Search Results (67,552)

Additive Manufacturing (AM) is a pivotal technology for transforming complex geometries with minimal tooling requirements. Among the several AM techniques, Wire Arc Additive Manufacturing (WAAM) is notable for its ability to produce large metal components, which makes it particularly appealing in the aerospace sector. However, precise control of the bead geometry, specifically bead width and height, is essential for maintaining the structural integrity of WAAM-manufactured parts. This paper introduces a methodology using a Deep Neural Network (DNN) model for forecasting the bead geometry in the WAAM process, focusing on gas metal arc welding cold metal transfer (GMAW-CMT) WAAM. This study addresses the challenges of bead geometry prediction by developing a robust predictive framework. Key process parameters, such as the wire travel speed, wire feed rate, and bead dimensions of the previous layer, were monitored using a Coordinate Measuring Machine (CMM) to ensure precision. The collected data were used to train and validate various regression models, including linear regression, ridge regression, regression, polynomial regression (Quadratic and Cubic), Random Forest, and a custom-designed DNN. Among these, the Random Forest and DNN models were particularly effective, with the DNN showing significant accuracy owing to its ability to learn complex nonlinear relationships inherent in the WAAM process. The DNN model architecture consists of multiple hidden layers with varying neuron counts, trained using backpropagation, and optimized using the Adam optimizer. The model achieved mean absolute percentage error (MAPE) values of 0.014% for the width and 0.012% for the height, and root mean squared error (RMSE) values of 0.122 for the width and 0.153 for the height. These results highlight the superior capability of the DNN model in predicting bead geometry compared to other regression models, including the Random Forest and traditional regression techniques. These findings emphasize the potential of deep learning techniques to enhance the accuracy and efficiency of WAAM processes. Full article

The production performances of fractured tight gas wells are closely related to several complex and unknown factors, including the formation properties, fracture parameters, gas–water two-phase flow, and other nonlinear flow mechanisms. The rate transient analysis (RTA) results have significant uncertainties, which should be quantified to evaluate the formation and fracturing treatment better. This paper provides an efficient method for uncertainty quantification in the RTA of fractured tight gas wells with multiple unknown factors incorporated. The theoretical model for making forward predictions is based on a trilinear flow model, which incorporates the effects of two-phase flow and other nonlinear flow mechanisms. The normalized rates and material balance times of both water and gas phases are regarded as observations and matched with the theoretical model. The unknowns in the model are calibrated using the ensemble Kalman filter (EnKF), which applies an ensemble of multiple realizations to match the observations and updates the unknown parameters step by step. Finally, a comprehensive field case from Northwestern China is implemented to benchmark the proposed method. The results show that the parameters and rate transient responses have wide ranges and significant uncertainties before history matching, while all the realizations in the ensemble can have good matches to the field data after calibration. The posterior distribution of each unknown parameter in the model can be obtained after history matching, which can be used to quantify the uncertainties in the RTA of the fractured tight gas wells. The ranges and uncertainties of the parameters are significantly narrowed down, but the parameters are still with significant uncertainties. The main contribution of the paper is the provision of an efficient integrated workflow to quantify the uncertainties in RTA. It can be readily used in field applications of multi-fractured horizontal wells from tight gas reservoirs. Full article

Industrial development has implicitly led to the development of new systems that increase the ability to provide services and products in real time. Autonomous mobile robots are considered some of the most important tools that can help both industry and society. These robots offer a certain autonomy that makes them indispensable in industrial activities. However, some elements of these robots are not yet very well outlined, such as their construction, their lifetime and energy consumption, and the environmental impact of their activity. Within the context of European regulations (here, we focus on the Green Deal and the growth in greenhouse gas emissions), any industrial activity must be analyzed and optimized so that it is efficient and does not significantly impact the environment. The added value of this paper is its examination of the activities carried out by mobile robots and the impact of their electronic components on the environment. The proposed analysis employs, as a central point, an analysis of mobile robots from the point of view of their electronic components and the impact of their activity on the environment in terms of energy consumption, as evaluated by calculating the emission of greenhouse gases (GHGs). The way in which the activity of a robot impacts the environment was established throughout the economic flow, as well as by providing possible methods of reducing this impact by optimizing the robot’s activity. The environmental impact of a mobile robot, in regard to its electronic components, will also be analyzed when the period of operation is completed. Full article

The pollination characteristics and flowering phenology of Calanthe sieboldii were evaluated to elucidate its reproductive characteristics and breeding systems. Field observations and artificial pollination experiments were conducted to study the pollination biology in Xuancheng City, Anhui Province. Meanwhile, gas chromatography–mass spectrometry (GC-MS) was employed to analyze the species’ volatile organic compounds (VOCs). Key findings include the following: (1) the flowering period extends from mid-April to mid-May, with a population-level flowering duration of 29 days in 2017, individual plant flowering averaging 20.22 days, and single flower longevity ranging from 12 to 23 days (mean = 19.30 days); (2) the species exhibits deceptive nectar guides devoid of nectar, indicating food-deceptive pollination, with Bombus sp. identified as its primary pollinator; (3) the pollinial–ovule ratio and hybridization index suggest a high level of self-compatibility without autonomous self-pollination, with no significant difference in pollination success between self- and outcross populations; (4) GC-MS analysis identified methyl benzoate and acacia-related compounds as the primary VOCs of C. sieboldii. These findings provide valuable insights into the conservation and sustainable management of orchids, particularly C. sieboldii. Full article

The development of effective bifunctional catalysts demonstrating high performance in both photocatalytic hydrogen evolution and selective hydrogenation of unsaturated compounds is of great interest for photocatalytic transfer hydrogenation. In this work, TiO₂ and Pd@TiO₂ catalysts were studied in two separate processes: photocatalytic H₂ evolution and conventional hydrogenation reactions. Photocatalytic properties of titanium dioxide synthesized by a simple precipitation method were compared with those of commercial ones. Commercial anatase with a lower agglomeration degree showed better activity in H₂ evolution. Further modification of the commercial anatase with Pd resulted in increasing its activity, achieving an H₂ evolution rate of 760 μmol/h g_cat. The Pd catalysts supported on different TiO₂ samples were tested in hydrogenation of acetylenic compounds. The activity of the Pd@TiO₂ catalysts was found to be dependent on the photocatalytic properties of TiO₂ supports. XPS studies of Pd catalysts indicated that commercial anatase with better photocatalytic properties provided easier reduction of Pd²⁺ to active Pd⁰ particles. The Pd catalyst supported on commercial anatase demonstrated the highest activity in the hydrogenation process. The W_C≡C rate achieved 2.6 × 10^–6, 9.0 × 10^–6 and 35.7 × 10^–6 mol/s for hydrogenation of 2-hexyne-1-ol, 5-hexyne-1-ol and 2-hexyne, respectively. The selectivity of the catalyst to target olefinic compounds was 94–96%. In addition, the hydrogenation rate was found to be significantly affected by reaction conditions such as hydrogen concentration and solvent composition. The W_C≡C rate decreased linearly with decreasing hydrogen concentration in a H₂:He gas mixture (30–100 vol%). Performing the reaction in 0.10 M NaOH ethanolic solution resulted in increasing the W_C≡C rate and selectivity of the process. The Pd catalyst was reused in an alkali medium (NaOH in ethanol) for 35 runs without significant degradation in its catalytic activity. Thus, the results obtained in this work can be useful in photocatalytic transfer hydrogenation. Full article

The Zonguldak coal basin is the area with the most important hard coal reserves in Turkey. This study focuses on coal samples extracted from three seams of the Kozlu Formation, specifically from the Kozlu underground mine, to assess the coals’ organic geochemical and petrographic properties. Analytical methods, including TOC-pyrolysis, biomarker analysis, and maceral distribution studies, were employed. Based on these analyses, the paleoenvironmental conditions and hydrocarbon generation potential of the coals were evaluated. The results reveal that the coals, characterized by high TOC, high HI, and low OI, contain type II–III kerogen. These findings, coupled with the high QI and low BI values, suggest the presence of oil–gas prone source rocks. Elevated Tmax (457–466 °C) and Rr (0.89%–1.17%) values indicate a maturity level ranging from mature to overmature stages. High GI and GWI values suggest a significant degree of gelification and wet conditions during formation. The high Pr/Ph (1–6.58), C₃₁R/C₃₀ hopane (<0.25), and low DBT/P (0.27–0.50) ratios show that the Acılık seam was formed in a lacustrine environment under anoxic–suboxic conditions, whereas the Büyük and Domuzcu seams were formed in a fluvial/deltaic environment under oxic conditions. The findings of this study suggest that the paleovegetation in coal-forming environments consisted of aquatic and herbaceous plants. Full article

During energy transition, where sustainability and environmental protection are increasingly prioritized, ensuring safety in coal exploitation remains a critical issue, especially in the context of worker safety. This research focuses on predicting methane concentrations in underground mines, which is vital for both safety and operational efficiency. The article presents a methodology developed to predict methane concentrations at specific points in mine workings using artificial neural networks. The core of this methodology is a forecasting model that allows for the selection and adjustment of the neural network to the phenomenon being studied. This model, based on measurements of ventilation parameters, including methane concentrations in a given area, enables the prediction of gas concentrations at measurement points. The results indicate that with appropriate neural network selection and based on ventilation measurements, it is possible to forecast methane concentrations at acceptable levels in selected excavation points. The effectiveness of these forecasts depends on their timing and the input data to the model. The presented example of applying this methodology in a real mine working demonstrates its high efficiency. The best results were obtained for a 5 min forecast, with slightly less accuracy for longer times (10, 15, 30, and 60 min), though all results remained at an acceptable level. Therefore, it can be concluded that the developed methodology can be successfully applied in underground mining operations to forecast dangerous methane concentrations. Its implementation should improve mining efficiency by reducing instances of exceeding permissible methane concentrations and enhance occupational safety. Full article

This contribution explores the development of a digital twin for industrial valves, with a focus on mitigating the costly consequences of valve malfunctions in large-scale industrial environments. Industrial valves are critical components in fluid and gas control systems where unexpected failures can lead to significant downtime and financial loss. Digital twins as virtual replicas of physical systems offer a promising solution as they enable real-time monitoring and predictive maintenance. This paper looks at the creation of a digital twin for a specific valve type (74BS from SchuF Armaturen und Apparatebau GmbH) and considers key aspects such as model development, sensor integration and IT infrastructure. A test bench is constructed to collect the measured values to support the validation of the digital twin. The integration of sensors and the development of an IT system for data processing are also described in detail. Finally, the technically relevant frequencies are identified in an FFT. Full article

A Si-based photodetector is the core device of Si-based optical interconnection; its material and performance are the key factors restricting its development. This paper conducts theoretical research on the issues of lattice mismatch between heterogeneous materials and low device responsivity in Si-based InGaAs photodetectors for the 1550 nm optical communication band. The material mismatch issue is addressed through the use of the high-aspect ratio trapping (ART) epitaxial technique, enabling the realization of high-performance Si-based III-V materials. By introducing a dielectric metasurface into the top layer of the structure, the light absorption efficiency is enhanced, realizing broadband optical absorption enhancement for Si-based photodetectors. This paper mainly focuses on designing the optimal parameters of the dielectric metasurface structure based on the finite-difference time-domain (FDTD) Solutions to achieve the performance analysis of a high-responsivity 1550 nm Si-based InGaAs photodetector. The results show that the quantum efficiency of the dielectric metasurface structure is theoretically estimated to be 88.8% and the response rate is 1.11 A/W, which is 2%~16% higher than that of the unetched structure in the whole band. The research results of this paper will provide new ideas for the development of novel, high-performance, and miniaturized Si-based photodetectors and lay a theoretical foundation for Si-based optical interconnection. Full article

The ongoing transition to energy systems with high shares of variable renewables motivates the development of novel thermal power cycles that operate economically at low capacity factors to accommodate wind and solar intermittency. This study presents two recuperated power cycles with low capital costs for this market segment: (1) the near-isothermal hydrogen turbine (NIHT) concept, capable of achieving combined cycle efficiencies without a bottoming cycle through fuel combustion in the expansion path, and (2) the intercooled recuperated water-injected (IRWI) power cycle that employs conventional combustion technology at an efficiency cost of only 4% points. The economic assessment carried out in this work reveals that the proposed cycles increasingly outperform combined cycle benchmarks with and without CO₂ capture as the plant capacity factor reduces below 50%. When the cost of fuel storage and delivery by pipelines is included in the evaluation, however, plants fired by hydrogen lose competitiveness relative to natural gas-fired plants due to the high fuel delivery costs caused by the low volumetric energy density of hydrogen. This important but uncertain cost component could erode the business case for future hydrogen-fired power plants, in which case the IRWI concept powered by natural gas emerges as a promising solution. Full article

Global warming and climate change are major concerns across multiple disciplines. Population growth, urbanization, and industrialization are significant contributing factors to such problems due to the escalating use of fossil fuels required to meet growing energy demands. The building sector uses the largest share of total global energy production and produces tons of greenhouse gas emissions. Emerging eco-friendly technologies, such as solar and wind energy harvesting, are being extensively explored; however, they are insufficient. Nature-inspired technologies could offer solutions to our problems. For instance, algae are microorganisms that use water, light, and CO₂ to produce energy and sustain life, and the exploitation of these characteristics in a built environment is termed algae building technology, which is a very efficient and green application suitable for a sustainable future. Algae-integrated façades show great versatility through biomass and energy production, wastewater treatment, shading, and thermal and acoustic insulation. In this paper, algae will be introduced as a robust tool toward a greener and more sustainable future. Algae building technology and its implementation will be demonstrated. Furthermore, steps for applying this sustainable strategy in Egypt will be discussed. Full article

The cultivation or ‘tillage’ system is one of the most important elements of agrotechnology. It affects the condition of the soil, significantly modifying its physical, chemical, and biological properties, and the condition of plants, starting from ensuring appropriate conditions for sowing and plant growth, through influencing the efficiency of photosynthesis and ultimately, the yield. It also affects air transmission and the natural environment by influencing greenhouse gas (GHG) emissions potentially. Ultimately, the cultivation system also has an impact on the farmer, providing the opportunity to reduce production costs. The described experiment was established in 1998 at the Brody Agricultural Experimental Station belonging to the University of Life Sciences in Poznań (Poland) on a soil classified as an Albic Luvisol, while the described measurements were carried out in the 2022/2023 season, i.e., 24 years after the establishment of the experiment. Two cultivation methods were compared: Conventional Tillage (CT) and No Tillage (NT). Additionally, the influence of two factors was examined: nitrogen (N) fertilization (0 N—no fertilization, and 130 N–130 kg N∙ha⁻¹) and the growth phase of the winter wheat plants (BBCH: 32, 65 and 75). The growth phase of the plants was assessed according to the method of the Bundesanstalt, Bundessortenamt and CHemische Industrie (BBCH). We present the results of soil properties, soil respiration, wheat plants chlorophyll fluorescence, and grain yield. In our experiment, due to low rainfall, NT cultivation turned out to be beneficial, as it was a key factor influencing the soil properties, including soil organic carbon (SOC) content and soil moisture, and, consequently, creating favorable conditions for plant nutrition and efficiency of photosynthesis. We found a positive effect of NT cultivation on chlorophyll fluorescence, but this did not translate into a greater yield in NT cultivation. However, the decrease in yield due to NT compared to CT was only 5% in fertilized plots, while the average decrease in grain yield resulting from the lack of fertilization was 46%. We demonstrated the influence of soil moisture as well as the growth phase and fertilization on carbon dioxide (CO₂) emissions from the soil. We can clearly confirm that the tillage system affected all the parameters discussed in the work. Full article

Rising global energy demand has intensified the need for sustainable building practices and reduced energy consumption in the construction sector. This study investigates the energy-saving potential of integrating innovative materials into building wall structures in semiarid climates. Specifically, we examine the combination of thermal insulation made from recycled textile waste and phase change materials (PCMs) in exterior walls. Using the dynamic simulation tool TRNSYS, we analyzed heat transfer through the modified wall assembly under semiarid climate conditions typical of Marrakech, Morocco. Our results show that this “bioclimatic” design significantly impacts cooling loads more than heating demands. The modified building achieved a 52% reduction in summer energy usage compared to a conventional reference building. This energy saving translates to a 39% decrease in greenhouse gas emissions. Importantly, this study confirms that this configuration maintains thermal comfort for occupants, with particular effectiveness during the hot summer months when cooling demands are highest. Full article

Due to the higher susceptibility of children to ionizing radiation, it is imperative to evaluate the radon activity concentration (RAC) in educational buildings, conduct additional investigations to identify radon entry routes, and implement remedial measures to minimize exposure to this radioactive gas. In Romania, educational buildings are a category of public buildings where it is mandatory to perform RAC measurements. The present study examines data obtained from 41 Romanian educational buildings, where initial and additional radon investigations were performed. The first objective was to identify the factors influencing the variability of the RAC inside the buildings. The second objective was to emphasize the importance of short-term (a few days), continuous measurements in identifying buildings with RAC exceeding the reference level. High RAC values were associated with the classrooms located on the ground floor of the building compared to the administrative ones. The multiple linear regression led to a coefficient of determination of 0.11, the relative humidity and the amount of precipitation being the main variables with a significant impact, kept in the model, the lack of a significant association between the indoor RAC and the radon potential in the soil being obtained. Comparison of the radon long-term integrated measurements with continuous, short-term, led to the suggestion of three different scenarios for the measurement work protocol. By following the suggested modifications, it is possible to accelerate the procedure in situations where the time needed to plan renovations and radon remedial measures is shorter than the time needed to conduct integrated measurements. Full article

Greenhouse gas emissions are a major factor contributing to global climate change and have received extensive attention from policymakers worldwide. As a cornerstone of China’s industry and a critical foundation of the global manufacturing sector, the introduction of carbon policies could increase production costs and reduce international competitiveness, thereby impacting its stable development. How can carbon emissions be reduced to meet the environmental standards of the international community while maintaining global market competitiveness? This paper develops a comprehensive set of indicators to assess the industrial resilience of the ferrous metal smelting and rolling industry. These indicators focus on the industry’s development capacity, market demand transformation, potential for technological innovation, and ability to adapt to external shocks and recover autonomously. Using the difference-in-differences (DID) model, it quantifies the effects of carbon policies from China and the EU on the industry’s resilience and examines adaptation mechanisms within the industrial chain. It is found that ferrous metal smelting and rolling industrial resilience has been strengthening, significantly influenced by national research and experimental development (R&D), gearing ratio, and government science and technology investments. China’s domestic carbon policies and the EU’s carbon policy have profoundly impacted the resilience of China’s ferrous metal industry, fostering green innovation and the transition to a low-carbon economy while ensuring industrial stability and competitiveness. Full article