4,319 results
Search Results
2. Review Paper. Characterization and Stability of Two-Phase Piecewise-Homogeneous Deformations
- Author
-
Fu, Y. B.
- Published
- 2004
3. Crumpled Paper
- Author
-
Ben Amar, M. and Pomeau, Y.
- Published
- 1997
4. Open-source micro-tensile testers via additive manufacturing for the mechanical characterization of thin films and papers.
- Author
-
Nandy, Krishanu, Collinson, David W., Scheftic, Charlie M., and Brinson, L. Catherine
- Subjects
- *
THIN films , *PAPER , *TENSILE strength , *MECHANICAL behavior of materials , *GRAPHENE oxide - Abstract
The cost of specialized scientific equipment can be high and with limited funding resources, researchers and students are often unable to access or purchase the ideal equipment for their projects. In the fields of materials science and mechanical engineering, fundamental equipment such as tensile testing devices can cost tens to hundreds of thousands of dollars. While a research lab often has access to a large-scale testing machine suitable for conventional samples, loading devices for meso- and micro-scale samples for in-situ testing with the myriad of microscopy tools are often hard to source and cost prohibitive. Open-source software has allowed for great strides in the reduction of costs associated with software development and open-source hardware and additive manufacturing have the potential to similarly reduce the costs of scientific equipment and increase the accessibility of scientific research. To investigate the feasibility of open-source hardware, a micro-tensile tester was designed with a freely accessible computer-aided design package and manufactured with a desktop 3D-printer and off-the-shelf components. To our knowledge this is one of the first demonstrations of a tensile tester with additively manufactured components for scientific research. The capabilities of the tensile tester were demonstrated by investigating the mechanical properties of Graphene Oxide (GO) paper and thin films. A 3D printed tensile tester was successfully used in conjunction with an atomic force microscope to provide one of the first quantitative measurements of GO thin film buckling under compression. The tensile tester was also used in conjunction with an atomic force microscope to observe the change in surface topology of a GO paper in response to increasing tensile strain. No significant change in surface topology was observed in contrast to prior hypotheses from the literature. Based on this result obtained with the new open source tensile stage we propose an alternative hypothesis we term ‘superlamellae consolidation’ to explain the initial deformation of GO paper. The additively manufactured tensile tester tested represents cost savings of >99% compared to commercial solutions in its class and offers simple customization. However, continued development is needed for the tensile tester presented here to approach the technical specifications achievable with commercial solutions. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
5. DEEP-DRAWING OF PAPER AND PAPERBOARD: THE ROLE OF MATERIAL PROPERTIES
- Author
-
Alexey Vishtal, and Elias Retulainen
- Subjects
Deep-drawing ,Formability ,Paper ,Mouldability ,Deformation ,Properties ,Elongation ,Biotechnology ,TP248.13-248.65 - Abstract
Fibre-based packaging materials are widely utilized all over the world. They have several important advantages in comparison with fossil-based packaging: biodegradability, recyclability, and renewability. However, fibre-based packaging cannot fully compete with plastic in its barrier properties. Also there are limitations regarding its shapes due to poorer formability. The deep-drawing forming process can be used for the production of advanced three-dimensional shapes from paper-based materials. Formability and related characteristics are essential for deep-drawing of paper-based materials. This paper aims to give an overview of the deep-drawing of paper-based materials with the emphasis on the experienced deformations, on the role of mechanical properties of materials in deep-drawing, and on the typical defects found in the shapes after the forming. Additionally, strategies are proposed to help mitigate common problems in deep-drawing.
- Published
- 2012
6. Analysis on the development of chemically-improved soil in railway engineering
- Author
-
Chen, Feng, Wang, Zhongjin, Zhang, Dong, and Zeng, Shuai
- Published
- 2024
- Full Text
- View/download PDF
7. Boosting the Extensibility Potential of Fibre Networks: A Review.
- Author
-
Vishtal, Alexey and Retulainen, Elias
- Subjects
PLASTIC fibers ,PACKAGING materials ,PAPER bags ,CHEMICAL bonds ,NATURAL resources - Abstract
Production of paper-based packaging is growing at the present moment and has great future prospects. However, the development of new packaging concepts is creating a demand for an improvement in the mechanical properties of paper. Extensibility is one of these properties. Highly extensible papers have the potential to replace certain kinds of plastics used in packaging. Extensibility is also important for the sack and bag paper grades and for runnability in any converting process. This paper reviews the factors that affect the extensibility of fibres and paper, and discusses opportunities for improving the straining potential of paper and paper-like fibre networks. It is possible to classify factors that affect extensibility into three main categories: fibre structure, interfibre bonding, and structure of the fibre network. Extensibility is also affected by the straining situation and the phase state of the polymers in the cell wall. By understanding the basic phenomena related to the elongation, and by combining different methods affecting the deformability of fibre network, extensibility of paper can be raised to a higher level. [ABSTRACT FROM AUTHOR]
- Published
- 2014
- Full Text
- View/download PDF
8. Deep-drawing of paper and paperboard
- Subjects
Deep-drawing ,formability ,paper ,properties ,deformation ,elongation ,mouldability - Abstract
Fibre-based packaging materials are widely utilized all over the world. They have several important advantages in comparison with fossil-based packaging: biodegradability, recyclability, and renewability. However, fibre-based packaging cannot fully compete with plastic in its barrier properties. Also there are limitations regarding its shapes due to poorer formability. The deep-drawing forming process can be used for the production of advanced three-dimensional shapes from paper-based materials. Formability and related characteristics are essential for deep-drawing of paper-based materials. This paper aims to give an overview of the deep-drawing of paper-based materials with the emphasis on the experienced deformations, on the role of mechanical properties of materials in deep-drawing, and on the typical defects found in the shapes after the forming. Additionally, strategies are proposed to help mitigate common problems in deep-drawing.
- Published
- 2012
9. Open-source micro-tensile testers via additive manufacturing for the mechanical characterization of thin films and papers
- Author
-
L. Catherine Brinson, Krishanu Nandy, Charlie M Scheftic, and David W. Collinson
- Subjects
lcsh:Medicine ,Electronics engineering ,Mechanical engineering ,Engineering and technology ,02 engineering and technology ,01 natural sciences ,Software ,Materials Testing ,Electron Microscopy ,lcsh:Science ,Tensile testing ,Thin Films ,Microscopy ,Multidisciplinary ,Physics ,Classical Mechanics ,Oxides ,Equipment Design ,3D printing ,021001 nanoscience & nanotechnology ,Deformation ,Atomic Force Microscopy ,Characterization (materials science) ,Printing, Three-Dimensional ,Physical Sciences ,Graphite ,Scanning Electron Microscopy ,Deformation (engineering) ,0210 nano-technology ,Reduction (mathematics) ,Research Article ,Paper ,Materials by Structure ,Materials Science ,Equipment ,Research and Analysis Methods ,010402 general chemistry ,Tensile Strength ,Open Source Hardware ,Ultimate tensile strength ,Damage Mechanics ,Buckling ,business.industry ,Scanning Probe Microscopy ,lcsh:R ,Software development ,0104 chemical sciences ,lcsh:Q ,business - Abstract
The cost of specialized scientific equipment can be high and with limited funding resources, researchers and students are often unable to access or purchase the ideal equipment for their projects. In the fields of materials science and mechanical engineering, fundamental equipment such as tensile testing devices can cost tens to hundreds of thousands of dollars. While a research lab often has access to a large-scale testing machine suitable for conventional samples, loading devices for meso- and micro-scale samples for in-situ testing with the myriad of microscopy tools are often hard to source and cost prohibitive. Open-source software has allowed for great strides in the reduction of costs associated with software development and open-source hardware and additive manufacturing have the potential to similarly reduce the costs of scientific equipment and increase the accessibility of scientific research. To investigate the feasibility of open-source hardware, a micro-tensile tester was designed with a freely accessible computer-aided design package and manufactured with a desktop 3D-printer and off-the-shelf components. To our knowledge this is one of the first demonstrations of a tensile tester with additively manufactured components for scientific research. The capabilities of the tensile tester were demonstrated by investigating the mechanical properties of Graphene Oxide (GO) paper and thin films. A 3D printed tensile tester was successfully used in conjunction with an atomic force microscope to provide one of the first quantitative measurements of GO thin film buckling under compression. The tensile tester was also used in conjunction with an atomic force microscope to observe the change in surface topology of a GO paper in response to increasing tensile strain. No significant change in surface topology was observed in contrast to prior hypotheses from the literature. Based on this result obtained with the new open source tensile stage we propose an alternative hypothesis we term 'superlamellae consolidation' to explain the initial deformation of GO paper. The additively manufactured tensile tester tested represents cost savings of >99% compared to commercial solutions in its class and offers simple customization. However, continued development is needed for the tensile tester presented here to approach the technical specifications achievable with commercial solutions.
- Published
- 2018
10. Deep-drawing of paper and paperboard:The role of material properties
- Author
-
Vishtal, A. and Elias Retulainen
- Subjects
Paper ,Deep-drawing ,lcsh:Biotechnology ,formability ,paper ,Properties ,deformation ,Mouldability ,elongation ,Deformation ,lcsh:TP248.13-248.65 ,properties ,Elongation ,mouldability ,Formability - Abstract
Fibre-based packaging materials are widely utilized all over the world. They have several important advantages in comparison with fossil-based packaging: biodegradability, recyclability, and renewability. However, fibre-based packaging cannot fully compete with plastic in its barrier properties. Also there are limitations regarding its shapes due to poorer formability. The deep-drawing forming process can be used for the production of advanced three-dimensional shapes from paper-based materials. Formability and related characteristics are essential for deep-drawing of paper-based materials. This paper aims to give an overview of the deep-drawing of paper-based materials with the emphasis on the experienced deformations, on the role of mechanical properties of materials in deep-drawing, and on the typical defects found in the shapes after the forming. Additionally, strategies are proposed to help mitigate common problems in deep-drawing.
- Published
- 2012
11. Extensible Cellulosic Fibre-polyurethane Composites Prepared via the Papermaking Pathway.
- Author
-
Vishtal, Alexey, Khakalo, Alexey, and Retulainen, Elias
- Subjects
CELLULOSE fibers ,POLYURETHANES ,NANOCOMPOSITE materials ,DISPERSION (Chemistry) ,POLYMERS - Abstract
Formable papers can be used as an alternative to rigid plastics for making 3D shapes for packaging applications. However, commercial use of formable paper is currently limited, due to its poor extensibility. Cellulosic fibres can be combined with polyurethanes to improve the deformability of resulting fibre-polymer composites. This work describes the effect of spray and wet-end addition of polyurethane dispersions to paper to enhance the extensibility and formability of paper. The increase in extensibility was directly proportional to the amount of polyurethane retained in the paper. Absolute improvements in extensibility were as high as 4 to 6 percentage points. Improved extensibility resulted in better formability of paper, which eventually could allow it to compete with plastic packaging in certain applications. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
12. Analysis of the plastic and elastic energy during the deformation and rupture of a paper sample using thermography
- Author
-
Mikael Nygårds, Caroline Hyll, and Hannes Vomhoff
- Subjects
Paper ,Thermal Analysis ,Materials science ,Infrared ,Thermal energy ,Thermography (temperature measurement) ,Uniaxial tensile testing ,Optics ,Infra-red cameras ,General Materials Science ,Thermal emittance ,Emittances ,Plastic deformation ,Rupture work ,Experimentation ,Tensile testing ,Range (particle radiation) ,Tensile Tests ,Paper samples ,Temperature measurement ,business.industry ,Elastic energy ,Mechanical energies ,Pappers-, massa- och fiberteknik ,Forestry ,Paper, Pulp and Fiber Technology ,Paper mechanics ,Deformation ,Elasticity ,Sack paper ,Pyrometry ,Emittance ,Thermography (imaging) ,Thermography ,Goniometer ,Elastic deformation ,Physics::Accelerator Physics ,business ,Experiments - Abstract
Thermography is a non-destructive technique which uses infrared radiation to obtain the temperature distribution of an object. The technique is increasingly used in the pulp and paper industry. To convert the detected infrared radiation to a temperature, the emittance of the material must be known. For several influencing parameters the emittance of paper and board has not previously been studied in detail. This is partly due to the lack of emittance measurement methods that allow for studying the influence of these parameters.An angle-resolved goniometric method for measuring the infrared emittance of a material was developed in this thesis. The method is based on the reference emitter methodology, and uses commercial infrared cameras to determine the emittance. The method was applied to study the dependence on wavelength range, temperature, observation angle, moisture ratio, sample composition, and sample structure of the emittance of paper and board samples. It was found that the emittance varied significantly with wavelength range, observation angle and moisture ratio. The emittance was significantly higher in the LWIR (Long-Wavelength Infrared) range than in the MWIR (Mid-Wavelength Infrared) range. The emittance was approximately constant up to an observation angle of 60° in the MWIR range and 70° in the LWIR range, respectively. After that it started to decrease. The emittance of moist samples was significantly higher than that of dry samples. The influence of moisture ratio on the emittance could be estimated based on the moisture ratio of the sample, and the emittance of pure water and dry material, respectively.The applicability of measured emittance values was demonstrated in an investigation of the mechanical properties of sack paper samples. An infrared camera was applied to monitor the generation of heat during a tensile test of a paper sample. It was found that the observed increase in thermal energy at the time of rupture corresponded well to the value of the elastic energy stored in the sample just prior to rupture. The measured emittance value provided an increased accuracy in the thermal energy calculation based on the infrared images.
- Published
- 2012
13. Coherent structures of suspension flow and their inheritance in paper
- Author
-
Jetsu, P., Minna Kellomäki, Karema, H., Salmela, J., Lappalainen, T., Piirto, M., and Baker, C.F.
- Subjects
headboxes ,papermaking ,paper machines ,flow ,paper ,deformation ,suspensions ,structure ,cockling - Abstract
By creating coherent flow structures at the vane tips of a headbox in a controlled manner it was shown that these coherent flow structures could be traced all the way from the slice chamber to paper. In addition, a correlation between the coherent structures and the structural cockling tendency of paper was found. Thus, important complementary information was created to serve the goal of finding a general linkage between structures in flow and paper.
- Published
- 2001
14. Prediction and compensation of countersinking depth error in drilling of thin-walled workpiece.
- Author
-
Zhang, Yuxi, Wu, Dan, Chen, Ken, and Hu, Kui
- Subjects
WORKPIECES ,WAGES ,CUTTING force ,MECHANICAL buckling ,FOURIER series ,AEROSPACE industries ,PAPER arts - Abstract
The countersink depth accuracy is a remarkable quality index in modern aerospace industry, and it needs to be controlled quite accurately due to the extremely tight tolerances. However, the wide use of the thin-walled workpiece with low stiffness makes it difficult to achieve the required tolerance because of the complex deformation in the countersinking process. Focusing on the accurate control of countersink depth in the drilling of thin-walled workpiece, this paper provides a novel insight into the study on predicting of the feasible workpiece deformation and compensating for the countersink depth error through both theoretical and experimental analyses. An analytical model of workpiece deformation is first presented with the Fourier series approach in this study, and the finite element simulation is carried out to verify the model precision. Then a flexible cutting force model is developed to help to analyze the effect of deformation on the thrust force in the countersinking process. A novel approach of integrated iterative algorithm, that considers both the deformation and the cutting force, is established to calculate the final feasible deformation and make decision for the countersink depth error compensation, and the generalized convergence and adaptability of this iterative algorithm are investigated based on the calculus theory. Finally, the proposed integrated methodology is verified by multivariate simulations and experiments, and the results show that the countersink depth accuracy could be effectively guaranteed by countersinking with compensation based on this integrated methodology. The work in this paper enables us to understand the causes of poor countersink depth accuracy in the drilling of thin-walled workpiece and develop new countersinking techniques to satisfy the tight tolerance. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
15. Micro-buckling of paper during blade metering
- Author
-
Alam, Parvez and Toivakka, Martti
- Subjects
- *
BEARINGS (Machinery) , *METERING pumps , *NUCLEAR reactor buckling , *CHEMICAL engineering , *ELASTIC analysis (Engineering) , *PHYSICS research - Abstract
Multiphysics models were used to simulate the deformational characteristics experienced by paper under metering blades. Paper is found to slip microscopically at the backing roll interface and subsequently buckle either side of the blade during metering operations. Micro-slippage of the paper at the interface is a linear function of the separation height incurred during buckling. The effects of altering the static coefficient of friction as well as the properties of the backing roll material are studied. Increasing the coefficient of static friction reduces the extent of buckling while a non-linear relationship is found to arise on increasing the elastic modulus of the backing roll material. The mechanisms involved in micro-buckling deformation are explicated herein. [Copyright &y& Elsevier]
- Published
- 2008
- Full Text
- View/download PDF
16. The Estimation of the Strength of Beams Structured by Scrapped Paper
- Subjects
Limit Analysis ,Beams ,Principle of Vertual Works ,Papercraft ,Swelling ,Deformation - Abstract
Nowadays our society demands the manufactured goods which are effective to reclaim, because natural resources are tendency to deccrease. So we should not noly reinvestigate the materials of goods, but also originate a new design method and a product system. Then we have investigated the srtucturing method and the strength about the beams whose material are scrapped paper. When the beam by scrapped paper is loaded, the deformation is large and moreover the cross section dose not mentaine flat. Therefore we cannot apply the traditional 'theory of elasticity' to the analysis and estimation of the deformation and strength. In this paper, we propose a new estimation method by analyzing the swelling caused when the papercraft beam is bended.
- Published
- 1998
17. Kinematic calibration of bracket type parallel posture alignment mechanism considering the gravity effect
- Author
-
Wang, Zhihao, Chen, Wenliang, Wang, Min, Xu, Qinghe, and Huang, Can
- Published
- 2019
- Full Text
- View/download PDF
18. Simulation Analysis and Key Performance Index for Experimental Verification of a New Type of Press Transmission Mechanism.
- Author
-
He, Yanzhong, Luo, Xiang, and Wang, Xingsong
- Subjects
MOTION analysis ,MACHINE tools ,TEST reliability ,MACHINE design ,RELIABILITY in engineering - Abstract
In this paper, the characteristics of special stamping process requirements and the shortcomings of existing application technology are studied. Through repeated motion simulation analysis and size optimization calculation, a kind of inertia-controlled molding press is proposed to make up for this technical vacancy. This paper first describes the working principle and structure scheme of the main transmission mechanism of the inertia-controlled molding press. With the help of Adams-View x64 2013, the main transmission mechanism is simulated and analyzed from the aspects of kinematics and dynamics, and a physical prototype is made to test the key reliability indexes of the main transmission mechanism. According to the test data, the static strength, stiffness, vibration characteristics, and dynamic characteristics of the 200 t inertia-controlled molding press are evaluated, which provides a reference for the design of this kind of machine tool. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
19. Jet Engine Turbine Mechanical Properties Prediction by Using Progressive Numerical Methods.
- Author
-
Spodniak, Miroslav, Hovanec, Michal, and Korba, Peter
- Subjects
JET engines ,STRAINS & stresses (Mechanics) ,FINITE element method ,TURBINES ,DEFORMATIONS (Mechanics) ,ARTIFICIAL neural networks ,PROPULSION systems - Abstract
The propulsion system for an aircraft is one of its most crucial systems; therefore, its reliable work must be ensured during all operational conditions and regimes. Modern materials, techniques and methods are used to ensure this goal; however, there is still room for improvement of this complex system. The proposed manuscript describes a progressive approach for the mechanical properties prediction of the turbine section during jet engine operation using an artificial neural network, and it illustrates its application on a small experimental jet engine. The mechanical properties are predicted based on the measured temperature, pressure and rpm during the jet engine operation, and targets for the artificial neural network are finite element analyses results. The artificial neural network (ANN) is trained using training data from the experimental measurements (temperatures, pressure and rpm) and the results from finite element analyses of the small experimental engine turbine section proposed in the paper. The predicted mechanical stress by ANN achieved high accuracy in comparison to the finite element analyses results, with an error of 1.38% for predicted mechanical stress and correlation coefficients higher than 0.99. Mechanical stress and deformation prediction of the turbine section is a time-consuming process when the finite element method is employed; however, the method with artificial neural network application presented in this paper decreased the solving time significantly. Mechanical structural analyses performed in ANSYS software using finite element modeling take around 30–40 min for one load step. In contrast, the artificial neural network presented in this paper predicts the stress and deformation for one load step in less than 0.00000044 s. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
20. Fatigue life optimization for 17-4Ph steel produced by selective laser melting
- Author
-
Jean-marc Linares, Julien Chaves-Jacob, Quentin Lopez, Jean-Michel Sprauel, Institut des Sciences du Mouvement Etienne Jules Marey (ISM), and Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS)
- Subjects
[SPI]Engineering Sciences [physics] ,Selective laser melting ,Additive manufacturing ,Mechanical Engineering ,17-4 Ph stainless steel ,Residual stress ,Material Paper type: Research paper ,Industrial and Manufacturing Engineering ,Fatigue ,Deformation - Abstract
Purpose The mechanical characterization of selective laser melting (SLM) parts is an industrial challenge. This paper aims to propose a methodology to control the fatigue life of 17-4Ph stainless steel by selecting the most relevant manufacturing parameters: i.e. laser power, laser travel speed, hatch spacing and laser defocusing. Design/methodology/approach A rough and refined design of experiment (DOE) is carried out to target the best combination of process parameters. A response surface model is then constructed to predict the parameter combination that optimizes the fatigue performance. Findings This study results show that the fatigue limit of the specimens manufactured by SLM (471.7 MPa at 107 cycles) has reached near 90% of the value found in samples machined from a bar. This demonstrates the applicability of the method proposed to optimize the SLM process and control the fatigue life of 17-4Ph stainless steel. The study results are compared with other research works and provide an increase of 18% to the fatigue limit. Originality/value This study showcases a DOE methodology to optimize the SLM parameters to achieve fatigue performance as great as that of solid 17-4Ph stainless steel.
- Published
- 2022
21. Two‐step active contour method based on gradient flow
- Author
-
Zhu, Linlin, Fan, Baojie, and Tang, Yandong
- Published
- 2010
- Full Text
- View/download PDF
22. Exploring the relevance between load-bearing capacity and surface friction behavior based on a layered hydrogel cartilage prototype
- Author
-
Zhang, Yunlei, Zhao, Weiyi, Zhao, Xiaoduo, Zhang, Jinshuai, Yu, Bo, Ma, Shuanhong, and Zhou, Feng
- Published
- 2024
- Full Text
- View/download PDF
23. Research on the Mechanism of Loose Deformation in Weak Fracture Zone Tunnel Surrounding Rock and Support Control.
- Author
-
Zheng, Xin, Huang, Feng, Wang, Sheng, and Xu, Wenxuan
- Abstract
In the fractured weak fault zone, rock mass exhibits low strength and poor self-stability. The geological conditions are complex, and when tunnels cross through fractured zones, significant deformations and collapses are prone to occur, leading to geological hazards. This paper investigates the in situ stress and deformation patterns of the Dongmachang Tunnel No. 1, proposing support solutions for addressing tunnel deformations through field experiments and numerical simulations. The on-site monitoring results indicate that despite implementing measures such as grouting reinforcement and temporary steel supports to control surrounding rock deformation, significant structural damage still occurred in the tunnel support system. The manifestations included severe sinking and cracking of the arch crown, strong inward deformation of the sidewalls, widespread cracking, crushing, and spalling of shotcrete, slight arching uplift, and severe distortion and twisting of steel arches forming a "Z" or "S" shape. To ensure tunnel safety and control the stability of excavations in weak fault zones, a comparison of tunnel deformation support schemes is conducted through field experiments and numerical simulations, indicating that replacing the upper tunnel structure and invert can effectively prevent tunnel deformations. These measures are vital for the sustainable development of tunnel. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
24. Cohomology and Crossed Modules of Modified Rota–Baxter Pre-Lie Algebras.
- Author
-
Zhu, Fuyang and Teng, Wen
- Subjects
ALGEBRA - Abstract
The goal of the present paper is to provide a cohomology theory and crossed modules of modified Rota–Baxter pre-Lie algebras. We introduce the notion of a modified Rota–Baxter pre-Lie algebra and its bimodule. We define a cohomology of modified Rota–Baxter pre-Lie algebras with coefficients in a suitable bimodule. Furthermore, we study the infinitesimal deformations and abelian extensions of modified Rota–Baxter pre-Lie algebras and relate them with the second cohomology groups. Finally, we investigate skeletal and strict modified Rota–Baxter pre-Lie 2-algebras. We show that skeletal modified Rota–Baxter pre-Lie 2-algebras can be classified into the third cohomology group, and strict modified Rota–Baxter pre-Lie 2-algebras are equivalent to the crossed modules of modified Rota–Baxter pre-Lie algebras. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
25. An Optimized Approach to Multistage Permanent Deformation Testing of Granular Materials.
- Author
-
Pérez-González, Erdrick and Bilodeau, Jean-Pascal
- Subjects
MATERIALS testing ,STRAIN rate ,GRANULAR materials ,CYCLIC loads ,DEFORMATIONS (Mechanics) - Abstract
Accurately characterizing permanent deformation in granular materials subjected to cyclic loading is crucial for pavement design. This paper introduces an alternative approach to characterizing permanent deformation in a framework that reduces the number of load cycle repetitions by applying an alternative analytical strategy based on plastic strain rate variation over time. The methodology uses a cycle-hardening approach to establish correlations between short-term (post-compaction) and long-term (shakedown state) plastic strain accumulation. This alternative approach provides an efficient means to accelerate the characterization of permanent deformation, ensuring the integrity and validity of the assessment in a more time-efficient and resource-optimized way. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
26. Investigation of the Deformation Behavior of Baffle Structures Impacted by Debris Flow Based on Physical Modelling.
- Author
-
Chen, Weizhi, Zhang, Bei, Xu, Na, and Huang, Yu
- Subjects
DEBRIS avalanches ,EVIDENCE gaps ,HAZARD mitigation ,IMPACT loads ,ENERGY dissipation - Abstract
The utilization of baffle structures as a highly effective strategy for mitigating debris flow has attracted significant scholarly attention in recent years. Although the predominant focus of existing research has been on augmenting the energy dissipation capabilities of baffle structures, their deformation behavior under impact load has not been extensively investigated. Addressing this research gap, the current study systematically designs a series of physical model experiments, incorporating variables such as baffle height, shape, and various combinations of baffle types to comprehensively analyze the deformation characteristics of baffles subjected to debris flow impact. The experimental results reveal that the deformation of baffle group structures demonstrates a marked non-uniform spatial distribution and exhibits a latency effect. Additionally, distinct baffle configurations show considerable variations in peak strain, suggesting that combining different baffle shapes can not only optimize energy dissipation but also enhance resistance to deformation. Moreover, the relationship between baffle height and the development of deformation in relation to energy dissipation capacity is inconsistent, indicating that deformation must be a key consideration in the design of baffle structures. Consequently, this paper advocates for the formulation of a deformation-based design strategy for baffle structures, with the findings presented herein providing a foundational reference for future studies. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
27. Pappersfiber karakterisering och kvantifiering
- Author
-
Sveinsson, Ívar
- Subjects
x-ray tomography ,Applied Mechanics ,Teknisk mekanik ,deformation ,characterization ,Paper fibre ,fiber - Abstract
With the advent of X-ray computerised tomography (CT), the possibility of capturing precise volumetric 3D images has become an invaluable tool within the material sciences. With tomographs and synchrotrons becoming more readily available to researchers and scanning time decreasing with newer equipment, the amount of data to be analysed is steadily rising. This rapid increase in data acquisition motivates the development of automatic methods to transform CT images from qualitative to quantitative data. In this work, a method to automatically characterise paper fibres from CT images based on their centre-line and mapping their deformation is presented. Methods for fibre characterisation are presented and tested on computer-generated fibres and CT images of paper fibres. Med tillkomsten av datorbaserd röntgentomografi (CT) har möjligheten att fånga exakta volymetriska 3D-bilder blivit ett ovärderligt verktyg inom materialvetenskapen. Den mängd data som ska analyseras växer hela tiden tack vare ökad tillgänglighet till tomografer och synkrotroner och minskad skanningstid i och med den tekniska utvecklingen av utrustningen som används. Denna snabba ökning av datainsamling motiverar utvecklingen av automatiska metoder för att omvandla CT-bilder från kvalitativa till kvantitativa data. I detta arbete presenteras en metod för att automatiskt karakterisera pappersfibrer från CT-bilder baserad på deras mittlinje och kartlägga deras deformation. Metoder för fiberkarakterisering presenteras och testas på datorgenererade fibrer och CT-bilder av pappersfibrer.
- Published
- 2021
28. Tangent curve utilization for description of mechanical behaviour of pressed mixture
- Author
-
D. Herák, A. Kabutey, A. Sedláček, and G. Gűrdil
- Subjects
compression ,loading ,jatropha ,sunflower ,bean ,pea ,wood ,paper ,chips ,deformation ,levenberg ,marquardt ,Agriculture (General) ,S1-972 - Abstract
This article is focused on the utilization of tangent curve for description of mechanical behaviour of pressed mixture under compression loading. The aim of this experiment was to determine the general equation describing deformation characteristics of pressed mixtures under compression loading and to verify this equation. The experiment was carried out using mixture of seeds of common sunflower (Heliantus annuus L.), jatropha ( Jatropha curcas L.), garden pea (Pisum sativum L.), common bean (Phaseolus vulgaris L.), and also mixture of spruce wood chips and waste paper chips. The results from the experiment showed that mechanical behaviour of the pressed mixtures under compression loading can be described by tangent curve function. From the determined coefficients of determination R2 it was clear that fitted tangent curve functions described the measured amounts exactly for all pressed mixtures. It can be therefore assumed that this tangent curve function is appropriate for use in pressing any pressed mixtures during linear compression.
- Published
- 2011
- Full Text
- View/download PDF
29. Elasticity modeling and estimation for haptic contact using a DD‐robot
- Author
-
Hyuk Park, Chung, Lee, Bum‐Hee, and Dr. Saunders, David
- Published
- 2007
- Full Text
- View/download PDF
30. ANALYSIS OF THE CONDITION OF A PIPE FIXED IN A CLAMPING DEVICE
- Author
-
Mahammadali Nuriyev and Emin Musa Afandiyev
- Subjects
clamp ,business.product_category ,Materials science ,lcsh:Mechanical engineering and machinery ,education ,0211 other engineering and technologies ,General Physics and Astronomy ,02 engineering and technology ,cartridge ,Stress (mechanics) ,stress ,Reliability (semiconductor) ,0203 mechanical engineering ,021105 building & construction ,Ultimate tensile strength ,lcsh:TJ1-1570 ,Drill ,business.industry ,paper gauge ,General Engineering ,deformation ,Structural engineering ,load ,holding capacity ,Wedge (mechanical device) ,Clamping ,lcsh:QC1-999 ,pipe ,020303 mechanical engineering & transports ,Deformation (engineering) ,business ,Casing ,lcsh:Physics - Abstract
Due to the fact that clamping devices are widely used in various industries, the requirements for the operation of such devices are constantly increasing. This is due to an increase in the general requirements for processing accuracy, as well as an increase in the forces acting on the clamped part. The reliability of these devices when working with thin-walled cylindrical parts is of great importance. Thin-walled cylinders used in mechanical engineering are subject to significant loads. With prolonged exposure to loads from clamping forces, as well as from axial tensile forces, plastic deformations of cylindrical parts occur. In the oil and gas industry, when clamping drill and casing pipes in some areas in the capture zone, stresses exceed the yield strength. Multiple clamping of the pipe will reduce the pipe wall in the gripping area, which causes premature pipe failure. Therefore, increasing the holding capacity of clamping mechanisms is relevant. Analysis of broken drill pipes, which have been operating in wedge grips for a long time, showed that in most cases the pipes undergo plastic deformation caused by damage to the pipe surface by the teeth of the ram. To clarify the actual conditions of loading the pipe and the possibilities of increasing the capacity of the clamping devices, studies of the contact pressures in the clamping zone were carried out. A new pipe clamping chuck is also presented, which provides a sufficiently high reliability of fastening of cylindrical parts.
- Published
- 2021
31. Modeling Object Motion on Arbitrary Unstructured Grids Using an Invariant Principle of Computational Domain Topology: Key Features.
- Author
-
Sarazov, Aleksey, Kozelkov, Andrey, Strelets, Dmitriy, and Zhuchkov, Roman
- Subjects
VISCOUS flow ,NAVIER-Stokes equations ,FLUID flow ,TOPOLOGY ,GEOMETRIC analysis ,COMPRESSIBLE flow ,MOTION - Abstract
This paper uses a finite volume algorithm to address the numerical modeling of fluid flow around moving bodies. The Navier–Stokes equations, which describe the flow of viscous compressible gas, along with key boundary conditions and discretization schemes, are presented. As the motion of boundaries typically leads to changes in the control volumes, the basic discretization schemes need to be adapted. This paper provides a detailed discussion on the adaptation of the initial system to deforming boundaries while preserving communication topology. The method for calculating the boundary velocity is a crucial element of the numerical scheme. The paper proposes an approach to reconstruct the boundary velocity vector using deformation analysis and the condition of geometric conservation. This approach ensures correct simulation results for arbitrary unstructured computational grids. A comparison of two approaches to reconstructing the boundary velocity vector for characteristic aviation problems in the direct formulation is presented. It is shown that the proposed approach allows for more accurate modeling of object motion on arbitrary grids using the "invariant" principle of the computational domain topology. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
32. Deformation of High Rise Cooling Tower through Projection of Coordinates Resulted from Terrestrial Laser Scanner Observations onto a Vertical Plane.
- Author
-
Beshr, Ashraf A. A., Basha, Ali M., El-Madany, Samir A., and El-Azeem, Fathi Abd
- Subjects
COOLING towers ,DEFORMATIONS (Mechanics) ,TALL buildings ,CONSTRUCTION materials ,OPTICAL scanners - Abstract
The appearance and development of new construction materials, technology and accurate geodetic instruments have led to the necessity of their inevitable use in the health monitoring, maintenance, and restoration of civil structures and special structures such as high-rise cooling towers. This paper presents an accurate practical and analytical method for determining the structural deformation and axis inclination of high rise cooling towers using terrestrial laser scanner (TLS) observations through the projection of tower surface points coordinates on a vertical plane. Four cooling towers in El-Mahla El-Kubra city, Egypt are observed and studied. Two of them with height 56 m, and the others were 36 m height. The studied four towers have different cross-section diameters along the tower height. Each tower has a cone shape with a curved wall. The equation of the tower wall is determined using TLS observations and least squares adjustment techniques. The equations of cone projection with a curved wall are derived and presented in this paper. From TLS observations, the radii and accuracy of each 2 m tower height are determined with center coordinates, and then the inclination of the tower axis is calculated and drawn. From the results of TLS observations, data processing, and analysis using the suggested techniques, it is deduced that there is a deformation in tower walls with small values. The specified technique for observations collection and TLS data analysis through projection on a vertical plane is significant and valuable for determining the structural deformation of circular high rise buildings and towers. From the results, there are obvious deformation values in some cooling towers, so maintenance work must be included. The towers also must be checked and monitored several times at brief intervals. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
33. Finite Element Simulation of Bending Thin-Walled Parts and Optimization of Cutting Parameters.
- Author
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Hailong, Ma, Aijun, Tang, Shubo, Xu, and Tong, Li
- Subjects
ELASTIC deformation ,TITANIUM alloys ,FINITE element method ,DENTAL metallurgy - Abstract
Aiming at the problems of large elastic deformation and low machining accuracy in cutting titanium alloy thin-walled parts, this paper establishes the finite element model of milling titanium alloy thin-walled parts, and simulates and analyses the milling process of titanium alloy thin-walled parts by the statics analysis module of ANSYS 15.0 software. The maximum deformation point of the workpiece in the milling process is determined. Then the combination of cutting parameters that can minimize the deformation is determined by the orthogonal experiments of four factors and four levels. This paper designs the single factor experiments, which study the distribution of the milling force and the deformation law of the parts in the milling process. Moreover, this paper carries out the optimal design of the cutting parameters by orthogonal experiments, which provides a reference for the selection of the cutting parameters for the bending thin-walled parts of titanium alloy. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
34. ANALYSIS BY THE FINITE ELEMENT METHOD OF THE TENSIONS AND DEFORMATIONS PRODUCED IN THE MECHANIZED SUPPORT BEAMS.
- Author
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ȘOICA, ALEXANDRA, URDEA, GHEORGHE BOGDAN, and FLOREA, VLAD ALEXANDRU
- Subjects
DEFORMATIONS (Mechanics) ,FINITE element method ,DIFFERENTIAL equations ,GIRDERS ,MATHEMATICAL models ,COMPUTER-aided design - Abstract
This paper presents the analysis by the finite element method of the tensions and deformations produced in the mechanized support beams. The finite element method allows the analysis of physical phenomena that can be described with the help of mathematical models made up of systems of differential equations with initial and boundary conditions. From the results obtained in this paper, it was observed that the asymmetries with the greatest influence are those with respect to the vertical-longitudinal plane of the mechanized support [ABSTRACT FROM AUTHOR]
- Published
- 2023
35. Мнения и факты в теоретических основах технологий искусственных волокон и целлюлозно-бумажного производства
- Subjects
Engineering ,структурообразование ,business.industry ,paper ,Pulp (paper) ,deformation ,Paper production ,thermofixation ,fibers ,engineering.material ,Pulp and paper industry ,деформация ,бумага ,гидрофобные взаимодействия ,sulphate cellulose ,волокна ,сульфатная целлюлоза ,structure formation ,hydrophobic interaction ,фазовые взаимодействия ,phase interactions ,activation ,активация ,business ,термофиксация - Abstract
В статье рассмотрены различные подходы к пониманию природы связей в целлюлозно-волокнистых системах. Анализ результатов многочисленных исследований показывает, что при изготовлении высокотехнологичных целлюлозно-бумажных изделий необходимо учитывать специфику процессов структурообразования в дисперсных системах, дисперсионной средой в которых является вода или её растворы, на каждом этапе в многоступенчатых системах химической переработки растительного сырья. В статье освещаются особенности диалектики развития прикладной науки (отрицание отрицания) и её влияние на решение проблем отечественной научной школы текстильной и целлюлозно-бумажной промышленности. Выделение физикохимии растворов высокомолекулярных соединений из коллоидной химии в отдельную науку явилось причиной создания теоретических основ технологии искусственных волокон и целлюлозно-бумажного производства. Игнорирование научных положений о структурообразовании дисперсных систем с точки зрения фазового взаимодействия их компонентов и релаксационного состояния является причиной сдерживания прогресса в совершенствовании технологических процессов целлюлозно-бумажного производства. Разработанные теоретические основы получения дисперсных структур с заданными механическими свойствами не были доведены до создания моделей технологических процессов, необходимых для изготовления отечественного технологического оборудования. Таким образом, исключение представлений коллоидной химии и её раздела – физико-химической механики из повседневной практики целлюлозно- бумажного производства препятствуют целенаправленному решению проблем при получении высокотехнологичных материалов., The article deals with different approaches to understanding the nature of bonds in cellulose-fibrous systems. Analysis of the results of numerous studies shows that in the manufacture of high-tech pulp and paper products it is necessary to take into account the specifics of the processes of structure formation in dispersed systems, the dispersion medium in which is water or its solutions, at each stage in multi-stage systems of chemical processing of vegetable raw materials. The article highlights the features of dialectics of applied science (denial of negation) and its impact on solving the problems of the domestic scientific school of textile and pulp and paper industry. The separation of physical chemistry of solutions of high-molecular compounds from colloidal chemistry into a separate science was the reason for the creation of the theoretical foundations of the technology of artificial fibers and pulp and paper production. Ignoring the scientific provisions on the structure formation of dispersed systems from the point of view of the phase interaction of their components and the relaxation state is the reason for holding back progress in improving the technological processes of pulp and paper production. The developed theoretical basis for obtaining dispersed structures with specified mechanical properties were not brought to the creation of models of technological processes necessary for the manufacture of domestic technological equipment. Thus, the exclusion of colloidal chemistry, and its section – physical and chemical mechanics, from the daily practice of pulp and paper production prevents the purposeful solution of problems in the production of high-tech materials., №225 (2018)
- Published
- 2018
- Full Text
- View/download PDF
36. Analysis of the Dihedral Corner Reflector's RCS Features in Multi-Resource SAR.
- Author
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Liu, Jie, Li, Tao, Ma, Sijie, Wen, Yangmao, Xu, Yanhao, and Nie, Guigen
- Subjects
LANDSLIDES ,ENERGY dissipation ,TIME series analysis - Abstract
Artificial corner reflectors are widely used in the vegetated landslide for time series InSAR monitoring due to their permanent scattering features. This paper investigated the RCS features of a novel dihedral CR under multi-resource SAR datasets. An RCS reduction model for the novel dihedral corner reflector has been proposed to evaluate the energy loss caused by the deviation between the SAR incident angle and the CR's axis. On the Huangtupo slope, Badong county, Hubei province, tens of dihedral CRs had been installed and the TSX–spotlight and Sentinel-TOPS data had been collected. Based on the observation results of CRs with more than ten deviation angles, the proposed reduction model was tested with preferable consistency under a real dataset, while 2 dBsm of systematic bias was verified in those datasets. The maximum incident angle deviation in the Sentinel data overlapping area is over 12°, which leads to a 2.4 dBsm RCS decrease for horizontally placed dihedral CRs estimated by the proposed model, which has also been testified by the observed results. The testing results from the Sentinel data show that in high, vegetation-covered mountain areas like the Huangtupo slope, the dihedral CRs with a 0.4 m slide length can be achieve 1 mm precision accuracy, while a side length of 0.2 m can achieve the same accuracy under TSX–spotlight data. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
37. Abelian Extensions of Modified λ -Differential Left-Symmetric Algebras and Crossed Modules.
- Author
-
Zhu, Fuyang, You, Taijie, and Teng, Wen
- Subjects
MODULES (Algebra) ,COHOMOLOGY theory ,ALGEBRA - Abstract
In this paper, we define a cohomology theory of a modified λ -differential left-symmetric algebra. Moreover, we introduce the notion of modified λ -differential left-symmetric 2-algebras, which is the categorization of a modified λ -differential left-symmetric algebra. As applications of cohomology, we classify linear deformations and abelian extensions of modified λ -differential left-symmetric algebras using the second cohomology group and classify skeletal modified λ -differential left-symmetric 2-algebra using the third cohomology group. Finally, we show that strict modified λ -differential left-symmetric 2-algebras are equivalent to crossed modules of modified λ -differential left-symmetric algebras. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
38. A Multisubstructure-Based Method for the Assessment of Displacement and Stress in a Fluid–Structure Interaction Framework.
- Author
-
Xie, Changchuan, Huang, Kunhui, Meng, Yang, Gao, Nongyue, and Zhang, Zhitao
- Subjects
FLUID-structure interaction ,VORTEX lattice method ,DISPLACEMENT (Psychology) ,STRAINS & stresses (Mechanics) ,STRESS concentration - Abstract
A multisubstructure-based method for assessing the deformation and stress of a fine-meshed model according to a coarse model was proposed. Integrating boundary conditions in a local fine-meshed model, a displacement mapping matrix from the coarse model to the fine-meshed model was constructed. The method was verified by a three-level panel in a fluid–structure interaction (FSI) framework by integrating the steady vortex lattice method (VLM). A comparison between the inner deformation distribution of the coarse model and that of the global fine-meshed model obtained from MSC.Nastran was carried out, and the results showed that the coarse model failed to demonstrate reliable strains and stresses. In contrast, the proposed method in this paper can effectively depict the inner deformation and critical stress distribution. The deformation error was lower than 8%, meeting engineering requirements. Moreover, the results of different working conditions can achieve a similar relative error of displacement for an identical position. The easy storage of the displacement mapping matrix and the convenience of the boundary information transformation among all substructure levels are prominent aspects. As a result, there is a solid foundation for addressing the time-dependent problem in spite of the simultaneity and region. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
39. Parametric Study of the Deep Excavation Performance of Underground Pumping Station Based on Numerical Method.
- Author
-
Zhang, Jiani, Yang, Zhenkun, and Azzam, Rafig
- Subjects
PUMPING stations ,EXCAVATION ,ELASTIC foundations - Abstract
Environmental responses to deep excavations are combined results of numerous factors. The effects of some factors are relatively straightforward and can be considered carefully during the design. On the other hand, more features impact excavation-induced performances indirectly, making their influences difficult to be clearly understood. Unfortunately, the complexity and non-repeatability of practical projects make it impossible to thoroughly understand these issues through realistic deep excavation projects. Therefore, parametric studies based on repeatable laboratory and numerical tests are desired to investigate these issues further. This work examines the influence of several key features on excavation-induced displacements through a series of 3D numerical tests. The study includes the choice of soil constitutive models, the modeling method of the soil–wall interface, and the influences of various key soil parameters. The comparison shows that the MCC model can yield a displacement field similar to the HSS model, while its soil movement is greatly improved compared to the MC model. Both the soil–wall interface properties and soil parameters impact the excavation-induced displacement to a large extent. In addition, the influence mechanisms of these parameters are analyzed, and practical suggestions are given. The findings of this paper are expected to provide practical references to the design and construction of future deep excavation projects. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
40. Numerical Investigation of Earth Berm Effects on Prefabricated Recyclable Supporting Structure in Circular Excavations.
- Author
-
Chen, Lichao, Guo, Chengchao, and Cao, Dingfeng
- Subjects
STRAINS & stresses (Mechanics) ,BENDING moment ,EXCAVATION ,SAFETY factor in engineering - Abstract
The prefabricated recyclable supporting structure (PRSS) is an innovative support system that integrates a steel skeleton with polymer waterproof technology. Earth berms are extensively adopted to support the PRSS, but there is limited understanding on the factors influencing their behavior in circular excavations. In this paper, a numerical model is first validated with a case history in Henan, China. Afterwards, the geometric parameters of the earth berms, including the height (H), the top width (B
1 ), and the bottom width (B2 ), on the behavior of the PRSS, are investigated. It is shown that, by increasing the height, top width and bottom width of earth berms, the lateral deflections, and bending moments of supporting piles, as well as the ground surface settlements, tend to decrease. However, the reduction effect of these parameters diminishes as well. Moreover, the raised effective formation level considering the effect of the earth berms on stability and deformation analyses is discussed. The factor of the safety of the excavation is almost doubled when axisymmetric conditions are considered compared to plane strain conditions. In deformation analysis, the raised effective formation level increases with the height of the earth berms until a steady value is reached. [ABSTRACT FROM AUTHOR]- Published
- 2024
- Full Text
- View/download PDF
41. Estimation of active surface deformation using PSInSAR technique of the Central Himalayan region.
- Author
-
Kothyari, Girish Ch., Dumka, Rakesh K., Luirei, Khayingshing, Kandregula, Raj Sunil, Taloor, Ajay Kumar, Malik, Kapil, Joshi, Achla, Patidar, Atul K., and Bhan, Uday
- Subjects
DEFORMATION of surfaces ,SYNTHETIC aperture radar ,GEODETIC observations - Abstract
The Kumaun Himalaya is considered as the most active part of the Central Seismic gap in the Indian Sub-continent. In this paper, we presented active surface deformation rates of the Kumaun region from February 2017 to February 2021 using the Persistent Scatterer Interferometric Synthetic Aperture Radar (PSI) technique. The cumulative displacement that occurred during the span of 4 years is ±55 mm, whereas the Line of Sight (LOS) deformation velocity rate ranges is ±7 mm/yr. Apart from PSI, we also estimated the b-value of the Kumaun region from 1803 to 2021 (399 events) and its value is 0.54 ± 0.03. A distinct NE-SW trend of b-value is observed where earthquakes with M>6 occurred towards NE of this trend. The PSIderived deformation reveals that the central part of the Inner Lesser Himalaya along with the Main Central Thrust (MCT) zone is dominated by uplift. The zone between the Munsiari Thrust (MT) and MCT in the central region shows the maximum uplift ranging 5-7 mm/yr which exactly lies above the mid-crustal ramp of the Main Himalayan Thrust (MHT). Our results are well corroborated with available observations of geodetic strain and peak ground acceleration values. However, the deformation patterns and highvelocity rates in the central part of the study area between MT and MCT indicate the accumulation of high stress. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
42. Insights into Deformation and Mechanism of a Reactivated Landslide Occurrence from Multi-Source Data: A Case Study in Li County, China.
- Author
-
Du, Yingjin, He, Kun, Hu, Xiewen, and Ma, Hongsheng
- Subjects
LANDSLIDES ,ROAD construction ,RAINFALL ,NATURAL disaster warning systems - Abstract
The investigation of reactivated landslides in the alpine-canyon areas suffers the difficult accessibility of precipitous terrain. In particular, when reactivated landslides occur along the major roads, efforts are focused on measuring ground surface displacements during road construction. Nevertheless, the ancient landslide deposits may reactivate after several years of road operation, while they show a stable state during the road construction. The characterization of this type of reactivated landslides is challenging, due to their complex mechanism and the limited monitoring data. Appropriate multi-source data can provide insights into deformation fields and enhance the understanding of landslide mechanisms, ensuring the outperformance of remedial works. This paper reports a recent Tangjiawan reactivated landslide along the Wenchuan-Maerkang Highway in Li County, China. The outcomes, including satellite InSAR, in situ real-time monitoring, and detailed ground and UAV investigation, conducted at this landslide are presented. Early deformation of the reactivated landslide began from 2019, with an InSAR-derived velocity of −11.7 mm/year, furthermore, a significant subsidence of about 21.2 mm, which occurred within a span of only 12 days from 3 June 2020 to 15 June 2020, was observed. The deformation characteristics derived from in situ monitoring during the remedial works were likely firstly associated with the initial unreinforced slope condition and the heavy rainfall. Subsequently, the displacement evolution transformed into deformation induced by time-dependent reduction in slope strength under rainfall conditions. The existing of unconsolidated deposits derived from ancient landslides, along with a fragile geo-structure consisting of rock blocks and gravels interlayered with breccias, exacerbated by large relief created a predisposition for landslide reactivation. Furthermore, 13 days of antecedent cumulative rainfall totaling 224.5 mm directly triggered the occurrence of a landslide event. The significance and implications of integrating multiple monitoring techniques are emphasized. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
43. Application of Stereo Digital Image Correlation on Facial Expressions Sensing.
- Author
-
Cheng, Xuanshi, Wang, Shibin, Wei, Huixin, Sun, Xin, Xin, Lipan, Li, Linan, Li, Chuanwei, and Wang, Zhiyong
- Subjects
DIGITAL image correlation ,FACIAL expression ,STEREO image ,EMOTIONS ,DIGITAL images - Abstract
Facial expression is an important way to reflect human emotions and it represents a dynamic deformation process. Analyzing facial movements is an effective means of understanding expressions. However, there is currently a lack of methods capable of analyzing the dynamic details of full-field deformation in expressions. In this paper, in order to enable effective dynamic analysis of expressions, a classic optical measuring method called stereo digital image correlation (stereo-DIC or 3D-DIC) is employed to analyze the deformation fields of facial expressions. The forming processes of six basic facial expressions of certain experimental subjects are analyzed through the displacement and strain fields calculated by 3D-DIC. The displacement fields of each expression exhibit strong consistency with the action units (AUs) defined by the classical Facial Action Coding System (FACS). Moreover, it is shown that the gradient of the displacement, i.e., the strain fields, offers special advantages in characterizing facial expressions due to their localized nature, effectively sensing the nuanced dynamics of facial movements. By processing extensive data, this study demonstrates two featured regions in six basic expressions, one where deformation begins and the other where deformation is most severe. Based on these two regions, the temporal evolutions of the six basic expressions are discussed. The presented investigations demonstrate the superior performance of 3D-DIC in the quantitative analysis of facial expressions. The proposed analytical strategy might have potential value in objectively characterizing human expressions based on quantitative measurement. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
44. Analytical Solution for the Deformation of Pipe Galleries Adjacent to Deep Excavation.
- Author
-
Xiang, Binhui, Liu, Ying, Cui, Jifei, and Yang, Zhenkun
- Subjects
ANALYTICAL solutions ,EXCAVATION ,BURIED pipes (Engineering) ,UNDERGROUND construction ,SOIL solutions ,ROCK deformation - Abstract
Deep excavations clearly impact adjacent existing properties and threaten their operational safety. Predicting the deformation of existing infrastructure induced by nearby underground construction is the main concern of urban underground development. This paper presents an analytical calculation method for predicting underground pipe gallery deformations induced by adjacent deep excavations. First, the authors assume the existing pipe gallery to be nonexistent in the soil and propose a solution to calculate the excavation-induced vertical movements of the soil at the position of the existing pipe gallery. Thereafter, the authors simplify the existing pipe gallery as an elastic beam on a Winkler foundation to calculate its deformation. Finally, the method is verified by the good agreement found between the calculated result and the field measurement of the construction of the Shanghai Hongqiao CBD project. The proposed analytical method of this work can provide accurate evaluation results for similar engineering projects. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
45. Crackling Wires
- Author
-
Sethna, James P.
- Published
- 2007
- Full Text
- View/download PDF
46. Permafrost Early Deformation Signals before the Norilsk Oil Tank Collapse in Russia.
- Author
-
Zhang, Peng, Chen, Yan, Ran, Youhua, and Chen, Yunping
- Subjects
OIL storage tanks ,PERMAFROST ,DEFORMATION of surfaces ,SYNTHETIC aperture radar ,DEFORMATIONS (Mechanics) - Abstract
Despite the profound roles of surface deformation monitoring techniques in observing permafrost surface stability, predetermining the approximate location and time of possibly occurring severe permafrost degradation before applying these techniques is extremely necessary, but has received little attention. Taking the oil tank collapse accident in the Norilsk region as a case, we explored this concern by analyzing the permafrost deformation mechanisms and determining early surface deformation signals. Regarding this case, we firstly applied the Small Baseline Subset Interferometric Synthetic Aperture Radar (SBAS-InSAR) technique to obtain its permafrost surface deformation rate, then utilized a sine model to decompose its interannual deformation and seasonal deformation, and finally compared the relationship between the topographic slope and deformation rate. Based on experimental results, we reveal that when the annual average temperature continuously increases at a rate of 2 ° C/year for 2∼3 consecutive years, permafrost areas with relatively large topographic slopes (>15 ° ) are more prone to severe surface deformation during the summer thaw period. Therefore, this paper suggests that permafrost areas with large topographic slopes (>15 ° ) should be taken as the key surveillance areas, and that the appropriate monitoring time for employing surface deformation monitoring techniques should be the summer thawing period after a continuous increase in annual average temperature at a rate of 2 ° C/year for 2∼3 years. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
47. Cohomology of nonabelian embedding tensors on Hom-Lie algebras.
- Author
-
Wen Teng, Jiulin Jin, and Yu Zhang
- Subjects
TENSOR algebra ,NONABELIAN groups ,ALGEBRA ,COHOMOLOGY theory ,INFINITESIMAL geometry - Abstract
In this paper, we generalize known results of nonabelian embedding tensor to the Hom setting. We introduce the concept of Hom-Leibniz-Lie algebra, which is the basic algebraic structure of nonabelian embedded tensors on Hom-Lie algebras and can also be regarded as a nonabelian generalization of Hom-Leibniz algebra. Moreover, we define a cohomology of nonabelian embedding tensors on Hom-Lie algebras with coeffcients in a suitable representation. The first cohomology group is used to describe infinitesimal deformations as an application. In addition, Nijenhuis elements are used to describe trivial infinitesimal deformations. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
48. Temporal Estimation of Non-Rigid Dynamic Human Point Cloud Sequence Using 3D Skeleton-Based Deformation for Compression.
- Author
-
Kim, Jin-Kyum, Jang, Ye-Won, Lee, Sol, Hwang, Eui-Seok, and Seo, Young-Ho
- Subjects
POINT cloud ,VIDEO compression ,JOINTS (Anatomy) ,POINT set theory ,SKELETON ,HUMAN beings - Abstract
This paper proposes an algorithm for transmitting and reconstructing the estimated point cloud by temporally estimating a dynamic point cloud sequence. When a non-rigid 3D point cloud sequence (PCS) is input, the sequence is divided into groups of point cloud frames (PCFs), and a key PCF is selected. The 3D skeleton is predicted through 3D pose estimation, and the motion of the skeleton is estimated by analyzing the joints and bones of the 3D skeleton. For the deformation of the non-rigid human PC, the 3D PC model is transformed into a mesh model, and the key PCF is rigged using the 3D skeleton. After deforming the key PCF into the target PCF utilizing the motion vector of the estimated skeleton, the residual PC between the motion compensation PCF and the target PCF is generated. If there is a key PCF, the motion vector of the target PCF, and a residual PC, the target PCF can be reconstructed. Just as compression is performed using pixel correlation between frames in a 2D video, this paper compresses 3D PCFs by estimating the non-rigid 3D motion of a 3D object in a 3D PC. The proposed algorithm can be regarded as an extension of the 2D motion estimation of a rigid local region in a 2D plane to the 3D motion estimation of a non-rigid object (human) in 3D space. Experimental results show that the proposed method can successfully compress 3D PC sequences. If it is used together with a PC compression technique such as MPEG PCC (point cloud compression) in the future, a system with high compression efficiency may be configured. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
49. Early systolic lengthening by speckle tracking echocardiography predicts outcome after coronary artery bypass surgery
- Author
-
Sune Pedersen, Rasmus Mogelvang, Peter Søgaard, Tor Biering-Sørensen, Philip Brainin, Søren Galatius, Flemming Javier Olsen, Gunnar Gislason, Allan Iversen, Thomas Fritz-Hansen, and Søren Lindberg
- Subjects
ESL, early systolic lengthening ,IDI, integrated discrimination improvement ,medicine.medical_specialty ,medicine.medical_treatment ,Speckle tracking echocardiography ,030204 cardiovascular system & hematology ,Revascularization ,03 medical and health sciences ,Coronary artery bypass surgery ,0302 clinical medicine ,Euroscore ii ,Internal medicine ,LVEF, left ventricular ejection fraction ,Medicine ,Diseases of the circulatory (Cardiovascular) system ,030212 general & internal medicine ,A, late transmitral inflow velocity ,LV, left ventricular ,IQR, interquartile range ,Original Paper ,business.industry ,Proportional hazards model ,CABG, coronary artery bypass graft ,E, early transmitral inflow velocity ,Prognosis ,HR, hazard ratio ,Deformation ,medicine.anatomical_structure ,surgical procedures, operative ,Systolic lengthening ,NRI, net reclassification index ,RC666-701 ,Cardiology ,GLS, global longitudinal strain ,CK-MB, creatine kinase myocardial band ,e’, early diastolic tissue velocity ,Cardiology and Cardiovascular Medicine ,business ,Clinical risk factor ,Early systolic ,Artery - Abstract
Highlights • Early systolic lengthening (ESL) is a paradoxical lengthening of myocardial fibers. • Speckle tracking echocardiography is a common imaging tool for assessment of ESL. • ESL was a predictor of cardiovascular and all-cause death in CABG patients. • Specifically, the prognostic value of ESL was enhanced in women undergoing CABG., Background Early systolic lengthening (ESL), a paradoxical stretch of myocardial fibers, has been linked to loss of myocardial viability and contractile dysfunction. We assessed the long-term prognostic potential of ESL in coronary artery bypass graft (CABG) patients. Methods We retrospectively included patients (n = 709; mean age 68 years; 85% men) who underwent speckle tracking echocardiography (median 15 days) prior to CABG. Endpoints were cardiovascular death (CVD) and all-cause mortality. We assessed amplitude of ESL (%), defined as peak positive strain, and duration of ESL (ms), determined as time from Q-wave on the ECG to peak positive strain. We applied Cox models adjusted for clinical risk assessed as EuroSCORE II. Results During median follow-up of 3.8 years [IQR 2.7–4.9 years], 45 (6%) experienced CVD and 80 (11%) died. In survival analyses adjusted for EuroSCORE II, each 1% increase in amplitude of ESL was associated with CVD (HR 1.35 [95%CI 1.09–1.68], P = 0.006) and all-cause mortality (HR 1.29 [95%CI 1.08–1.54], P = 0.004). Similar findings applied to duration of ESL (per 10ms increase) and CVD (HR 1.12 [95%CI 1.02–1.23], P = 0.016) and all-cause mortality (HR 1.09 [95%CI 1.01––1.17], P = 0.031). The prognostic value of ESL amplitude was modified by sex (P interaction
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- 2021
50. Effects of Mechanical Signaling on Plant Cell Cytosolic Calcium
- Author
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Haley, Ann, Russell, Angela J., Wood, Nicola, Allan, Andrew C., Knight, Marc, Campbell, Anthony K., and Trewavas, Anthony J.
- Published
- 1995
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