Effective suppression of vibration is essential for surface quality and tool longevity in machining. This study assesses the viability of Electromechanical Impedance Spectroscopy (EMIS)-based structural health monitoring as a compact alternative to microphone-assisted Fast Fourier Transform (FFT) analysis during the milling of Al-7075-T6. Experiments were conducted with a constant axial depth of cut of 0.5 mm while feed rate (50–70 mm/min) and spindle speed (1200–4300 rpm) were varied. A surface-bonded piezoelectric sensor recorded impedance signatures simultaneously with acoustic data. Dominant modes detected by EMIS lay between 90 Hz and 1.5 kHz and coincided with FFT peaks. The discrepancy between the two methods remained within 1.54–10.78%. The close agreement indicates that a single EMIS sensor can provide reliable, operator-independent vibration diagnostics without the extensive signal-conditioning infrastructure required by microphones. EMIS offers a pathway for real-time, closed-loop vibration control in milling applications.
Electrohydrodynamic inkjet printing technology can generate femtoliter-scale droplets, which provides significant advantages in additive manufacturing. With these advantages, electrohydrodynamic inkjet printing technology shows broad application prospects in repairing micro/nano-scale complex structures in flexible electronic devices and high-resolution displays. During the repair process, precise control of printed droplet volume is required according to target volume requirements. However, due to the complexity of the printing process, traditional theoretical and simulation methods face challenges in achieving effective volume control. This paper proposes a supervised learning-based electrohydrodynamic droplet volume control method. The algorithm innovatively establishes new strategy samples through historical datasets, which include the deviation between current droplet volume and target volume, current process parameters, and changes in process parameters for the next iteration. Based on a feedforward control strategy, we employ a multilayer perceptron (MLP) supervised algorithm to achieve printing parameter recommendation, significantly improving printing efficiency. Volume control experiments conducted on the established electrohydrodynamic printing platform show that the standard volume filling rate can reach 98%, and the control can be completed within a single control cycle.
Electrohydrodynamic direct-writing (EDW) is widely applied in the field of micro-nano manufacturing due to its advantage of rapid deposition of line structure. However, due to the difficulty of bending-torsion coupled modeling for EDW with large deformation, the mechanism and effective control strategies of EDW still unclear. This study firstly establishes a three-dimensional geometrically exact model for EDW using Euler angles. It contains differential equations for the mass conservation, the jet geometry, the jet kinematics, the jet dynamics, and the electric field and charge. Euler angles are used to exactly describe the jet’s geometric variation. A theoretical electric field description for non-uniform electric field is introduced. The universality of the model is validated by reducing the governing equations system to a two-dimensional steady-state situation. The geometrically exact model established in this study is useful for revealing the mechanism of EDW and exploring its control strategies.
TDM PON technology widely deployed since the early and has evolved with ease to support the increasing bandwidth demands of FTTH. This research work presents the design and performance evaluation of a bidirectional 20 Gbps Time and Wavelength Division Multiplexed Passive Optical Network (TWDM-PON). The system designed by eight channels operating at 2.5 Gbps each and is analyzed using return-to-zero (RZ), non-return-to-zero (NRZ), carrier-suppressed return-to-zero (CSRZ) and duo-binary (DB) modulation formats. Performance metrics such as Q-factor and bit error rate (BER) are evaluated under varying input power conditions. The performance comparison is made in terms of Q factor and BER for varying transmitter powers. It is found that DB modulation format gives best performance when power budget improvement is sought. For low power condition (less than -15 dBm) DB modulation format gives superior performance. High dispersion tolerance in DB makes the system better with low power budget.
This study investigates the seismic response of reinforced concrete (RC) moment-resisting frame structures by analyzing the structural implications of integrating the staircase core. A six-story RC building, regular in plan and elevation, was adopted as the reference configuration (Model A), excluding the staircase. Three alternative models (B, C, and D) incorporated the staircase at varying plan locations to assess its influence. A comprehensive modal and response spectrum was conducted in accordance with RPA99/Version 2003 and BAEL91 design provisions. The introduction of the staircase core resulted in notable reductions in the fundamental period, emergence of torsional modes, particularly in models C and D, and significant redistributions of internal forces in both beams and columns. Short-column effects were observed in members adjacent to the staircase, raising concerns about potential brittle shear failure. The presence of the staircase core increased longitudinal and transverse reinforcement demands in critical columns, with amplification rates reaching up to 60%. These results show that the staircase plays a crucial role in modifying global stiffness, torsional response, and local demand concentrations. Neglecting the staircase core in structural modelling can lead to unconservative seismic assessments and increased vulnerability to damage or collapse under seismic excitations. The study provides an argument for its systematic inclusion in analytical models to ensure resilient and code-compliant design strategies.
In response to the challenges of low brightness, low contrast, and severe noise in low-light images, this paper proposes a lightweight, multi-scale, frequency- and spatial-domain collaborative low-light image enhancement network—FRT-Net. This method integrates classical Retinex theory with modern deep learning techniques. The Retinex decomposition module explicitly separates reflectance and illumination, providing the network with physical interpretability. A multi-scale feature extraction module is designed to capture global brightness trends and local texture details in parallel. Additionally, a frequency-domain FFT filtering branch is introduced to address spectral deficiencies and suppress noise. The CBAM attention mechanism is embedded to adaptively recalibrate channel and spatial weights, enhancing key feature representation. Finally, a comprehensive loss function is employed to collaboratively optimize brightness enhancement, detail recovery, color fidelity, and noise suppression. Experimental results on three mainstream benchmark datasets—LOLv1, LOLv2_real, and LOLv2_syn—demonstrate that FRT-Net ranks among the top two methods in terms of PSNR, SSIM, and LPIPS metrics, achieving an average PSNR of 22.98 dB, SSIM of 0.866, and LPIPS of only 0.075. The model contains only 0.55 million parameters(M) and requires 32.81 GFLOPs, meeting the real-time application demands of mobile devices. Ablation studies verify the effectiveness of each module. With its excellent performance and lightweight design, FRT-Net provides an efficient and robust visual perception foundation for practical applications such as nighttime autonomous driving and security surveillance.
In molten metal flow length tests using a spiral die with a thin gap, a non-filled region of molten metal was observed in the middle of the flow length in some test pieces. The influences of die gap, plunger speed and die temperature on the position and length of the non-filled region were investigated. Both the die gap and molten metal speed significantly affected the occurrence, position and length of non-filled region. The phenomenon of molten metal flow stoppage in the middle of flow length is discussed based on the non-filled regions in the test pieces.
This paper aims to analyze the behavior of DC corona discharge in wire-to-cylinder electrostatic precipitators. The principal operation of these types of electrostatic precipitators is based on the corona discharge on which their performance depends. In many industrial plants, particulate matter created in the industrial process is carried as dust in the hot exhaust gases. These dust-laden gases pass through an electrostatic filter. The aim of this investigation is to determine the important parameters of the corona discharge influenced by the applied voltage and bias voltage for three cylinders of different diameters. These parameters are done by using the Tassicker’s circular biased probe, which is incorporated at the same level of the surface in the precipitator electrode collector. Current-voltage curves are particularly analyzed. Experimental results show that discharge parameters are strongly affected by the applied voltage, biased voltage, and spacing between the high-voltage electrode and probe for both polarities.
Diffusion Absorption Refrigeration (DAR) systems offer a sustainable alternative to vapor compression refrigeration by utilizing thermal energy instead of mechanical work, making them well-suited for renewable energy applications and waste heat recovery. This review presents a comprehensive analysis of DAR systems, incorporating a statistical evaluation of various research aspects. It focuses on energy sources, alternative working fluids, system configurations, and their impact on the coefficient of performance (COP) and operating temperature. The evolution of DAR technology is traced from early theoretical models to recent experimental developments, supported by a bibliometric study that highlights key research trends, contributing countries, and periods of increased academic activity. The review assesses DAR performance in terms of efficiency improvements, integration of renewable energy, and the use of alternative working fluids. Bibliometric data indicate a growing research interest since 1990, with a notable peak in 2019, and significant contributions from China, India, Germany, and the United States. The study concludes by emphasizing the need for further research into advanced working fluids, the integration of thermal energy storage to enhance stability, and the development of computational models for optimized design and performance. Addressing these challenges will help advance DAR technology as a viable, sustainable cooling solution, supporting innovation and contributing to global energy sustainability.
An effective and ecologically plastic waste (PW) management system that is either directly or indirectly related to the Sustainable Development Goals (SDGs) and waste to clean energy initiatives like SDGs 7, 11, 12, 13, and 14 can be achieved through the innovative and sustainable process of pyrolysis. The aim of this study is to evaluate the effectiveness of a miniature pyrolysis pilot plant developed to manage plastic waste generated in Ovia North-East, Nigeria. The PW utilized in this study was collected daily from residences, businesses, marketplaces, and hospitals. At the collecting location, it was categorized using plastic identification code into PET, HDPE, PVC, LDPE, PP, and PS. A bomb calorimeter (ASTM D 5865-85) was used to experimentally establish the sorted PW's heating value (HV). A thermogravimetric analyzer (SII 6300 EXSTAR, Seiko Instruments) was used to evaluate the mass loss of PW in order to ascertain how its composition varied with temperature and time. After being shredded to smaller pieces, the PW was put into the reactor both independently and in combination. To ascertain the pyrolysis oil yield (POY) from known masses of distinct PWs (0.5 kg, 1.5 kg----5 kg), a performance test was conducted. According to the results obtained, PET PW had the lowest hydrogen carbon (H/C) ratio when compared to other PW samples. The performance of the H/C ratio is arranged as follows: HDPE (0.2034) > LDPE (0.1971) > PP (0.1737) > PS (0.1290) > PVC (0.1278) >PET (0.1188). Additionally, the PWs with the highest heating values used in this study were HDPE (44.57 MJ/kg), LDPE (44.44 MJ/kg), PS (41.22 MJ/kg), PVC (41.01 MJ/kg), PP (44.53 MJ/kg), and PET (22.87 MJ/kg). Besides, the mixed plastic waste stream (MPWs) produces the most pyrolysis oil, although the POY yield potential varies according to the PWs' composition. Furthermore, the least amount of POY was recorded by PVC. The following is the order of the PW POY: MPWs > PS > HDPE > LDPE > PP > PET > PVC. This study has demonstrated that generated plastic waste in Ovia North-East LGA, Nigeria, can be processed into solid char and pyrolysis oil using the developed Miniature Pyrolysis Pilot Plant, thereby protecting the ecosystems, human health, resources, and the climate, which are in line with SDGs 3, 6, 14, and 15.
Considering the dearth and limited supply of potable water for daily consumption globally, developing a desalination technique to produce water sufficient for the need has become imperative. This study examines the improvement of freshwater productivity in a single-slope solar still by incorporating a solar preheating system. The proposed design utilizes solar still distillation to preheat the feed water before it enters the distillation basin. This approach aims to increase the temperature gradient between the water surface and the glass cover, thereby accelerating the evaporation and condensation process. Experimental evaluations were conducted under varying climatic conditions and flow rates, with and without the preheater. We note that the productivity has improved at each flow rate as follows: at a flow rate of 1 L/min, the improvement percentage reached 96% (CLISS:130 g/hr and CLIPSS:170 g/hr), at a flow rate of 2 L/min, the improvement percentage reached 73% (CLISS:180 g/hr and CLIPSS: 220 g/hr), while the improvement percentage at 3 L/min became 61% (CLISS:240 g/hr and CLIPSS:290 g/hr.), and at a flow rate of 4 L/min, it reached 64% (CLISS:280 g/hr. and CLIPSS: 320 g/hr.), and up to a flow rate of 8 liters/minute, the productivity improvement percentage between the two systems reached 31% (CLISS:310 g/hr. and CLIPSS:340 g/hr.). The results showed that the preheated system significantly improved solar thermal performance and daily production, especially during the early morning and late afternoon hours. Compared to a conventional design, the preheated system achieved an overall productivity increase of 25% to 35%.
The LEAPET model is a cross-layer design for Wireless Sensor Networks (WSNs) that combines the functionalities of already existing Low-Energy Adaptive Clustering Hierarchy (LEACH), Power-Efficient Gathering in Sensor Information Systems (PEGASIS), and Adaptive Time Division Multiple Access (TDMA) protocols to improve energy efficiency and data transmission. Since rapid energy depletion of the sensor nodes is a major concern of WSNs, LEAPET overcomes this limitation by leveraging hierarchical clustering, chain-based data aggregation, and adaptive time-division scheduling to optimise both energy usage and communication efficiency. In this study, the LEACH forms clusters and chooses Cluster Heads (CHs). All other members within the cluster will send data to the CH instead of an individual data transmission to the base station (BS). The PEGASIS introduces chain-based data routing, which reduces energy consumption by limiting long-distance transmissions. In the PEGASIS chain formation, each node aggregates data sent to it and then transmits it to the neighbouring node in the chain until the aggregated data reaches the chain leader, which forwards it to the BS. To reduce the data collision from the chain leaders of the PEGASIS chain, an adaptive TDMA technique was used to allocate time slots for data transmission. The performance of the LEAPET protocol was compared to the existing LEACH and PEGASIS protocols using the number of alive nodes after rounds of data transmission, energy consumption and network lifetime metrics. The results of the simulations show that LEAPET outperforms existing LEACH and PEGASIS in terms of prolonged network lifetime, energy consumption and throughput. All simulations were carried out using the MATLAB programming language.
As electric vehicles (EVs) gain traction in low- and middle-income countries, their role in grid modernization and energy resilience has become increasingly relevant. This paper explores the transformative potential of bidirectional charging, Vehicle-to-Grid (V2G) and Grid-to-Vehicle (G2V), in two emerging clean mobility landscapes: Pakistan and Sub-Saharan Africa (SSA). While both regions grapple with fragile power infrastructure and nascent EV markets, they also share promising conditions for decentralized energy solutions, including rising urbanization, policy interest, and renewable energy capacity.We present a comparative analysis of the clean mobility ecosystem, policy readiness, and energy mix dynamics in Pakistan and SSA, contextualizing the promise and pitfalls of V2G/G2V adoption. To complement the policy and systems-level insights, we simulate the grid impact of varying EV penetration scenarios (baseline, low-density, and high-density) under both unidirectional (G2V) and bidirectional (V2G) frameworks. Using realistic adoption figures and residential 7–11 kW charger profiles, we model hourly load interactions to assess how EVs can either burden or stabilize local grids. Our findings reveal that while G2V adoption under high-density scenarios introduces significant early-evening grid stress, V2G strategies during peak demand periods can offset this load, effectively transforming EVs into distributed energy assets. The results underscore the need for region-specific charging policies, infrastructure investment, and digital control systems to harness the co-benefits of clean mobility and grid flexibility. Ultimately, we argue that V2G and G2V systems, if strategically implemented, can accelerate both electrified transport and energy transition pathways in Pakistan and SSA.
Electromechanical impedance (EMI) sensing with bonded piezoelectric patches is a compact option for structural health monitoring at high frequencies. This study evaluates the detectability of submillimeter microcracks in an Inconel 718 plate using a surface-bonded lead zirconate titanate (PZT) transducer through a finite element-based harmonic analysis. A two-dimensional coupled-field model represents a 20 × 20 × 5 mm³ plate and a PIC255 patch with an in-plane size of 10 × 10 × 0.5 mm³. The model performs a 10–100 kHz voltage sweep at 0.5 V to compute electrical resistance. Damage is introduced as circular notch-like defects with diameters of 0.25, 0.50, and 0.75 mm at nine locations that vary the sensor-to-defect distance. A mesh convergence study ensures numerical stability. Damage sensitivity is quantified using Root Mean Square Deviation (RMSD) of impedance signatures relative to the healthy baseline. Results show that frequency bands around local resonances provide the strongest separation between healthy and damaged states, with the most discriminative band observed near 54–57 kHz. RMSD increases monotonically with defect diameter and decreases with distance from the sensor, demonstrating an anisotropic positional sensitivity that is stronger along the patch axis.
Phase Change Materials (PCMs) have become popular for thermal energy storage (TES) uses due to their large latent heat capacity and almost isothermal performance. However, melting rates and the overall effectiveness of the system are constrained by their intrinsically poor heat conductivity. Considering latest studies investigating innovative shapes and combinations to optimize heat transfer achievement, fin insertion has become an effective and affordable upgrade technique. The most recent computational and experimental studies on fin-enhanced latent heat thermal energy storage (LHTES) systems are covered in this review, with a concentrate on how fin materials, forms, and configurations enhance PCM melting performance. Fin shapes such as longitudinal, radial, tree-like, spiral, T-shaped, V-shaped, fractal, and hybrid fins have been studied with respect to temperature uniformity, natural convection impacts, and melting time decrease. The outcomes demonstrate that improving fin shape could decrease melting times by as much as 70%, with geometric and tree-like fins performing better due to increased conduction–convection coupling. Furthermore, included in the research are design trade-offs involving fin volume against surface area as well as the impact of computational optimization in the design of fin shape. subsequently, research gaps and future initiatives are noted, with a focus on the possibility of hybrid improvement techniques that combine heat transfer fluid optimization or high-conductivity additives with advanced fin design.
This study examines the thermodynamic performance of a ternary refrigerant mixture composed of R32, R1234ze (E), and R152a (20/20/60 % by mass fraction) as a low-global warming potential (GWP) alternative to R410A in vapour compression refrigeration systems. The simulation was performed using REFPROP under standard operating conditions linked with an engineering equation solver, including 5 K of superheating and 5 K of subcooling. Under different operating conditions of constant evaporation temperature (T e = 5 °C) with varying condensation temperatures (T C ) (40 to 55 °C by step 2.5°C). Key parameters, including cooling capacity (Qₑ), compressor work (W c ), pressure ratio (P r ), discharge temperature (T D ), mass flow rate (ṁ), and volumetric efficiency (ηᵥ), were evaluated to assess performance. The mixture’s discharge temperature was slightly lower than that of R410A; this will reduce compressor thermal stress and increase compressor life span. Charts illustrating the effect of Tc on all performance indicators were created. In addition to thermodynamic analysis, safety considerations were reviewed. Despite its mild flammability (A2L), the adopted mixture demonstrated stable operation across various conditions and offers potential for applications where safety measures can be effectively implemented. The results indicate that the new mixture presents an energy-efficient and environmentally sustainable replacement for R410A. Further experimental validation is recommended to confirm these findings in real-world scenarios.
This work offerings a numerical study of natural convection heat transfer within a triangular enclosure having a centrally positioned cylindrical heating source. The effect of the heat source size is investigated by varying its non-dimensional diameter from 0.1 to 0.5. The eating source cylinder and enclosure are maintained at constant temperatures. The buoyancy-driven flow field is analyzed using streamline distributions, non-dimensional velocity magnitudes, and isotherm contours. Results reveal that the size of the internal heating source significantly affects the thermal performance of the combined structure. For small values of , the flow remains weak and localized, with limited convective motion. As increases to moderate values ≈0.3, recirculation regions intensify, velocity fields expand, and thermal plumes rise symmetrically, which indicates enhanced convective transport. However, additional increasing of values leads to flow constriction, reduced circulation strength, and causes less effective heat transfer. It is found that the average Nusselt number decreases with increasing due to diminished temperature gradients and restricted fluid motion despite the larger surface area provided by bigger cylinders. The results are applicable for the design of passive electronic cooling systems, solar thermal collectors, and other natural heat convection-based enclosures.
Natural convective in enclosures are very important topics in thermal engineering because they find versatile industrial applications. An internal circular cylinder's vertical position and heat source on fluid flow and heat transfer in a triangular cavity are investigated. Numerical simulations were carried out to analyze variations in the average Nusselt number, streamline topology, temperature distribution, and velocity fields by using ANSYS Fluent. The results show that the Nusselt number rises from approximately 0.91–0.94 at lower positions (Y = 0.1–0.3) to a maximum of about 0.97 near Y = 0.4 driven by intensified thermal gradients and buoyancy-induced circulation. Within the upper-to-mid region (Y = 0.2–0.4) the formation of large adjacent vortices enhances macro-scale mixing, resulting in nearly a 4% improvement in heat transfer relative to the reference case. At mid-level positions (Y = 0.4–0.6) quasi-steady symmetric circulations are sustained, maintaining effective convection with Nu values of 0.95–0.97. In contrast, at higher locations (Y = 0.7–0.9), the weakening of vortex strength leads to flow stagnation and localized deterioration in heat transfer, reducing Nu to about 0.90–0.92. Overall, the findings underscore the critical importance of internal component placement in improving natural cooling performance, and further suggest that the most efficient thermal behavior is achieved when the cylinder and heat source are positioned within 0.2 < Y < 0.4, offering practical guidance for optimizing the thermal design of triangular enclosures.
