6,525 research outputs found
Corrected values for boiling points and enthalpies of vaporization of elements in handbooks
Full text linkThe scientific community relies upon the veracity of the scientific data in handbooks and databases. In a previous work, the authors developed a systematic, intelligent, and potentially automatic method to detect errors in such resources based on artificial neural networks (ANNs). This method revealed variations from (10 to 900) % in tables of property data for elements in the periodic table and pointed out the ones that are most probably correct. In this paper, we focus on the details of employing this method for analyzing the data of boiling points and enthalpies of vaporization recorded in different handbooks. The method points out the values that are likely to be correct. To verify the method employed, a detailed discussion of the data with reference to the original literature sources is given as well as factors that may affect the accuracy of the prediction.<br/
Swanson-Hysell-Group/2021_AX_BD: Zhang et al., 2021 data and code
No full textThis repository is associated with the following published paper:
Yiming Zhang, Nicholas L. Swanson-Hysell, Mark D. Schmitz, James D.4Miller Jr., Margaret S. Avery. (2021). Synchronous emplacement of the anorthosite xenolith-bearing Midcontinent Rift diabase and one of the largest lava flows on Earth. Geochemistry, Geophysics, Geosystems.
This repository contains paleomagnetic and geochronology data, code related to data analysis and visualization, and the manuscript itself
Wind Field Digital Twins Sandbox System for Transmission Towers
No full textGiven the digitalization trends within the field of engineering, we propose a practical approach to engineering digitization. This method is established based on a physical sandbox model, camera equipment and simulation technology. We propose an image processing modeling method to establish high-precision continuous mathematical models of transmission towers. The calculation of the wind field is realized by using wind speed calculations, a load-wind-direction-time algorithm and the Continuum-Discontinuum Element Method (CDEM). The sensitivity analysis of displacement- and acceleration-controlled transmission tower loads under two different wind direction conditions is conducted. The results show that the digital model exhibits a proportional relationship with the physical dimensions of the transmission tower model. The error between the numerical simulation results and the experimental results falls within a reasonable range. Nodes at higher positions of the transmission tower experience significantly higher forces compared to those at lower positions, and the structural forms with larger windward projected areas yield similar simulation results. The proposed digital twin system can help monitor the performance of structural bodies and assess the disaster degree in extreme conditions. It can guide specific maintenance and repair tasks
Supplemental Material - Dynamic response control of centrifugal pendulum vibration absorber with motion-limiting device during startup in gravity field
No full textSupplemental Material for Dynamic response control of centrifugal pendulum vibration absorber with motion-limiting device during startup in gravity field by Yi Zhang, Guangqiang Wu, Yiming Long in Journal of Vibration and Control</p
Continuous-discontinuous element method for three-dimensional thermal cracking of rocks
No full textThermal cracking of rocks can significantly affect the durability of underground structures in engineering practices such as geothermal energy extraction, storage of nuclear waste and tunnelling in freeze-thaw cycle induced areas. It is a scenario of strong coupled thermomechanical process involving discontinuity behaviours of rocks. In this context, a numerical model was proposed to investigate the thermal cracking of rocks, in a framework of the continuous-discontinuous element method (CDEM) for efficiently capturing the initiation and propagation of multiple cracks. A simplex integration strategy was adopted to account for the influences of temperature-dependent material properties. Several benchmark tests were considered and the obtained results were compared with analytical solutions and numerical results from the literature. The results show that the fracture degree of the cases when considering temperature-dependent material parameters had 10% differences approximately compared with the cases with constant parameters. (C) 2023 Institute of Rock and Soil Mechanics, Chinese Academy of Sciences. Production and hosting by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/)
Virtual displacement based discontinuity layout optimization
No full textDiscontinuity layout optimization (DLO) is a relatively new upper bound limit analysis method. Compared to classic topology optimization methods, aimed at obtaining the optimum design of a structure by considering its self-weight, building cost, or bearing capacity, DLO optimizes the failure pattern of the structure under specific loading conditions and constraints by minimizing the dissipation energy. In this work, we present a modified DLO algorithm that contains all of the advantages of DLO. It is referred to virtual displacement-based discontinuity layout optimization (VDLO). VDLO takes the stress state of a loaded structure as a snapshot and correspondingly provides the optimum failure pattern, which greatly extends the application potential of DLO. Numerical examples indicate the effectiveness and flexibility of VDLO. It is regarded as a highly promising supplemental tool for other numerical methods in element-/node-based frameworks
Markov fluid queue model for rechargeable sensor nodes with abnormal death
No full textThe rechargeable sensor network is promising for various applications. However, improving network performance is challenging, because the energy depletion of the sensor nodes will result in abnormal death of the nodes. In this paper, we propose a hybrid framework to model the abnormal death of the sensor nodes. Based on the Markov fluid queue theory, the model includes three parts, namely utilizing a Markov process to simulate the charging behavior, a queuing model to trace the working mechanism of rechargeable sensor nodes, and a continuous fluid process to indicate the energy level of sensor nodes. The numerical results show that our model can effectively predict the probability of abnormal death and stationary energy consumption of the sensor nodes.</p
A novel heterogeneous CPU/GPGPU-accelerated 3D CDEM and its application to modeling deep roadway excavation
No full textTo improve the accuracy and computational efficiency of the CDEM for deep coal mine roadway excavation modeling, this study proposes a heterogeneous CPU/GPGPU-accelerated solver that integrates a mixed continuous-discontinuous media algorithm. The solver employs an explicit time integration method combined with a modular approach for 3D tetrahedral solid finite elements and fracturable penalty springs, which model rock fracture behavior and the transition from continuum to discontinuum in rock masses. To maximize computational efficiency, the solver uses a hybrid CPU/GPGPU framework with SIMD parallel techniques, achieving up to 600-fold speedup on a single GPGPU. The solver's accuracy is validated for both quasi-static and dynamic problems, and its scalability across different hardware accelerators is demonstrated. Modeling results from the 22nd mining area of the Quandian coal mine show significant shear deformation and crack evolution in the soft rock, particularly at the intersection of the roof slab and sidewall, where stress concentration and large deformation are most pronounced. These findings validate the efficiency and reliability of the proposed method for simulating and analyzing underground excavation processes
An interface constitutive model of plastic tensile-compressive damage under impact loading based on continuous-discontinuous framework
No full textBullet penetration test is a classic impact loading test, which involves complex dynamic elastic-plastic response. Conventionally, this process was often described using a single high -strain -rate constitutive model, which could only capture a specific type of failure during the impact damage process. Furthermore, these constitutive models were mostly defined on element and posed the risk of computational divergence(element distortion). In this work, a novel constitutive model for combined tensile-compressive damage in interface element was developed within a Continuous-Discontinuous Element Method(CDEM) framework. This model successfully captures the processes of pit formation and target collapse during projectile penetration. The tension and compression damage parts of the developed interface constitutive model were validated through Brazilian splitting test and interface direct shear test. Subsequently, bullet penetration test is simulated and the postpenetration velocity is compared with published results from other studies, with computational errors found to be within 2.56%, thus validating the accuracy of the developed interface constitutive model
Numerical Analysis of Perforation during Hydraulic Fracture Initiation Based on Continuous-Discontinuous Element Method
No full textPerforation is a pivotal technique employed to establish main flow channels within the reservoir formation at the outset of hydraulic fracturing operations. Optimizing perforation designs is critical for augmenting the efficacy of hydraulic fracturing and boosting oil or gas production. In this study, we employ a hybrid finite-discrete element method, known as the continuous - discontinuous element method (CDEM), to simulate the initiation of postperforation hydraulic fractures and to derive enhanced design parameters. The model incorporates the four most prevalent perforation geometries, as delineated in an engineering technical report. Real -world perforations deviate from the ideal cylindrical shape, exhibiting variable cross-sectional profiles that typically manifest as an initial constriction followed by an expansion, a feature consistent across all four perforation types. Our simulations take into account variations in perforation hole geometries, cross-sectional diameters, and perforation lengths. The findings show that perforations generated by the 39g DP3 HMX perforating bullet yield the lowest breakdown pressure, which inversely correlates with increases in sectional diameter and perforation length. Moreover, this study reveals the relationship between breakdown pressure and fracture degree, providing valuable insights for engineers and designers to refine perforation strategies
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