Abstract Low latency and energy-efficient design are important requirements for Reinforcement Learning (RL) algorithms deployed on embedded and edge computing systems. Software based Q-learning shows increased power consumption as well as the overhead of sequential execution. The paper shows an energy-efficient FPGA architecture for the Q-learning update based on High Level Synthesis (HLS). An FPGA accelerator targeting the device platform Xilinx Zynq-7000 (xc7z020clg400-1) has been designed and implemented. Loop pipelining and precision fine-tuning design techniques were applied to optimize the architecture. This improvement was achieved by 50 percent as a baseline architecture got a latency of 14 cycles, which was reduced to 7 cycles when the architecture was pipelined with loops. A relative comparison of fixed point (ap_fixed<16,8>) and floating point implementations has shown that the floating point arithmetic increases the number of LUTs used by 4 times, the number of DSPs used by more than 2 times, and the delay by 29 cycles. Post implementation power analysis for fixed-point architecture shows that its energy consumption is about 4 times less per Q-update operation than a floating-point design. The results show that pipelined fixed-point FPGA architectures are a good solution to speed up the reinforcement learning process in resource-limited embedded systems.
Abstract Given the demands of contemporary technology, as well as the complexity and diversity of manufacturing due to the quick updates of products, the traditional design of cotter joints has become inappropriate. One useful tool in this regard is computer-aided design (CAD) of cotter joints. Initially, finite element analysis showed great promise in simulating several mechanical applications. Finite element analysis can reduce the number of physical prototypes and experiments produced while optimizing each component throughout the design process. This study aims to design and analyze a new cotter joint to prevent failure in standard cotter joints due to the concentration of stresses in them. Then, the mechanical properties of the joints are determined using the integration between SOLIDWORKS software (version 2020) and ANSYS software (version R22). The deflections, von Mises, and shear stress values in joint elements are computed via the finite element technique. Finite element analysis evaluated the proposed cotter joint and was validated through strength verification. The proposed joint exhibited improved structural reliability. The factor of safety for tensile increased from 1.18 to 1.38, the factor of safety for shear from 1.36 to 1.93, and the factor of safety for bearing from 1.50 to 1.88, respectively. In addition, the margins of safety have increased from 0.18, 0.36, and 0.50 to 0.38, 0.93, and 0.88, respectively, which shows the improvement in load-carrying capacity and decrease in the risk of failure in case of axial loading. The results show that the proposed cotter joint has better structural safety and load-carrying performance with higher factors of safety and margins of safety as compared to the conventional design, which makes it more suitable for high-load engineering applications.
Abstract Climate change, rising global surface temperatures, and global warming pose significant environmental and human challenges. These environmental changes negatively impact weather patterns and ambient temperatures, affecting the amount of heat transferred to buildings in summer and lost in winter. Maintaining standard indoor temperatures requires electricity consumption through air conditioning. Researchers are working to address these challenges to protect the environment and human health, reduce electricity consumption, and meet sustainability requirements in the Iraqi construction sector. Traditional Iraqi clay bricks, shaped with various geometric patterns and perforations, were tested to improve their thermal performance and compare it to solid, non-perforated bricks. The experiments were conducted in a 1 × 1 × 2 m test chamber, insulated on all sides except the eastern side, where the test wall is located, which is exposed to external weather conditions and sunlight. An air conditioning unit was installed inside the test chamber to maintain the standard temperature during the tests. These perforated clay bricks, available in 25 and 35 mm diameters, demonstrated excellent thermal performance, reducing heat loads and minimizing the need for cooling during building renovations, thus lowering air conditioning energy consumption. These bricks exhibited the highest energy savings, resulting in an estimated 24 and 25% reduction, respectively, in thermal energy penetration into buildings. The thermal test of the highest energy-reducing bricks was conducted by sealing the 35 mm diameter holes with plastic plugs at both ends of each hole. This means that the air volume that filled the holes was reduced significantly, resulting in a 40% increase in energy reduction compared to solid bricks.
Abstract This study investigates the structural response of composite stiffened panels containing a circular delamination under axial compression. A comprehensive finite element model was developed using a cohesive-zone interface formulation and couples it with local and global buckling responses. The model was validated against experimental data with errors below 6% for both critical buckling and ultimate failure loads. A stiffened panel configuration close to the previously experimentally tested one was used to investigate the influence on buckling load and ultimate load due to delamination diameter, depth, and position on the skin plate. The results demonstrate that diameter is the most dominant parameter, accounting for up to 54% effect on buckling load and 77% on ultimate load. This was followed by depth, which notably affects stiffness (by up to 18%) and strength (by 6%). The interaction between diameter and depth was also significant, contributing to 27% effect on buckling load and 15% on ultimate load. In contrast, the influence of delamination position within the tested range was lesser than 2%. A key finding is the close correlation between post-buckling stiffness degradation, residual strength, and energy absorption capacity. This enables establishing the post-buckling stiffness ratio as an early-warning indicator of delamination-induced instability.
Abstract This paper discusses the influence of molybdenum disulfide (MoS 2 ) and chromium carbide (Cr 2 C 3 ) with different weight percentages of reinforcements on the mechanical properties of Duralumin based metal matrix composite. The composites were produced using a systematic experimental approach into which the compositions of Duralumin mixed with nano Cr 2 C 3 (3, 4, 5%), and MoS 2 (2, 3, 4%) were altered. The composite materials mechanical characteristics of Vickers hardness, impact strength, tensile strength, and yield strength were investigated for the prepared specimens. It was found that although an optimum percentage of MoS 2 did enhance the strength of yielding and ductility was maintained, a higher Cr 2 C 3 content did enhance tensile strength significantly and hardness value. Based on the experimental outcomes, the optimal combination of 93% Duralumin, 5% Cr 2 C 3 , and 2% MoS 2 yields the maximum mechanical properties of tensile strength of 201.7 MPa, Vickers hardness of 141 VHN, and yield strength of 168 MPa. Conversely, the reinforcement content also had a slight depreciation on the impact strength. At 5% Cr 2 C 3 and 2% MoS 2 of reinforcement it shows a strong interfacial bonding with the Duralumin matrix was ensured by the well distributed dispersion of Cr 2 C 3 and MoS 2 reinforcements in lower concentrations, as shown by SEM analysis.
Abstract Throughout this work, the vibratory response under resonance and non-resonance conditions of a simply supported (S-S), straight railway beam bridge incorporating a ballasted superstructure and subjected to moving vertical loads is studied. A specific type of nonlinearity is considered, namely, the variation of structural stiffness with the amplitude of vibration. The structure is simulated using the Bernoulli-Euler (B-E) beam theory, with stiffness characterized as a nonlinear function following three approximations: power law, non-linear law, and exponential function. Focusing on the first mode of vibration, the resulting nonlinear equation of motion is solved numerically through combined use of the central difference scheme (FDM) and the Runge-Kutta method (RKM). The obtained results indicate that the amplitude-dependent stiffness, as described by the first two approaches, significantly affects the bridge's behavior, especially on the resonant speeds. This dependence leads to a notable increase in the first frequency (stiffening effect) and, as a result, in the critical velocity. Furthermore, influences of the power law exponent, the initial vibration amplitude and the intensity of the applied force on the vibratory response are also investigated. For the last approximation, the opposite effect was observed, a result that indicates that the studied mechanical system exhibits softening behavior, resulting in an 11% reduction of the fundamental frequency and a 10% reduction of the critical speed.
Abstract Belleville washers made of Shape Memory Alloy (SMA) merge the unique properties of these materials with the advantages of conical disc spring geometry. Recent research has focused on characterizing these devices under cyclic compression. Key studies have involved numerical simulations and experimental testing. The findings confirm excellent recentering and energy dissipation capabilities of SMA Belleville washers, establishing them as prime candidates for next-generation seismic dampers for buildings and bridges. However, further investigation is required to optimize SMA Belleville washers by finding the cone angle and thickness that maximize energy dissipation. Considering damping devices fabricated by stacking Belleville washers, which rely on the pseudo-elastic effect, this work details an original methodology for systematic optimization of their design. This encompasses a preliminary elastic based sizing performed using adapted stress formulas, which is followed by a refinement stage employing Finite Element Analysis, via the 2020 R2 release of Ansys Mechanical solver. By generating a set of viable design alternatives, this novel methodology facilitates the efficient identification of the optimal configuration to maximize damping energy for given design constraints. The effectiveness of this approach was validated through case studies focused on optimizing SMA Belleville washers within advanced vibration suppression dampers.
Numerous disturbances frequently affect complex control systems operating in uncertain environments. Active Disturbance Rejection Control (ADRC) is a relatively modern control approach that offers strong potential for delivering stable and reliable system performance. Nevertheless, the design, analysis, and validation of such controllers are typically conducted in the time domain. This study employs frequency-domain analysis to assess the stability and effectiveness of an ADRC system. As a case study, a highly nonlinear, uncertain, time-invariant model of an exoskeleton system used in the rehabilitation therapy of an elderly patient was analyzed using loop gain frequency response. The obtained results indicate that exoskeleton systems controlled by ADRC exhibit a high degree of robustness. In particular, despite significant variations in plant characteristics, the bandwidth and stability margins remain relatively constant. Additionally, similar consistency was observed in sensitivity to input disturbances. Therefore, this control system presents a promising option for managing real-world control scenarios with challenging uncertainties due to its demonstrated characteristics.
The development of the Wireless Power Transfer (WPT), also known as wireless charging, has revolutionized the charging process of Electric Vehicles (EVs), providing for greater safety, automation, and convenience compared to the traditional conductive charging process. However, the issue of misaligned coils between the transmitter and the receiver remains a major concern for the effective power transfer rate in the wireless charging process and the subsequent successful commercialization of wireless charging technology. In this regard, an effective approach to the above problem has been proposed by this paper. A theoretical study for the distribution of the magnetic field for different square coil geometries was carried out to analyze the effect of the turns, spacing, and phase of the current for flux uniformity. Using nonlinear programming, a non-uniform distance coil was designed to reduce the variance of the magnetic flux intensity. The results showed the optimized coil to be superior compared to the conventional uniform coils. In addition, the DNN model was trained for the prediction of the relationship between the phase differences of the coil currents and the magnetic flux within the designated regions of the coil array using 500 data sets. The trained network obtained an R 2 value of 0.9997, thus validating the high precision of the trained network. The results obtained validated the fact that the magnetic flux density within the planar coil could be greatly enhanced by the optimal phase arrangement. The proposed method effectively counteracts one of the biggest hindrances in WPT, coil misalignment, through the integration of advanced EM design and data-driven predictive modeling techniques. The results of the study provide a new insight for the development of intelligent and dynamic WPT techniques to retain high transfer efficiencies irrespective of the misalignment levels. Integration of non-uniform coil design and optimized techniques from the realm of the neural network provides a major breakthrough in the development of efficient wireless charging techniques for the envisioned EV framework of the coming years.
Renewable energy systems and distributed energy systems have been adopted to accelerate the development of a smart grid. It manages solar and wind generation to ensure economic viability and environmental sustainability, but remains a challenge for modern energy infrastructure. Some of the serious concerns with smart grids include energy management, ethical compliance, and stakeholder trust. Fuzzy logic handles uncertainty and linguistic reasoning. It is possible to create Fuzzy Inference systems based on specific rules to enable sustainability goals, such as minimizing carbon emissions, reducing costs, and maximising power reliability. This Fuzzy Inference System (FIS) architecture is integrated with Multi-Objective Reinforcement Learning (MORL) and enhances the system's behaviour in accordance with sustainability principles. Simulated results indicate that the proposed FRS-MORL-based framework exhibits stable learning, desirable sustainability performance with an average reward of −14.9, reduced operational costs, effective control of underground carbon emissions, and reliable supply actions, while ensuring transparency and trustworthiness through interpretable fuzzy decision rules.
Multi-axis prosthetic feet are designed to replicate the natural anatomical motion of the human foot and enhance functional gait performance. This study aimed to design, fabricate, and clinically evaluate a locally manufactured multi-axis ankle–foot prosthesis that anatomically replicates the four principal motions—plantarflexion, dorsiflexion, inversion, and eversion—and to compare its performance with reference values of the human foot. This work represents the first locally developed multi-axis ankle–foot prosthesis in Iraq, designed as a purely mechanical system without electronic components, combining CNC machining and carbon-fiber 3D printing to achieve anatomically realistic motion and cost-effective production. The prosthetic foot was modeled in SolidWorks to reproduce the kinematics of the ankle–foot complex and fabricated using a combination of CNC machining and 3D printing. Tensile and bending tests were conducted on Al-7075-T651 and PA6-CF according to ASTM standards to confirm their structural suitability, while compression tests were performed on NBR and PU to determine elastic modulus and deformation behavior for soft-tissue mimicry. Clinical evaluation included gait trials with a force plate and G-Walk sensor system, capturing ground reaction forces (GRFs), spatiotemporal parameters, and ankle range of motion (ROM). The prosthesis achieved ROM values closely matching human anatomy: ∼15.5° dorsiflexion, ∼30° plantarflexion, and ∼±10.5° inversion/eversion. GRF components and spatiotemporal gait parameters were within normal reference ranges. Compression tests confirmed elastic behavior comparable to biological soft tissues, enabling shock absorption and improving walking comfort. G-Walk data demonstrated smooth phase transitions and good dynamic stability. The proposed multi-axis foot provides anatomically realistic motion and physiologically acceptable gait performance. The combination of structural material integrity and compliant elements ensures natural joint behavior, making this locally fabricated design a promising solution for clinical application and future multi-patient trials.
This paper introduces an electromechanical model of a latching solenoid that includes permanent magnets. The study proposes a new way based on force measurements to determine the electromechanical parameters in the system of equations to calculate the magnetic co-energy as a function of the current and the iron core's position. The magnetic flux of the permanent magnet is determined by also force measurement. Once the magnetic co-energy and flux are known, the electrical and mechanical equations are derived using the Lagrange's equation of the second kind. The accuracy of the method is verified by comparing simulation results with experimental data.
Dye-sensitized solar cells (DSSCs) offer low-cost and flexible photovoltaic operation but still suffer from slow electron transport, limited dye adsorption, and recombination losses in TiO 2 nanoparticle photoanodes. While TiO 2 nanotubes and TiCl 4 post-treatment have individually shown benefits, their combined effect particularly using TiO 2 nanotubes with optimized TiCl 4 deposition remains largely unexplored, leaving a key gap in understanding their synergistic impact. This study presents a hybrid TiO 2 photoanode composed of TiO 2 nanoparticles blended with TiO 2 nanotubes (TNTs), combined with an optimized TiCl 4 post-treatment to enhance charge transport and surface passivation. Composite films containing 5–20 wt% TNTs were fabricated to determine the optimal composition, with 10 wt% providing the best balance of electron mobility and surface area. The optimized photoanode were treated with TiCl 4 (Titanium Tetrachloride) at concentrations ranging from 30 to 120 mM. Studies revealed that a 90 mM treatment substantially enhanced dye adsorption and reduced charge recombination. The proposed study attained an efficiency of 88.4%, a 26.9% improvement over the untreated TNT-based cell (about 69.6%) and a substantial increase compared to the bare TiO 2 nanoparticle cell (about 5.98%). The modified sample had a higher short-circuit current density ( J sc = 18.38 mA cm −2 ) and an improved open-circuit voltage ( V oc = 0.71 V). Electrochemical impedance spectroscopy confirmed reduced charge-transfer resistance, while UV–Vis absorbance analysis verified improved dye uptake. Overall, this study demonstrates for the first time a systematic dual-parameter optimization of TiO 2 nanotube loading and TiCl 4 molecular-layer treatment, provides an efficient, economically viable strategy for improving DSSC performance, offering a promising pathway for next-generation TiO 2 -based photoanodes.
This study presents an advanced control strategy for switched reluctance motors applied in eco-friendly marine propulsion systems. To address the challenges of low-speed control precision and torque ripple inherent in SRMs, a novel integration of a high-gain DC-DC single-ended primary inductance converter with a bridge resonance converter is proposed to efficiently boost and regulate DC voltage. A proportional-integral (PI) controller optimized via the grey wolf optimization algorithm is developed to enhance speed control accuracy and significantly reduce torque fluctuations. Comparative simulations in MATLAB/SIMULINK (Ver 2024a), supported by hardware prototyping and experimental validation, demonstrate that the GWO-optimized PI controller outperforms classical PI control by delivering superior dynamic response, reduced torque ripple, and precise speed tracking. The proposed approach advances marine electric propulsion technology by offering a robust, efficient, and environmentally sustainable solution for SRM control.
Social classes are often influenced by numerous factors such as education level, labor market position, income, and property ownership, including housing and consumption. This also extends to sports sociology, where sports consumption can play a role. It is worth noting that the middle class may exhibit different consumption habits compared to both lower and upper classes. A recent survey was conducted to investigate differences in sports engagement, health status, and the consumption of general and specific food supplements across different social strata. Statistical analysis revealed a strong correlation between sports conservatism and sports engagement. However, no correlation was found between sports consumption and social stratification levels. Individuals who participate in sports tend to be more health-conscious and have a higher intake of supplements, particularly protein and vitamins. Among the middle class, those who were highly involved in sports appeared to consume more supplements related to digestion. This suggests that sports engagement among the middle class is linked to health consciousness and selective supplement consumption when compared to other social classes.
The current study explores the effects of primary nozzle exit diameter (PNED) and velocity ratio (VR) on the decay and mixing behaviour of coaxial, correctly expanded sonic jets using numerical simulations. Coaxial jets with 3 mm lip and three primary nozzle exit diameters of 6 mm, 9 mm, and 12 mm were examined while ensuring a constant secondary nozzle width of 6 mm. A singular free jet, which corresponds to the primary nozzle of the coaxial configuration, was utilized for comparative analysis. The axial Mach number decay and jet flow characteristics were systematically investigated to elucidate the dynamics of mixing. The findings indicate that the coaxial jet with a 6 mm primary nozzle demonstrates the most efficient mixing performance among the configurations assessed. Both PNED and VR significantly influence the behaviour of the coaxial jet. Notably, a velocity ratio of 0.2 was identified as yielding the highest mixing efficiency in comparison to the alternative velocity ratios. The simulations effectively captured the principal flow characteristics and aligned well with the empirical results. This investigation provides significant insights for the optimization of coaxial jet designs, particularly in contexts that necessitate effective mixing and regulated jet behaviour within aerospace, propulsion, and industrial applications.
The European Union recognizes environmental sustainability and innovation as key drivers of economic growth, competitiveness, and environmental protection. To monitor progress in this area, the European Commission launched the Eco-Innovation Index in 2011, managed by the Directorate-General for Environment (DG ENV). The index tracks the performance of EU Member States in eco-innovation, evaluates their contributions to sustainable development, and helps to identify best practices and lagging regions to support evidence-based policymaking. This study, conducted in connection with the December 2024 update of the index, analyzes the evolution of eco-innovation research in the scientific literature over the past 25 years. Using bibliometric analysis with the Biblioshiny application, the study examines data from Scopus and Web of Science to identify key trends and developments in the field. The results reveal the growing importance of the topic, the three periods of research, and highlight the most influential journals in eco-innovation research. It sheds light on the geographically fragmented collaborative networks among authors (led by Spain, China, Italy and Slovakia), and traces the evolution of thematic areas over time. It is clear that research should move towards more practical applications, as the theoretical foundations have been developed in recent years. These insights offer valuable guidance for companies, SMEs, policymakers, and future scholars by mapping influential contributions, emerging research directions, and potential policy applications. It is inevitable to keep an eye on the economic part and based on the literature we can state that economic development and eco-innovation should go hand-in-hand.
Today's strategies in urban architecture most often consist of large-scale interventions that are delayed in time. These interventions mainly try to influence the urban structure, but are less able to bring about localised changes. Alternative methods of intervention therefore need to be developed. The tissue-like functioning of the city can be helped by point interventions that focus on the urban planning problem at hand and are relatively quick. The paper deals with the background theory of such interventions and presents the practical side of this by presenting and analysing a concrete project in Debrecen. The research briefly reviews the relevant theoretical background of the topic, followed by the presentation of a concrete, field-implemented case study. The experiment contributes to a shift in spatial perception among users and highlights a real problem of spatial use, thereby preparing the ground for an urban intervention that may subsequently be realised through non-illegal methods.
The increasing demand for lightweight, high-strength materials in the aerospace and automotive industries has led to extensive research into sustainable alternatives to conventional composites. This research addresses the pressing need for environmentally friendly materials by investigating the potential of natural fibre-reinforced composites, specifically those using Pongamia Pinnata, Lannea Coromandelica, and Bauhinia Variegata fibres. The significant problem recognized in existing natural fibre composites is high degradation due to thermal loads and low mechanical properties making them unsuitable for critical applications such as Unmanned Aerial Vehicles (UAVs) and automotive components. The objective of this investigation is to enhance a sustainable composite material that is not limited to environmental benefits of natural fibres but also satisfies mechanical and thermal behaviours for UAV and automotive applications. This research focuses on improving the thermal stability, mechanical behaviour, and overall performance of different bio fibre composites by adopting chemical treatments and testing of different combinations of composites. Thermogravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC) are conducted to validate the thermal integrity and degradation behaviour and structural analysis is conducted to analyse the characteristics of deformation, strain, stress, and energy absorption. Pongamia Pinnatta (PP1) and Pongamia Pinnata + Lannea Coromandelica + Bauhinia Variegata (PPLCBV6) samples exhibit high thermal stability (7.78 and 8.18 mW min −1 ) and mechanical behaviour, so they are suitable for lightweight, heat-resistant UAV parts. Incase of Lannea Coromandelica + Bauhinia Variegata (LCBV5) and Pongamia Pinnata + Bauhinia Variegata (PPBV4) samples possess higher energy, temperature absorption (613.4 and 624.4 °C) and durability, so they are suitable alternatives for automobile components.
Pulse Width Modulation (PWM) techniques are vital for voltage source inverters (VSIs) to deliver high-quality, controlled outputs. The output voltage harmonic spectrum reveals the distinct performance of different PWM algorithms. Conventional PWM methods focus on enhancing performance parameters such as increasing the fundamental component, reducing total harmonic distortion (THD), minimizing switching losses, and selectively eliminating harmonics. In modern applications, additional challenges such as harmonic power dispersion and electromagnetic interference mitigation are also critical. This paper primarily addresses the enhancement of harmonic power dispersion through random PWM (RPWM) techniques. Unlike traditional deterministic PWM strategies, RPWM generates non-deterministic harmonic profiles, effectively spreading harmonic energy across a wider frequency range and thereby reducing acoustic noise in drive applications. A set of carrier-based RPWM techniques is proposed to improve VSI performance. These are implemented on a field-programmable gate array (FPGA) platform, confirming high-speed operation, less power dissipation, and efficient hardware utilization. The effectiveness of the FPGA implementation is validated through MATLAB–Simulink co-simulation, demonstrating the proposed RPWM methods' superiority in harmonic power dispersion and system performance.
