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Keywords = non-conservative energy principle

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12 pages, 3174 KiB  
Article
Modeling and Control for an Aerial Work Quadrotor with a Robotic Arm
by Wenwu Zhu, Fanzeng Wu, Haibo Du, Lei Li and Yao Zhang
Actuators 2025, 14(7), 357; https://doi.org/10.3390/act14070357 - 21 Jul 2025
Viewed by 240
Abstract
This paper focuses on the integrated modeling and disturbance rejection of the aerial work quadrotor with a robotic arm. First, to address the issues of model incompleteness and parameter uncertainty commonly encountered in traditional Newton–Euler-based modeling approaches for such a system, the Lagrangian [...] Read more.
This paper focuses on the integrated modeling and disturbance rejection of the aerial work quadrotor with a robotic arm. First, to address the issues of model incompleteness and parameter uncertainty commonly encountered in traditional Newton–Euler-based modeling approaches for such a system, the Lagrangian energy conservation principle is adopted. By treating the quadrotor and robotic arm as a unified system, an integrated dynamic model is developed, which accurately captures the coupled dynamics between the aerial platform and the manipulator. The innovative approach fills the gap in existing research where model expressions are incomplete and parameters are ambiguous. Next, to reduce the adverse effects of the robotic arm’s motion on the entire system stability, a finite-time disturbance observer and a fast non-singular terminal sliding mode controller (FNTSMC) are designed. Lyapunov theory is used to prove the finite-time stability of the closed-loop system. It breaks through the limitations of the traditional Lipschitz framework and, for the first time at both the theoretical and methodological levels, achieves finite-time convergence control for the aerial work quadrotor with a robotic arm system. Finally, comparative simulations with the integral sliding mode controller (ISMC), sliding mode controller (SMC), and PID controller demonstrate that the proposed algorithm reduces the regulation time by more than 45% compared to ISMC and SMC, and decreases the overshoot by at least 68% compared to the PID controller, which improves the convergence performance and disturbance rejection capability of the closed-loop system. Full article
(This article belongs to the Special Issue Advanced Learning and Intelligent Control Algorithms for Robots)
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32 pages, 7667 KiB  
Article
Development of a Non-Uniform Heat Source Model for Accurate Prediction of Wheel Tread Temperature on Long Downhill Ramps
by Jinyu Zhang, Jingxian Ding and Jianyong Zuo
Lubricants 2025, 13(6), 235; https://doi.org/10.3390/lubricants13060235 - 24 May 2025
Cited by 1 | Viewed by 714
Abstract
Accurately simulating the thermal behavior of wheel–brake shoe friction on long downhill ramps is challenging due to the complexity of modeling appropriate heat source models. This study investigates heat generation during the frictional braking process of freight train wheels and brake shoes under [...] Read more.
Accurately simulating the thermal behavior of wheel–brake shoe friction on long downhill ramps is challenging due to the complexity of modeling appropriate heat source models. This study investigates heat generation during the frictional braking process of freight train wheels and brake shoes under long-slope conditions. Four heat source models—constant, modified Gaussian, sinusoidal, and parabolic distributions—were developed based on energy conservation principles and validated through experimental data. A thermomechanical coupled finite element model was established, incorporating a moving heat source to analyze the effects of different models on wheel tread temperature distribution and its evolution over time. The results show that all four models effectively simulate frictional heat generation, with computed temperatures, deviating by only 6.0–8.2% from experimental measurements, confirming their accuracy and reliability. Among the models, the modified Gaussian distribution heat source, with its significantly higher peak local heat flux (2.82 times that of the constant model) and rapid attenuation, offers the most precise simulation of the non-uniform temperature distribution in the contact region. This leads to a 40% increase in the temperature gradient variation rate and effectively reproduces the “hot spot” effect. The new non-uniform heat source model accurately captures local temperature dynamics and predicts frictional heat transfer and thermal damage trends. The modified Gaussian distribution model outperforms others in simulating local temperature peaks, offering support for optimizing braking system models and improving thermal damage prediction. Future research will refine this model by incorporating factors like material wear, environmental conditions, and dynamic contact characteristics. Full article
(This article belongs to the Special Issue Tribology in Railway Engineering)
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11 pages, 239 KiB  
Article
Examining Romosozumab Adherence and Side Effects in Osteoporotic Patients After Surgical Fracture Fixation: A Comparative, Descriptive, and Hypothesis-Generating Study with Non-Fractured Controls
by Amarildo Smakaj, Umberto Tarantino, Riccardo Iundusi, Angela Chiavoghilefu, Lorenzo Abbondante, Chiara Salvati, Chiara Greggi and Elena Gasbarra
Diseases 2025, 13(5), 148; https://doi.org/10.3390/diseases13050148 - 11 May 2025
Viewed by 588
Abstract
Objectives: The study aims to evaluate adherence to Romosozumab treatment in osteoporotic patients after surgical fracture fixation and compare side effects with non-fractured controls on the same therapy. Methods: This retrospective case–control study was conducted at the Orthopaedic Department of Policlinico Universitario di [...] Read more.
Objectives: The study aims to evaluate adherence to Romosozumab treatment in osteoporotic patients after surgical fracture fixation and compare side effects with non-fractured controls on the same therapy. Methods: This retrospective case–control study was conducted at the Orthopaedic Department of Policlinico Universitario di Roma “Tor Vergata”, following the principles of the Declaration of Helsinki. It included postmenopausal women aged over 60, with the case group receiving Romosozumab after fracture fixation, and the control group consisting of women on Romosozumab therapy without fracture fixation. Exclusion criteria included psychiatric conditions, contraindications to Romosozumab, high-energy trauma, or other bone metabolism disorders. Data on fractures, surgeries, FRAX (Fracture Risk Assessment Tool) scores, BMD (Bone Mineral Densit) values, and follow-up details were collected. Side effects, including nasopharyngitis and severe events like hypocalcemia, stroke, and myocardial infarction, were recorded. Adherence was assessed via pharmacy records and patient interviews during routine clinical follow-up visits. Statistical analysis was performed using descriptive statistics, t-tests, and chi-square tests. Results: The study included 25 patients, with 12 in the surgical group and 13 in the conservative treatment group. The surgical group had a mean age of 67.3 years and a follow-up of 374 days, while the conservative group had a mean age of 76.4 years and a follow-up of 287 days. The surgical group underwent various fracture treatments, including femoral, humeral, and distal radius fractures, while the conservative group was treated with immobilization. There were no significant differences in FRAX scores or BMD values between the two groups. Vitamin D levels increased significantly in both groups after supplementation, but parathyroid hormone levels showed no difference. No new fractures occurred, and surgical patients had no delayed union or nonunion, though two had superficial wound infections. Conclusions: Both groups adhered well to Romosozumab therapy, with no severe side effects; minor side effects included myalgia in the surgical group and shoulder arthralgia in the conservative group. Romosozumab is well-tolerated and adherent in osteoporotic patients after osteosynthesis surgery, with adverse events similar to non-fractured individuals. While the study design is appropriate, multicenter trials would improve the sample size and allow for subgroup analysis based on fracture type and demographics. Full article
19 pages, 897 KiB  
Article
Stable Multipoint Flux Approximation (MPFA) Saturation Solution for Two-Phase Flow on Non-K-Orthogonal Anisotropic Porous Media
by Pijus Makauskas and Mayur Pal
Technologies 2025, 13(5), 193; https://doi.org/10.3390/technologies13050193 - 9 May 2025
Viewed by 1258
Abstract
This paper extends the multipoint flux approximation (MPFA-O) method to model coupled pressure and saturation dynamics in subsurface reservoirs with heterogeneous anisotropic permeability and non-K-orthogonal grids. The MPFA method is widely used for reservoir simulation to address the limitations of the two-point flux [...] Read more.
This paper extends the multipoint flux approximation (MPFA-O) method to model coupled pressure and saturation dynamics in subsurface reservoirs with heterogeneous anisotropic permeability and non-K-orthogonal grids. The MPFA method is widely used for reservoir simulation to address the limitations of the two-point flux approximation (TPFA), particularly in scenarios involving full-tensor permeability and strong anisotropy. However, the MPFA-O method is known to suffer from spurious oscillations and numerical instability, especially in high-anisotropy scenarios. Existing stability-enhancing techniques, such as optimal quadrature schemes and flux-splitting methods, mitigate these issues but are computationally expensive and do not always ensure monotonicity or oscillation-free solutions. Building upon prior advancements in the MPFA-O method for pressure equations, this work incorporates the saturation equation to enable the simulation of a coupled multiphase flow in porous media. A unified framework is developed to address stability challenges associated with the tight coupling of pressure and saturation fields while ensuring local conservation and accuracy in the presence of full-tensor permeability. The proposed method introduces stability-enhancing modifications, including a local rotation transformation, to mitigate spurious oscillations and preserve physical principles such as monotonicity and the maximum principle. Numerical experiments on heterogeneous, anisotropic domains with non-K-orthogonal grids validate the robustness and accuracy of the extended MPFA-O method. The results demonstrate improved stability and performance in capturing the complex interactions between pressure and saturation fields, offering a significant advancement in subsurface reservoir modeling. This work provides a reliable and efficient tool for simulating coupled flow and transport processes, with applications in CO2 storage, hydrogen storage, geothermal energy, and hydrocarbon recovery. Full article
(This article belongs to the Section Construction Technologies)
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24 pages, 4359 KiB  
Review
MSW Incineration Bottom Ash-Based Alkali-Activated Binders as an Eco-Efficient Alternative for Urban Furniture and Paving: Closing the Loop Towards Sustainable Construction Solutions
by Josep Maria Chimenos, Fabian Cuspoca, Alex Maldonado-Alameda, Jofre Mañosa, Joan Ramon Rosell, Ana Andrés, Gerard Faneca and Luisa F. Cabeza
Buildings 2025, 15(9), 1571; https://doi.org/10.3390/buildings15091571 - 7 May 2025
Viewed by 687
Abstract
Innovative approaches in the Portland cement industry, aligned with circular economy principles, offer a promising solution to reduce the environmental impacts. These methods can initially target the architectural elements with lower structural demands, such as urban furniture and paving, before being applied to [...] Read more.
Innovative approaches in the Portland cement industry, aligned with circular economy principles, offer a promising solution to reduce the environmental impacts. These methods can initially target the architectural elements with lower structural demands, such as urban furniture and paving, before being applied to areas with higher cement usage. Alkali-activated binders (AABs) made from secondary resources present a sustainable alternative to Portland cement (PC), promoting resource recovery, conservation, and a low-carbon economy. Incinerator bottom ash (IBA), traditionally landfilled, has shown potential as a precursor for AABs due to its aluminosilicate content. Repurposing IBA for urban furniture and paving transforms it into a valuable secondary resource. Accordingly, this is the first study to utilize IBA as the sole precursor for urban furniture or paving applications. Research, including state-of-the-art studies and proof of concept developed in this work, demonstrates that IBA-based AABs can produce cast concrete suitable for non-structural urban elements, meeting the technical, environmental, and ecotoxicological standards. Using IBA in AAB formulations not only reduces the reliance on primary raw materials but also contributes to significant energy savings in binder production and lowers greenhouse gas (GHG) emissions, resulting in a reduced carbon footprint. Furthermore, producing concrete from local residual resources, such as IBA, facilitates the reintegration of municipal waste into the production cycle at its point of origin, fostering a sustainable approach to urban development and supporting the circular economy. Full article
(This article belongs to the Special Issue Advances in the Implementation of Circular Economy in Buildings)
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20 pages, 12097 KiB  
Article
Research on Micro-Intervention Strategies for Energy-Saving Renovation of the Envelope Structures in Existing Brick–Wood Ancient-Style Buildings
by Xingke Zhao, Chenxi Li, Fuduo Ma, Guanyi Jin and Zhilin Shi
Buildings 2025, 15(9), 1569; https://doi.org/10.3390/buildings15091569 - 6 May 2025
Cited by 1 | Viewed by 495
Abstract
In the global low-carbon era, building energy conservation has achieved significant success. However, especially in the culture and tourism industry, there are many brick–wood buildings that imitate ancient styles. As their appearance authenticity and structural safety must be maintained, energy-saving retrofits face multiple [...] Read more.
In the global low-carbon era, building energy conservation has achieved significant success. However, especially in the culture and tourism industry, there are many brick–wood buildings that imitate ancient styles. As their appearance authenticity and structural safety must be maintained, energy-saving retrofits face multiple constraints. For such buildings, regulating building energy consumption through the renovation of the enclosure structure has practical value in supporting the achievement of carbon peaking and carbon neutrality goals. This study addresses the contradiction between the preserving architectural forms and improving energy efficiency in the energy-saving renovation of brick–wood buildings that imitate ancient styles. It presents a “Three-Micro” technical system grounded in the minimum-intervention principle, integrating micro-intervention implantation, micro-realignment regulation, and micro-renewal iteration. Through modular node design, it combines traditional construction with modern energy-saving techniques and systematically devises an energy-saving retrofit plan for such existing buildings. Through simulation and verification using the case of the Northwest Corner Tower in the Imperial City of Shengjing, the results show that the energy-saving rate of the building itself is 58.47%, while the comprehensive energy-saving rate is 87.56%. Both meet the evaluation criteria for ultra-low energy consumption buildings under the relevant standards, which proves the feasibility of the “Three-Micro” technical system. It provides solutions for the energy-saving renovation of similar buildings, especially those brick–wood buildings that imitate ancient styles and have a high degree of completion (a high level of imitation of ancient architecture). At the same time, it also holds important reference value for the energy-saving renovation of some non-core ancient buildings that are commonly used in everyday life, such as those serving as ticket offices, exhibition halls, administrative offices, etc. Full article
(This article belongs to the Section Building Energy, Physics, Environment, and Systems)
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16 pages, 2967 KiB  
Article
Study on the Effect of Non-Uniform Ventilation on Energy and Plant Growth in a Greenhouse
by Ziteng Wang, Aiqun Bao, Jialei Li, Jinhong He, Kaiwen Wang, Xinke Wang and Xianpeng Sun
Horticulturae 2025, 11(2), 166; https://doi.org/10.3390/horticulturae11020166 - 5 Feb 2025
Viewed by 930
Abstract
The progress of local environmental regulation in protected agriculture is sluggish, particularly concerning the local air supply, which poses a significant obstacle to greenhouse energy-saving research. This study establishes a test platform for local air supply in winter and summer by integrating design [...] Read more.
The progress of local environmental regulation in protected agriculture is sluggish, particularly concerning the local air supply, which poses a significant obstacle to greenhouse energy-saving research. This study establishes a test platform for local air supply in winter and summer by integrating design principles from human settlements’ supply air bag models with crop growth requirements. By utilizing a supply air bag to direct fresh air from the air conditioning system to specific areas within the greenhouse, non-uniform ventilation is created. Research has revealed that varying air supply levels in summer exerts a significant influence on environmental conditions, crop growth, and energy efficiency. Noticeable temperature stratification and cooling effects were observed within the conditioning greenhouse. The growth of lettuce was moderately enhanced, with mid-level local air supply demonstrating superior cooling effectiveness and range compared to the other two levels. Optimal control efficacy and energy conservation were achieved through mid-level local air supply. During daytime experiments in winter, this system did not have a significant impact on the greenhouse environment; however, during nighttime experiments, it consistently provided warming effects to maintain temperatures above the minimum requirement for lettuce growth. Therefore, utilizing air supply bags at secure specific positions and implementing targeted air supply methods within cultivation areas in greenhouses can facilitate the creation of suitable local environments for crop growth while achieving energy savings. Future research in this field could focus on further refining air supply bag models to enhance energy efficiency and local environmental control effects. Full article
(This article belongs to the Special Issue Latest Advances in Horticulture Production Equipment and Technology)
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20 pages, 1952 KiB  
Proceeding Paper
Energy-Efficient Path Planning for Commercial Aircraft Formation Flights
by Olivia Curtis, Yibing Xie, Man Liang and Cees Bil
Eng. Proc. 2024, 80(1), 15; https://doi.org/10.3390/engproc2024080015 - 6 Jan 2025
Viewed by 847
Abstract
The increasing global demand for air travel over the past three decades has led to heightened congestion, environmental concerns, and operational inefficiencies. This study explores the potential of commercial aircraft formation flight, inspired by the energy-saving flight patterns of migratory birds, to enhance [...] Read more.
The increasing global demand for air travel over the past three decades has led to heightened congestion, environmental concerns, and operational inefficiencies. This study explores the potential of commercial aircraft formation flight, inspired by the energy-saving flight patterns of migratory birds, to enhance fuel efficiency on the busy Melbourne to Sydney city-pair route. The methodology is divided into macroscopic and microscopic levels, addressing both strategic planning and detailed flight optimisation. The macroscopic level focuses on route optimisation, formation flight planning, air traffic management integration, and environmental impact. The microscopic level involves adjustments to individual aircraft flight profiles to ensure minimum separation, flight safety, and efficiency. Using a gradient-based optimisation algorithm applied to a constrained nonlinear multivariable function, this study aims to minimise fuel consumption and travel time while maintaining the required separation distances. The mathematical formulation and algorithm pseudocode provides a clear framework for implementation. The experimental results demonstrate the potential of formation flight to optimise fuel efficiency and resolve path conflicts on the Melbourne to Sydney route; despite a conservative 5% fuel efficiency improvement for the follower aircraft, the total fuel consumption decreased by 2.5–2.65% compared to the non-formation flight. These findings support the feasibility of applying formation flight principles to commercial aviation in Australia for improved fuel efficiency and operation performance of busy short-haul routes. Full article
(This article belongs to the Proceedings of 2nd International Conference on Green Aviation (ICGA 2024))
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17 pages, 293 KiB  
Article
Lie Symmetry Analysis, Closed-Form Solutions, and Conservation Laws for the Camassa–Holm Type Equation
by Jonathan Lebogang Bodibe and Chaudry Masood Khalique
Math. Comput. Appl. 2024, 29(5), 92; https://doi.org/10.3390/mca29050092 - 10 Oct 2024
Cited by 1 | Viewed by 1120
Abstract
In this paper, we study the Camassa–Holm type equation, which has applications in mathematical physics and engineering. Its applications extend across disciplines, contributing to our understanding of complex systems and helping to develop innovative solutions in diverse areas of research. Our main aim [...] Read more.
In this paper, we study the Camassa–Holm type equation, which has applications in mathematical physics and engineering. Its applications extend across disciplines, contributing to our understanding of complex systems and helping to develop innovative solutions in diverse areas of research. Our main aim is to construct closed-form solutions of the equation using a powerful technique, namely the Lie group analysis method. Firstly, we derive the Lie point symmetries of the equation. Thereafter, the equation is reduced to non-linear ordinary differential equations using symmetry reductions. Furthermore, the solutions of the equation are derived using the extended Jacobi elliptic function technique, the simplest equation method, and the power series method. In conclusion, we construct conservation laws for the equation using Noether’s theorem and the multiplier approach, which plays a crucial role in understanding the behavior of non-linear equations, especially in physics and engineering, and these laws are derived from fundamental principles such as the conservation of mass, energy, momentum, and angular momentum. Full article
(This article belongs to the Special Issue Symmetry Methods for Solving Differential Equations)
18 pages, 5895 KiB  
Article
Research on Rock Energy Constitutive Model Based on Functional Principle
by Hongmiao Lv, Xiaochen Yang, Yue Yu and Wenbo Liu
Symmetry 2024, 16(9), 1250; https://doi.org/10.3390/sym16091250 - 23 Sep 2024
Cited by 2 | Viewed by 1000
Abstract
The essence of rock fracture can be broadly categorized into four processes: energy input, energy accumulation, energy dissipation, and energy release. From the perspective of energy consumption, the failure of rock materials must be accompanied by energy dissipation. Dissipated energy serves as the [...] Read more.
The essence of rock fracture can be broadly categorized into four processes: energy input, energy accumulation, energy dissipation, and energy release. From the perspective of energy consumption, the failure of rock materials must be accompanied by energy dissipation. Dissipated energy serves as the internal driving force behind rock damage and progressive failure. Given that the process of rock loading and deformation involves energy accumulation and dissipation, the rock constitutive model theory is expanded by incorporating energy principles. By introducing the dynamic energy correction coefficient, according to the law of the conservation of energy, the total energy exerted by external loads on rocks is equal to the energy dissipated through the dynamic energy inside the rocks. A new type of energy constitutive model is established through the functional principle and momentum principle. To validate the model’s accuracy, a triaxial compression test was conducted on sandstone to examine the stress–strain behavior of the rock during the failure process. A sensitivity analysis of the parameters introduced into the model was conducted by comparing the model results, which helped to clarify the innate laws of significance of these parameters. The results indicated that the energy model more accurately captures the non-linear mechanical behavior of sandstone under high-stress loading conditions. The model curve fits the test data to a high degree. The fitting curve was basically consistent with the changing trend of the test curve, and the correlation coefficients were all above 0.90. Compared with other models, the model based on the energy principle not only accurately reflects the rock’s stress–strain curve, but also reflects the energy change law of rock. This has reference value for the safety analysis of rock mass engineering under loading conditions and aids in the development of anchoring and support schemes. The research results can fill in the blanks that exist in the energy method in terms of rock deformation and failure and provide a theoretical basis for deep rock engineering. Moreover, this research can further improve and extend the rock mechanics research system based on energy. Full article
(This article belongs to the Section Engineering and Materials)
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25 pages, 5472 KiB  
Review
Principles and Methods for Improving the Thermoelectric Performance of SiC: A Potential High-Temperature Thermoelectric Material
by Yun Xing, Bo Ren, Bin Li, Junhong Chen, Shu Yin, Huan Lin, Jie Liu and Haiyang Chen
Materials 2024, 17(15), 3636; https://doi.org/10.3390/ma17153636 - 23 Jul 2024
Cited by 11 | Viewed by 2550
Abstract
Thermoelectric materials that can convert thermal energy to electrical energy are stable and long-lasting and do not emit greenhouse gases; these properties render them useful in novel power generation devices that can conserve and utilize lost heat. SiC exhibits good mechanical properties, excellent [...] Read more.
Thermoelectric materials that can convert thermal energy to electrical energy are stable and long-lasting and do not emit greenhouse gases; these properties render them useful in novel power generation devices that can conserve and utilize lost heat. SiC exhibits good mechanical properties, excellent corrosion resistance, high-temperature stability, non-toxicity, and environmental friendliness. It can withstand elevated temperatures and thermal shock and is well suited for thermoelectric conversions in high-temperature and harsh environments, such as supersonic vehicles and rockets. This paper reviews the potential of SiC as a high-temperature thermoelectric and third-generation wide-bandgap semiconductor material. Recent research on SiC thermoelectric materials is reviewed, and the principles and methods for optimizing the thermoelectric properties of SiC are discussed. Thus, this paper may contribute to increasing the application potential of SiC for thermoelectric energy conversion at high temperatures. Full article
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12 pages, 3939 KiB  
Article
Young’s Modulus and Hardness Identification of Extruded Aluminum by Scratching Damper
by Chun-Nam Wong, Anand Vyas, Wai-On Wong and Ruqi Sun
Machines 2024, 12(6), 413; https://doi.org/10.3390/machines12060413 - 17 Jun 2024
Viewed by 1425
Abstract
A special vibration damper is proposed for Young’s modulus and hardness identification through a scratching process on extruded aluminum. This paper presents the design and working principle of a scratching damper based on a scratching device. A non-contact electromagnetic shaker is used to [...] Read more.
A special vibration damper is proposed for Young’s modulus and hardness identification through a scratching process on extruded aluminum. This paper presents the design and working principle of a scratching damper based on a scratching device. A non-contact electromagnetic shaker is used to generate the shaking force for test sample vibration. The required forces on the scratched material during the scratching process are generated by an adjustable compression spring. The proposed damper is designed and tested on an extruded aluminum 3004 sample for the determination of its Young’s modulus and hardness, and validation is performed using the standard test instruments. The physical dimensions of the scratching tracks are measured using a microscope and utilized to compute the scratching energy factor. Load curves are obtained at different divisions of the scratching process. The loop energy during the scratching process of the tested object is measured and used for the determination of sample material properties. Furthermore, the energy conservation law, scratch energy release rate of semi-conical scratch head, and loop energy release rate are established to determine the Young’s modulus and hardness of the sample. Their estimation accuracies are evaluated. The proposed method has several advantages over the traditional methods, including low cost, directness, and high repeatability. The results suggest this to be used as an alternative to the standard modulus and hardness tester. Full article
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19 pages, 1253 KiB  
Article
Optimizing Mixed-Model Synchronous Assembly Lines with Bipartite Sequence-Dependent Setup Times in Advanced Manufacturing
by Asieh Varyani, Mohsen Salehi and Meysam Heydari Gharahcheshmeh
Energies 2024, 17(12), 2865; https://doi.org/10.3390/en17122865 - 11 Jun 2024
Cited by 2 | Viewed by 1308
Abstract
In advanced manufacturing, optimizing mixed-model synchronous assembly lines (MMALs) is crucial for enhancing productivity and adhering to sustainability principles, particularly in terms of energy consumption and energy-efficient sequencing. This paper introduces a novel approach by categorizing sequence-dependent setup times into bipartite categories: workpiece-independent [...] Read more.
In advanced manufacturing, optimizing mixed-model synchronous assembly lines (MMALs) is crucial for enhancing productivity and adhering to sustainability principles, particularly in terms of energy consumption and energy-efficient sequencing. This paper introduces a novel approach by categorizing sequence-dependent setup times into bipartite categories: workpiece-independent and workpiece-dependent. This strategic division streamlines assembly processes, reduces idle times, and decreases energy consumption through more efficient machine usage. A new mathematical model is proposed to minimize the intervals at which workpieces are launched on an MMAL, aiming to reduce operational downtime that typically leads to excessive energy use. Given the Non-deterministic Polynomial-time hard (NP-hard) nature of this problem, a genetic algorithm (GA) is developed to efficiently find solutions, with performance compared against the traditional branch and bound technique (B&B). This method enhances the responsiveness of MMALs to variable production demands and contributes to energy conservation by optimizing the sequence of operations to align with energy-saving objectives. Computational experiments conducted on small and large-sized problems demonstrate that the proposed GA outperforms the conventional B&B method regarding solution quality, diversity level, and computational time, leading to energy reductions and enhanced cost-effectiveness in manufacturing settings. Full article
(This article belongs to the Section K: State-of-the-Art Energy Related Technologies)
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24 pages, 3851 KiB  
Article
Evaluating the Contribution of Lean Construction to Achieving Sustainable Development Goals
by Sada Hasan, Zeynep Işık and Gökhan Demirdöğen
Sustainability 2024, 16(8), 3502; https://doi.org/10.3390/su16083502 - 22 Apr 2024
Cited by 11 | Viewed by 3948
Abstract
The construction industry is scrutinized and criticized for its impact on environmental degradation. Nowadays, while the lean construction philosophy and Sustainable Development Goals (SDGs) aim to alleviate the adverse environmental effects of the construction industry, their synergies remain unclear and ambiguous. Therefore, this [...] Read more.
The construction industry is scrutinized and criticized for its impact on environmental degradation. Nowadays, while the lean construction philosophy and Sustainable Development Goals (SDGs) aim to alleviate the adverse environmental effects of the construction industry, their synergies remain unclear and ambiguous. Therefore, this study aims to explore the synergies between lean construction principles and the Sustainable Development Goals (SDGs) and their combined efficacy in mitigating the environmental footprint of the construction industry. In the study, a comprehensive three-step methodology, involving a literature review, focus group discussions, and quantitative Delphi technique analysis, was employed. The analysis uncovers that SDGs (ensuring clean water and sanitation, promoting clean energy, fostering economic growth and decent work, improving infrastructure and innovation, building sustainable cities and communities, promoting responsible consumption and production, conserving oceans, and preserving terrestrial ecosystems) have 63 extremely important linkages and 251 very important linkages with lean construction principles. The analysis results indicate that the synergies are categorized under economic (39%), environmental (42%), and social (19%) factors. Moreover, the strategic triad of lean principles, i.e., “Reducing non-value-adding, focusing on all processes, and continuous improvement”, emerged as key in fostering extremely important interactions. This study’s novelty lies in its integrating of Koskela’s lean principles with the 17 SDGs and 169 targets of Agenda 2030, offering strategic insights for aligning construction processes with the broader 2030 agenda for enhanced sustainability in the construction industry. The findings contribute to finding out the how lean construction principles serve the SDGs. Full article
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17 pages, 8038 KiB  
Article
A Non-inductive Coil Design Used to Provide High-Frequency and Large Currents
by Qing Zhu and Yu Su
Sensors 2024, 24(7), 2027; https://doi.org/10.3390/s24072027 - 22 Mar 2024
Viewed by 1574
Abstract
Currently, cutting-edge, high-frequency current sources are limited by switching devices and wire materials, and the output current cannot take into account the demands of a high peak and low rise time at the same time. Based on the output demand of a current [...] Read more.
Currently, cutting-edge, high-frequency current sources are limited by switching devices and wire materials, and the output current cannot take into account the demands of a high peak and low rise time at the same time. Based on the output demand of a current source, a non-inductive coil for providing high-frequency, high current sources with low rise times is designed. The coil is appropriately designed according to the principle of the ampere-turn method, where several turns of wire are utilized to linearly synthesize the current to obtain high-frequency currents with amplitudes up to 30 kA. However, the inductance formed after winding the coil could possess a hindering effect on the high-frequency current. In the present investigation, based on the law of energy conservation and utilizing the principle of transformer coupling, the inductor’s hindering effect on high-frequency currents is appropriately eliminated by consuming the stored energy of the inductor innovatively. Theoretical calculations and practical tests show that the inductance of a two-layer 28-turn coil is 42 times smaller than that of a two-layer, 28-turn perfect circular spiral PCB coil. The measured inductance is only 6.69 μH, the output current amplitude is calculated to be up to 33 kA with a rise time of 20 ns, and the output waveform corresponding to a 1 MHz square wave is not remarkably distorted. This effective design idea could be very helpful in solving the problem of high peak values and low rise times in high-frequency, high-current source output design. Full article
(This article belongs to the Section Electronic Sensors)
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