Search Results (305)

Calcined clays are increasingly recognized as strategic supplementary cementitious materials for reducing clinker consumption and the environmental impacts of construction. However, life cycle assessments typically represent metakaolin production using a single carbon footprint value, despite substantial differences in calcination technology, energy supply, and feedstock characteristics. This study develops a parameterized cradle-to-gate carbon inventory for metakaolin production and evaluates how this variability affects the environmental assessment of low-carbon construction materials. The methodology combines process-based theoretical modeling, mass and energy balances, literature-derived industrial data, and life cycle assessment. A full-factorial scenario analysis was performed for three calcination technologies: rotary kiln, fluidized bed, and flash calcination, while systematically varying fuel source, electricity mix, kaolinite purity, feedstock moisture, and transport distance. The resulting inventories were subsequently propagated into representative LC3 cement and metakaolin-based geopolymer formulations to quantify their influence at the construction-material level. Across 648 production scenarios, the carbon footprint of metakaolin ranged from 34 to 578 kg CO₂e t⁻¹, demonstrating that production conditions define the environmental performance. Fuel selection was identified as the principal emission driver, while moisture content and feedstock purity produced secondary effects. The variability propagated to downstream products, resulting in carbon footprints of 363–527 kg CO₂e t⁻¹ for LC3 cement and 167–357 kg CO₂e m⁻³ for metakaolin-based geopolymers despite identical material compositions. For the building sector, the proposed framework enables designers, material producers, and LCA practitioners to select calcined clay production routes consistent with the carbon targets of concrete, mortar, masonry, precast elements, and other cement-based building applications. It therefore provides a practical basis for incorporating LC3 and geopolymer technologies into lower-carbon building projects while avoiding environmental benefits based on non-representative upstream assumptions. Full article

The electrostatic rotary bell (ESRB) sprayer is widely used in the coating industry due to its ability to achieve uniform film thickness and reasonable paint transfer efficiency. However the efficiency of paint transfer and spraying coverage in ESRB systems remain highly sensitive to process parameters. Therefore, optimizing these parameters is essential to reducing paint consumption, energy use, and environmental impact. In this study, a simulation model of the ESRB spraying process was established using ANSYS/Fluent. The spraying flow field, paint deposition profile, and film thickness distribution were validated through the experiment. Based on a single-factor test and the Box–Behnken response surface method, a multi-parameter optimization framework was designed to investigate the effects of six spraying process parameters, including inner and outer shaping air flow rate, bell rotational speed, applied voltage, target distance, and paint flow rate, on coating pattern width and paint transfer efficiency. Based on the Z-score standardization, a mathematical model of the comprehensive score with six factors was established to evaluate spraying efficiency and paint transfer efficiency and predict optimal spraying process parameters. The results indicate that voltage and spray distance are significant factors affecting the comprehensive score, with the order of influence being voltage > spray distance. The optimal parameters were as follows: bell rotational speed X1, 40 kr/min; inner shaping air flow rate X2, 196 sl/min; outer shaping air flow rate X3, 298 sl/min; paint flow rate X4, 249 cc/min; applied voltage X5, 52 kV; and target distance X6, 154 mm. Validation tests showed deviation between the predicted comprehensive score and the actual value from simulation and experiment were 2.03% and 1.36%, respectively. These results demonstrate that the proposed optimization model has high reliability and can be used to optimize spraying process parameters. Full article

Biocomposites reinforced with natural fibres are receiving increased attention due to growing concern over the environmental impacts of their synthetic counterparts. Grass mowed from roadside verges has the potential to serve as an alternative to commonly used natural fibres and as a renewable feedstock for the biocomposite industry. However, it is generally treated as waste due to its high volume, seasonal availability, contamination (e.g., with metals and plastic bottles), and legal status. In this study, a techno-economic assessment was performed for different roadside grass valorisation scenarios covering the entire value chain from mowing and pre-treatment to fibre and biocomposite granule production. In addition, a screening greenhouse gas emissions assessment based on the main energy and material inputs was performed for fibre production. This screening assessment provides an initial indication of the operational environmental performance and is not intended to represent a complete life cycle or integrated sustainability assessment. One scenario investigated a value chain with flail mowing and grass fibres as the final product. Grass fibres can be produced at €528/t when mowing costs are included and as low as €295/t when mowing costs are excluded under the processor/incremental-cost perspective. A reduction of 6.4% in fibre price was estimated for the rotary-mowing scenario when mowing costs were excluded. In comparison, the market price of commonly available natural fibres ranges from €300 to €4000/t, although the price is strongly dependent on fibre quality, which was not considered in this assessment. Another scenario considered biocomposite granules consisting of 25% fibres, 60% polylactic acid, and 15% filler as the final product. The biocomposite granules can be produced at €1073/t and €1013/t with and without mowing costs, respectively. The production cost of the granules is largely influenced by the price of the polymer matrix and the compound composition, while the average market price is approximately €2000/t. Overall, the results indicate that roadside grass fibres may be cost-competitive under the evaluated assumptions. The screening assessment resulted in 364.20–701.32 kg CO₂-eq/t fibre for the flail system and 275.96–327.96 kg CO₂-eq/t fibre for the rotary system, depending on whether mowing was excluded or included. Drying energy and diesel consumption associated with mowing and collection were identified as the main operational emission sources. Full article

This review systematically synthesizes recent advances in road snow and ice removal equipment, with emphasis on operating mechanisms, applicable conditions, key parameters, and development trends. Mechanical ice-breaking and snow removal equipment—including rolling, rotary-cutting, impact, snowplow, and rotary brush systems—is evaluated in terms of operating principles and engineering applicability. The energy input modes and dominant performance factors of hot-air, steam, microwave, and laser deicing technologies are then summarized. In addition, the structural configurations and functional coordination of mechanically integrated and thermal–mechanical snow removal vehicles are examined. These technologies differ substantially in ice-breaking capability, operating speed, energy consumption, and risk of pavement damage. Current research is further limited by inconsistent performance metrics, insufficient validation under field operating conditions, and inadequate parameter matching among functional units. Future studies should therefore emphasize snow and ice condition sensing, adaptive regulation of operating parameters, and coordinated control of multiple functional units. This review provides a systematic basis for equipment selection, performance evaluation, and the design of integrated road snow and ice removal systems. Full article

High-quality and high-efficiency machining of film cooling holes (FCHs) is critical for enhancing the performance of gas turbines and aero-engines. Nanosecond fiber lasers offer advantages such as high stability, good beam quality, and ease of integration. However, when machining FCHs, issues including low drilling efficiency and significant thermal effects severely limit their industrial applications. In this study, a dual-rotary trepanning system was developed based on a nanosecond fiber laser, a galvanometer, and a five-axis cradle machine. High-quality FCHs with a diameter of 0.6 mm were efficiently machined in a 3-mm-thick DD6 superalloy plate within only 6.5 s. Compared with the method using machine tool rotation alone, the average recast layer thickness on the inner wall was reduced by 62.1% to 6.7 μm, and the average surface roughness was reduced by 61.1% to 0.35 μm. These improvements are primarily attributed to the galvanometer speed being two orders of magnitude higher than that of the machine tool, which significantly reduces the laser pulse overlap rate and the thermal accumulation effect. Moreover, the kerf widened by the galvanometer rotation allows the ablation products to expand more fully and be expelled efficiently, thereby reducing impact, scratching, and debris adhesion on the inner wall and improving the drilling efficiency. Furthermore, 10 × 10 FCH arrays were machined on both vertical and inclined plates, demonstrating high consistency and stability, indicating the potential for industrial applications in the field of FCH machining. Full article

The production of hot mix asphalt (HMA) is energy-intensive, resulting in carbon dioxide (CO₂) and greenhouse gas (GHG) emissions. The primary energy source (accounting for over 97%) and emissions source is the rotary drum employed for the drying and heating of the aggregates. Quantifying the CO₂ emissions associated with combustion is of crucial importance in order to facilitate a more profound comprehension of the environmental impacts of HMA production. The objectives of this study are to develop a methodological framework for the quantification of combustion-related carbon dioxide emissions in the context of asphalt production. The proposed framework investigates three complementary approaches: (i) an energy-balance-based thermal energy (TE) model, (ii) recordings of fuel consumption and (iii) direct measurement of exhaust-gas composition. By applying these methods in parallel and cross-comparing their results batch by batch, the framework enables reliable verification of actual CO₂ emissions from the module A3—production stage of asphalt manufacturing. In this stage, the predominant source of greenhouse gases is fuel combustion during aggregate drying and heating. A comprehensive set of data was collected from two HMA batch plants, each operating under distinct conditions. The parameters considered included fuel type, asphalt mixture type, asphalt production time, aggregate moisture content, mixing temperature, and production rate. The TE model demonstrated a robust linear correlation with measured energy consumption (R² = 0.97), and fuel-based CO₂ estimates exhibited minimal discrepancy compared to direct exhaust-gas measurements on average (mean difference 1.0%; t-test p = 0.674). However, systematic discrepancies were observed between the two plants (with overestimation of up to 20% at one plant (AP1) and underestimation of up to 12% at the other (AP2)). This demonstrates that energy-based CO₂ estimation methods require plant-specific calibration against direct measurement before they can be reliably applied in life cycle assessment (LCA) and environmental product declaration (EPD) practice. Measured CO₂ emission intensities ranged from 17.39 to 21.76 kg/t at AP1 and from 16.05 to 18.44 kg/t at AP2; the casing-losses factor of the TE model was calibrated to CL = 23% for the studied diesel-fired plants (mean deviation +0.4% from measured energy); and aggregate moisture content explained 74% of the variance in measured energy consumption (R² = 0.743). Full article

Rotary tillage–seeding combined operations require stable power take-off (PTO) speed during rotary tillage and accurate tracking of the prescribed travel speed for seeding. Existing energy management strategies for hybrid electric tractors mainly focus on fuel economy and commonly use fixed objective weights, limiting their ability to adjust control priorities under changing operating conditions. To address this issue, an operation-quality-oriented energy management strategy based on model predictive control, termed OQ-EMS/MPC, is proposed. An equivalent combined-operation condition was constructed using the PTO-side rotary-tillage load, drive-side equivalent traction load, segmented travel-speed reference, and equivalent seeding-quality risk. A condition-severity index integrating the PTO-load coefficient of variation, PTO-load impact intensity, and equivalent seeding-quality risk was developed to distinguish steady, fluctuating, and impact-dominated conditions. Based on the identified condition, the weights assigned to PTO-speed regulation, equivalent seed synchronization, and energy economy were adjusted online. These weights were used in the MPC to optimize torque allocation among the engine, motor-generator 1 (MG1), and motor-generator 2 (MG2). The proposed strategy was validated on a dual-side loading bench and compared with a rule-based energy management strategy and a fixed-weight MPC strategy. The overall PTO-speed root-mean-square error (RMSE) was reduced to 1.76 r/min, representing reductions of 58.40% and 45.66% relative to the two comparative strategies, respectively. The equivalent seed-synchronization RMSE was reduced by 69.15% and 52.66%, respectively. Under the impact-dominated condition, the PTO-speed RMSE decreased to 1.65 r/min. The normalized composite cost decreased by 13.53% and 6.26%, while the equivalent fuel consumption increased by 3.40% and 3.76%, respectively. The results demonstrate that the proposed strategy improves PTO-speed stability and equivalent seed-synchronization performance as operating severity increases while accounting for energy economy. Full article

Agricultural soil contact components, including ploughshares, rotary blades, and furrow openers, form the active interface between machinery and complex field media. Operating in multiphase environments, these tools face severe abrasive wear, impact fatigue, and interfacial adhesion. These destructive forces irreversibly alter edge geometry and drastically degrade macroscopic operation quality. This review integrates tillage and precision seeding components into a unified tribological framework. It highlights the nonlinear relationship between microscopic material removal and geometric edge retention. Profile degradation is heavily dictated by soil texture, where sandy soils cause micro-cutting, clay soils induce severe adhesion, and gravelly soils produce impact fracture. To predict these complex wear behaviours accurately, coupled multiphysics numerical simulation using the discrete element method for particle flow dynamics and finite element analysis for transient contact stress provides a highly robust methodology. Mitigating these failures requires a functionally zoned surface engineering approach. Carbide hardfacing offers localized abrasion resistance, while polymer composite layers and bionic nonsmooth structures effectively interrupt continuous liquid films in wet cohesive soils. Ultimately, integrating online multidimensional sensing with full life cycle digital-twin models represents the future trajectory for developing adaptive and highly durable agricultural equipment. Full article

With the rapid proliferation of internet of vehicles applications, vehicle users in urban road scenarios face ever-increasing demands for low-latency and energy-efficient processing of computation-intensive tasks. The traditional fixed terrestrial infrastructure offers limited coverage in complex urban environments, making it difficult to satisfy the differentiated quality of service requirements of large-scale vehicle populations. To fully exploit the advantages of unmanned aerial vehicles (UAVs) in terms of flexible deployment and on-demand service provisioning, we propose a UAV-assisted mobile edge computing architecture tailored for urban road scenarios. By modeling realistic urban road terrain with varying elevations, we construct a two-tier cooperative network consisting of multiple rotary wing UAVs and ground vehicles. Aiming at maximizing the total system energy consumption, we formulate a mixed integer nonlinear programming problem that minimizes total system energy consumption through joint optimization of UAV flight trajectories and vehicle task offloading decisions while comprehensively accounting for task latency constraints, UAV flight velocity constraints, and the impact of three-dimensional terrain on air-to-ground channels. Considering the high-dimensional, non-convex, mixed integer, and strongly coupled nature of the problem, we design a genetic algorithm (GA)-based UAV trajectory design and offload allocation algorithm. The proposed approach encodes UAV trajectories as real-valued vectors and offloading decisions as binary vectors, employs a penalty function method to handle constraints, and achieves efficient global search through tournament selection, single-point crossover, and Gaussian mutation operators. Simulation results verify that the proposed algorithm converges reliably to feasible solutions under varying task data sizes and vehicle densities and achieves up to 20.6% energy savings compared to the benchmark schemes. The experimental results validate the necessity and effectiveness of jointly optimizing UAV trajectory and task offloading in urban road scenarios. Full article

The rotational error motion of precision aerostatic rotary stages substantially affects the accuracy of machining and measuring equipment. A comprehensive and flexible error modeling method is absent. This paper develops an analytical model for the error motion of an aerostatic rotary stage bearing, utilizing linear superposition and spatial force equilibrium principles. The error motion of an orifice-restricted rotary stage is computed using this approach. The impact of bearing manufacturing inaccuracies (e.g., journal roundness, thrust plate profile) and micro-vibrations caused by internal turbulence is analyzed. Finally, the model was validated experimentally using the reversal method. The results indicate that bearing manufacturing errors positively correlate with error motion, and micro-vibration considerably influences errors at the sub-100 nm level. The relative error between the predicted and measured values is less than 15%, confirming the validity and applicability of this modeling and analytical approach. This research enhances error motion analysis methods and offers a novel constructive reference for predicting and optimizing error motion in precision aerostatic rotary stages. Full article

The Digital Twin (DT) technology has emerged as one of the most prominent technologies for different applications including the machine condition monitoring, fault diagnosis, and predictive maintenance over the past decade. However, a major challenge in its widespread adoption is the development of comprehensive and generalized Digital Twin solutions. To address this, the LIVE Digital Twin framework has been introduced as a structural framework to develop and operate Digital Twins. LIVE stands for the main four stages of the framework: Learn, Identify, Verify, and Extend. A crucial aspect of LIVE Digital Twins is the integration of both Low-Fidelity (LF) and High-Fidelity (HF) simulations to manage various stages of Digital Twins’ life span. This paper uses the LIVE Digital Twin philosophy for predictive maintenance of rotary machines and focuses on the creation and application of an integrated dynamic Low-Fidelity simulation required as a main feature of this system. As part of this effort, a Simple Structural Dynamics (SSD) model was developed based on Finite Element Analysis (FEA) and Newmark’s time integration method. The Simple Structural Dynamics model was applied to a case study involving a rotary machine, where fundamental frequencies, mode shapes, and transient responses were analyzed for both healthy and faulty conditions. The results obtained using Simple Structural Dynamics were compared with those generated by a High-Fidelity simulation, demonstrating that Simple Structural Dynamics effectively predicts the system behavior while remaining computationally efficient enough to perform real-time simulations using the sensor data collected. The Simple Structural Dynamics proved to be computationally efficient, and it is highly scalable. Furthermore, the study thoroughly examined the impact of different defects, including cracks, unbalance, and bearing faults. Full article

The valorization of industrial mining and organic wastes in construction materials constitutes a key strategy for reducing the environmental impact of the sector. In this context, the present study aims to evaluate the sustainability of innovative Artificial Lightweight Aggregates (ALAs) manufactured from mixtures of inorganic industrial wastes—such as granite and slate cutting sludge and aggregate washing sludge—together with organic wastes, like cork dust, coffee grounds, and olive pits. The methodology included a Life Cycle Assessment (LCA), considering different waste compositions and manufacturing conditions. The results show that the developed ALAs exhibit favorable environmental performance as their bulk density decreases, with an overall environmental impact lower than that of conventional lightweight aggregates made from expanded clay, achieving a reduction in the carbon footprint of up to 7%. Likewise, the comparative analysis reveals that the process stage with the greatest environmental impact is the heat energy required during the sintering stage in the rotary kiln, which in some cases accounts for more than 90% of the total impact. In summary, the results demonstrate the feasibility of obtaining ALAs manufactured solely from waste with a lower carbon footprint compared to traditional expanded clay aggregates. Furthermore, the study highlights that the process stages with the highest contributions to environmental impact are the transport of raw materials and the high-temperature sintering of the ALAs in the rotary kiln. Thus, their production from waste contributes to the valorization of by-products, fostering circular economy strategies and supporting decarbonization processes within the construction sector. Full article

Dry gas seals (DGSs) are currently the preferred sealing method for high-speed rotating machinery, widely used in the fields of petrochemicals and energy and power. This study analyzes the effect of groove structure and operating parameters (rotary ring speed and inlet pressure) on the performance of the sealing system. The results show that a swallowtail-like groove demonstrates a dual effect of improving film stability and reducing leakage under specific working conditions. Specifically, under the inlet pressure of 4.5852 MPa and rotational speed of 10,380 rpm, the swallowtail-like groove achieves a 1.84% reduction in leakage and a 0.32% increase in opening force compared with a conventional spiral groove. Rotational speed has the greatest impact on the gas film stability of the cluster spiral groove. Increasing inlet pressure enhances the dynamic stabilization of gas film. Dynamic analysis indicates that the opening force demonstrates a linear proportionality with inlet pressure, whereas leakage follows an exponential growth. This work can provide guidance for optimizing the groove structure in dry gas sealing systems. Full article

The objective of this study was to examine the impact of using a rotary jet head (RJH) on the biosynthesis of byproducts of yeast metabolism and their role in shaping the flavor and aroma profile of bottom fermentation beer (lager style). The tests were conducted on an industrial scale, with fermentation in 3800 hL fermentation tanks. Experiments were conducted in a minimum of six replicates. The main quality indicators, including ethanol concentration and pH, were analyzed, along with key volatile compounds such as acetaldehyde, esters, higher alcohols, and DMS. Additionally, beer samples—both those fermented using forced mixing and those produced conventionally—were subjected to sensory evaluation. The study found that RJH did not cause changes in either the final ethyl alcohol concentration (6.74% in both samples) or the pH measurement results. The rotary jet head increased synthesis of certain volatile components, such as fusel alcohols by 5% and acetate esters by 14% for ethyl acetate and by almost 12% for isoamyl acetate. On the other hand, a more than threefold (8.23 to 2.54 mg/L) decrease in the undesirable acetaldehyde was observed in samples fermented with forced mixing. The resulting beers exhibited statistically significant differences in chemical composition; however, sensory analysis did not reveal these differences. This finding underscores the efficacy of the rotary jet head in expediting the beer production process without compromising its sensory quality. Full article

This article presents a geometric analysis of the influence of topology on the performance of Rotary Traveling Wave Oscillators (RTWOs), enabling a fair comparison between RTWO topologies by enforcing a constant total resonator length regardless of dimensions or topology. Based on this approach, a comparison is carried out to evaluate the impact of different topologies on the performance of the oscillator. Results show that geometric modifications can increase the oscillation frequency by up to $530\mathrm{M}\mathrm{H}\mathrm{z}$ while slightly reducing power consumption. Validation is performed through electromagnetic simulations in ADS Momentum for RLCG parameter extraction and electrical simulations in HSPICE to obtain oscillation frequency and power consumption. Under identical geometric conditions, the resonator topology significantly modifies oscillator behavior, particularly in structures with fewer abrupt geometric discontinuities. Finally, figures of merit are used to evaluate RTWO performance, highlighting the trade-offs between oscillation frequency, power consumption and integration area. Full article