Search Results (1,279)

Anaerobic digestion is a sustainable approach for waste treatment and renewable biogas production. A key parameter for large-scale applications is the Biochemical Methane Potential (BMP), which enables methane yield estimation and facilitates process scale-up. This study introduces an automated, low-cost prototype for BMP testing, comprising three 2-L reactors with provisions for future expansion. Control and data acquisition are carried out by low-cost embedded systems integrated with sensors for pressure, temperature, pH, and biogas flow. The system was evaluated using a mixture of pig manure and sludge from a local wastewater treatment plant. Real-time monitoring of temperature, pH, and biogas production was achieved. The heat exchanger, designed through transient energy balance modeling, increased the reactor temperature from 20 °C (lab temp.) to 38 °C in 400 s. Overall, the prototype demonstrated reliable performance, achieving rapid heating, stable monitoring, and precise biogas flow quantification through both displacement and pressure methods. Full article

This study presents the development of a portable DOBI meter prototype designed for the rapid, low-cost evaluation of crude red palm oil (RPO) quality. The device employs two narrow-spectrum LEDs (UV at 269 nm and visible at 446 nm) as light sources, paired with a broadband photodiode (PD) detector to measure light absorption in a quartz cuvette containing 95% hexane-diluted oil samples. Dedicated LED driver circuits, a PD receiver module, and microcontroller-based data acquisition and display systems were integrated into a compact enclosure. Calibration procedures involved the measurement of LED emission spectra and PD responses, followed by standard curve generation using known RPO concentrations. The results from the DOBI meter were validated against a commercial spectrophotometer (Merck Prove 600), demonstrating high accuracy with less than 5% deviation. Further analysis of RPO extracted from microwave-treated mesocarps showed consistent DOBI values and carotenoid concentrations across both instruments. The developed device offers a reliable, accessible alternative for assessing palm oil quality, particularly in field or small-scale industrial settings. Full article

The increasing adoption of high-performance DC motor control in embedded systems has driven the development of cost-effective solutions that extend beyond traditional software-based optimization techniques. This work presents a refined hardware-centric approach implementing real-time particle swarm optimization (PSO) directly executed on STM32 microcontroller for DC motor speed control, departing from conventional simulation-based parameter-tuning methods. Novel hardware-optimized composition of an interval type-2 fuzzy logic controller (FLC) and a PID controller is developed, designed for resource-constrained embedded systems and accounting for processing delays, memory limitations, and real-time execution constraints typically overlooked in non-experimental studies. The hardware-in-the-loop implementation enables real-time parameter optimization while managing actual system uncertainties in controlling DC micro-motors. Comprehensive experimental validation against conventional PI, PID, and PIDF controllers, all optimized using the same embedded PSO methodology, reveals that the proposed FT2-PID controller achieves superior performance with 28.3% and 56.7% faster settling times compared to PIDF and PI controllers, respectively, with significantly lower overshoot at higher reference speeds. The proposed hardware-oriented methodology bridges the critical gap between theoretical controller design and practical embedded implementation, providing detailed analysis of hardware–software co-design trade-offs through experimental testing that uncovers constraints of the low-cost microcontroller platform. Full article

This paper presents the design and testing of a lightweight, low-cost robotic arm with an extended vertical range. The 9-degree-of-freedom (DOF) system comprises a 6-DOF arm and a 3-DOF gripper. To minimize weight, the six wrist and gripper joints are cable-driven, with all actuators relocated to the shoulder assembly. As a result, the wrist and gripper only weigh 222 g and 113 g, respectively, significantly reducing the inertia on the end effector. The arm utilizes a SCARA-configuration that slides along a tower for extended vertical reach. A key innovation is a closed-section frame that attaches the arm to the tower, in which the bending and torsional loads from the payload can be directly transferred onto the static structure. In contrast to conventional design, this design does not require the shoulder motor to take the bending load directly. Instead, the motor only needs to overcome the rolling friction of the reaction load. Experimental results demonstrate that this approach reduces the required motor torque by a factor of 30. Consequently, the prototype can manipulate a 3 kg payload at a 0.5 m lateral reach while weighing only 4.5 kg, costing USD 1200, and consuming a maximum of 11.1 W of power. Full article

Improving the energy efficiency of traditional production methods while preserving their cultural and economic value is a challenge aligned with the Sustainable Development Goals of the 2030 agenda. Refrigeration during cheese maturation is particularly energy-intensive, contributing significantly to greenhouse gas emissions and operating costs. An approach to make traditional cheese production more sustainable, through the development of a prototype ripening chamber with a natural refrigerant-based refrigeration system powered by renewable energy was studied. A dedicated system based on an Internet of Things architecture was developed using low-cost sensors, microcontroller units, and single-board computers to enable real-time measurement and monitoring of environmental variables and energy consumption throughout the ripening process. A comparative analysis was conducted using ewe’s milk cheese, produced and ripened with Protected Designation of Origin conditions, in both the prototype and the conventional chambers over four weeks, quantifying energy consumption and evaluating product quality. Results demonstrate the technical feasibility of energy efficient and sustainable refrigeration systems, as well as the possibility of retrofitting installed cheese ripening chambers with affordable IoT monitoring systems, while maintaining traditional cheese quality standards. Full article

In today’s fast-paced world, secure and efficient access control is crucial for places like schools, gated communities, and corporate campuses. The system must overcome the issues of manual checking and record maintenance of traditional methods like RFID cards or license plate recognition. Our work introduces a budget-friendly, automated solution. A prototype was developed for a vehicle sticker recognition system to control and monitor gate access at NFC IET University as a case study. The automated system design will replace manual checking by detecting the car stickers issued to each vehicle by the university administration. An optimized lightweight YOLOv8 model is trained to identify three categories: IET stickers (authorized for access), non-IET stickers (unauthorized), and no sticker (denied access). A webcam connected to the Raspberry Pi 4 scans approaching vehicles. Authorized vehicles are allowed when the relevant class is detected, which signals a servo motor to open the gate. Otherwise, access to the gate is denied, and infrared (IR) sensors close the gates. A second set of IR sensors and a servo motor was also added to manage the exit side, preventing unauthorized tailgating. The system’s modular design makes it adaptable for different environments, and its use of affordable hardware and open-source tools keeps costs low, which is ideal for smaller institutions or communities. The prototype model is tested and trained on self-collected datasets comprising 506 images. Full article

This paper presents a novel continuous-wave Doppler RADAR system for real-time speed measurement of moving objects, implemented using software-defined radio (SDR). Unlike traditional high-cost solutions typically found in research centers or specialized laboratories, this prototype offers a low-cost, compact, and easily deployable platform that lowers the entry barrier for experimentation and research. Operating within the 70 MHz–6 GHz range, SDR enables highly flexible signal processing; in this implementation, a 5.5 GHz carrier is selected to improve the detection precision by exploiting its reduced bandwidth for more accurate observation of frequency shifts. The carrier is modulated with a 2 kHz signal, and Doppler frequency deviations induced by object motion are processed to calculate velocity. Using a Welch spectral estimator, the system effectively reduces noise and extracts the Doppler frequency with high reliability. The prototype achieves speed measurements up to 196.36 km/h with approximately 2% error in the 0–100 km/h range, confirming its suitability for road traffic monitoring. A key innovation of this work is its single-antenna cross-polarized configuration, which simplifies hardware requirements while maintaining measurement accuracy. Furthermore, the system’s portability and open-access design make it ideal for in-vehicle applications, enabling direct deployment for automotive testing, driver-assistance research, and educational demonstrations. All design files and implementation details are openly shared, eliminating patent restrictions and encouraging adoption in low-resource academic and research environments. Full article

Microfluidic paper-based analytical devices (µPADs) are ideal for point-of-care diagnostics due to their low cost, compact size, and ease of use. However, current designs have limited multiplexing capabilities, making it difficult to simultaneously detect pathogens and biomarkers in the same sample. In this work, we introduce NanoArrayPAD−X, a novel µPAD design that combines wax-printed microfluidic networks with an array of nanoprobes for the simultaneous detection of multiple targets. This is achieved by distributing the sample through the microfluidic network containing X detection areas. There, targets are captured through physical interactions and recognized by specific antibody-coated nanoprobes released from the nanoprobe array. This generates X dots whose color depends on the concentration of the targets in the sample. A NanoArrayPAD−5 platform capable of detecting five targets was developed to aid in the diagnosis of ventilator-associated pneumonia (VAP). The sensor array could detect Pseudomonas aeruginosa, Klebsiella pneumoniae, Staphylococcus aureus, Escherichia coli, and the inflammatory biomarker myeloperoxidase (MPO) with a total turnaround time of 25 min, which is faster than waiting for an overnight culture and the results of an ELISA. Notably, our prototype successfully detected the targets in 87 bronchial aspirate (BAS) specimens, thus demonstrating the suitability of the platform for analyzing complex samples with sputum-like qualities. These findings establish NanoArrayPAD−X as a promising tool for the rapid, multiplexed screening of respiratory pathogens and biomarkers, with potential for guiding personalized antimicrobial therapy in suspected cases of nosocomial pneumonia. Full article

Predictive maintenance helps reduce operational costs and improve machine reliability by anticipating failures. However, existing solutions are often too expensive or complex for small rotating machinery such as fans or low-power motors. This work presents a low-cost, IoT-based monitoring system using an ESP32 microcontroller combined with MEMS sensors (an accelerometer and a microphone). The system continuously collects vibration and acoustic signals, which are then processed using RMS and FFT techniques. Machine learning algorithms, such as anomaly detection or basic classification, are used to identify deviations from normal operation. A working prototype was tested under various fault conditions, including imbalance and wear. The system successfully identified abnormal states through signal deviations in both time and frequency domains, with over ~73% detection accuracy. The proposed solution is cost-effective, simple to implement, and well-suited for educational or industrial environments. It demonstrates the potential of embedded systems and basic signal analysis for scalable predictive maintenance applications. Full article

This paper reviews and analyzes three types of vertical-axis wind rotors: the classic Savonius, spiral Savonius, and Darrieus designs. Using numerical modeling methods, including computational fluid dynamics (CFD), their aerodynamic characteristics, power output, and efficiency under different operating conditions are examined. Key parameters such as lift, drag, torque, and power coefficient are compared to identify the strengths and weaknesses of each rotor. Results highlight that the Darrieus rotor demonstrates the highest efficiency at higher wind speeds due to lift-based operation, while the spiral Savonius offers improved stability, smoother torque characteristics, and adaptability in turbulent or low-wind environments. The classic Savonius, though less efficient, remains simple, cost-effective, and suitable for small-scale urban applications where reliability is prioritized over high performance. In addition, the study outlines the importance of blade geometry, tip speed ratio, and advanced materials in enhancing rotor durability and efficiency. The integration of modern optimization approaches, such as CFD-based design improvements and machine learning techniques, is emphasized as a promising pathway for developing more reliable and sustainable vertical-axis wind turbines. Although the primary analysis relies on numerical simulations, the observed performance trends are consistent with findings reported in experimental studies, indicating that the results are practically meaningful for design screening, technology selection, and siting decisions. Unlike prior studies that analyze Savonius and Darrieus rotors in isolation or under heterogeneous setups, this work (i) establishes a harmonized, fully specified CFD configuration (common domain, BCs, turbulence/near-wall treatment, time-stepping) enabling like-for-like comparison; (ii) couples the transient aerodynamic loads p(θ,t) into a dynamic FEA + fatigue pipeline (rainflow + Miner with mean-stress correction), going beyond static loading proxies; (iii) quantifies a prototype-stage materials choice rationale (aluminum) with a validated migration path to orthotropic composites; and (iv) reports reproducible wake/torque metrics that are cross-checked against mature models (DMST/actuator-cylinder), providing design-ready envelopes for small/medium VAWTs. Overall, the work provides recommendations for selecting rotor types under different wind conditions and operational scenarios to maximize energy conversion performance and long-term reliability. Full article

Small-scale wind turbines are becoming increasingly important in renewable energy systems due to their ability to operate in low-wind-speed environments and adapt to various installation locations, especially in areas with energy shortages. This paper presents the design, analysis and development of a Helical Vertical Axis type Wind Turbine (H-VAWT) using uPVC pipe as the blade material, offering a lightweight, low-cost, and corrosion resistant solution. The blade structure is optimized for use in residential and off-grid areas with unstable wind conditions. Structural analysis is conducted in ANSYS, including static load analysis (deformation, equivalent stress, shear stress, maximum stress), torsional and bending stress, and modal analysis to assess mechanical performance and vibrational stability. Three blade designs are initially considered, and the helical model (0–45° twist) is selected based on simulation results. The prototype is successfully fabricated and tested under different wind speeds, showing effective power generation, with favorable results in power output, power coefficient, tip-speed ratio (TSR), and relative velocity. Full article

As electric vehicles (EVs) face increasing power demands, rapid charging requirements, and harsh operating conditions, efficient thermal management of lithium-ion batteries is critical for safety and performance. This study evaluates a liquid-cooled thermal management system for dry battery packs using computational fluid dynamics (CFD) simulations and experimentation. The battery pack was modeled in SolidWorks and analyzed using ANSYS Fluent. Simulation results showed a peak battery temperature of 47 °C, with coolant temperature rising from 17.1 °C to 37.4 °C, achieving a 10 °C reduction in battery temperature. Experimental validation yielded comparable outcomes, with a maximum battery surface temperature of 47.2 °C and coolant outlet temperature of 26.1 °C, indicating a 21.1 °C temperature drop. The strong correlation between simulation and experimental data confirms the system’s effectiveness in maintaining safe thermal conditions. Additionally, a low-cost prototype was developed, underscoring the practical viability and scalability of the proposed solution. Full article

This study presents a transmitarray antenna design operating at a center frequency of 9 GHz, addressing the need for high-gain and broad bandwidth antennas in modern data communication. The proposed design is structured as a quad-layer configuration using FR-4 dielectric substrates. The transmitarray’s phase profile is tailored to deliver a wideband flat response with low Side Lobe Level (SLL) and stable aperture efficiency across the operating band. It achieves a 1-dB gain bandwidth of 12.12% (from 8.56 GHz to 9.67 GHz) and a 3-dB gain bandwidth of 49.43% (from 8.45 GHz to 13.46 GHz) with an aperture efficiency of 21.3%. A prototype of the proposed design with 11 × 11 elements was fabricated and measured, and its measurement results closely aligned with simulation results, validating its performance. The proposed simple design realizes reduced complexity and fabrication costs while expanding operational gain bandwidth, thereby demonstrating substantial promise for next-generation X-band communication systems. Full article

This paper introduces an open-source software framework for implementing Field-Oriented Control (FOC) on a Brushless DC Motor (BLDC) across its entire speed range. The control strategy employs a Direct FOC method with a single Hall sensor combined with Space Vector Pulse Width Modulation (SVPWM) and complementary sensorless techniques. The BLDC motor and supporting circuits are modeled and validated through both simulation and hardware implementation. A modular software architecture enables deployment via distinct system components, promoting hardware abstraction and reducing platform-specific dependencies. The entire setup is conceptualized and executed in MATLAB/Simulink R2024b and the framework supports remote experimentation through a web-based interface, requiring only a single MATLAB license. This scalable solution is designed for academic researchers and industry practitioners alike, offering an accessible low-cost platform for motor control development, validation, and early-stage prototyping. Full article

This paper proposes a battery emulator based on a bidirectional non-inverting buck-boost power electronics converter. With the capability of bidirectional operation, it can emulate both charging and discharging processes. The proposed emulator is controlled with the advanced I² dual current-mode control (I²DCMC) algorithm, combined with a feedforward control, which ensures fast and accurate tracking of the voltage and current characteristics of the batteries. The emulator is universal in terms of the various mathematical models of the batteries, which can be implemented in real time. It has no limitations regarding different battery types. Detailed analysis and the design procedure of the proposed battery emulator are presented. The performances of the emulator are validated with simulation and experimental results for three battery types: polymer Li-ion, conventional Li-ion, and lead–acid battery. Both steady and transient states are analyzed, especially transitions between charging and discharging phases. The possibility of simple time scaling of charging/discharging processes is successfully achieved and demonstrated, which is very important in making tests faster, with preserved battery characteristics. Considering its low-cost and user-friendly operation, the proposed emulator can be a good alternative to the real batteries in experimental tests of different power electronics systems. The prototype, which is developed for the experimental verification of the emulator, is designed for and limited to the research of lower power ratings systems of up to 100 W. It is suitable in education to easily demonstrate the behavior of the batteries in multiple scenarios in controlled laboratory conditions. Full article