Hasil untuk "Mechanical engineering and machinery"

Haibo Zhang, Qingyuan Zhao, Yingxin Zhao et al.

Predicting the evolution of wear in metallic structural components is vital for accurately estimating the lifetime of engineering equipment. However, this remains a significant challenge due to the prohibitively large number of cycles required for traditional experiments or simulations. To address this, we established a data-driven approach to predict metal wear evolution during dynamic mechanical interactions. Our methodology involves two main steps: developing a high-fidelity finite element (FE) model to accurately simulate the wear, and then training a deep learning model that uses applied loads and historical wear data to predict future wear evolution. We selected contact wire clips in a high-speed railway system as a practical example, where the accuracy of our numerical model was successfully validated by experimental results in calculating wear distribution. The subsequent deep learning model demonstrated high accuracy (R2>0.95) in predicting future wear depth at distinct positions against ground truth data. This presented approach offers a wide range of applications for predicting the wear evolution of equipment in various engineering fields.

Luo Bowei, Zhou Yongquan, Xiao Haibing et al.

To investigate the ablation mechanism and characteristics of femtosecond laser cutting of CVD diamonds, experimental and theoretical studies were conducted. The effects of different laser parameters on kerf quality were studied. It showed that the original kerf obvious cracks and significant carbonization due to ns-laser cutting process. By adopting green fs-laser with parameters around ablation threshold, kerfs with no microscopic cracks were found with the surface roughness of 5.278 µm. SEM-FIB analysis revealed the average thickness of carbonization layer reduced to 1.206 µm compared with the initial thickness of 2.211 µm. Further experiments were conducted in the nitrogen atmosphere, where the roughness of kerfs furtherly decreased to 2.705 µm with no graphitization layer. It revealed that material removal for CVD diamonds during femtosecond laser processing was mainly occurred via sublimation. The thermal affected region could be effectively suppressed to achieve cold processing effect. XRD analysis of the kerfs indicated the precipitation of graphite phase due to thermal effects during laser process, while the introduction of femtosecond laser with protective gas could effectively suppress graphite phase formation and promote the quality of kerfs, thus achieving the clean kerfs of CVD diamonds.

Fang Guo, Haiying Cheng, Yongzhen Deng et al.

Lei Chen, Xiaomin Cheng

Peng Zhang, Rumin Teng

Yafeng Wang, Jijun Liu

Swaminathan Nithya, Arularasi Veerabadrasamy, Gunasekaran Kandaswamy et al.

Laurabelle Gautier, Sandra Wiart-Letort, Alexandra Massé et al.

For monitoring animal adaptation when facing environmental challenges, and more specifically when addressing the impacts of global warming—particularly responses to heat stress and short-term fluctuations in osmotic regulations in the different organs influencing animal physiology—there is an increasing demand for digital tools to understand and monitor a range of biomarkers. Microneedle arrays (MNAs) have recently emerged as promising devices minimally invasively penetrating human skin to access dermal interstitial fluid (ISF) to monitor deviations in physiology and consequences on health. The ISF is a blood filtrate where the concentrations of ions, low molecular weight metabolites (<70 kDa), hormones, and drugs, often closely correlate with those in blood. However, anatomical skin differences between human and farm animals, especially large animals, as well as divergent tolerances of such devices among species with behavior specificities, motivate new MNA designs. We addressed technological challenges to design higher microneedles for farm animal (pigs and cattle) measurements. We designed microneedle arrays composed of 37 microneedles, each 2.8 mm in height, using dextran-methacrylate, a photo-crosslinked biocompatible biopolymer-based hydrogel. The arrays were characterized geometrically and mechanically. Their abilities to perforate pig and cow skin were demonstrated through histological analysis. The MNAs successfully absorbed approximately 10 µL of fluid within 3 h of application.

Haifu Xing

Zetao Li, Xiaochun Tie, Xin Wang et al.

Zewang Wu, Yunchao Wang, Qi Hong

Bertrand Meyer

Vibe coding, the much-touted use of AI techniques for programming, faces two overwhelming obstacles: the difficulty of specifying goals ("prompt engineering" is a form of requirements engineering, one of the toughest disciplines of software engineering); and the hallucination phenomenon. Programs are only useful if they are correct or very close to correct. The solution? Combine the creativity of artificial intelligence with the rigor of formal specification methods and the power of formal program verification, supported by modern proof tools.

Jan-Paul Ruiken, Jörn Villwock, Matthias Kraume

Acoustic levitation can provide significant benefits for many fundamental research questions. However, it is important to consider that the acoustic field influences the measurement environment. This work focuses on the dissolution of immobilised drops using acoustic levitation in liquid–liquid systems. Previous work demonstrated that the acoustic field of standing waves impacts mass transfer by affecting the spread of dissolved substances in the continuous phase in two distinct ways: (I) solutes may either pass through nodal planes of the standing waves or (II) not pass. The binary systems examined for case (I) are 1-hexanol–water and 1-butanol–water, and for case (II), n-butyl acetate–water and toluene–water. This work quantifies the intensification effect of acoustic levitation on dissolution for the two types of behaviour, by comparing them with reference measurements of mechanically attached dissolving drops. The system was designed to ensure minimal intensification. The minimum intensification of mass transfer for levitating drops in the used setup of case (I) was 25%, and for case (II), it was 65%, both increasing with decreasing surface-equivalent diameter. With this understanding, acoustic levitation can be used more accurately in the field of mass transfer studies.

Yaohui Zheng, Wentao Huang, Yangyang Liu et al.

In Ti-6Al-4V titanium alloy micro-machining, since the uncut chip thickness (UCT) is comparable to the radius of the tool cutting edge, there exists a minimum uncut chip thickness (MUCT), and when the UCT is smaller than the MUCT, the plowing effect dominates the cutting process, which seriously affects the machined surface quality and tool life. Therefore, the reliable prediction of the MUCT is of great significance. This paper used Deform to establish an orthogonal cutting simulation model, studied the effect of the dead metal zone (DMZ) on the micro-cutting material flow, determined the DMZ range, and proposed a new method for determining the MUCT based on the DMZ. Cutting experiments were conducted to verify the accuracy of the simulation model firstly by cutting force, and then confirming the accuracy of the DMZ-based MUCT determination method through chip analysis and surface quality analysis. Finally, the effects of different cutting conditions on DMZ and MUCT were further investigated using the proposed DMZ-based MUCT determination method. The results show that the MUCT of Ti-6Al-4V titanium alloy is 4.833 μm for a tool cutting edge radius of 40 μm and a cutting speed of 10 m/min. The DMZ boundary can be used as the boundary of micro-cutting plastic deformation, and the ratio of MUCT to cutting edge radius, <i>h_p</i>/<i>r_n</i> will gradually decrease with the increase in the tool cutting edge radius and the cutting speed.

Ziyan Huang, Yongming Bian, Meng Yang

AbstractThe establishment of a robust standard components database is essential in various industries to streamline product development and ensure quality. This paper presents a system for querying standard components data, leveraging the power of logical filtering and semantic retrieval. The structured approach of this system includes a well-defined database structure, logical filtering capabilities at different data levels, and advanced semantic retrieval techniques. The outputs of the system demonstrate its effectiveness in handling user queries, analysing unstructured data, and providing meaningful feedback based on logical filtering outcomes. This research contributes to the efficient utilization of standard components data through an innovative and powerful digital query system.

Yan Zhang, Junsong Cai, Lei Liu et al.

Mingde Gong, Zhong Jin, Yue Zhang et al.

AbstractAccurate motion control is the premise for the unmanned excavator to complete the operation. In this paper, the motion control of a 22 t hydraulic excavator is studied. By establishing the dynamic model of the 4-degree-of-freedom excavator working device, the external interference caused by gravity, centripetal force, Coriolis force and inertia to the hydraulic cylinder is compensated. The bucket load and related parameters in the excavation process are identified online, and the motion control accuracy of the excavator is improved. Based on the dynamic model, the motion control method of the unmanned excavator is given. The simulation and experimental results show that this motion control strategy can effectively improve the autonomous operation accuracy of the excavator.

Bradley P. Allen, Filip Ilievski

Knowledge engineering is the process of creating and maintaining knowledge-producing systems. Throughout the history of computer science and AI, knowledge engineering workflows have been widely used given the importance of high-quality knowledge for reliable intelligent agents. Meanwhile, the scope of knowledge engineering, as apparent from its target tasks and use cases, has been shifting, together with its paradigms such as expert systems, semantic web, and language modeling. The intended use cases and supported user requirements between these paradigms have not been analyzed globally, as new paradigms often satisfy prior pain points while possibly introducing new ones. The recent abstraction of systemic patterns into a boxology provides an opening for aligning the requirements and use cases of knowledge engineering with the systems, components, and software that can satisfy them best. This paper proposes a vision of harmonizing the best practices in the field of knowledge engineering by leveraging the software engineering methodology of creating reference architectures. We describe how a reference architecture can be iteratively designed and implemented to associate user needs with recurring systemic patterns, building on top of existing knowledge engineering workflows and boxologies. We provide a six-step roadmap that can enable the development of such an architecture, providing an initial design and outcome of the definition of architectural scope, selection of information sources, and analysis. We expect that following through on this vision will lead to well-grounded reference architectures for knowledge engineering, will advance the ongoing initiatives of organizing the neurosymbolic knowledge engineering space, and will build new links to the software architectures and data science communities.

Carlos Alberto Saenz Cortez, Johanna Mariel Vilela Saldarriaga

Mediante monitoreos ornitológicos realizados en las ex relaveras de Azalia y Chonta del 9 al 12 de marzo de 2021, ubicadas en el Distrito de Goyllarisquizga (Pasco), se ha determinado que la calidad ambiental es de ponderación Media. Señalándose, además, que es importante la restauración y reforestación de los componentes ecológicos de ellas ya que, según los resultados obtenidos, el 89.06% de las especies encontradas se encuentran registradas en la Lista roja de especies amenazadas de la UICN, catalogadas como Leves según la versión 3.1 de la segunda edición de las Categorías y criterios de la Lista roja de la UICN. Asimismo, el 10.92% de aves son endémicas de la zona, que significaría que solo pueden habitar ese tipo de ecosistemas, y el 3.36% de aves son catalogadas como CITES y se ubican en el Apéndice II de CITES, por lo que se puede concluir que el 89.06% de las especies son sensibles.

Hasan Mehedi, Xiaobin Wang, Shilong Ye et al.

Decarbonization of the power sector in China is an essential aspect of the energy transition process to achieve carbon neutrality. The power sector accounts for approximately 40% of China’s total CO2 emissions. Accordingly, collaborative optimization in power generation expansion planning (GEP) simultaneously considering economic, environmental, and technological concerns as carbon emissions is necessary. This paper proposes a collaborative mixed- integer linear programming optimization approach for GEP. This minimizes the power system’s operating cost to resolve emission concerns considering energy development strategies, flexible generation, and resource limitations constraints. This research further analyzes the advantages and disadvantages of current GEP techniques. Results show that the main determinants of new investment decisions are carbon emissions, reserve margins, resource availability, fuel consumption, and fuel price. The proposed optimization method is simulated and validated based on China’s power system data. Finally, this study provides policy recommendations on the flexible management of traditional power sources, the market-oriented mechanism of new energy sources, and the integration of new technology to support the attainment of carbon-neutral targets in the current energy transition process.