Hasil untuk "Bridge engineering"

Xin Wang, Yuwei Zhang, Haonan Si et al.

Defect engineering is widely applied in transition metal dichalcogenides (TMDs) to achieve electrical, optical, magnetic and catalytic regulation. Vacancies, regarded as a type of extremely delicate defect, are acknowledged to be effective and flexible in general catalytic modulation. However, the influence of vacancy states in addition to concentration on catalysis still remains vague. Thus, via high throughput calculations, the optimized sulfur vacancy (S-vacancy) state in terms of both concentration and distribution is initially figured out among a series of MoS2 models for the hydrogen evolution reaction (HER). In order to realize it, a facile and mild H2O2 chemical etching strategy is implemented to introduce homogeneously distributed single S-vacancies onto MoS2 nanosheet surface. By systematic tuning of the etching duration, etching temperature and etching solution concentration, comprehensive modulation of the S-vacancy state is achieved. The optimized HER performance reaches a Tafel slope of 48 mV dec-1 and an overpotential of 131 mV at 10 mA cm-2, indicating the superiority of single S-vacancies over agglomerate S-vacancies. This is ascribed to the more effective surface electronic structure engineering as well as the boosted electrical transport properties. Bridging the gap, to some extent, between precise design from theory and practical modulation in experiments, the proposed strategy extends defect engineering to a more sophisticated level for further unlocking the potential of catalytic performance enhancement.

C. Koch, K. Georgieva, Varun Kasireddy et al.

R. Beard, T. McLain

Autonomous unmanned air vehicles (UAVs) are critical to current and future military, civil, and commercial operations. Despite their importance, no previous textbook has accessibly introduced UAVs to students in the engineering, computer, and science disciplines--until now. Small Unmanned Aircraft provides a concise but comprehensive description of the key concepts and technologies underlying the dynamics, control, and guidance of fixed-wing unmanned aircraft, and enables all students with an introductory-level background in controls or robotics to enter this exciting and important area. The authors explore the essential underlying physics and sensors of UAV problems, including low-level autopilot for stability and higher-level autopilot functions of path planning. The textbook leads the student from rigid-body dynamics through aerodynamics, stability augmentation, and state estimation using onboard sensors, to maneuvering through obstacles. To facilitate understanding, the authors have replaced traditional homework assignments with a simulation project using the MATLAB/Simulink environment. Students begin by modeling rigid-body dynamics, then add aerodynamics and sensor models. They develop low-level autopilot code, extended Kalman filters for state estimation, path-following routines, and high-level path-planning algorithms. The final chapter of the book focuses on UAV guidance using machine vision. Designed for advanced undergraduate or graduate students in engineering or the sciences, this book offers a bridge to the aerodynamics and control of UAV flight.

Jeong-Yun Sun, Xuanhe Zhao, Widusha R Illeperuma et al.

Lei Zhang, Guojing Yang, Blake N. Johnson et al.

Critical-sized bone defect repair remains a substantial challenge in clinical settings and requires bone grafts or bone substitute materials. However, existing biomaterials often do not meet the clinical requirements of structural support, osteoinductive property, and controllable biodegradability. To treat large-scale bone defects, the development of three-dimensional (3D) porous scaffolds has received considerable focus within bone engineering. A variety of biomaterials and manufacturing methods, including 3D printing, have emerged to fabricate patient-specific bioactive scaffolds that possess controlled micro-architectures for bridging bone defects in complex configurations. During the last decade, with the development of the 3D printing industry, a large number of tissue-engineered scaffolds have been created for preclinical and clinical applications using novel materials and innovative technologies. Thus, this review provides a brief overview of current progress in existing biomaterials and tissue engineering scaffolds prepared by 3D printing technologies, with an emphasis on the material selection, scaffold design optimization, and their preclinical and clinical applications in the repair of critical-sized bone defects. Furthermore, it will elaborate on the current limitations and potential future prospects of 3D printing technology. STATEMENT OF SIGNIFICANCE: 3D printing has emerged as a critical fabrication process for bone engineering due to its ability to control bulk geometry and internal structure of tissue scaffolds. The advancement of bioprinting methods and compatible ink materials for bone engineering have been a major focus to develop optimal 3D scaffolds for bone defect repair. Achieving a successful balance of cellular function, cellular viability, and mechanical integrity under load-bearing conditions is critical. Hybridization of natural and synthetic polymer-based materials is a promising approach to create novel tissue engineered scaffolds that combines the advantages of both materials and meets various requirements, including biological activity, mechanical strength, easy fabrication and controllable degradation. 3D printing is linked to the future of bone grafts to create on-demand patient-specific scaffolds.

Takeo Yamada, Y. Hayamizu, Yuki Yamamoto et al.

Qing Li, Qing Li, K. Luo et al.

Over the past few decades, tremendous progress has been made in the development of particle-based discrete simulation methods versus the conventional continuum-based methods. In particular, the lattice Boltzmann (LB) method has evolved from a theoretical novelty to a ubiquitous, versatile and powerful computational methodology for both fundamental research and engineering applications. It is a kinetic-based mesoscopic approach that bridges the microscales and macroscales, which offers distinctive advantages in simulation fidelity and computational efficiency. Applications of the LB method have been found in a wide range of disciplines including physics, chemistry, materials, biomedicine and various branches of engineering. The present work provides a comprehensive review of the LB method for thermofluids and energy applications, focusing on multiphase flows, thermal flows and thermal multiphase flows with phase change. The review first covers the theoretical framework of the LB method, revealing the existing inconsistencies and defects as well as common features of multiphase and thermal LB models. Recent developments in improving the thermodynamic and hydrodynamic consistency, reducing the spurious currents, enhancing the numerical stability, etc., are highlighted. These efforts have put the LB method on a firmer theoretical foundation with enhanced LB models that can achieve larger liquid-gas density ratio, higher Reynolds number and flexible surface tension. Examples of applications are provided in fuel cells and batteries, droplet collision, boiling heat transfer and evaporation, and energy storage. Finally, further developments and future prospect of the LB method are outlined for thermofluids and energy applications.

Yuanyuan Cui, Yujie Ke, Chang Liu et al.

Abstract Rapid development of the thermochromic glazing technique promises next-generation architectural windows with energy-saving characteristics by intelligently regulating indoor solar irradiation via modulating windows' optical properties in response to the surrounding temperature. Vanadium dioxide (VO2) is a promising material for energy-saving smart windows due to its reversible metal-to-insulator transition near room temperature and accompanying large changes in its optical properties. This review provides a comprehensive overview of the application of VO2 to smart windows with particular emphasis on recent progress from the electronic, atomic, nano, and micron perspectives. The effects of intrinsic atomic defects, elemental doping, and lattice strain on VO2 nanocrystals are examined. Nano- and microscale morphology engineering approaches that aim to enhance the thermochromic performance and impart practical multi-functionalities are summarized. Finally, the challenges and future directions of VO2-based smart windows are elaborated to bridge the gap between the lab research and large-scale practical applications.

Helmut Ltkepohl

Chuancheng Jia, A. Migliore, Na Xin et al.

Yu-Xing Yao, Xiang Chen, Chong Yan et al.

The performance of Li-ion batteries (LIBs) is highly dependent on their interfacial chemistry, which is regulated by electrolytes. Conventional electrolyte typically contains polar solvents to dissociate Li salts. Herein we report a weakly-solvating electrolyte (WSE) that consists of a pure non-polar solvent, which leads to a peculiar solvation structure where ion pairs and aggregates prevail under a low salt concentration of 1.0 M. Importantly, WSE forms unique anion-derived interphases on graphite electrodes that exhibit fast-charging and long-term cycling characteristics. First-principles calculations unravel a general principle that the competitive coordination between anions and solvents to Li ions is the origin of different interfacial chemistries. By bridging the gap between solution thermodynamics and interfacial chemistry in batteries, this work opens a brand-new way towards precise electrolyte engineering for energy storage devices with desired properties.

Jacob Bear, M. Corapcioglu

G. Box, G. Jenkins, G. Reinsel et al.

S. Doebling, C. Farrar, M. Prime et al.

L. Frýba

Yonzhi Lin, Mingxian Yuan, Ping Liao et al.

To investigate the relationship between load, damage, and fatigue life of complex engineering components under stress, this paper modifies the existing continuous nonlinear damage model based on the distortion energy density theory to reflect the usage and stress characteristics of Q345 steel components in bridges. A nonlinear damage model that accounts for actual complex stress conditions is proposed, and the model parameters are calculated using twist–bending fatigue test data. The cumulative damage predicted by the modified model under varying fatigue stress levels is analyzed as a function of the number of fatigue cycles. Furthermore, the modified model is microscopically validated through scanning electron microscopy (SEM) observation and analysis of twist–bending fatigue unloading specimens. Finally, according to the engineering application of the modified model in the complex load environments of steel bridges, a comparative analysis is conducted between the general nonlinear damage model, the modified nonlinear damage model, and the actual damage observed in bridge components. The actual component damage, calculated based on the component’s natural frequency, closely matches the damage predicted by the nonlinear damage correction model using bridge monitoring data. In contrast, a significant discrepancy exists between the damage values predicted by the nonlinear damage correction model and those from the general nonlinear damage model. The observed discrepancy confirms the improvement effect and engineering significance of the modified nonlinear damage theory. Furthermore, the study reveals that under the same equivalent stress amplitude, reliability decreases nonlinearly as the expected service life increases. Conversely, for a fixed expected service life, reliability declines more rapidly with higher equivalent stress amplitudes.

Ramakrishna Allam, B. Kothainayagi, P.A. Sudhir et al.

The AYUSH sector relies mainly on medicinal plants and metals, which form the foundation of traditional healing practices. However, all plants are often inaccessible to many students due to geographic and seasonal limitations. To bridge this gap, Ayurveda Medical College, in collaboration with, Incubation Center and Engineering College, initiated a pilot project to develop a Virtual Herbal Garden a Solution for problem statement given by All India Institute of Ayurveda, under Smart India Hackathon 2024. This digital platform offers an immersive, interactive, and user-friendly learning experience, enabling users to explore medicinal plants in detail. The garden includes 3D models, multimedia resources, and comprehensive information on five medicinal plants: Cassia fistula, Ocimum sanctum, Aloe vera, Mentha piperita, and Azadirachta indica. The Virtual Herbal Garden is expected to become a valuable educational tool, promoting awareness and understanding of plants used in traditional medicine in the AYUSH sector.

Ji Yeon Ha, Tae Wook Song, Petrina Jebamani et al.

Abstract Background Advancing cancer immunotherapy requires engineering synthetic immunomodulators that integrate precise receptor targeting, tunable activity, and compatibility with modular biologic formats. The Inducible T-cell Co-Stimulator (ICOS) is a clinically validated co-stimulatory receptor whose engagement enhances T-cell function. However, the development of ICOS-targeting biologics has been hindered by limited receptor affinity and format-dependent agonist activity. To address this, we applied a protein engineering framework to optimize the ICOS ligand (ICOS-L) as a high-affinity, modular component for precision immune modulation. Results Using yeast surface display–based directed evolution, we identified an ICOS-L variant (Y8) containing two synergistic mutations (Q51P and N57H) that improved human ICOS (hICOS) binding affinity by ~ 100-fold relative to wild-type. Structural modeling revealed that Q51P enhances backbone rigidity via a proline-induced conformational constraint, while N57H introduces a salt bridge with Asp86 in hICOS. These mutations reconfigure the receptor-binding interface to support high-affinity engagement. Functionally, Y8 induced potent T-cell proliferation and IFN-γ secretion. When genetically fused to pembrolizumab, Y8 further enhanced T-cell activation and tumor cell lysis, demonstrating synthetic synergy between PD-1 blockade and ICOS agonism. Among fusion formats, light-chain conjugation (pembrolizumab-L-Y8) exhibited superior functional output, highlighting the importance of geometric configuration in optimizing fusion-based agonism. Conclusion This study establishes Y8 as a high-affinity ICOS-L variant with robust co-stimulatory function, capable of potentiating anti–PD-1 immunotherapy through modular fusion design. The integration of Y8 into therapeutic antibody scaffolds provides a versatile engineering framework for the development of next-generation immunomodulatory biologics, offering opportunities to overcome resistance and enhance clinical efficacy in cancer immunotherapy.

Liyun Li, Zixuan Li, Ling Lei et al.

Relying on a foundation pit project leveraging the covered semi-top-down method with synchronous construction of the superstructure and substructure in Beijing, the whole process of construction was simulated by using ABAQUS finite-element software. The impact of the whole construction on the surrounding ground, the adjacent building, and the retaining structure were studied, and the influence of the existing building, the strength of diaphragm wall, and the construction process were carried out. As shown from the results, the foundation pit and the existing building are in a safe state during the whole construction process. The ground settlement shows an obvious groove shape. The deformation of the diaphragm wall has obvious spatial effects, which changes from “single peak” to “double peaks”. The maximum horizontal displacement of strata behind the diaphragm wall occurs at a depth of 22.5 m, which is 1.4–2.0 times the top horizontal displacement. The presence of existing buildings reduced the ground settlement between the buildings and the excavation surface. The construction process has little impact on the settlement of adjacent existing buildings, which can be adjusted appropriately.

Zhongyao Li, Qingyang Ren, Haonan Li et al.

The common freeze-thaw environments in engineering construction in cold regions are unidirectional and all-directional, while most of the rock freeze-thaw tests conducted in the laboratory are performed only in the all-directional direction. In this paper, the freeze-thaw damage characteristics of fractured red sandstone under different freeze-thaw loading modes are investigated. By designing unidirectional and all-directional freezing and thawing tests, the frost swelling force, temperature change and strain during freezing and thawing were monitored, and the microporous change mechanism was analyzed by scanning electron microscopy. It was found that the peak frost gravity of unidirectional freezing was lower, with 3.6 MPa for unidirectional freezing and 4.5 MPa for all-directional freezing. during unidirectional freezing, the peak frost swelling force appeared with a time lag, and there were no frost cracks in the samples. The temperature monitoring results showed that the temperature at the bottom of the unidirectionally frozen samples decreased slower and was higher than that at the top of the samples, and the temperature gradient effect was obvious. Scanning electron microscopy observation showed that after 20 freeze-thaw cycles, the inter-granular cementing material of sandstone decreased significantly and the smoothness of the granules increased, indicating that the freeze-thaw cycle damaged the microstructure of sandstone, but the degree of damage of the unidirectional freezing sample material was weak.