Search Results (15,021)

This paper presents a waveguide bandpass filter that integrates bending and twisting functions, utilizing mixed TE₁₀₁ and TE₁₀₂ mode resonators. Benefiting from the mixed utilization of TE₁₀₁ and TE₁₀₂ resonators, the desired stopband suppression and low insertion loss are achieved. To verify the feasibility of this approach, a sixth-order Chebyshev bandpass filter centered at 20.4 GHz is designed, with a bandwidth of 1.6 GHz (FBW = 7.84%) and a return loss of more than 20 dB. The filter also achieves 120° bending in the propagation direction and 90° rotation in polarization. This prototype is fabricated following the stereolithography (SLA) process using photosensitive resin, followed by metallization through electroplating to achieve a lightweight design. The measurements exhibit great consistency with the simulations. Full article

Large language models (LLMs) have demonstrated remarkable capabilities in text generation, which also raise numerous concerns about their potential misuse, especially in educational exercises and academic writing. Accurately identifying and tracing the origins of LLM-generated content is crucial for accountability and transparency, ensuring the responsible use of LLMs in educational and academic environments. Previous methods utilize binary classifiers to discriminate whether a piece of text was written by a human or generated by a specific LLM or employ multi-class classifiers to trace the source LLM from a fixed set. These methods, however, are restricted to one or several pre-specified LLMs and cannot generalize to new LLMs, which are continually emerging. This study formulates source LLM tracing in a class-incremental learning (CIL) fashion, where new LLMs continually emerge, and a model incrementally learns to identify new LLMs without forgetting old ones. A training-free continual learning method is further devised for the task, the idea of which is to continually extract prototypes for emerging LLMs, using a frozen encoder, and then to perform origin tracing via prototype matching after a delicate decorrelation process. For evaluation, two datasets are constructed, one in English and one in Chinese. These datasets simulate a scenario where six LLMs emerge over time and are used to generate student essays, and an LLM detector has to incrementally expand its recognition scope as new LLMs appear. Experimental results show that the proposed method achieves an average accuracy of 97.04% on the English dataset and 91.23% on the Chinese dataset. These results validate the feasibility of continual origin tracing of LLM-generated text and verify its effectiveness in detecting cheating in student coursework. Full article

Measuring surface soil moisture is vital for understanding water availability, agricultural productivity, and climate change impacts, as well as for drought prediction and water resource management. However, obtaining accurate data is challenging due to the lack of reliable probes that work across diverse soil types and conditions. This study evaluated a prototype dielectric probe developed by Daiki Rika Kogyo Co., Ltd., Saitama, Japan, through controlled laboratory experiments. The probe measures the real and imaginary parts of dielectric permittivity over 10–150 MHz in a 5.6 cm diameter, with a 2 cm length volume, achieving a ±2% accuracy for the real part of oil–ethanol and ethanol–water mixtures (3.26–79). The imaginary part of the dielectric permittivity of aqueous solutions is convertible into electrical conductivity (EC) with reasonable accuracy. For variably saturated sand, the real part is convertible to a volumetric soil-moisture content (≥0.10 m³m⁻³) using a custom equation. The probe’s variable-frequency measurements reduce the limitations of fixed-frequency approaches, accounting for the EC, clay, porosity, and organic matter effects. With its VNA principle and simultaneous measurement of dielectric properties, it offers innovative capabilities for addressing water management, agriculture, and climate prediction challenges. Full article

This article presents social research, conducted through interviews with experts involved in land administration in Colombia, on the possibility of using the Fit-For-Purpose methodology, combined with indirect methods, to accelerate the capture of cadastral data. The experts were asked about the design of a data capture system, using a mobile application, to acquire data on properties and their approximate coordinates, as well as the data of their owners, where the owners themselves are the ones who declare these data. A functional prototype has also been developed and tested in Spain. Results: The design is well received, understood as a declaration by owners, especially in rural areas; further processing of the information by technicians of the competent authority is necessary; involving the population has a positive impact on the perception that owners have regarding cadastral processes; some technical and training challenges must be taken into account, to ensure consistency and quality in the data collected; and the prototype tests demonstrate, due to the low GPS accuracy of mobile phones, that the identification of boundaries over a base map is possible in properties of one hectare or more. Full article

In the current landscape of hearing rehabilitation, ear mold manufacturing typically involves the injection of silicone into the external ear canal (EEC) of each patient. This invasive procedure poses several risks, including the potential for silicone residue retention and tympanic membrane perforation, which may necessitate surgical intervention. To mitigate these risks, we present the design of a video otoscope that integrates a scanner capable of capturing high-precision, real-time images of the EEC’s geometry. The developed device allows (i) the generation of a 3D CAD model leading to the direct, quick, and low-cost production of customized hearing aids using 3D printing and (ii) the establishment of medical protocols for carrying out diagnoses and monitoring of hearing pathology evolution using methodologies based on Artificial Intelligence. Furthermore, the use of customized hearing aids that allow the application of Rhythmic Auditory Stimulation (RAS) and music therapy enhances audiology as an alternative and innovative way to treat cognitive and degenerative diseases, as well as pathological disorders. Full article

This study is part of a broader project, the Open Source Bionic Hand, which aims to develop and control, in real time, a low-cost 3D-printed bionic hand prototype using signals from the muscles of the forearm. This work is intended to implement a bimodal signal acquisition system, which uses EMG signals and Force Myography (FMG) in order to optimize the recognition of gesture intention and, consequently, the control of the bionic hand. The implementation of this bimodal EMG-FMG system will be described. It uses two different signals from BITalino EMG modules and Flexiforce™ sensors from Tekscan™. The dataset was built from thirty-six features extracted from each acquisition using two of each EMG and FMG sensors in extensor and flexor muscle groups simultaneously. The extraction of features is also depicted, as well as the subsequent use of these features to train and compare Machine Learning models in gesture recognition through MATLAB’s Classification Learner tool (v2.2.5 software). Preliminary results obtained from a dataset of three healthy volunteers show the effectiveness of this bimodal EMG/FMG system in the improvement of the efficacy on gesture recognition as it is shown, for example, for the Quadratic SVM classifier that raises from 75.00% with EMG signals to 87.96% using both signals. Full article

Background/Objectives: African Swine Fever (ASF) is one of the most significant infectious diseases affecting both domestic pig and wild boar populations, leading to substantial economic and biosanitary consequences. In Europe, disease management relies on stringent biosecurity measures and surveillance through diagnosis, highlighting the urgent need for an effective and safe vaccine for ASF control. In this context, the VACDIVA project has generated several promising vaccine candidates, including those with the EP153R gene deleted and replaced by the eGFP reporter gene. Methods: In this study, pEP153R and eGFP proteins were produced using recombinant technology and demonstrated their antigenicity and DIVA capability through indirect ELISA. Additionally, a prototype serological DIVA test was designed and developed. The assay is based on the detection of antibodies against both DIVA antigens and the well-established immunogenic p72 protein. Results: This preliminary DIVA diagnostic assay complements vaccine candidates based on a genotype II ASFV strain, featuring the deletion of the EP153R gene and/or the insertion of the eGFP reporter gene, exemplified by the Lv17/WB/Rie1-∆CD vaccine candidate. Conclusions: This approach could potentially improve surveillance during prospective vaccination campaigns. Full article

Upcycling is identified as a process of the transformation of waste materials to which it is possible to give a value of artistic or environmental quality. To date, the greatest use of upcycling can be found in the design, art and fashion sectors. As in other sectors, one of the biggest challenges in the construction industry in the future is the search for new ways to reuse discarded materials. In this sense, upcycling is a new technique for the recovery of removed waste but with a much lower use of energy and resources than the regeneration of recycled material. With respect to these issues, the aim of this paper is to present the results of a design experimentation aimed at defining methodologies and tools for the reuse of building components from the decommissioning or renovation processes of existing buildings, with an approach that integrates both the disassembling and the re-assembling of construction elements, in line with the sustainable development and climate neutrality goals that the European Union aims to achieve by 2050. The methodology used made use of a field experiment by means of the creation of a prototype that made it possible to evaluate the results of the study which, if on the one hand made it possible to define an appropriate procedure for upcycling, on the other hand highlighted how these procedures save energy and reduce the emission of CO₂ in the environment. In this specific case, the experimentation gave the following results: energy savings 2038.92 kWh; CO₂ reduction 641.80 kg compared to a similar intervention from scratch. Therefore, the definition of a replicable and scalable operational process for the upcycling activity applied to architecture allows, by means of the reuse of those building materials and construction elements that still have a useful life, and which can, therefore, be used in the field of architecture, for a profitable contribution to the development of sustainable procedures in the field of architecture and the circular economy. Full article

In this article, we propose, for the first time, to apply the flux-switching permanent magnet (OR-FSPM) generator to the oscillating water column wave energy conversion (OWC-WEC), and a novel dual three-phase 24-slot/46-pole OR-FSPM generator for OWC-WEC is designed and analyzed. The feasible phase-shift angle (PH-Angle) between the two sets of windings, namely 0°, 30° and 60°, is analyzed. The electromagnetic performance of the generator under three winding configurations is investigated, including PM flux linkage, back electromotive force (EMF), open-circuit rectified voltage, inductance, cogging torque, electromagnetic torque and unbalanced magnetic force (UMF). The prototype is manufactured, and the experimental results are consistent with that of the finite-element analysis (FEA) results. The generator with 0° and 60° PH-Angle winding configuration has stronger fault tolerance. When the 30° PH-Angle winding configuration is adopted, it has the maximum back-EMF fundamental amplitude, maximum average electromagnetic torque and the minimum torque ripple, and there is no UMF when a single set of windings is running. Therefore, the proposed novel OR-FSPM generator with 30° PH-Angle winding configuration is more suitable for OWC-WEC. Full article

This paper focuses on a solution of target self-positioning when a Global Navigation Satellite System (GNSS) is denied. It is composed of Inertial Navigation Systems (INS), Signals of Opportunities (SOPs), and a navigation prototype. One of the options for navigation via SOP (NAVSOP) is to utilize cellular signals, such as Long Time Evolution (LTE). When the prior information is insufficient, the location of the base station (BS) is obtained by collecting the demodulation of the downlink signal, and the synchronization signal is used for static time offset correction. In view of the large positioning error of the trilateral positioning method based on Received Signal Strength (RSS), a multi-station positioning optimization method is proposed by introducing the robust regression. Monte Carlo simulation experiments indicate that the method has improved the positioning failure and insufficient accuracy. Aiming at the influence of the state estimation errors on filtering results, the Second Order Mutual Difference (SOMD) method with the noise covariance R, which is independent of the existing Extended Kalman Filter (EKF) framework and combined with Redundant Measurement Noise Covariance Estimation (RMNCE), is applied to the model. The simulation results show that the average error of the robust model is 10.28 m, which is better than the EKF method. Finally, a vehicle test in constant speed has been carried out. The results show that the proposed model can realize self-positioning with limited BS location information, and the positioning accuracy can reach 11.68 m over a 283 m trajectory. Full article

The variable-flux memory machine (VFMM) can perform flexible online PM flux adjustment by utilizing a magnetizing current pulse, effectively extending the machine operation range. However, the continuous flux adjustment (CFA) method generally suffers from sophisticated control effort due to frequent actions of the power converters. Thus, a new two-state magnetization state (TS-MS) manipulation method is developed to simplify the MS manipulation process, while maintaining almost the same operating envelope compared to the CFA method. In addition, for further extension of the operation region, this paper proposes a novel two-state linear FW (TS-LFW) strategy with simple implementation. In the TS-LFW strategy, piecewise linear approximations for FW are, respectively, planned at MS1 and MS2. Distinctively, the determination of the two working MS of all the two-state methods in this paper is discussed to avoid the unnecessary MS manipulations. Finally, the feasibility and effectiveness of the proposed TS-LFW strategy are verified through the experimental results on a hybrid magnetic circuit VFMM (HMC-VFMM) prototype. Full article

An embedded coupled tank system (CTS) based on an ARM Cortex M7 microcontroller is developed for liquid level control, utilizing three nonlinear control strategies: fuzzy logic controller (FLC), feedback linearization (FL)-based proportional integral derivative (PID) controller, and FL-based FLC. The goal is to maintain an accurate predefined water level in the second tank and compare the performance of these controllers in terms of overshoot, settling time, and tracking accuracy. The CTS model is developed using physical parameters obtained from a real experimental setup. The controllers are first simulated in Matlab/Simulink and then tested on a physical CTS prototype, featuring a microcontroller interface with pumps, actuators, and sensors for real-time control and data acquisition. A custom graphical user interface and software are developed for conducting experiments and acquiring data. Results show that FL-based FLC and FL-based PID controllers offer better overshoot and tracking performances than FLC on nonlinear CTS. However, FLC and FL-based FLC outperform FL-based PID in settling time, with FL-based FLC showing very good performance in terms of tracking accuracy, overshoot, and settling time. Full article

Ti-6Al-4V is a well-known alloy for its low density and excellent corrosion resistance, making it popular in aerospace, marine, medical, and automotive applications. However, at elevated temperatures, the alloy forms oxides, leading to embrittlement. In additive manufacturing, particularly in the direct energy deposition (DED) process, which involves high temperatures, the alloy experiences oxidation. An inert gas chamber provides shielding during the process but limits the size of the manufactured components, and deposition in a vacuum chamber can alter the chemical composition of the alloy. Local shielding is a technique generally used for such applications, but it uses a high volume of shield gas, contributing to environmental contamination. This study presents a novel approach for the development and preliminary evaluation of a prototype nozzle attachment system for the additive manufacturing (AM) of Ti-6Al-4V using a direct energy deposition (DED) process in an open-air environment system. The system was designed to reduce shield gas consumption by providing conformal shielding in critical areas. This was achieved by dividing the shielding area into eight segments, with each of the eight attachments of the nozzle attachment system selectively activated to supply shield gas only where required. Four different shield gas flow rates of 20, 25, 30, and 35 SCFH were tested at three different locations under the attachment to investigate the optimal flow rate. The results proposed maintaining a baseline flow rate of 5 SCFH in all attachments and employing 60 SCFH during transitions between attachments for rapid shielding. The system maintained oxygen concentration levels below 200 PPM within 2.1 s, with an average gas consumption of 65 SCFH, underlining an 85% reduction compared to other studies. These findings highlight the potential of this system for future implementation and scalability for reactive metal depositions like Ti-6Al-4V in AM using DED processes. This study addresses the need for an effective shielding environment during deposition while minimizing the shield gas consumption. A nozzle attachment system was designed and developed to provide conformal shielding during the deposition process. Key parameters, such as the shielding flow rate, activation time, and shielding range of the nozzle attachments, were investigated. The system successfully delivered shield gas to the critical areas and provided a safe environment for deposition. Argon consumption was reduced by 85% compared to other studies in the same field, with an optimal flow rate of 25 Standard Cubic Feet per Hour (SCFH) of shielding gas used to cover all critical areas in the experiments. The effect of the laminar and turbulent flow of shield gas on the deposition path was also analyzed in this study. Full article

This paper conducts a comprehensive experimental comparison of two widely used additive manufacturing (AM) processes, Fused Deposition Modeling (FDM) and Stereolithography (SLA), under standardized conditions using the same test geometries and protocols. FDM parts were printed with both Polylactic Acid (PLA) and Acrylonitrile Butadiene Styrene (ABS) filaments, while SLA used a general-purpose photopolymer resin. Quantitative evaluations included surface roughness, dimensional accuracy, tensile properties, production cost, and energy consumption. Additionally, environmental considerations and process reliability were assessed by examining waste streams, recyclability, and failure rates. The results indicate that SLA achieves superior surface quality ($R_a\approx 2\mathsf{\mu }\mathrm{m}$ vs. 12–$13\mathsf{\mu }\mathrm{m}$) and dimensional tolerances ($\pm 0.05\mathrm{mm}$ vs. $\pm 0.15$–$0.20\mathrm{mm}$), along with higher tensile strength (up to $70\mathrm{MPa}$). However, FDM provides notable advantages in cost (approximately 60% lower on a per-part basis), production speed, and energy efficiency. Moreover, from an environmental perspective, FDM is more favorable when using biodegradable PLA or recyclable ABS, whereas SLA resin waste is hazardous. Overall, the study highlights that no single process is universally superior. FDM offers a rapid, cost-effective solution for prototyping, while SLA excels in precision and surface finish. By presenting a detailed, data-driven comparison, this work guides engineers, product designers, and researchers in choosing the most suitable AM technology for their specific needs. Full article

Although robots are increasingly expected to perform inspection tasks in three-dimensional ferromagnetic structural environments, magnetic-wheeled climbing robots face significant challenges in overcoming obstacles and transiting between planes. In this paper, we propose a novel bicycle-like magnetic-wheeled climbing robot, named BiMagBot, featuring two magnetic wheels that allow the adaptive adjustment of magnetic adhesion without the need for active control. The front wheel incorporates an arc tentacle mechanism that rotates a ring magnet to adjust the magnetic adhesion, while the rear wheel uses an eccentric shaft-hole design to facilitate a smooth transition of magnetic adhesion between surfaces. The magnetic forces acting on both wheels during transitions through concave corners were analyzed and discussed via simulations to elucidate the underlying principles. A prototype of the robot was developed and tested experimentally. The results show that the front and rear wheels can adjust the magnetic adhesion during the transition of corners with angles ranging from 90° to 315°. The robot only weighs 1.6 kg, but it can carry a weight of 2 kg with a speed of 0.9 m/s to transit across concave corners, demonstrating comprehensive capabilities in plane transition, ease of control, and load capacity. Full article