Search Results (96)

Hydrogen-powered aircraft constitute a transformative innovation in aviation, motivated by the imperative for sustainable and environmentally friendly transportation solutions. This paper aims to concentrate on the design of hydrogen powertrains employing a system approach to propose representative design models for distribution and propulsion systems. Initially, the requirements for powertrain design are formalized, and a use-case-driven analysis is conducted to determine the functional and physical architectures. Subsequently, for each component pertinent to preliminary design, an analytical model is proposed for multidisciplinary analysis and optimization for powertrain sizing. A double-wall pipe model, incorporating foam and vacuum multi-layer insulation, was developed. The internal and outer pipes sizing were performed in accordance with standards for hydrogen piping design. Valves sizing is also considered in the present study, following current standards and using data available in the literature. Furthermore, models for booster pumps to compensate pressure drop and high-pressure pumps to elevate pressure at the combustion chamber entrance are proposed. Heat exchanger and evaporator models are also included and connected to a burning hydrogen engine in the sizing process. An optimal liner pipe diameter was identified, which minimizes distribution systems weight. We also expect a reduction in engine length and weight while maintaining equivalent thrust. Full article

Underwater acoustic sensor networks, crucial for marine monitoring, face significant challenges, including limited bandwidth, high delay, and severe energy constraints. Addressing these limitations requires an energy-efficient design to ensure network survivability, reliability, and reduced operational costs. This paper proposes an artificial intelligence-driven framework aimed at enhancing energy efficiency and sustainability in applications of marine wildlife monitoring in underwater sensor networks, according to the vision of implementing an underwater acoustic sensor network. The framework integrates intelligent computing directly into underwater sensor nodes, employing lightweight AI models to locally classify marine species. Transmitting only classification results, instead of raw data, significantly reduces data volume, thus conserving energy. Additionally, a software-defined radio methodology dynamically adapts transmission parameters such as modulation schemes, packet length, and transmission power to further minimize energy consumption and environmental disruption. GNU Radio simulations evaluate the framework effectiveness using metrics like energy consumption, bit error rate, throughput, and delay. Adaptive transmission strategies implicitly ensure reduced energy usage as compared to non-adaptive transmission solutions employing fixed communication parameters. The results illustrate the framework ability to effectively balance energy efficiency, performance, and ecological impact. This research contributes directly to ongoing development in sustainable and energy-efficient underwater wireless sensor network design and deployment. Full article

Background and Objectives: The needle path is crucial for preoperative localization of deep thoracic pulmonary nodules using CT-guided patent blue dye (PBD) injection. This study aimed to evaluate the efficacy and safety of four categorized needle approach paths tailored to the anatomical location of the nodules. Materials and Methods: We retrospectively evaluated data from 50 consecutive patients (50 deep pulmonary nodules), who underwent CT-guided localization with PBD injection, between November 2015 and May 2023 at our hospital. The nodules could be divided into four categories: (1) perifissural nodules, (2) paravertebral nodules, (3) paramediastinal nodules, and (4) deep parenchymal nodules, according to their location relative to the thoracic organs and the visceral pleura. Needle approach methods and needle pathway lengths were recorded. Clinical and radiological features, technical information, pathological results, and procedure-related complications were analyzed. Results: All 50 dyes were successfully identified by thoracoscopy and then resected without major complication. The mean nodule diameter and the nodular depth were 10.3 (range, 4.7–21.0) mm and 16.1 (range, 0.1–52.2) mm. The needle pathway length was 7.7 (range, 4.5–11.7) cm. The mean procedure time was 16 (range, 8–26) minutes. Asymptomatic pneumothorax developed in twenty-four patients (48.0%), and focal parenchymal hemorrhage occurred in four patients (8.0%) after localization. No patients required chest tube insertion or resuscitation. Conclusions: Strategic needle approach paths provide precise localization of deep thoracic pulmonary nodules with minimal complications. These methods offer a practical framework for improving thoracoscopic surgery in challenging deep thoracic cases. Full article

Background and Objectives: Cystic echinococcosis (CE) remains a significant health concern in endemic areas, including Romania, where hepatic hydatid cysts frequently require surgical treatment. Surgery represents the cornerstone of therapy, particularly in large, complicated, or symptomatic cysts, where medical or minimally invasive options may be insufficient. This study aims to investigate the clinical characteristics, risk factors, and postoperative evolution of patients undergoing surgical intervention for hepatic CE in a tertiary care center over a five-year period. Materials and Methods: This retrospective study examined data from 62 patients who underwent surgical procedures for hepatic CE during a 5-year period. The analysis focused on demographic parameters, cyst morphology, surgical techniques employed, and postoperative complications, with particular attention to the frequency, management, and outcomes of biliary fistulas. Results: The study cohort had an average age of 44.1 years, with a slight predominance of female patients (51.6%). The majority of cysts (62.9%) were located in the right hepatic lobe, with an average diameter of 10.9 cm. Postoperative complications were recorded in 25.8% of cases, with biliary fistulas being the most frequent (12.9%). Patients who developed biliary fistulas presented significantly larger cysts (152.13 ± 105.68 mm vs. 102.20 ± 37.86 mm, p = 0.012) and required an extended length of hospitalization, particularly in high-output cases (29 vs. 9.3 days, p = 0.045). Hospital stays and treatment expenses were notably higher among patients with biliary fistulas. Conclusions: Biliary fistulas were observed exclusively in patients who underwent partial cystectomy. This finding highlights the need for increased caution when performing partial cystectomy, especially in cases involving large or recurrent cysts, where the risk of postoperative biliary fistulas is higher. Tailoring the surgical technique based on cyst characteristics and incorporating intraoperative strategies to manage or prevent biliary leakage may help reduce morbidity. Early identification and multidisciplinary management of high-risk cases are key to improving outcomes in hepatic CE. Full article

Efficient ship scheduling in inland waterways is critical for maritime transportation safety and economic viability. However, traditional scheduling methods, primarily based on First Come First Served (FCFS) principles, often produce suboptimal results due to their inability to account for complex spatial–temporal dependencies, directional asymmetries, and varying ship characteristics. This paper introduces SSRL (Ship Scheduling through Reinforcement Learning), a novel framework that addresses these limitations by integrating three complementary components: (1) a Q-learning framework that discovers optimal scheduling policies through environmental interaction rather than predefined rules; (2) a clustering mechanism that reduces the high-dimensional state space by grouping similar ship states; and (3) a sliding window approach that decomposes the scheduling problem into manageable subproblems, enabling real-time decision-making. We evaluated SSRL through extensive experiments using both simulated scenarios and real-world data from the Xiaziliang Restricted Waterway in China. Results demonstrate that SSRL reduces total ship waiting time by 90.6% compared with TSRS, 48.4% compared with FAHP-ES, and 32.6% compared with OSS-SW, with an average reduction of 57.2% across these baseline methods. SSRL maintains superior performance across varying traffic densities and uncertainty conditions, with the optimal information window length of 13–14 ships providing the best balance between solution quality and computational efficiency. Beyond performance improvements, SSRL offers significant practical advantages: it requires minimal computation for online implementation, adapts to dynamic maritime environments without manual reconfiguration, and can potentially be extended to other complex transportation scheduling domains. Full article

Introduction: Locally advanced renal cell carcinoma (RCC) with intravenous tumor thrombus (IVTT) represents 4–10% of renal tumors. This review assesses the safety and outcomes of minimally invasive techniques, specifically laparoscopic (LAP) and robotic-assisted (RA) methods, for treating RCC with IVTT. Methods: A literature search across several databases identified 54 studies (42 case series, 12 cohort studies) for analysis. Perioperative outcomes, including operative time, blood loss, transfusion rates, length of stay, and complications, were compared based on IVTT levels. Results: LAP and RA techniques were feasible for low-level IVTT, showing similar perioperative results. RA outperformed LAP in high-level IVTT with shorter operative times and lower blood loss and transfusion rates, despite managing more complex cases. RA maintained stable cancer-specific mortality (CSM) and metastasis rates, whereas LAP exhibited higher rates in high-level cases. Both techniques had low local recurrence rates. Conclusion: RA may be a superior option for RCC with IVTT, especially in high-level cases, but the data come mainly from specialized centers, signaling a need for multicenter validation and standardized criteria. Long-term outcomes require further study to assess RA’s non-inferiority to LAP. Full article

Background/Objectives: Primary hyperparathyroidism (PHPT) is a prevalent endocrine disorder, with ectopic mediastinal parathyroid adenomas accounting for up to 30% of cases, posing significant diagnostic and surgical challenges. While traditional management relies on invasive procedures, minimally invasive techniques such as video-assisted thoracoscopic surgery (VATS) have emerged as viable alternatives. This study addresses a gap in the current literature by presenting our experience with VATS for mediastinal ectopic parathyroid adenomas, particularly in underreported retrotracheal/paraesophageal locations. By integrating a retrospective case series with a systematic literature review, we highlight evolving surgical strategies and their implications for patient outcomes in anatomically complex cases. Methods: A retrospective analysis was conducted over a three-year period on patients diagnosed with mediastinal ectopic parathyroid adenomas. Data on demographic characteristics, preoperative imaging, surgical techniques, intraoperative findings, and postoperative outcomes were collected. This study primarily compared the outcomes of VATS with those of traditional thoracotomy, with a focus on surgical success, complication rates, and length of hospital stay. Results: Six patients underwent surgical resection for mediastinal ectopic parathyroid adenomas (two intrahymic and four retrotracheal/paraesophgeal). VATS was the preferred approach in all cases, with one patient requiring conversion to thoracotomy due to challenging vascular anatomy. Surgical success, defined as the normalization of postoperative serum calcium levels, was achieved in all cases. The median operative time was 80 min, and the mean hospital stay was 6.25 days. One patient developed transient postoperative hypocalcemia, necessitating supplementation. No major surgical complications were observed. Conclusions: This study supports VATS as a safe and effective approach for mediastinal ectopic parathyroid adenoma resection, offering reduced morbidity and shorter recovery times compared to traditional open surgery. The findings align with emerging evidence advocating for minimally invasive techniques in complex mediastinal surgeries. Full article

Named data networking (NDN) is a content-centric network architecture that requires efficient name lookup to forward packets based on hierarchical content names. Whereas IP lookup operates on fixed-length addresses, NDN name lookup must identify the longest matching prefix (LMP) from a variable-length name space, making it computationally challenging. Hash table-based approaches provide O (1) search complexity but often require multiple accesses due to the unknown LMP length. To mitigate excessive off-chip memory accesses, Bloom filter-assisted pre-checking is commonly employed. However, conventional Bloom filter-based approaches can only perform membership tests and do not provide information about the next search range, which limits their ability to effectively reduce Bloom filter accesses. This paper proposes a distance-encoded Bloom filter to improve name lookup efficiency. It encodes two distance values into the Bloom filter, enabling a more refined search range compared to binary search-based methods. By utilizing these encoded distances, the proposed scheme not only reduces the number of Bloom filter queries but also ensures that only prefix nodes need to be stored in the hash table. This helps reduce hash collisions and minimize off-chip memory accesses. Experimental evaluation using large-scale FIB datasets shows that the proposed approach reduces both Bloom filter accesses and hash table lookups, which contributes to improving overall lookup performance. Full article

Aiming at the requirement of high stress ratio reinforcement in space steel structures, a novel method for enshancing the load-bearing capacity of casings through indirect welding to produce a reinforced steel pipe is introduced. To investigate how the mechanical properties of steel pipe members change when reinforced using this method, a series of welding reinforcement axial compression tests were designed, incorporating local reinforcements at various positions and with different initial stress ratios. By comparing the reinforced specimens with those left unreinforced, we obtained insights into the failure modes, ultimate bearing capacities, and strain data of the steel pipes. To further validate the findings, 236 finite element models were developed. These models allowed for a comprehensive analysis of the numerical results alongside the experimental data, taking into account the thermal effects of welding. Quantitative analyses were performed to assess the impact of the initial stress ratio, initial defects, welding heat effects, slenderness ratio, the area ratio between the reinforcement and the pipe, and the length of the reinforcement on the ultimate bearing capacity of the reinforced members. The findings indicate that residual stresses resulting from the welding process have a minimal influence on the ultimate bearing capacity. The method maintains over 75% of its efficiency even at initial stress ratios up to 0.8. Additionally, the study elucidates the rules governing the impact of localized reinforcement on the mechanical properties of loaded steel pipe members. Combining the theoretical calculations with numerical simulations, an empirical formula for estimating the ultimate bearing capacity of the reinforced pipe specimens was derived. The relative error of the formula is less than 10% with the experimental outcomes and the finite element analysis results thereby offering a reliable tool for engineering applications. Full article

Unmanned Aerial Vehicles (UAVs) are widely used in applications such as land assessment, surveillance, and rescue operations, where they are often required to cover multiple disjoint regions. Coverage Path Planning (CPP) aims to determine optimal paths for UAVs to cover these areas. While CPP for single regions has been extensively studied, multi-region CPP with multiple UAVs remains underexplored. Existing methods typically focus on minimizing path length, but often neglect the nonlinear variations in energy consumption during flight, limiting their practical applicability. This paper addresses the multi-UAV, multi-region CPP as a variant of the Vehicle Routing Problem (VRP) with energy estimation. We propose an approach that optimizes UAV flight speeds to minimize energy consumption, supported by an accurate energy estimation algorithm. In addition, a heuristic algorithm is developed to balance the distribution of tasks among UAVs, considering both the scanning and transit times. Experiments using real-world data from the Changsha urban area demonstrate that our approach outperforms state-of-the-art methods in computational efficiency and energy savings, highlighting its potential for practical UAV deployment. Full article

Monitoring mangrove phenology requires frequent, high-resolution remote sensing data, yet satellite imagery often suffers from coarse resolution and cloud interference. Traditional methods, such as denoising and spatiotemporal fusion, faced limitations: denoising algorithms usually enhance temporal resolution without improving spatial quality, while spatiotemporal fusion models struggle with prolonged data gaps and heavy noise. This study proposes an optimized mangrove phenology extraction approach (OMPEA), which integrates Landsat and MODIS data with a denoising algorithm (e.g., Gap Filling and Savitzky–Golay filtering, GF–SG) and a spatiotemporal fusion model (e.g., Enhanced Spatial and Temporal Adaptive Reflectance Fusion Model, ESTARFM). The key of OMPEA is that GF–SG algorithm filled data gaps from cloud cover and satellite transit gaps, providing high-quality input to ESTARFM and improving its accuracy of NDVI imagery reconstruction in mangrove phenology extraction. By conducting experiments on the GEE platform, OMPEA generates 1-day, 30 m NDVI imagery, from which phenological parameters (i.e., the start (SoS), end (EoS), length (LoS), and peak (PoS) of the growing season) are derived using the maximum separation (MS) method. Validation in four mangrove areas along the coastal China shows that OMPEA significantly improves the potential to capture mangrove phenology in the presence of incomplete data. The OMPEA significantly increased usable data, adding 7–33 Landsat images and 318–415 MODIS images per region. The generated NDVI series exhibits strong spatiotemporal consistency with original data (R²: 0.788–0.998, RMSE: 0.007–0.253) and revealed earlier SoS and longer LoS at lower latitudes. Cross-correlation analysis showed a 2–3 month lagged effects of temperature on mangroves’ growth, with precipitation having minimal impact. The proposed OMPEA improves the possibility of capturing mangrove phenology under non-continuous and low-resolution data, providing valuable insights for large-scale and long-term mangrove conservation and management. Full article

The accurate measurement of orchard canopy volume serves as a crucial foundation for wind regulation and dosage adjustments in precision orchard management. However, existing methods for measuring canopy volume fail to satisfy the high precision and real-time requirements necessary for accurate variable-rate applications in fruit orchards. To address these challenges, this study develops a canopy volume measurement model for orchard spraying using LiDAR point cloud data. In the domain of point cloud feature extraction, an improved Alpha Shape algorithm is proposed for extracting point cloud contours. This method improves the validity judgment for contour line segments, effectively reducing contour length errors on each 3D point cloud projection plane. Additionally, improvements to the mesh integral volume method incorporate the effects of canopy gaps in height difference calculations, significantly enhancing the accuracy of canopy volume estimation. For feature selection, a random forest-based recursive feature elimination method with cross-validation was employed to filter 10 features. Ultimately, five key features were retained for model training: the number of point clouds, the 2D point cloud contour along the X- and Z-projection directions, the 2D width in the Y-projection direction, and the 2D length in the Z-projection direction. During model construction, the study optimized the hyperparameters of partial least squares regression (PLSR), backpropagation (BP) neural networks, and gradient boosting decision trees (GBDT) to build canopy volume measurement models tailored to the dataset. Experimental results indicate that the PLSR model outperformed other approaches, achieving optimal performance with three principal components. The resulting canopy volume measurement model achieved an R² of 0.9742, an RMSE of 0.1879, and an MAE of 0.1161. These results demonstrate that the PLSR model exhibits strong generalization ability, minimal prediction bias, and low average prediction error, offering a valuable reference for precision control of canopy spraying in orchards. Full article

Background and Objectives: A tracheostomy is a frequently performed surgical intervention in intensive care units (ICUs) for patients requiring prolonged mechanical ventilation. This procedure can offer significant benefits, including reduced sedation requirements, improved patient comfort, and enhanced airway management. However, it is also associated with various risks, and the absence of standardized clinical guidelines complicates its implementation. This study aimed to determine the prevalence of tracheostomy among ICU patients, while also evaluating patient characteristics, complication rates, and overall outcomes related to the procedure. Materials and Methods: We conducted an observational, cross-sectional, point-prevalence survey across eight ICUs in Italy. Data were collected over two 24 h periods in March and April 2024, with a focus on ICU characteristics, patient demographics, the details of tracheostomy procedures, and associated complications. Results: Among the 92 patients surveyed in the ICUs, 31 (33.7%) had undergone tracheostomy. The overall prevalence of tracheostomy was found to be 9.1%, translating to a rate of 1.8 per 1000 admission days. The mean age of patients with a tracheostomy was 59.5 years (SD = 13.8), with a notable predominance of male patients (67.7%). Neurological conditions were identified as the most common reason for ICU admission, accounting for 48.4% of cases. Tracheostomy procedures were typically performed after a mean duration of 12.9 days of mechanical ventilation, primarily due to difficulties related to prolonged weaning (64.5%). Both early and late complications were observed, and 19.35% of tracheostomized patients did not survive beyond one month following the procedure. The average length of stay in the ICU for these patients was significantly extended, averaging 43.0 days (SD = 34.3). Conclusions: These findings highlight the critical role of tracheostomy in the management of critically ill patients within Italian ICUs. The high prevalence and notable complication rates emphasize the urgent need for standardized clinical protocols aimed at optimizing patient outcomes and minimizing adverse events. Further research is essential to refine current practices and develop comprehensive guidelines for the management of tracheostomy in critically ill patients. Full article

Background: Significant intraoperative and postoperative blood loss are rare but possibly life-threatening complications after lung resection surgery either during open or minimally invasive procedures. Microporous Polysaccharide Haemospheres (ARISTA™AH) have demonstrated time-efficient haemostasis, lower postoperative blood volumes and a lower blood transfusion requirement, without any identified adverse events across other specialities. The primary aim of our study was to evaluate the impact of ARISTA™AH on short-term postoperative outcomes in thoracic surgery. Our secondary aim was to compare ARISTA™AH with other commonly used haemostatic agents. Methods: We retrospectively reviewed a prospectively collected database of consecutive early-stage lung cancer patients surgically treated in two European centres (October 2020–December 2022). Exclusion criteria included open surgery, patients with coagulopathy/anticoagulant medication, major intraoperative bleeding, non-anatomical lung resection and age <18 years. The cohort was divided into five groups according to the haemostatic agent that was used. Propensity score matching was used to estimate the effect of ARISTA™AH on various intra- and postoperative parameters (continuous and binary outcome modelling). Results: A total of 482 patients (M/F:223/259; VATS 97/RATS 385) with a mean age of 68.9 (±10.6) years were analysed. In 253 cases, ARISTA™AH was intraoperatively used to control bleeding. This cohort of patients had a significant reduction in total drain volume by 135 mls (standard error 53.9; p = 0.012). The use of ARISTA™AH did reduce the average length of a hospital stay (−1.47 days) and the duration of chest drainage (−0.596 days), albeit not significantly. In the ARISTA™AH group, we observed no postoperative bleeding, no blood transfusion requirement, no 30-day mortality and no requirement for redo surgery. The use of ARISTA™AH significantly reduced the odds of postoperative complications, as well as the need for transfusion and redo surgery. Conclusions: Our data showed that Microporous Polysaccharide Haemospheres are a safe and effective haemostatic device. Their use has a positive effect on the short-term postoperative outcomes of patients surgically treated for early-stage lung cancer. Full article

Background and Objectives: The present study aims to assess and compare the accuracy of post-space impressions captured by three different intraoral scanners (IOS) using various canal diameters. Methods: Three extracted natural maxillary central incisors were selected and prepared for a 1 mm wide margin and a 3 mm ferrule. All steps required for the endodontic procedure were performed, and the post space was prepared using post drills. The post length was kept constant at 12 mm, whereas the width was varied (Group 1: 1.4 mm, Group 2: 1.6 mm, and Group 3: 1.8 mm). Three IOSs (Trios3, iTero2, and Medit i700) were used to acquire a digital impression of the prepared post space. Each tooth was scanned 10 times by each scanner. So, in the end, 90 digital images were recorded, and the STL files were stored. GC Pattern resin was used to fabricate resin post and core patterns, which were scanned using an extraoral scanner (EOS). The STL file obtained was used as the reference file. To evaluate the trueness of the tested IOSs, each three-dimensional scan from an IOS was superimposed on the reference scan with the help of the Medit Design software 2.1.4. The software generates color plots and gives numerical values as deviations in the Root mean square (RMS) for the variance between the two superimposed scans. The data collected was tabulated for statistical analysis. One Way ANOVA was used to test the significance difference between three different IOSs, followed by Bonferroni Post-hoc test pairwise test to identify the differences between every two different IOS. Statistical significance was set at p < 0.05. Results: The mean deviation for trueness in post space impression values recorded by the Medit i700 was highest among groups 1, 2, and 3 [0.825 (±0.071), 0.673 (±0.042) and 0.516 (±0.039), respectively], followed by iTero2 [0.738 (±0.081), 0.569 (±0.043) and 0.470 (±0.037), respectively] and Trios3 [0.714 (±0.062), 0.530 (±0.040) and 0.418 (±0.024), respectively]. Significant differences were found between the groups for all three IOSs (Trios3: p-value < 0.0001; iTero2: p-value < 0.0001; Medit i700: p-value < 0.0001). Conclusions: Within the limitations of this study, it can be concluded that Trios3 IOS has higher accuracy (as it exhibited minimal deviation for trueness) in recording post space, followed by iTero2 and Mediti700 IOS. As the diameter of the post space is increased, the accuracy of recording by IOS increases. For all the tested IOSs (except for Trios3 and iTero2, when used to record post space with 1.8 mm canal diameter), the deviations in trueness were higher than the clinically acceptable limits. Thus, IOSs should be used cautiously when recording impressions of post spaces. Full article