Search Results (224)

This paper addresses the economic–environmental dispatch (EED) problem in DC power grids integrating thermoelectric and photovoltaic generation. A multi-objective optimization model is developed to minimize both fuel costs and CO₂ emissions while considering power balance, voltage constraints, generation limits, and thermal line capacities. To overcome the non-convexity introduced by quadratic voltage products in the power flow equations, a convex reformulation is proposed using second-order cone programming (SOCP) with auxiliary variables. This reformulation ensures global optimality and enhances computational efficiency. Two test systems are used for validation: a 6-node DC grid and an 11-node grid incorporating hourly photovoltaic generation. Comparative analyses show that the convex model achieves objective values with errors below 0.01% compared to the original non-convex formulation. For the 11-node system, the integration of photovoltaic generation led to a 24.34% reduction in operating costs (from USD 10.45 million to USD 7.91 million) and a 27.27% decrease in CO₂ emissions (from 9.14 million kg to 6.64 million kg) over a 24 h period. These results confirm the effectiveness of the proposed SOCP-based methodology and demonstrate the environmental and economic benefits of renewable integration in DC networks. Full article

This study analyses the application of the Friction Stir Welding (FSW) process on polymeric materials manufactured by additive manufacturing (AM), specifically with polylactic acid (PLA). FSW is a solid-state welding process characterized by its low heat input and minimal distortion, which makes it ideal for the assembly of complex or large components made by additive manufacturing. To evaluate its effectiveness, a portable FSW device was developed for the purpose of joining PLA specimens made by AM using different filler densities (15% and 100%). Two tool geometries (a cylindrical and truncated cone) were utilized by varying the parameters of rotational speed, tilt angle, and feed rate. The results revealed two different process stages, transient and steady-state, and showed differences in weld quality depending on the material density, tool type, and material addition. The study confirms the viability of FSW for joining PLA parts made by AM and suggests potential applications in industries that require robust and precise joints in plastic parts, thereby helping hybrid manufacturing to progress. Full article

Objective: Mandibular expansion remains controversial due to concerns about long-term stability and effectiveness. While maxillary expansion protocols are well established, investigations into mandibular expansion remain limited. This study evaluates the efficacy of the Clara Expander appliance for mandibular expansion in early mixed dentition, assessing skeletal and dental changes using cone-beam computed tomography (CBCT). Materials and Methods: This prospective longitudinal study was conducted in Valencia, Spain, with a population of healthy children aged 6–10 years presenting negative osseodental mandibular discrepancies. CBCT scans were performed before and after treatment to evaluate mandibular dimensional changes, with statistical analyses conducted and a significance threshold of p < 0.05. A total of seven subjects were included in this case series, allowing for a descriptive analysis of treatment outcomes within this specific clinical context. Results: CBCT analysis confirmed significant mandibular expansion following the Clara Expander protocol. Post-treatment findings showed statistically significant increases in dental parameters, including Tooth 6 (furcation, MD = −2.25; p = 0.015), Tooth E (furcation, cementoenamel junction, vestibular, lingual, all p < 0.001), Tooth D (all variables significant), and Tooth C (furcation, MD = −4.18; p = 0.002; cementoenamel junction, MD = −3.56; p = 0.015). Conclusions: The Clara Expander appliance effectively promotes skeletal and dental mandibular expansion, with minimal adverse effects. Its user-friendly, non-invasive design enhances patient compliance and outcomes, contributing valuable data to the field of mandibular expansion and informing future research and clinical applications. Full article

Background and Objectives: The extraction of mandibular third molars poses challenges due to their proximity to the mandibular canal and risk of inferior alveolar nerve (IAN) injury. Accurate preoperative evaluation is essential to minimize complications. This study assessed the three-dimensional positional relationship between the mandibular canal and lower third molars using cone-beam computed tomography (CBCT), aiming to identify anatomical positions associated with increased surgical risk. Materials and Methods: This retrospective study analyzed 253 CBCT scans of fully developed lower third molars. The mandibular canal position was classified as apical (Class I), buccal (Class II), lingual (Class III), or interradicular (Class IV). Contact was categorized as no contact, contact with a complete or defective white line, or canal penetration. In no-contact cases, the apex–canal distance was measured. Statistical analysis included descriptive and contingency analyses using the Chi-Square Likelihood Ratio test. Results: Class I was most common (70.8%) and presented the lowest risk, while Classes III and IV showed significantly higher frequencies of canal contact or penetration. Class II exhibited shorter distances even in no-contact cases, suggesting residual risk. Statistically significant associations were found between canal position and both contact type (p < 0.001) and apex–canal distance (p = 0.046). Conclusions: CBCT offers valuable insight into the anatomical relationship between third molars and the mandibular canal. High-risk positions—particularly lingual and interradicular—require careful assessment. Even in the absence of contact, close proximity may pose a risk and should inform surgical planning. Full article

Background and Objectives: Evaluating jaw augmentation procedures usually necessitates pre- and postoperative tomographic imaging. Ethical considerations emphasize minimizing radiation exposure. Given that panoramic radiographs (PR, 2D) offer a lower radiation dose compared to cone-beam CT (CBCT, 3D), this study explores the feasibility of estimating tooth root volume from PR, potentially allowing safer clinical assessments with reduced radiation exposure. Materials and Methods: To develop a mathematical approximation method, the 2D tooth root surface in PR was defined as an elliptical model and a cuboid (3D). The true root volume (mm³) was gathered from CBCTs. The missing link for tooth root volume assessment in 2D radiographs is the depth of the root (vestibulo-oral dimension). It was hypothesized that the tooth root surface and its volume are related. A correlation factor “r” corresponding to the tooth roots’ depths was then calculated. Descriptive and inferential statistics were computed (p < 0.05). Results: The mathematical model was performed on 27 molars with an average volume of 472.83 mm³ (±130.25–CBCT). The factor “r” (obtained by dividing the true root volume from CBCT by the total root surface from PR) was computed as 8.04 (±1.90). Using “r” for the volume calculation in the cuboid model, an average volume of 472.37 (±152.92) for the 27 molars was computed. These volumes did not differ significantly. Conclusions: This study demonstrates that a mathematical model using elliptical projections from panoramic radiographs reliably estimates molar root volume, yielding comparable results to CBCT while reducing radiation exposure. Full article

This study investigates the complementary noise control capabilities of two passive jet noise mitigation strategies: a traditional ejector nozzle and a novel application of 3M™ Nextel™ 312 ceramic fabric as a thermal–acoustic liner on the central cone of a micro turbojet nozzle. Three nozzle configurations, baseline, ejector, and Nextel-treated, were evaluated under realistic operating conditions using traditional and advanced acoustic diagnostics applied to data from a five-microphone circular array. The results show that while the ejector provides superior directional suppression and low-frequency redistribution, making it ideal for far-field noise control, it maintains high total energy levels and requires structural modifications. In contrast, the Nextel lining achieves comparable reductions in overall noise, especially in high-frequency ranges, while minimizing structural impact and promoting spatial energy dissipation. Analyses in both the time-frequency and spatial–spectral domains demonstrate that the Nextel configuration not only lowers acoustic energy but also disrupts coherent noise patterns, making it particularly effective for near-field protection in compact propulsion systems. A POD analysis further shows that NEXTEL more evenly distributes energy across mid-order modes, indicating its role in smoothing spatial variations and dampening localized acoustic concentrations. According to these results, ceramic fabric linings offer a lightweight, cost-effective solution for reducing the high noise levels typically associated with drones and UAVs powered by small turbojets. When combined with ejectors, they could enhance acoustic suppression in compact propulsion systems where space and weight are critical. Full article

To address the challenges of water coning and early water breakthrough commonly encountered during the development of bottom-water gas reservoirs, this study establishes a fully coupled numerical simulation model integrating a horizontal wellbore, inflow control device (ICD) screens, and a zonal water control system. A novel “dual inflow performance index” method is introduced for the first time, enabling separate calculation of the pressure drops induced by gas and water phases flowing through the ICDs, thereby improving the accuracy of pressure simulations throughout the production lifecycle. The model divides the entire production system into four physically distinct subsystems, the bottom-water gas reservoir, ICD screens, production compartments, and the horizontal wellbore, which are dynamically coupled through transient interflow exchange. Based on geological parameters from the SPE10 dataset, the model simulates realistic production scenarios. The results show that the proposed model accurately captures the time-dependent increase in ICD pressure drop as fluid properties evolve during production. Moreover, the zonal water control method outperforms the single ICD-based control strategy in water control performance, achieving a 23% reduction in cumulative water production. Additionally, the water control intensity of the ICD screens increases nonlinearly with the reduction in the number of openings. In highly heterogeneous reservoirs with significant permeability contrast, effective suppression of water coning can only be achieved by setting a minimal number of openings in the high-permeability compartments, resulting in up to a 15% reduction in cumulative water production. The timing of production compartment shutdown exerts a significant influence on water control performance. The optimal strategy is to first identify the water breakthrough point through unconstrained production simulation as production with all eight ICD screen openings fully open and then shut down the high-permeability production compartment around this critical time. This approach can suppress cumulative water production by up to 27%. Overall, the proposed model offers a practical and robust tool for optimizing completion design and water control strategies in complex bottom-water gas reservoirs. Full article

Hops (Humulus lupulus L.) are a critical component in beer brewing. The growing demand for craft beer has increased interest in hop cultivation in non-traditional regions where unfavorable climatic conditions hinder optimal yield and quality. To address these challenges, this study investigates the effects of plant growth regulators (PGRs) on hop cone yield and chemical compositions. In two separate studies, year-1 Cascade hops were subjected to various PGR treatments in the field. PGR treatments generally had minimal effect on the dry cone yield in study I. In study II, a combination of Ethephon at 45 mg/L and ProGibb at 3 mg/L significantly increased the cone yield by 125% compared to the control. While all treatments had a “good quality” hop storage index, a combination of Ethephon and ProGibb produced alpha acid percentages within the commercial standard range. Ethephon at 30 mg/L combined with ProGibb at 2 mg/L enhanced bitterness and aroma, delivering the highest concentration of volatile organic compounds at 569.7 mg/L, thereby enhancing aroma compounds associated with fruity esters, monoterpenes, and sesquiterpenes. This study demonstrates that specific PGR treatments can improve the chemical composition of hops grown in non-traditional regions, with implications for optimizing aroma and bitterness in beer. Full article

In postmenopausal women with high-grade cervical intraepithelial neoplasia (CIN3), hysterectomy is frequently performed after loop electrosurgical excision procedure (LEEP) due to the concern for residual disease or occult carcinoma. However, the decision to proceed with hysterectomy is often made without validated predictive criteria, increasing the risk of overtreatment or underdiagnosis. The aim of this study is to identify independent predictors of residual CIN2+ (CIN2, CIN3, adenocarcinoma in situ, invasive carcinoma) or invasive disease in hysterectomy specimens following LEEP in this high-risk population. Methods: We conducted a multicenter retrospective study including 154 postmenopausal women (aged 50–75) who underwent total hysterectomy within 12 months after LEEP for histologically confirmed CIN3. Data collected included human papillomavirus (HPV) genotyping (pre- and post-LEEP), endocervical curettage (ECC), cone margin status, transformation zone type, and histopathological outcomes of the hysterectomy specimen. Logistic regression and ROC curve analysis were used to assess predictive factors. Results: Residual disease (CIN2+, AIS, or carcinoma) was found in 38 patients (24.7%), including 7 cases (4.5%) of occult carcinoma. Persistent high-risk HPV post-LEEP was the strongest independent predictor (adjusted OR for HPV 16/18: 74.0; p < 0.001), followed by positive ECC (OR: 3.64; p = 0.028). Cone margin status was not independently associated. The multivariate model showed good discriminative performance (AUC = 0.860; sensitivity 67.2%, specificity 72.8%). Conclusions: Our findings suggest that persistent high-risk HPV infection and positive ECC are reliable predictors of residual or occult disease. These markers should be integrated into post-LEEP follow-up protocols to better identify candidates for hysterectomy and minimize unnecessary surgeries. Full article

Background/Objectives: Partial maxillectomy frequently results in severe impairments of oral functions, such as difficulties in chewing, speech, swallowing, and facial appearance. Immediate prosthetic rehabilitation is challenging because soft tissue healing is typically required before impression taking. This study aimed to (1) develop a comprehensive digital workflow for fabricating immediate obturator prostheses using preoperative data and (2) assess their early clinical effectiveness in restoring oral functions after surgery. Methods: In this prospective clinical study, 20 patients undergoing partial maxillectomy from January 2023 to January 2025 were enrolled. A digital workflow combining cone-beam computed tomography (CBCT), intraoral scanning, CAD/CAM design, and 3D metal printing was implemented. Obturator prostheses were digitally designed preoperatively and inserted immediately post-resection. Functional outcomes were postoperatively evaluated after one month using the Obturator Functioning Scale (OFS), which measures functional, speech, esthetic, and psychosocial aspects. Results: The digitally fabricated immediate obturator prostheses were successfully placed intraoperatively in all patients. Most participants reported mild to moderate difficulties, with speech-related issues being the most common, while esthetic concerns were minimal. Masticatory function was satisfactorily restored in 75% of cases, and 60% of patients experienced minimal fluid leakage during swallowing. No significant differences were found between genders. Patients with larger defects tended to report greater functional challenges. Conclusions: The digitally planned immediate obturator prosthesis provides a practical and effective solution for early rehabilitation following partial maxillectomy. This digital workflow reduces patient discomfort, restores key oral functions, and facilitates psychosocial recovery. Full article

Aiming to solve optimization scheduling difficulties caused by the double uncertainty of source-side photovoltaic (PV) output and load-side demand response in active distribution networks, this paper proposes a two-stage distribution robust optimization method. First, the first-stage model with the objective of minimizing power purchase cost and the second-stage model with the co-optimization of active loss, distributed power generation cost, PV abandonment penalty, and load compensation cost under the worst probability distribution are constructed, and multiple constraints such as distribution network currents, node voltages, equipment outputs, and demand responses are comprehensively considered. Secondly, the second-order cone relaxation and linearization technique is adopted to deal with the nonlinear constraints, and the inexact column and constraint generation (iCCG) algorithm is designed to accelerate the solution process. The solution efficiency and accuracy are balanced by dynamically adjusting the convergence gap of the main problem. The simulation results based on the improved IEEE33 bus system show that the proposed method reduces the operation cost by 5.7% compared with the traditional robust optimization, and the cut-load capacity is significantly reduced at a confidence level of 0.95. The iCCG algorithm improves the computational efficiency by 35.2% compared with the traditional CCG algorithm, which verifies the effectiveness of the model in coping with the uncertainties and improving the economy and robustness. Full article

In the zenith-horizon placement for achieving minimum geometric dilution of precision (GDOP), one access node or sensor is positioned along the z-axis, while the remaining nodes are placed symmetrically on a three-dimensional (3D) cone. This configuration yields the minimum GDOP at the cone’s tip, which we term the designated min-GDOP point. However, in practical localization applications, the unknown node is not necessarily located at this designated min-GDOP point; instead, it may be situated anywhere within an area. As a result, evaluating localization accuracy across the entire area, rather than at a single point, is more relevant. Averaged horizontal dilution of precision (HDOP) and GDOP across the region provide more meaningful metrics for system-wide performance than values computed only at a specific location. Although many recent positioning applications leverage multiple unmanned aerial vehicles (UAVs), many established fixed sensor deployments predate the widespread adoption of UAVs. This paper proposes a novel approach with a single UAV working in conjunction with existing fixed access nodes for positioning. This approach offers improved adaptability for fixed infrastructure while circumventing the expense of establishing entirely new UAV systems, thus providing a valuable compromise. We investigate the criteria of average HDOP and GDOP over the given area. The objective is to determine optimal UAV positions along the flight path that minimize the average HDOP and/or GDOP across the area. Due to the analytical complexity, we employ numerical methods. Our simulation results demonstrate that minimizing average HDOP and GDOP often requires different UAV positions, depending on the number of access nodes and the size of the area. Consequently, achieving simultaneous minimization of both metrics with a single UAV trajectory is generally infeasible. When minimizing the average HDOP with a small number of access nodes, aligning the UAV’s XY-plane angle with those of the stationary nodes, offset by ${60}^{\circ }$, proves advantageous. This angular alignment becomes less critical as the number of access nodes increases. For scenarios where both HDOP and GDOP are important, UAV placement can be optimized by selecting appropriate trade-offs. Additionally, we quantify how increasing the number of access nodes improves the average HDOP and GDOP over the specified area. Full article

Background/Objectives: This ex vivo study aimed to evaluate the diagnostic performance of ultra-low-dose (ULD) cone-beam computed tomography (CBCT) protocols in detecting vestibular bone defects for immediate implant planning, using intraoral scan (IOS) data as a reference. Methods: Four CBCT protocols (ENDO, A, B, C) were applied to four dried human skulls using a standardized setup and a single CBCT unit (Planmeca ProMax^® 3D Mid, Planmeca Oy, Helsinki, Finland). All scans were taken at 90 kV, with varying parameters: (1) ENDO (40 × 50 mm, 75 µm, 12 mA, 80–120 µSv, 15 s), (2) A (50 × 50 mm, 75 µm, 9 mA, 20–40 µSv, 5 s), (3) B (100 × 60 mm, 150 µm, 7.1 mA, 22–32 µSv, 5 s), and (4) C (100 × 100 mm, 200 µm, 7.1 mA, 44 µSv, 4 s). Vestibular root surfaces of single-rooted teeth (FDI regions 15–25 and 35–45) were digitized via IOS and exported as STL files. CBCT datasets were superimposed using 3D software (Blender 2.79), and surface defects were measured and compared using one-sample t-tests and Bland–Altman analysis. The level of significance was set at p < 0.05. Results: A total of 330 vestibular surfaces from 66 teeth were analyzed. Compared to the IOS reference, protocols ENDO and A showed minimal differences (p > 0.05). In contrast, protocols B and C exhibited statistically significant deviations (p < 0.05). Protocol B demonstrated a mean difference of −0.477 mm² with limits of agreement (LoA) from −2.04 to 1.09 mm² and significant intra-rater variability (p < 0.05). Protocol C revealed a similar mean deviation (−0.455 mm²) but a wider LoA (−2.72 to 1.81 mm²), indicating greater measurement variability. Overall, larger voxel sizes were associated with increased random error, although deviations remained within clinically acceptable limits. Conclusions: Despite statistical significance, deviations for protocols B and C remained within clinically acceptable limits. ULD CBCT protocols are, thus, suitable for evaluating vestibular bone defects with reduced radiation exposure. Full article

Objective: This study aims to evaluate the stress distribution on endodontically treated anterior teeth restored using different restorative materials and different post lengths versus endocrowns employing finite element analysis (FEA). Methods: An extracted human central incisor tooth with a fully formed apex was scanned using high-resolution cone beam computed tomography (CBCT) to generate 3D finite element models. Six models of restorations of badly destructed central incisor were grouped according to the type of ceramic material and post length versus endocrown restorations. Group V-L: Vita Enamic, long post (10 mm intra-radicular), Group C-L: Celtra Duo, long post (10 mm intra-radicular), Group V-Sh: Vita Enamic, short post (3 mm intra-radicular), Group C-Sh: Celtra Duo, short post (3 mm intra-radicular), Group V-E: Vita Enamic endocrown (3 mm intra-radicular), and Group C-E: Celtra Duo endocrown (3 mm intra-radicular). A static load of 200 N was applied to the palatal surface at a 45 degree angle to the tooth’s long axis. The maximum equivalent von Mises stress and maximum principal stress were analyzed at four locations: the finish line, coronal third of the root (12 mm from the apex), middle third of the root (8 mm from the apex), and apical third of the root (4 mm from the apex). Results: Group C-L exhibited the highest maximum VM stress and PS at the finish line, in addition to the highest maximum VM stress and PS at the root apical third, while group C-Sh reported the least maximum VM stress at the root apical third among the groups. All Celtra Duo groups reported higher maximum VM stress than the corresponding groups of Vita Enamic at the finish line and root coronal thirds. However, at the root middle and apical thirds, both materials recorded similar stresses. Conclusions: Short posts and Vita Enamic endocrowns showed minimal stress, especially at the finish line, while long posts increased stress and fracture risk. The findings support conservative restorations without posts, although clinical validation is needed to confirm their long-term effectiveness and safety. Full article

Background: A 19-year-old female patient reported to the Department of Conservative Dentistry, Medical University of Gdańsk, with pain in the left lateral incisor. During the attempt to perform root canal treatment on tooth 22, we encountered difficulties in locating the canal opening, which resulted in treatment failure. Radiographic examinations revealed Pulp Canal Obliteration and a root fracture with a double fracture line, resulting in two root fragments. The prognosis for this tooth was poor, with extraction being the most likely outcome. Methods: To provide effective therapy, a 3D-printed endodontic guide was utilized, allowing for more precise localization of the canal in a tooth with a calcified root canal and complex fracture morphology. An intraoral scan and cone-beam computed tomography (CBCT) were performed, followed by the design of the guide. This facilitated accurate planning of the entry path for endodontic instruments, promoting minimally invasive treatment and reducing the loss of tooth structure. Results: Through navigated endodontics, the treatment became more predictable, and the risk of iatrogenic complications was minimized, significantly improving the prognosis of the therapy. Clinical and radiological examinations conducted after 12 months demonstrated successful treatment and preservation of the tooth in the oral cavity. Conclusions: The obtained results suggest that the use of guided endodontics can improve outcomes in cases with pulp canal obliteration and complex fractures, offering a minimally invasive and predictable approach. Full article