performance was evaluated in terms of chemical oxygen demand (COD_Cr) and total organic carbon (TOC) removal efficiencies and specific energy consumption (SEC) for COD_Cr removal. The Al scrap (20 g/L) showed the optimal overall performance, achieving COD_Cr and TOC removal efficiencies of 29.28% and 25.62%, respectively, with an SEC comparable to that of the Al electrode. Electrolyte addition improved the energy efficiency under all conditions, with NaNO₃ 10 mM yielding the lowest SEC (0.57 kWh/kg-COD_Cr), and aeration negatively affected both removal efficiency and energy consumption. Although acidic conditions (pH 2) resulted in high apparent removal, most of the reduction occurred during pre-treatment pH adjustment, and the highest energy efficiency was achieved at pH 7 (0.47 kWh/kg-COD_Cr). These results demonstrate that Al turning scrap is a promising alternative anode material for electrochemical treatment of SCFs with optimized electrolyte addition and operating pH enabling improved energy efficiency. Full article

This study proposes a three-dimensional forward modeling framework for geoelectric current distribution under high-voltage direct current (HVDC) monopolar operation. The proposed approach is based on a multi-resolution resistor network (MR-RN) discretization, in which gradient fusion interpolation is employed to suppress flux discontinuities at coarse–fine interfaces, and exterior equivalent boundary resistors are introduced to approximate open boundaries, enabling efficient and stable large-scale three-dimensional forward modeling. Compared with the traditional structured grid and finite element method (FEM), the proposed MR-RN achieves comparable accuracy while reducing computation time by up to 96% and the number of degrees of freedom by two orders of magnitude. Case studies on layered Earth, boundary extension, and substation–field coupling demonstrate that the MR-RN model maintains errors within 1–3%, confirming its suitability for large-scale HVDC ground return simulations and geoelectric safety assessment. Full article

Gasless Transaxillary Robotic Thyroidectomy (G-TART) has undergone significant refinement through the adoption of novel strategies to enhance surgical precision and safety. In this paper, we describe a novel technique that integrates dynamic endoscope repositioning, called the “swing technique”, with the use of a specialized intraoperative neuromonitoring (IONM) probe—Modena Robotic Probe—designed for robotic applications. The procedure, performed using the Da Vinci Xi system (Intuitive Surgical, Sunnyvale, CA, USA), incorporates intermittent IONM during recurrent laryngeal nerve (RLN) dissection. The swing technique involves real-time adjustment of the 30° endoscope between robotic ports to improve visualization within the confined transaxillary (TA) surgical field, particularly during contralateral dissection. Simultaneously, the Modena Robotic Probe, a custom monopolar stimulation probe developed in collaboration with Dr. Langer Medical GmbH for connection to the AVALANCHE^® SI2 neuromonitor, allows precise RLN mapping and verification throughout the operation. This approach could facilitate accurate anatomical tracking, minimize the risk of thermal or mechanical nerve injury, and enable safe navigation in a narrow operative TA tunnel. The adoption of advanced imaging techniques in conjunction with specialized robotic instrumentation may contribute to enhanced surgical safety and accuracy, emphasizing the importance of procedure-specific robotic approaches in thyroid surgery. Full article

The high rate of photovoltaic integration poses significant challenges in terms of violations of voltage limits in power grids. Additionally, the operational behavior of PV systems under fault conditions requires thorough investigation in receiving-end grids. This paper analyzes the dynamic coupling characteristics between reactive power and transient voltage in a receiving-end grid with high PV penetration and multiple HVDC infeeds, considering typical AC and DC fault scenarios. Voltage adaptability issues in PV generation systems are also examined. Through an enhanced sensitivity analysis method, the suppression capabilities of transient voltage peaks are quantified in the control parameters of low-voltage ride-through (LVRT) and high-voltage ride-through (HVRT) photovoltaic inverters. On this basis, a hierarchical optimization strategy for PV inverter control parameters is proposed to mitigate post-fault transient voltage peaks and improve the transient voltage response both during and after faults. The feasibility of the proposed method has been verified through simulation on a revised 10-generator 39-bus power system. Following optimization, the transient voltage peak is reduced from 1.263 to 1.098. This validation offers support for the reliable grid connection of the Henan Power Grid. In the events of the N-2 fault at 500 kV and Tian-zhong HVDC monopolar block fault, the post-fault voltage at each node remains below 1.1 p.u. This serves as evidence of a significant enhancement in transient voltage stability within the Henan Power Grid, demonstrating effective improvements in power supply reliability and operational performance. Full article

The ever-growing scale of offshore wind power integration has led coastal provincial power grids to face the common issue of insufficient AC grid structure capacity. An effective solution involves constructing an offshore–onshore mono–bipolar hybrid high voltage DC (HVDC) system by integrating an offshore wind monopolar HVDC with an onshore embedded bipolar HVDC. Firstly, the limitations of existing AC structures in coastal grids when undertaking offshore wind power integration are analyzed through N-1 security verification, and the applicability of conventional power evacuation approaches is assessed from both theoretical and practical engineering standpoints. Subsequently, an offshore–onshore mono–bipolar hybrid HVDC system is proposed. Meanwhile, based on operational requirements and the analysis of the structural features, a coordinated control strategy for the hybrid HVDC system under both symmetric and asymmetric operation modes is designed. Finally, a simulation model is built on the PSCAD/EMTDC platform to verify the feasibility of the hybrid HVDC system control strategy in the coastal power grid and the effectiveness of the system to improve the wind power consumption capacity of the coastal power grid. Full article

This study investigates the operational performance and optimization of a real greywater treatment system utilizing aluminum (Al)-based electrocoagulation (EC). The EC process was systematically evaluated and optimized through Response Surface Methodology (RSM) using the Box–Behnken Design (BBD), focusing on three critical parameters: pH, current density, and electrolysis time. Greywater samples collected from domestic sources were characterized by key physicochemical parameters including pH, COD, TSS, turbidity-ty, and electrical conductivity. The electrochemical treatment was conducted using a batch reactor equipped with Al electrodes in a monopolar configuration. Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDS), X-ray Diffraction (XRD), and Fourier-Transform Infrared Spectroscopy (FTIR) were employed to characterize both the electrodes and the generated sludge. Results revealed a maximum COD removal efficiency of 86.34% under optimized conditions, with current density being the most influential factor, followed by its significant interaction with pH. The developed quadratic model exhibited high predictive accuracy (R² = 0.96) and revealed significant nonlinear and interaction effects among the parameters. Sludge characterization confirmed the presence of amorphous aluminum hydroxide and oxyhydroxide phases, indicating effective coagulant generation and pollutant capture. The treated greywater met physicochemical criteria for non-potable reuse, such as agricultural irrigation, supporting resource recovery objectives. These findings demonstrate that EC is a low-waste, chemically efficient, and scalable process for decentralized wastewater treatment, aligning with the goals of sustainable chemical engineering. Full article

Background and Objectives: Modified radical mastectomy (MRM) is a common surgical procedure, with outcomes that are influenced by the instruments used in the operation. This meta-analysis aimed to compare “cold cutting” or “traditional” techniques and monopolar or bipolar electrocautery. Materials and Methods: A comprehensive search of five databases was conducted, with only studies of adult patients undergoing MRM in clearly defined groups selected. Data from 12 RCTs and 3 cohort studies summarizing 1372 participants was extracted and then synthesized using random-effects models. Risk of Bias was assessed for each of the included studies using the RoB-2 or ROBINS-I tool. Results: Scalpel or scissor use in dissection and flap raising was associated with a significantly lower risk of seroma formation (LogOR = −0.90, 95% CI: −1.26 to −0.54, p < 0.01). Conversely, electrocautery demonstrated advantages including reduced operative time (MD = −13.14 min, 95% CI: −19.58 to −6.70, p < 0.01) and decreased intraoperative blood loss (MD = −171.60 mL, 95% CI: −259.35 to −84.41, p < 0.01). No statistically significant differences were observed in total drain output (MD = −16.45 mL, 95% CI: −170.96 to 138.06, p = 0.83) or duration of drainage (MD = 0.41 days, 95% CI: −0.41 to 1.23, p = 0.32). Similarly, rates of infection, ecchymosis, and flap necrosis did not differ significantly between techniques. Conclusions: Electrocautery should be employed in patients who benefit from a shorter operative time and lower blood loss, while patients in better clinical condition should benefit from cold cutting techniques. Data on patient-reported outcomes and wound cytokine levels were sparse and inconsistent. This meta-analysis was registered in PROSPERO (ID: CRD420251059886). Full article

This study focuses on the design and optimization of a monopolar electrode configuration for the hybrid electrochemical treatment of real washing machine wastewater. A combined electrocoagulation (EC) and electro-oxidation (EO) system was optimized to maximize pollutant removal efficiency while minimizing energy consumption. The monopolar setup employed mixed metal oxide (MMO) and aluminum anodes, along with a stainless steel cathode, operating under controlled conditions with sodium chloride as the supporting electrolyte. An applied current density of 15 mA cm⁻² achieved 90% chemical oxygen demand (COD) removal, 98% surfactant degradation, complete turbidity reduction within 120 min, and pH stabilization near 8. Additionally, electrochemical disinfection achieved <2 MPN/100 mL, with no detectable phenols and the presence of organic anions such as oxalate and acetate. These results demonstrate the effectiveness of an optimized monopolar EC–EO system as a cost-efficient and sustainable strategy for wastewater treatment and potential water reuse. Further studies should focus on refining energy consumption and monitoring reaction by-products to enhance large-scale applicability. Full article

This paper presents a comprehensive review of High-Voltage Direct-Current (HVDC) systems, focusing on their technological evolution, fault characteristics, and advanced signal processing techniques for fault detection. The paper traces the development of HVDC links globally, highlighting the transition from mercury-arc valves to Insulated Gate Bipolar Transistor (IGBT)-based converters and showcasing operational projects in technologically advanced countries. A detailed comparison of converter technologies including line-commutated converters (LCCs), Voltage-Source Converters (VSCs), and Modular Multilevel Converters (MMCs) and pole configurations (monopolar, bipolar, homopolar, and MMC) is provided. The paper categorizes HVDC faults into AC, converter, and DC types, focusing on their primary locations and fault characteristics. Signal processing methods, including time-domain, frequency-domain, and time–frequency-domain approaches, are systematically compared, supported by relevant case studies. The review identifies critical research gaps in enhancing the reliability of fault detection, classification, and protection under diverse fault conditions, offering insights into future advancements in HVDC system resilience. Full article

This paper presents a comprehensive study on the formulation and solution of the power flow problem in bipolar direct current (DC) distribution networks with unbalanced constant power loads. Using the nodal voltage method, a unified nonlinear model is proposed which accurately captures both monopolar and bipolar load configurations as well as the voltage coupling between conductors. The model assumes a solid grounding of the neutral conductor and known system parameters, ensuring reproducibility and physical consistency. Seven iterative algorithms are developed and compared, including three Newton–Raphson-based formulations and four quasi-Newton methods with constant Jacobian approximations. The proposed techniques are validated on two benchmark networks comprising 21 and 85 buses. Numerical results demonstrate that Newton-based methods exhibit quadratic convergence and high accuracy, while quasi-Newton approaches significantly reduce computational time, making them more suitable for large-scale systems. The findings highlight the trade-offs between convergence speed and computational efficiency, and they provide valuable insights for the planning and operation of modern bipolar DC grids. Full article

Background and Objectives: With the increasing life expectancy, the frequency of total thyroidectomies in elderly patients has risen, raising concerns regarding hemorrhage and recurrent laryngeal nerve palsy compared to the general population. Therefore, considering the frequent alteration of the coagulation status in such patients, innovative methods able to reach an accurate hemostasis appear highly desirable. This retrospective multicentric study aimed to compare the postoperative outcomes of patients treated with conventional hemostasis with patients treated with the Harmonic Scalpel (HS) and gelatin–thrombin matrix (Floseal). Materials and Methods: Patients undergoing total thyroidectomy were retrospectively enrolled and categorized into two groups: Group A patients underwent surgery with the Harmonic Scalpel and Floseal, while Group B underwent traditional hemostasis surgery with ligations and monopolar electrocautery. The primary endpoint was the drain output after 24 and 48 h and the presence of significant blood loss. Secondary endpoints included the presence of seroma, wound infection, hematoma, laryngeal nerve palsy, surgery duration, and onset of post-surgical hypocalcemia. Results: From January 2014 to January 2024, 870 individuals participated in the study. Group A (gelatin–thrombin and HS) comprised 502 patients, while Group B (Standard Hemostasis—control group) comprised 368 patients. The 24 h drain output was 52 ± 25 mL in Group A vs. 113 ± 27 mL in Group B, p = 0.003, while the 48 h drain output was 95 ± 29 mL in Group A and 113 ± 27 mL in Group B (p = 0.002). Significant blood loss occurred in eight patients (2.2%) of Group B vs. three cases (0.6%) in Group A (p = 0.039). Also, neck hematoma (p = 0.012), seroma (p = 0.005), and reoperation (p = 0.052) values were significantly lower in Group A. Conclusions: Surgery aided with HS, and gelatin–thrombin was associated with lower major and minor complications compared to the conventional approach, guarantying reduced operative time, ensuring hemostasis, and preserving parathyroid glands, even in elderly patients. Full article

While the high-voltage direct current (HVDC) transmission system is in monopolar operation, it produces thousands of amperes of ground-return currents (GRCs). Accurate computation of the GRCs is essential for assessing safety implications for nearby industrial infrastructure. Current three-dimensional forward models of GRCs are typically constructed based on discrete differential equations, and their solving efficiency is constrained by the increased degrees of freedom resulting from the fine discretization grids in high-conductivity conductors and ground points. To address this issue, we present a new resistor network (RN) forward solver based on a multi-resolution grid approach. This solver utilizes an RN to avoid the massive degrees of freedom resulting from fine discretization of high-voltage conductors and enhances grid discretization efficiency near the surface grounding system through multi-resolution grids. We demonstrate, through multiple three-dimensional geoelectrical model cases, that the proposed method reduces the forward modeling misfit to 1% and possesses only 3‰ of the required discrete elements compared to traditional approaches. Furthermore, practical HVDC grid model analyses indicate the successful application of the proposed method for GRC analysis in complex geoelectric conditions. Full article

Background: Transurethral resection of the prostate (TURP) has been the standard surgical treatment for Benign Hyperplasia of the Prostate (BPH) for decades. Our objective was to evaluate the outcome of our new technique: Monopolar Transurethral Enucleoresection of the Prostate (TUERP) with apical release (bring it all to centre). Methods: A prospective study of all cases undergoing TUERP at a tertiary centre from January 2020 to October 2022 was performed. Patient demographics, intraoperative variables and postoperative results along with follow-up data were collected. Data of all the cases who had completed a one-year follow-up post-surgery were included and analysed. Results: A total of 240 patients with complete data including a one-year follow-up were included. Mean prostatic volume was 55.3 ± 11.6 gm, and 28 (11.67%) cases were >100 gm. The mean operative time was 31.7 ± 7.6, and mean haemoglobin drop at 24 h was 0.73 ± 1.21 gm/dL. The overall complication rate was 16.67%, with only two (0.83%) Clavien–Dindo III complications (haematuria and clots needing evacuation) and the other complications being Clavien–Dindo I/II complications. Sustained improvement at 1 year of follow-up was noted: Qmax: 25.2 ± 5.6 mL/s, IPSS: 4.7 ± 2.5 and PVR: 22.5 ± 9.6 mL. Conclusions: Monopolar TUERP with a modified Nesbit’s enucleoresection with apical release can be considered a promising technique, which needs further studies to be validated with appropriate comparisons. Full article

BACKGROUND: The resection of brain tumors can be critical concerning localization, but is a key point in treating gliomas. Intraoperative neuromonitoring (IONM), awake craniotomy, and mapping procedures have been incorporated over the years. Using these intraoperative techniques, the resection of eloquent-area tumors without increasing postoperative morbidity became possible. This study aims to analyze short-term and particularly long-term outcomes in patients diagnosed with high-grade glioma, who underwent surgical resection under various technical intraoperative settings over 14 years. METHODS: A total of 1010 patients with high-grade glioma that underwent resection between 2004 and 2018 under different monitoring or mapping procedures were screened; 631 were considered eligible for further analyses. We analyzed the type of surgery (resection vs. biopsy) and type of IONM or mapping procedures that were performed. Furthermore, the impact on short-term (The National Institute of Health Stroke Scale, NIHSS; Karnofsky Performance Scale, KPS) and long-term (progression-free survival, PFS; overall survival, OS) outcomes was analyzed. Additionally, the localization, extent of resection (EOR), residual tumor volume (RTV), IDH status, and adjuvant therapy were approached. RESULTS: In 481 patients, surgery, and in 150, biopsies were performed. The number of biopsies decreased significantly with the incorporation of awake surgeries with bipolar stimulation, IONM, and/or monopolar mapping (p < 0.001). PFS and OS were not significantly influenced by any intraoperative technical setting. EOR and RTV achieved under different operative techniques showed no statistical significance (p = 0.404 EOR, p = 0.186 RTV). CONCLUSION: Based on the present analysis using data from 14 years and more than 600 patients, we observed that through the implementation of various monitoring and mapping techniques, a significant decrease in biopsies and an increase in the resection of eloquent tumors was achieved. With that, the operability of eloquent tumors without a negative influence on neurological outcomes is suggested by our data. However, a statistical effect of monitoring and mapping procedures on long-term outcomes such as PFS and OS could not be shown. Full article

Background: Transoral pharyngeal surgery is mainly feasible with the use of a microscope or robotic systems. Data about alternative methods, with lower costs and easier availability, are sparse. We intended to examine to what extent the endoscope-holding arm is a suitable alternative to the microscope or robotic systems. Material and Methods: We retrospectively reviewed subjects who underwent pharyngeal tumor resection with the endoscope-holding arm in our university department. Results: We identified 13 subjects who underwent transoral pharyngeal surgery between November 2020 and November 2023. Most subjects presented with an oropharyngeal tumor (6/11 in the lateral wall or tonsil; 4/11 in the tongue base). The oropharyngeal lateral wall or tonsillar tumors were exposed with a standard mouth gag. The tongue-base tumors or hypopharyngeal tumors were exposed with an operating laryngoscope. Advantages over the microscope included an angled view. Advantages over robotic systems included haptic feedback and a faster setup. Advantages over both the microscope and robotic systems included lower costs and easier availability. Visualization with the endoscope was sufficient and similar to that of the microscope. Bimanual action was possible with surgical forceps and a monopolar electrode. Conclusions: Transoral pharyngeal surgery was feasible with the endoscope-holding arm. The endoscope-holding arm could be a cost-efficient alternative to the microscope or robotic systems. Full article