Search Results (503)

Self-optimizing control (SOC) aims to maintain controlled variables associated with system energy consumption at constant setpoints, thereby enabling near-optimal operation under various disturbance conditions. A core challenge in SOC scheme design is the selection of appropriate self-optimizing controlled variables (SOCVs). To address this challenge, a genetic programming (GP)-based method is proposed to identify linear combinations of process variables that minimize energy consumption, which enhances the scientific rigor and efficiency of SOCV selection. The proposed method is validated through a case study involving a dividing-wall column (DWC) for the separation of an ethanol-propanol-butanol ternary mixture. The derived SOC scheme incorporates three concentration-temperature cascade control loops to ensure the maintenance of product purities, alongside a temperature-inferential SOC loop dedicated to energy minimization. In this SOC loop, the liquid split ratio serves as the manipulated variable, while the GP-derived SOCV is a linear combination of temperatures from three sensitive stages. Closed-loop simulation results confirm that the proposed SOC scheme achieves stable and energy-efficient operation across multiple disturbance scenarios. Notably, compared with conventional control schemes featuring fixed liquid split ratios or single-temperature SOCVs, the proposed scheme eliminates the need for additional temperature measurements while realizing reduced energy consumption. Full article

The use of seawater in mineral processing poses significant challenges for solid–liquid separation, including polymer chain contraction, accelerated coagulation, and brittle aggregate formation. This study evaluates the impact of fractional dosing of anionic polyacrylamide (PAM) on the formation, structure, and sedimentation performance of flocs in quartz-kaolinite suspensions prepared in seawater. Four dosing schemes (1, 2, 3, and 4 pulses) were analyzed, maintaining a total dose of 15 g/t and flocculation times of 75, 90, and 105 s. Sedimentation assays, kinetic monitoring using FBRM, size distributions, fractal dimensions, and bulk density were integrated to characterize the aggregation process. The results show that all fractional strategies outperform single-pulse dosing, with the three-pulse scheme (0–30–60 s) standing out, achieving the highest settling rates, the most significant fines reduction, and the best structural robustness. FBRM kinetics reveal stepped growth, less shear breakage, and more stable maturation when polymer addition is divided temporally. Consistently, fractal dimension and aggregate density reach their maximum values after three 90 s pulses, indicating more compact, less porous structures. Zeta potential analysis confirms a strong polymer-particle interaction in kaolinite under high salinity. The superior performance of the multi-pulse strategy is explained by the progressive availability of active polymer segments during aggregate formation and maturation. Each pulse is incorporated into a partially structured suspension, in which unoccupied mineral surfaces and flocs from the early stages of consolidation still exist. This staggered adsorption avoids local overdosing associated with flash injections, improves bridging efficiency, reduces brittle aggregate formation, and promotes more uniform restructuring. Full article

In this paper, we propose a novel concept of a modular, multiport, single-stage, bidirectional, isolated, three-phase AC-DC converter system. This new system is realized using add-ons to a standard voltage source inverter, including both grid-connected AC-DC converters, like PWM rectifiers, and AC-drive DC-AC inverters. The proposed add-on converters provide isolated DC ports and can be installed into existing inverters of the abovementioned types, with no need for any modification of their topology or control system. Moreover, the add-on converters provide a minimum transistor count and high efficiency. The efficiency of the proposed add-on converters can be further improved by switching the type of pulse width modulation (PWM) scheme based on their operating point. The proposed converter system is validated for a power of 20 kW, an output voltage of 500–800 V DC, and a 40 kHz PWM frequency. Full article

Numerous commercial products are used in poultry farms to maintain water quality and prevent pathogen dispersion, but their actual impact on broiler chicks’ performance and gut health remains underreported. This study aimed to investigate the effects of three commercial poultry water disinfectants on broiler chicks’ performance and the physicochemical characteristics of gastrointestinal content when continuously added to drinking water. A total of 144 one-day-old Ross^® 308 broiler chicks were randomly allocated into four treatment groups: Group A (negative control), Group B (0.01–0.025% v/v Product A [H₂O₂ + silver complex]), Group C (0.01–0.04% v/v Product B [H₂O₂ + peracetic acid]), and Group D (0.05–0.1% w/v Product C [peroxides]). Body weight (BW) was measured weekly, while average daily weight gain (ADWG), average daily feed intake (ADFI), and feed conversion ratio (FCR) were calculated for different time periods. Additionally, on days 15 and 40, the pH of the crop, gizzard, duodenum, jejunum, and cecum contents was assessed, while the viscosity of jejunal and ileal contents were also measured. Statistical analysis revealed that all water disinfectants significantly (p ≤ 0.05) reduced BW, ADWG, and ADFI during the early growth phase, followed by either recovery or stabilization in the later stages. Drinking water disinfectants induced significant changes in intestinal physicochemical parameters, including reductions in pH of the content in the jejunum (p ≤ 0.05) during early growth and increased gizzard pH (p ≤ 0.05) and digesta viscosity (p ≤ 0.05) at later ages. These findings suggest that continuous water disinfection can suppress broiler chicks’ performance during the early stages of growth while significantly altering the physicochemical characteristics of gastrointestinal content. Further research is needed to investigate the mechanism that underlaying these results and optimize dosage schemes that balance pathogen control with the health, welfare, and performance of broilers. Full article

Characterized by zero-carbon, congestion-free, and high-capacity features, the utilization of metro systems for collaborative passenger-and-freight transport (the metro-based underground logistics system, M-ULS) has been recognized as a favorable alternative to facilitate automated freight transport in future megacities. This article constructs a three-echelon M-ULS network and establishes a multi-objective bilevel programming model, considering the interests of both government investment departments and transport enterprises. The overall goal of the study is to establish a transportation network with the lowest construction cost, lowest operating cost, and highest facility utilization rate, taking into account factors such as population density, transportation conditions, land resources, logistics demand, and metro station location, under given cost parameters and demand conditions. The upper-level model takes government investment as the main body and aims to minimize the total cost, establishing an optimization model for location selection allocation paths with capacity constraints; the lower-level model aims to minimize the generalized cost for freight enterprises by simulating the competition between traditional transportation and the M-ULS mode. In addition, a bi-level programming model solving framework was established, and a multi-stage precise heuristic hybrid algorithm based on adaptive immune clone selection algorithm (AICSA) and improved plant growth simulation algorithm (IPGSA) is designed for the upper-level model. Finally, taking the central urban area of Beijing as an example, four network scales are set up for numerical simulation research to verify the reliability and superiority of the model and algorithm. By analyzing and setting key indicators, an optimal network configuration scheme is proposed, providing a feasible path for cities to improve logistics efficiency and reduce the impact of logistics externalities under limited land resources, further strengthening the strategic role of subway logistics systems in urban sustainable development. Full article

As product complexity and customization levels continue to rise in high-end manufacturing, optimizing and controlling multistage manufacturing processes (MMPs) presents growing challenges. However, existing MMP research has largely focused on optimizing relatively fixed process routes, while limited attention has been paid to the route selection problem itself, particularly the global selection of process routes under real-world conditions where MMPs stages are mutually coupled and characterized by uncertainty. Therefore, the present study focuses on the fundamental challenge of process route decision-making for complex products within MMPs. A hybrid decision model is developed that incorporates expert knowledge and explicitly quantifies uncertainty arising from decision inconsistency and linguistic ambiguity. The proposed model consists of three main components: expert weighting, criterion weighting, and comprehensive ranking of process schemes. Expert and criterion weights are derived using the Enhanced Analytic Hierarchy Process (EAHP) to address inconsistency in expert judgments, while the ranking of alternatives is performed using a novel Combined Compromise Solution (CoCoSo) rule within an Interval Type-2 Fuzzy Sets (IT2FS) linguistic environment. Furthermore, the effectiveness of the proposed framework is validated through a case study on the multistage manufacturing process of compact aerospace heat exchangers. The results demonstrate that the proposed approach provides effective decision support for selecting robust process schemes during the initial planning phase of MMPs. Full article

Urban UAV imagery presents challenges for reliable feature matching owing to complex 3D structures and depth discontinuities. Conventional 2D-based outlier rejection methods often fail to maintain geometric consistency under significant altitude variations or viewpoint differences, resulting in the rejection of valid correspondences. To overcome these limitations, a depth-guided local outlier rejection methodology is proposed which integrates monocular depth estimation, DBSCAN-based clustering, and local geometric model estimation. Depth information estimated from single UAV images is combined with feature correspondences to form pseudo-3D coordinates, enabling spatially localized registration. The proposed method was quantitatively evaluated in terms of Precision, Recall, F1-score, and Number of Matches, and was applied as a depth-guided front-end to three representative 2D-based outlier rejection schemes (RANSAC, LMedS, and MAGSAC++). Across all image sets, the depth-guided variants consistently achieved higher Recall and F1-score than their conventional 2D counterparts, while maintaining comparable Precision and keeping mismatches low. These results indicate that introducing depth-guided pseudo-3D constraints into the outlier rejection stage enhances geometric stability and correspondence reliability in complex urban UAV imagery. Accordingly, the proposed methodology provides a practical and scalable solution for accurate registration in depth-varying urban environments. Full article

Today, reducing carbon footprints requires the development of technologies to utilize CO₂, particularly by converting it into valuable chemical products. One approach is plasma-catalytic CO₂ splitting into CO and O₂. The task of separating such a ternary mixture is nontrivial and requires the development of an efficient method. In this paper, we have developed a comprehensive scheme for the separation of a CO₂/CO/O₂ mixture using membrane technology. The novelty of this work lies in the development of a complete scheme for separating the products of plasma-chemical decomposition of CO₂ to produce a CO concentrate. The calculations utilized the principle of a reasonable balance between the recovery rate and the energy consumption of the separation process. This scheme allows production of a CO stream with a purity of 99%. To achieve this goal, we have proposed the sequential use of CO₂-selective membranes based on polysiloxane with oligoethyleneoxide side groups (M-PEG), followed by polysulfone (PSF) hollow-fiber membranes to separate CO and O₂. For these membranes, we measured the CO permeability for the first time and obtained the selectivity for CO₂/CO and O₂/CO. The potential of membrane separation was demonstrated through a three-stage process, which includes recycling of the CO removal stream and concentration after CO₂ plasmolysis. This process was calculated to yield a highly pure CO stream containing 99 mol% with a recovery rate of 47.9–69.4%. The specific energy consumption for the separation process was 30.31–0.83 kWh per 1 m³ of feed mixture, and the required membrane area was between 0.1 m² for M-PEG and 42.5–107 m² for PSF, respectively. Full article

This study systematically investigates the post-construction settlement behavior of high-fill red clay embankments, focusing on the influences of three key factors (water content, degree of compaction, and lift thickness) and the effectiveness of geogrid-based reinforcement measures. A three-dimensional finite-element model based on the Mohr–Coulomb constitutive theory was established using MIDAS GTS NX 2022 R1 to simulate staged construction processes and long-term settlement under self-weight loading. The results indicate that settlement is predominantly concentrated in the upper fill zone adjacent to the slope surface, with displacement contours sagging inward toward the fill interior, while the underlying foundation undergoes negligible deformation. An elevated water content and reduced degree of compaction significantly enhance the compressibility of red clay, leading to increased settlement magnitudes and prolonged stabilization periods. Excessively thick lifts result in inadequate deep compaction, thereby inducing larger final settlements. Two reinforcement schemes (geogrid combined with anti-slide piles and geogrid combined with a gravity retaining wall) were verified to effectively mitigate post-construction settlement, with the former achieving a more pronounced improvement in the embankment stability coefficient. Based on the comprehensive analysis, optimal construction control parameters for high-fill red clay embankments are proposed: precise regulation of water content, maximization of compaction degree, and adoption of a lift thickness of approximately 30 cm. The findings of this study provide quantitative technical support and design references for the settlement control of similar high-fill red clay embankment projects in southern China’s mountainous and hilly regions. Full article

In rectifier design, the key parameters are the voltage–conversion ratio and the power conversion efficiency. A new circuit design approach is presented in which a capacitor-based, cross-coupled, differential-driven topology is used to boost the voltage–conversion ratio. The scheme also integrates an auxiliary current path to raise the power conversion efficiency. To demonstrate its practicality, two three-stage rectifiers were designed and fabricated using standard 65 nm CMOS technology. The designs were tested under various conditions to assess their performance. The first rectifier targets indoor light energy harvesting applications. It achieves a peak voltage conversion ratio of 3.94 and a maximum power conversion efficiency of 58.7% when driving a 600 Ω load, while supplying over 2 mA of output current. The second rectifier is optimized for RF energy harvesting at 2.4 GHz. Experimental results indicate that it can deliver 70 µA to a 50 kΩ load, with a peak voltage conversion ratio of 5 and a power conversion efficiency of 17.5%. Full article

To reduce downtime of the Tunnel Boring Machine and improve construction efficiency of subway tunnels, the tunnel–station synchronous construction method was implemented in the Qingdao metro. In this method, the TBM advanced continuously through the station, while the upper station was excavated in stages using the primary support arch covering technique. Focusing on a construction scheme with low-grade temporary segments, this study develops a three-dimensional numerical model to investigate the mechanical response of shield lining during the simultaneous construction of a subway station and tunnel. The Mohr–Coulomb model and the Elastic model were employed to represent the mechanical behavior of the surrounding rock and support structure, respectively. The deformation, bending moment, axial force, and residual bearing capacity coefficients of the shield lining were systematically examined across six distinct construction stages. The results showed that asymmetric gradual unloading of the surrounding rock at the arch part caused the vertical displacement of the shield lining to be predominantly upward, with a maximum heave of 1.51 mm. Horizontal displacement exhibited significant asymmetry. During station arch excavation, asymmetric unloading led to an increase and clockwise shift in the bending moments of the shield lining. The axial forces transitioned from compression to tension at specific locations (40° and 240°), whereas the removal of temporary supports had only a minor influence. The maximum tensile stress of the shield lining increased by 3.35 times in Stage III and reached 0.69 MPa in Stage V, representing a 1.65-fold increase compared to the previous stage. Although the residual bearing capacity coefficient generally satisfied safety requirements throughout the construction process, it decreased to a minimum of 0.88 in Stage V, a 7% reduction relative to Stage IV, necessitating close monitoring. This study not only confirmed the safety of using temporary segments made of lower-grade concrete (C30) in tunnel–station synchronous construction but also provided valuable insights for optimizing construction schemes and controlling key risks, such as structural deformation, in similarly complex urban environments. Full article

The riveting process is conventionally performed at a constant feed rate, overlooking the distinct deformation mechanisms inherent in its successive stages. This study introduces a novel compound feed rate approach to enhance the riveting quality of 2A10 aluminum alloy countersunk head rivets. A three-dimensional finite element model, validated experimentally, was developed to simulate the riveting process, segmented into three stages: free upsetting, hole wall interference, and driven head formation. An orthogonal experimental design was employed to investigate the effects of varying feed rates (1, 5, 10 mm/s) within these stages on key quality metrics: interference distribution, uniformity, and driven head geometry. Results demonstrate that increasing the feed rate reduces average interference but increases the driven head diameter, revealing a stage-dependent influence. A multi-objective optimization framework, integrating gray relational analysis with the entropy weighting method, was applied to balance these competing objectives. The optimal compound feed rate scheme of 10-1-10 mm/s (for the three stages, respectively) was identified. This optimized scheme improved interference uniformity by 1%, increased the critical shank-end interference (Point H) by 10.9%, and enhanced driven head dimensions compared to conventional constant-rate riveting. Full article

A gap test is a relatively new experimental and numerical test proposed by Bažant and co-workers. The test is designed to show that the effective mode I (opening mode) fracture energy depends strongly on the crack-parallel normal stress. Other typical tests (for instance three-point bending) are not able to capture this influence. The gap test is therefore considered as a breakthrough in fracture mechanics. The authors of this paper tried to recreate numerically the gap test in a concrete specimen using a plasticity-based damage model for concrete, the so-called concrete damaged plasticity in Abaqus software. A specimen in the gap test is in the form of a concrete beam with a notch. At the first stage of the test the specimen is supported with poly-propylene pads. A static scheme of the specimen changes when the gap between the specimen and roller supports vanishes, exactly when the full yield of pads occurs. The gap test revealed the fact that the initial fracture energy varies its value depending on normal stress parallel to a crack propagating from the notch. To calculate the initial fracture energy, the authors of this paper used the size effect law. The results obtained by the authors are comparable with the laboratory and numerical results presented by Nguyen and co-workers. Full article

Generative AI is bringing revolutionary changes to architectural design. From data-driven and sustainable perspectives, this study introduces scientific data analysis methods to explore the specific application scenarios and effectiveness of generative AI in the early, middle, and late stages of architectural project design, while also examining its potential value in the field of sustainability. The research first synthesizes industry viewpoints through online data analysis. Secondly, it selects three typical practical architectural projects of different scales and types in which the author participated in comparative testing, recording the time, operational processes, and outputs required for schemes generated by the “traditional creative workflow” vs. the “AI-assisted workflow” at various stages. A multi-dimensional evaluation is conducted combining subjective questionnaires and objective performance simulation data. This study finds that generative AI can significantly enhance design efficiency and scheme diversity and guide the construction of sustainability dimensions, but challenges exist in quality control and technology integration. This research will provide an empirical framework and data benchmarks for architectural practitioners, clarifying a new design path of “data-driven–human–machine collaboration–sustainable optimization”, which holds significant reference value for promoting the transformation of the construction industry towards high efficiency and low carbon. Full article

Centrifugal pumps are essential to modern marine engineering systems for fluid transport. This study is to analyze the typical failure causes of sediment erosion and energy dissipation in a multi-stage centrifugal pump with different blade installation angles α using numerical simulation approach and on-site testing. Three different schemes with α = 0°, 10.85°, and 21.7° were designed. The installation angle of the blade influenced sediment erosion and energy dissipation through three key aspects: turbulent flow, particle motion, and wall roughness. Turbulent and friction dissipation, which are related to the blade angle and sediment erosion, are the leading causes of the pump failure. The symmetrical blade installation, turbulence intensity, particle impact velocity, and wall friction inside the unit were the highest, resulting in the most severe turbulence loss, wall loss, and sediment erosion under this scheme, with the maximum friction loss being 320 W·m⁻³·K⁻¹. Complex turbulence intensifies the intensity of particle motion, with the maximum sediment erosion rate E = 0.000052 kg·m⁻²·s⁻¹. Compared to Plan 1 and Plan 3, the performance can be improved by more than 20% and 23%, respectively. There was a positive correlation between the friction loss and erosion rate. The research presented in this study provides a novel perspective on the operation of a pump to prevent sediment erosion failure. Full article