Search Results (518)

Energy storage systems (ESSs) installed alongside traditional photovoltaic (PV) power plants are primarily used to track planned output, which often results in low utilization rates and extended payback periods. Moreover, existing research inadequately addresses actual grid frequency fluctuation characteristics and lacks multi-timescale optimization frameworks. To address these issues, this paper proposes a day-ahead and intraday multi-market coordinated rolling optimization strategy that integrates energy market trading with Automatic Generation Control (AGC) frequency regulation services through a zone-based frequency regulation control strategy. The strategy first defines distinct regulation zones based on regional control deviations, enabling a dynamic power allocation approach for the energy storage system. Recognizing that conventional constant power control can lead to battery overcharging, over-discharging, and reduced cycle life, the strategy introduces state of charge (SOC)-based variable power charging and discharging constraint coefficients. These constraints ensure the battery operates safely within its optimal range. Furthermore, an electrochemical energy storage life decay model is developed to quantify battery degradation. To accommodate the uncertainty in PV output, Latin hypercube sampling is employed. A day-ahead dispatch model is established to maximize the system’s total daily operating revenue, and rolling optimization is applied during the intraday phase to correct deviations from the day-ahead forecast. Finally, simulation studies using actual data from a PV power plant demonstrate that the proposed strategy achieves a total daily revenue of 107,477 ¥, representing a 24.6% improvement over energy market-only participation; battery aging costs are reduced by 11.1% compared to the scenario without zone-based frequency regulation control. Results indicate that the proposed strategy effectively balances battery life degradation against market revenue, significantly improving the overall operational efficiency and economic viability of PV-storage hybrid systems. Full article

The growing penetration of electric vehicles (EVs) and distributed photovoltaic (PV) generation is increasing operational uncertainty in distribution networks and intensifying long-standing challenges such as higher power losses, rising peak demand, and voltage instability. To address these issues, this paper proposes a multi-objective optimization framework for the strategic placement of smart meters equipped with demand response (DR) capability in radial distribution systems. Unlike conventional placement approaches that mainly focus on monitoring or reducing non-technical losses, the proposed method integrates active load control into the planning stage and explicitly considers the stochastic behavior of loads, PV generation, and electric vehicle charging stations (EVCSs). The problem is formulated with four objectives: minimizing total power losses, substation peak demand, voltage deviation penalty, and installation cost. A scenario-based stochastic model is employed to represent operational variability across the network. The resulting nonlinear mixed discrete optimization problem is solved using the Non-dominated Sorting Genetic Algorithm II (NSGA-II), an evolutionary multi-objective optimization technique that generates a set of Pareto-optimal solutions representing trade-offs among conflicting objectives. Smart meters are allowed to curtail a portion of controllable demand during critical loading conditions, which helps reduce feeder loading and improve voltage profiles. The proposed approach is evaluated on the IEEE 33-bus and IEEE 69-bus distribution systems. Simulation results demonstrate significant reductions in power losses and peak demand, with the IEEE 33-bus system achieving up to a 26.2% reduction in power losses and 52.5% reduction in substation peak demand compared with existing metaheuristic approaches. The results also indicate improved voltage stability and effective performance in the IEEE 69-bus system, confirming the importance of topology-aware DR-enabled planning. Overall, the findings show that embedding demand response capability within smart meter allocation can significantly enhance the resilience and operational efficiency of modern distribution networks with high EV and PV penetration. Full article

This study proposes a rigorous methodology for the optimal placement of voltage regulators in the Guayacanes feeder of the Buena Fe substation, Ecuador, by integrating electrical feeder modeling, exhaustive search, and multi-criteria decision-making. The feeder was modeled in detail by incorporating its radial topology, nodal electrical parameters, and representative operating conditions under minimum- and maximum-load scenarios. Based on this model, a set of technical evaluation criteria was established to quantify the impact of regulator installation, including active power losses, reactive power losses, global voltage deviation, average voltage variation, and voltage imbalance. An exhaustive search strategy was then implemented to evaluate all feasible regulator-location alternatives over the candidate nodes, thereby ensuring a complete exploration of the solution space. The resulting alternatives were ranked using the Weighted Sum Method (WSM) and the Technique for Order Preference by Similarity to Ideal Solution (TOPSIS), allowing the comparison of candidate locations from a multi-criteria perspective. The results indicate that node MTS 108932 provides the most technically favorable overall solution, achieving the greatest improvement in voltage profile quality and the most significant reduction in electrical losses. In addition, a sensitivity analysis was conducted by varying the weighting structure of the decision criteria, confirming the robustness of the selected alternative under different decision-maker preference scenarios. The proposed framework provides a technically sound decision-support methodology for voltage regulation planning in real radial distribution systems. Full article

During the start stage of ship welding, obtaining the three-dimensional coordinates of welding target points is affected by confined installation space, surface reflection, and deployment constraints. This paper proposes a low-complexity point-wise three-dimensional localization method based on two-dimensional visual planar guidance and one-dimensional point-laser distance constraints. A direct computation model of the laser incident point in the robot base coordinate system is established from the tool center point pose, the extrinsic parameters of the point-laser module, and real-time ranging data, enabling target-point coordinate estimation without dense three-dimensional reconstruction. A dual-stage stabilization strategy is introduced by combining ranging-level filtering, spatial coordinate smoothing, and outlier suppression. Image error-based visual closed-loop alignment is further used as a pre-measurement step to ensure that the point laser acts on the target region. Experimental results show that, after workplane-level extrinsic correction, independent validation points achieve a mean three-dimensional Euclidean error of 1.54 mm with a standard deviation of 0.28 mm. The average planar error in closed-loop alignment experiments is 1.124 mm. Passive binocular depth measurement on the current platform still yields an RMSE of 6.16 mm after linear correction. A simulated fillet-weld task verifies the feasibility of the complete perception-to-execution workflow. The proposed method provides a low-complexity coordinate acquisition route for discrete welding target points before arc ignition. Full article

Low-impact development (LID) facilities can significantly mitigate runoff and purify pollutants. However, their operational efficiency is highly influenced by regional rainfall characteristics, posing challenges to sustainable development in urban water management. This study investigates the degradation of runoff control efficacy in two LID installations located in Xi’an (semi-humid region) and Yangzhou (humid region) and examines the impact of continuous rainfall across different climatic zones. The results reveal that in both study areas, over 75% of annual rainy days experienced continuous rainfall, accounting for more than 80% of total rainfall volume. During continuous rainfall, the declining infiltration capacity of LID facilities reduces their performance, and the operational effectiveness of the LID facilities may deviate to some extent from the design goals. The lower attenuation coefficients observed in Yangzhou indicate that its LID facilities were more strongly affected by continuous rainfall than those in Xi’an. Regarding the designed annual runoff control targets, Xi’an achieved an average effectiveness of 83.7% at 60–85% design levels, outperforming Yangzhou by 12.09%. When increasing design rainfall, Xi’an exhibited increments of 41.0–200.7% for targets ranging from 60% to 80%, whereas Yangzhou required substantially larger increases for targets of 60–70%. Notably, achieving control targets above 85% in Xi’an and 75% in Yangzhou solely through increased design rainfall proved unfeasible. The study highlights that continuous rainfall affects LID performance in both humid and semi-humid regions, with facilities in more humid climates being particularly susceptible. These findings underscore the need for climate-adaptive LID design strategies to support long-term sustainable urban development goals. Full article

Phantom congestion in highway tunnels reduces operational efficiency and destabilizes traffic flow. In this study, the effects of a pacemaker system (PMS) on traffic operation in the Geumnam Tunnel on the Seoul–Yangyang Expressway were evaluated using a before–after analysis based on long-term vehicle detection system (VDS) data. Unlike past studies, this study provides an integrated empirical evaluation by jointly examining changes in spatiotemporal traffic flow, traffic capacity, and speed improvement at different level of service. The analyses were conducted using data from five VDS detectors installed upstream and downstream from the tunnel. After PMS installation, (i) increased average and 25th-percentile speeds at most detector locations and decreased speed standard deviation were observed near the tunnel exit and downstream sections, (ii) the maximum traffic volume increased from 1661 to 1765 veh/h/lane, and (iii) the mean speed and 25th-percentile speed increased by 6.5%, indicating speed-reduction alleviation among low-speed vehicles. Thus, the PMS increases vehicle speed, reduces speed variability, and enhances traffic flow stability and processing capability. These findings provide empirical evidence for the operational effectiveness of a PMS as a practical tool for mitigating phantom congestion in highway tunnel sections, reducing speed differences between vehicles, and improving traffic stream stability. Full article

The present investigation provides a comparative quality evaluation of Grade-60 steel rebars produced by induction furnace (IF)-based industries. In addition to analyzing quality variations in different industrial processes, this study aims to evaluate their compliance with international standards such as ASTM A615/615M. Samples of rebars from six local producers were collected, and their chemical compositions, microstructural features, hardness profiles, and tensile properties, including yield and tensile strengths, were analyzed. A special focus was given to analyzing the case–core microstructure, the presence of martensite rings, and impurity density, which substantially affect strength and ductility. Additionally, the electrochemical investigation was conducted at different temperature ranges, from 50 °C to 100 °C. Potentiodynamic polarization (PDP), electrochemical impedance spectroscopy (EIS) with open-circuit potential (OCP) was used to analyze the corrosion behavior of different samples in seawater. The finding suggests that the majority of rebars achieved the minimum requirements of ASTM 615 for Grade-60, except for some manufacturers, where minor deviation was noticed. However, significant variation in mechanical properties and chemical composition was observed among all six industries (A–F). Manufacturers are consistently exhibiting the highest mechanical properties, with a maximum yield strength of 580 MPa and tensile strength of 760 MPa (12 mm diameter sample). In contrast, various samples from E and F manufacturers recorded the lowest values, such as a minimum yield strength of 365 MPa (Industry F, 16 mm diameter) and a critically low elongation of 9.5% for sample E of 16 mm diameter. Microstructural analysis further confirmed the formation of martensite rim structures in samples of manufacturer A, evidencing the efficient thermomechanical treatment system installation in industries. Full article

Energy is a critical resource for human progress and societal well-being, but its generation must be environmentally clean and sustainable. Photovoltaic (PV) systems are a key renewable energy solution, but they must be optimized. This research is part of that effort. Many PV system designs with the same components are created, analyzed, and compared with the help of the System Advisor Model (SAM) version 2025.4.16. The one-row South azimuth PV system 1-2-15-S is the one with the highest annual energy production of 14,348 kWh/year, with the lowest installation space of 52.1 m² and the lowest payback period of 4.9 years, but it is suitable for comparatively small PV plants. The multi-row South azimuth PV systems are the most widely used and versatile. They offer comparatively high performance, an average installation space requirement, and a good payback period. Their optimal ground coverage ratio is in the range 0.3–0.6. For large projects, the East–West azimuth PV systems require 50–60% lower installation surface area, but they might generate from 15 to 30% less energy per year, and are suitable for high daily energy price deviations. The rest of the designs investigated have their unique advantages and disadvantages, which are compared. Full article

Accurate knowledge of the thermal transmittance (U-value) of existing building envelopes is essential for reliable energy performance assessment and the planning of energy-efficient refurbishment measures. However, in practice, the material composition of existing walls is often unknown, and installing measurement devices may be restricted due to limited accessibility, the risk of structural damage, or varying on-site boundary conditions. Although several in situ methods for determining the U-value have been proposed in the literature, systematic comparisons of their performance under real environmental conditions remain limited. This lack of comparative evaluation makes it difficult to select the most appropriate method under specific practical constraints. To address this gap, this study presents a comprehensive experimental comparison of four in situ U-value measurement methods applied simultaneously to the same building element under identical real boundary conditions, providing new insights into their accuracy, uncertainty, and practical applicability. In this study, four in situ techniques commonly used to determine the thermal transmittance (U-value) were tested on a double-leaf brick wall at the University of Stuttgart: heat flow meter (HFM), infrared thermography (IRT), infrared thermometer (IRTM), and thermometric method (THM). The measurements were carried out over several days under real boundary conditions, during which air temperature, surface temperature, and heat flux were recorded at regular intervals. The results show that all four techniques can be reliably used under real boundary conditions, with the measured U-values lying within a comparable range. Differences among the methods were observed, largely due to their varying sensitivity to environmental influences and sensor placement. A comparison between the upper and lower parts of the wall indicated that its thermal response is non-uniform, and the observed deviations can be attributed to its inhomogeneous structure. By outlining the strengths and limitations of each technique and comparing their measurement outcomes, this study provides practical guidance for selecting suitable approaches for in situ U-value determination. Furthermore, the findings support future efforts to refine thermal evaluation methods and improve energy performance in existing buildings. Full article

To address long-duration, high-impact extreme events, this study investigates resilience enhancement optimization dispatching for hydro–wind–solar power systems under continuous multi-day extreme scenarios. A mathematical model is constructed with the resilience objective of minimizing the average load deviation percentage and the economic objective of maximizing the total power generation of the system, while considering constraints such as water balance. The solution steps are provided in this paper. A case study of the Laxiwa hydropower station and nearby wind and photovoltaic power stations demonstrates the following: (1) The compensatory regulation capability of hydropower can be leveraged to enhance power system resilience under continuous multi-day extreme scenarios, and there is a trade-off between resilience and economic objectives. (2) The ability of hydropower to enhance power system resilience is limited by several factors, such as installed capacity, existing reservoir storage, minimum output constraints, and available storage capacity, making it insufficient to fully prevent issues like power shortage, the curtailment of renewable energy, and water spillage. (3) The impact of extreme wind and solar power outputs on the power system exhibits a cumulative effect under continuous multi-day extreme scenarios, and in concurrent scenarios, there is a certain offsetting effect between the impacts of under- and over-generation. This paper provides technical support and a reference for optimizing resilience-oriented scheduling and exploring mechanisms in hybrid hydro–wind–solar power systems under extreme conditions. Full article

Due to their higher installation position and smaller diameter compared to conductors, DC overhead ground wires are more susceptible to severe icing during cold waves. To investigate the icing growth characteristics of ultra-high voltage (UHV) DC ground wires under the coupled effect of flow and electric fields, this study considers the unique operational conditions of UHV DC ground wires. Based on the physical processes of charged droplet motion, flow-around, collision, and freezing around the ground wire, a numerical model for simulating icing under the coupled flow-electric field interaction is established. The influence of factors such as wind speed, droplet size, and icing morphology on icing development under the coupled field is numerically analyzed. Furthermore, observations of icing morphology on UHV ground wires under natural conditions were conducted. The results indicate that under icing conditions, charged droplets of different sizes exhibit significant differences in trajectory deviation during flow-around and collision with the ground wire, with larger droplets being more significantly affected by the electric field force. Under the influence of the electric field, the local droplet collision coefficient on the ground wire surface can increase by 3.4% to 128.9%. Compared to uncharged conditions, icing coverage under charged conditions extends from the windward side to the leeward side, and the icing rate increases accordingly. Natural observations reveal that icing on the ground wire surface under the DC electric field often forms protruding ice tips, which enhance electric field concentration, leading to increased local droplet collision coefficients and icing rates. This, in turn, further promotes the formation of irregular and rough ice accretion. The findings of this study provide technical insights for predicting and simulating icing on UHV DC ground wires. Full article

Contemporary art conservation increasingly relies on digital technologies capable of delivering accurate, non-invasive documentation across multiple scales. Within this framework, the study addresses the challenges of documenting and monitoring artworks integrated into historical architectural contexts, proposing an interdisciplinary and need-driven approach where conservation requirements guide technological choices. The methodology combines four survey techniques (static and mobile laser scanning, photogrammetry, and structured-light acquisition) to evaluate their effectiveness within a multi-scale workflow supporting conservation-oriented documentation. The workflow is tested on the Centro per la Scultura Contemporanea in Cagli, Italy, a museum where contemporary installations are structurally and conceptually connected within the historical architectural space. The paper presents a comparative assessment of the four sensors, considering both qualitative and quantitative parameters. Comparative analyses of the resulting point clouds was carried out using cloud-to-cloud distance measurements with a terrestrial laser scanning dataset as reference. Error distribution and geometric deviations are assessed to evaluate the performance of each sensor according to the scale and purpose of the survey. The results demonstrate that accessible and portable instruments can produce datasets targeted at conservation processes, when integrated within coherent digital workflows, in which architectural, spatial, and object-scale models are combined to create a digital documentation framework. Full article

Plastic injection molding in cleanrooms involves high thermal loads and strict particle limits. The hot surfaces of the injection molding machine and peripherals increase the cooling demand of the heating, ventilation, and air conditioning system to an undefined amount. Moreover, the generation of buoyancy-driven plumes has the potential to disturb the cleanroom airflow around the injection mold, thereby risking cross contamination of the manufactured components. The present study quantifies the global heat load of injection molding machines in an ISO Class 7 cleanroom with a laminar flow microenvironment around the mold. Therefore, a measurement-based method to determine the heat load of a complete injection molding production cell is applied to a hydraulic and an electric machine. This method revealed that the heat load of the isolated machines is process-independent, whereas the total heat load of the complete production cell scales linearly with mold temperature. Moreover, the emitted heat to the cleanroom is considerable lower than the injection molding machine’s installed power. Secondly, the airflow regime and particle transport in the mold area are analyzed. This is achieved by means of schlieren visualization and aerosol measurements. The introduction of a modified Archimedes number, incorporating mold size and convective heat flux, has led to the observation of a correlation between flow regimes and the resulting particle load. This enables the selection of case-dependent FFU velocities that deviate from the conventional recommendation of an air speed of 0.45 m/s ± 20%. Despite the presence of a filter-fan unit, the particle load near the injection mold cavity increases for flow conditions that exceed a critical Archimedes number. Full article

Series arc faults on the DC side of photovoltaic (PV) systems are a critical hazard that can trigger system fires. Conventional contact-based detection methods suffer from cumbersome installation and high retrofit cost, whereas existing non-contact approaches mostly rely on megahertz-level high-frequency sampling and therefore require expensive radio-frequency instrumentation or high-performance computing platforms. As a result, it remains difficult to simultaneously achieve strong interference immunity and real-time performance on low-cost embedded devices with limited resources. To address this engineering paradox between high-frequency sampling and constrained computational capability, this paper proposes a fully embedded, non-contact arc fault detection system based on a 12–80 kHz low-frequency sub-band selection strategy. By exploiting the physical characteristic of broadband energy elevation induced by arc faults, the proposed strategy avoids dependence on high-bandwidth hardware. Guided by this strategy, a Moebius-topology coaxial shielded loop antenna is employed as the near-field sensor, while an ultra-simplified passive analog front end is constructed directly by using the on-chip programmable gain amplifier and analog-to-digital converter of the microcontroller unit, enabling efficient signal acquisition and fast Fourier transform processing within the target sub-band. To cope with complex background noise in the low-frequency range, an environment-adaptive baseline mechanism based on exponential moving average and exponential absolute deviation is developed for dynamic decoupling. In addition, a lightweight INT8-quantized multilayer perceptron is introduced as a nonlinear auxiliary module, thereby forming a robust hybrid decision architecture with complementary rule-based and artificial intelligence components. Experimental results show that, under the tested household, laboratory, and PV-site conditions, the proposed system achieved an overall detection rate of 97%, while the remaining 3% mainly corresponded to failed ignition or non-sustained arc attempts rather than persistent false triggering during normal monitoring. Full article

Aiming at the problems of main cable geometry calculation and control accuracy in construction for long-span asymmetric suspension bridges, this paper proposes a practical method for main cable geometry calculation of asymmetric suspension bridges based on the Rushankou Bridge. Firstly, a hanger–pylon–girder model was established to obtain the constraint force at the hanger top. Then, with the mid-span sag of the main cable set as the control target, the coordinates and unstressed length of the main cable in the completed bridge state were obtained based on the pylon–cable model. Finally, the final main cable geometry and unstressed length were obtained based on the main cable–hanger–pylon–girder model. The reliability of the method in this paper was validated by engineering monitoring data. Using the simulation model, the influence laws and degrees of parameters including temperature, main cable elastic modulus, main cable weight, hanger force and main girder weight on the main cable geometry were investigated. It is indicated that the method in this paper is capable of accurately calculating the main cable shape of asymmetric suspension bridges. After the installation of cable clamps and hangers, the theoretical and measured deformations of the main cable are in good agreement. The theoretical and measured values at the mid-span L/2 of the main span are −233.9 cm and −234.7 cm, respectively, with a deviation of 8 mm. The largest discrepancy between the calculated and actual deformations of the main cable is located at 7L/8 of the main span, which is merely 2.2 cm. The deformation of the main cable is greatly affected by temperature changes; each 1 °C temperature variation leads to a mid-span deformation of about 2.4 cm in the main cable. If the influence of temperature variation on main cable geometry is ignored during construction, it will cause errors in the main cable elevation after installation. The effect of the main cable elastic modulus on its deformation cannot be neglected, and a 10% variation in the main cable elastic modulus leads to a 58 cm change in the main cable geometry. Full article