Showing papers on "Deformation (meteorology) published in 2019"

Holography at finite cutoff with a T 2 deformation

Abstract: We generalize the $$ T\overline{T} $$ deformation of CFT2 to higher-dimensional large-N CFTs, and show that in holographic theories, the resulting effective field theory matches semiclassical gravity in AdS with a finite radial cutoff. We also derive the deformation dual to arbitrary bulk matter theories. Generally, the deformations involve background fields as well as CFT operators. By keeping track of these background fields along the flow, we demonstrate how to match correlation functions on the two sides in some simple examples, as well as other observables.

GeoMeasurements by Pulsing TDR Cables and Probes

Abstract: Introduction Basic Physics Monitoring Soil Moisture Field Experience and Verification of Soil Moisture Measurement Monitoring Localized Deformation in Rock Field Experience and Verification of Rock Deformation Measurement Monitoring Soil Deformation Monitoring Structural Deformation Air-Liquid Interfaces Electronics Software Appendices

2- and 3-Dimensional Myocardial Strain in Cardiac Health and Disease

Abstract: Advances in speckle-tracking echocardiography allowed the rise of deformation imaging as a feasible, robust, and valuable tool for clinical routine. The global or segmental measurement of strain can objectively quantify myocardial deformation and can characterize myocardial function in a novel way. However, the proper interpretation of deformation measurements requires understanding of cardiac mechanics and the influence of loading conditions, ventricular geometry, conduction delays, and myocardial tissue characteristics on the measured values. The purpose of this manuscript is to review the basic concepts of deformation imaging, briefly describe imaging modalities for strain assessment, and discuss in depth the underlying physical and pathophysiological mechanisms which lead to the respective findings in a specific disease.

Real-time detection of surface deformation and strain in recycled aggregate concrete-filled steel tubular columns via four-ocular vision

Abstract: This study presents a dynamic real-time detection method for surface deformation and full field strain in recycled aggregate concrete-filled steel tubular columns (RACSTCs). Automatic calibration and dynamic surface tracking measurement are utilized and mathematical models combining the four-ocular visual coordinates and point cloud matching are proposed. The 3D deformation of the RACSTCs under low cyclic loading are gathered every 60 s as sample images. The four-ocular vision system constitutes two groups of binocular stereoscopic vision systems. The 3D deformation surface is reconstructed by multi-ocular vision coordinate association, image preprocessing, and point cloud registration. The measurement results are validated by comparison against laser range finder data. The standard deviation mean value of 10 specimens measured by the proposed method relative to the true value is 1.23%; the mean error of the maximum absolute value is 2.82%.

Study on the Mechanical Properties and Mechanical Response of Coal Mining at 1000 m or Deeper

Abstract: As shallow coal resources are gradually depleted, resource exploitation extends from the shallow into the deep, where the mechanical properties of the coal rocks change significantly. To study the mechanical properties and mining-induced response characteristics of deep coal rocks. On a laboratory scale, laboratory tests and mining mechanics simulations were conducted on coal samples recovered from 1000 m or deeper using a rock mechanics testing system called MTS815 Flex Test GT. On the engineering scale, considering the roadway Ji-14-31050, buried in Pingdingshan Coal Mine No. 12 as the research base, four parameters—anchor bolt stress, borehole stress, roof displacement, and roadway convergence distortion—were monitored to study the mining-induced mechanical response characteristics of the coal rocks. The laboratory-scale study showed that the tensile strength and deformation of the deep coal rocks were generally small when destroyed; the tensile strength was in the range of 0.07–0.15 MPa, indicating low strength and high brittleness; the average compression strength of the coal rocks at 1000 m or deeper was 111.7 MPa, which was significantly greater than that of coal rocks at shallower depths. The axial strain and volumetric strain of the deep coal rocks were also greater than those of the shallow coal rocks, indicating significant plasticity. Under the conditions of pillarless mining, the axial deformation, lateral deformation, and volume deformation of deep coal samples all show a large deformation platform near the peak stress, corresponding to the area in which the volumetric deformation showed a trend of expansion; furthermore, the peak stress was significantly lower in this area. The study on the engineering scale showed the coal mining-affected area (approximately 70 m) along the mining direction of the Ji-14-31050 coal mining face with a depth of over 1000 m in the Pingdingshan No. 12 mine was obviously larger than that of the shallow coal seams. As the mining face advanced, the anchor bolt stress, the roof separation, and the roadway section deformation showed similar patterns of increasing variation. In an area 30-m away from the mining face, the supporting pressure peaked, and the anchoring stress, roof separation, and tunnel cross-sectional deformation all changed significantly, displaying the surging phenomenon. At the same time, the roadway sidewall deformation was significantly greater than the deformation between the roof and floor. Clearly, as the mining depth extended deeper, the mining-induced stress field became increasingly more intense, and the coal mining-affected area increased noticeably. Meanwhile, the surrounding rock deformation and roof separation increased significantly, making it more difficult to control the stability of the rocks surrounding the roadway. The results of this study can provide guidance for roadway support, engineering design and mining technology optimization when mining at 1000 m or deeper.

Effect of temperature on the stacking fault energy and deformation behaviour in 316L austenitic stainless steel

Abstract: The stacking fault energy (SFE) is often used as a key parameter to predict and describe the mechanical behaviour of face centered cubic material. The SFE determines the width of the partial disloc ...

The generation and validation of a CUF-based FEA model with laser-based experiments

Abstract: Architectural structures today are increasingly complex and structural health monitoring plays an important role in guaranteeing their safety. How to improve the reliability of deformation analysis...

Direct imaging of short-range order and its impact on deformation in Ti-6Al.

Abstract: Chemical short-range order (SRO) within a nominally single-phase solid solution is known to affect the mechanical properties of alloys. While SRO has been indirectly related to deformation, direct observation of the SRO domain structure, and its effects on deformation mechanisms at the nanoscale, has remained elusive. Here, we report the direct observation of SRO in relation to deformation using energy-filtered imaging in a transmission electron microscope (TEM). The diffraction contrast is enhanced by reducing the inelastically scattered electrons, revealing subnanometer SRO-enhanced domains. The destruction of these domains by dislocation planar slip is observed after ex situ and in situ TEM mechanical testing. These results confirm the impact of SRO in Ti-Al alloys on the scale of angstroms. The direct confirmation of SRO in relationship to dislocation plasticity in metals can provide insight into how the mechanical behavior of concentrated solid solutions by the material's thermal history.

Contour parallel tool path planning based on conformal parameterisation utilising mapping stretch factors

Abstract: Parameterisation-based methods for planning tool paths on mesh surfaces have been developing for years. The issue of existing mapping deformation which results in machining error has not been suffi...

Strain-Stiffening of Agarose Gels

Abstract: Strain-stiffening is one of the characteristic properties of biological hydrogels and extracellular matrices, where the stiffness increases upon increased deformation. Whereas strain-stiffening is ...

Finite Element Analysis of Additive Manufacturing Based on Fused Deposition Modeling: Distortions Prediction and Comparison With Experimental Data

Abstract: Additive manufacturing (or three-dimensional (3D) printing) is constantly growing as an innovative process for the production of complex-shape components. Among the seven recognized 3D printing technologies, fused deposition modeling (FDM) covers a very important role, not only for producing representative 3D models, but, mainly due to the development of innovative material like Peek and Ultem, also for realizing structurally functional components. However, being FDM a production process involving high thermal gradients, non-negligible deformations and residual stresses may affect the 3D printed component. In this work we focus on meso/macroscopic simulations of the FDM process using abaqus software. After describing in detail the methodological process, we investigate the impact of several parameters and modeling choices (e.g., mesh size, material model, time-step size) on simulation outcomes and we validate the obtained results with experimental measurements.

Deformation Characteristics and Determination of Optimum Supporting Time of Alteration Rock Mass in Deep Mine

Abstract: In the tectonic belt, the stability of surrounding metamorphic rock was studied systematically using field investigation, laboratory analysis, theoretical derivation and engineering application. Based on the Jinchuan Mine geological conditions, the exposed surrounding rock of the roadway and its deformed features were analysed. The results of X-ray diffraction and scanning electron microscopy shows that the microstructures of altered rocks affected by structural belts were significant loose, the fractures and pores were well developed, and the composition of clay minerals was more abundant. Then, A nonlinear rheological constitutive model based on the modified Nishihara model is deduced. The actual monitoring data and the rheological parameters of the surrounding rock mass in the Jinchuan Mine area were determined. And these data were used to obtain the optimum secondary-support time by inverse analysis. Finally, the joint support technology of bolt and anchor cable was proposed. The field practice shows that this support method is favourable to the long-term stability of roadway and can effectively reduce the deformation of roadway surrounding rock.

Fatigue Deformation Model of Plain and Fiber-Reinforced Concrete Based on Weibull Function

Abstract: A novel model based on the three-parameter Weibull function is proposed to describe the three-stage fatigue deformation behavior of plain and fiber-reinforced concrete. The fatigue strain a...

Soft Magnetic Skin for Continuous Deformation Sensing

Abstract: Recent progress in soft‐matter sensors has shown improved fabrication techniques, resolution, and range. However, scaling up these sensors into an information‐rich tactile skin remains largely limited by designs that require a corresponding increase in the number of wires to support each new sensing node. To address this, a soft tactile skin that can estimate force and localize contact over a continuous 15 mm2 area with a single integrated circuit and four output wires is introduced. The skin is composed of silicone elastomer loaded with randomly distributed magnetic microparticles. Upon deformation, the magnetic particles change position and orientation with respect to an embedded magnetometer, resulting in a change in the net measured magnetic field. Two experiments are reported to calibrate and estimate both location and force of surface contact. The classification algorithms can localize pressure with an accuracy of >98% on both grid and circle pattern. Regression algorithms can localize pressure to a 3 mm2 area on average. This proof‐of‐concept sensing skin addresses the increasing need for a simple‐to‐fabricate, quick‐to‐integrate, and information‐rich tactile surface for use in robotic manipulation, soft systems, and biomonitoring.

A peridynamic investigation on crushing of sand particles

Abstract: Particle crushing underpins important macroscopic behaviour of granular materials such as yielding, deformation, dilatancy, failure, mobility and packing features. The crushing condition and crushi...