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1
Honório, Leonardo M., Milena F. Pinto, Maicon J. Hillesheim, Francisco C. de Araújo, Alexandre B. Santos e Delfim Soares. "Photogrammetric Process to Monitor Stress Fields Inside Structural Systems". Sensors 21, n. 12 (10 giugno 2021): 4023. http://dx.doi.org/10.3390/s21124023.
Testo completoAbstract (sommario):
This research employs displacement fields photogrammetrically captured on the surface of a solid or structure to estimate real-time stress distributions it undergoes during a given loading period. The displacement fields are determined based on a series of images taken from the solid surface while it experiences deformation. Image displacements are used to estimate the deformations in the plane of the beam surface, and Poisson’s Method is subsequently applied to reconstruct these surfaces, at a given time, by extracting triangular meshes from the corresponding points clouds. With the aid of the measured displacement fields, the Boundary Element Method (BEM) is considered to evaluate stress values throughout the solid. Herein, the unknown boundary forces must be additionally calculated. As the photogrammetrically reconstructed deformed surfaces may be defined by several million points, the boundary displacement values of boundary-element models having a convenient number of nodes are determined based on an optimized displacement surface that best fits the real measured data. The results showed the effectiveness and potential application of the proposed methodology in several tasks to determine real-time stress distributions in structures.
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Hubbard, Timothy L. "Judged Displacement: A Modular Process?" American Journal of Psychology 107, n. 3 (1994): 359. http://dx.doi.org/10.2307/1422879.
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Galaguz, Y. P., e G. L. Safina. "Modeling of suspension displacement process". Vestnik MGSU, n. 8 (agosto 2018): 944–51. http://dx.doi.org/10.22227/1997-0935.2018.8.944-951.
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Song, Zhan Ping, Jing Liu e An Nan Jiang. "Studying the Three Dimensional Excavation Effect Affecting the Monitoring Displacement of Metro Station". Advanced Materials Research 594-597 (novembre 2012): 1285–89. http://dx.doi.org/10.4028/www.scientific.net/amr.594-597.1285.
Testo completoAbstract (sommario):
In tunnel construction process, Because monitoring points setting always get behind with tunnel heading and occurred space effect which induces displacement loss and affects the monitoring accuracy. Studying tunnel space affect has important meaning to the monitoring data analysis. The paper takes Dalian Metro Station as research back ground, adopted three dimensional elastic-plastic numerical test method and carried out the excavation process simulation. Studied the convergence displacement and sedimentation displacement variation regulation along with the distance to tunnel heading face. The simulation results state that the nearer to the tunnel heading, the displacements of surrounding rock are smaller. Analyzed the ratio of displacement loss induced by space effect and amended the monitoring displacements of Dalian Metro Station.
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Cai, Yan-yan, Bing-xiong Tu, Jin Yu, Yao-liang Zhu e Jian-feng Zhou. "Numerical Simulation Study on Lateral Displacement of Pile Foundation and Construction Process under Stacking Loads". Complexity 2018 (2018): 1–17. http://dx.doi.org/10.1155/2018/2128383.
Testo completoAbstract (sommario):
Lateral displacement of pile foundation is crucial to the safety of an overall structure. In this study, a numerical simulation on the lateral displacement of pile foundation under stacking loads was conducted to determine its relation with different influencing factors. Simulation results demonstrated that stacking loads at the pile side mostly influence the lateral displacement of pile foundation. The lateral displacement of pile foundation increases by one order of magnitude when the stacking loads increase from 100 kPa to 300 kPa. Other influencing factors are less important than stacking loads. Lateral displacements of the pile body and at the pile top can be reduced effectively by increasing the deformation modulus of surface soil mass, reducing the thickness of soft soil, and expanding pile diameter. Our analysis indicates that a nonlinear relationship exists between the lateral displacement at the pile top and the pile diameter. The lateral resistance of the pile body can be enhanced by coupling the stacking load along piles and the axial force at the pile top. An actual large-scale engineering project was chosen to simulate the effects of postconstructed embankment on lateral displacement and axial force of bridge pile foundation under different construction conditions and to obtain the lateral displacement of the pile body and the negative frictional resistance caused by soft soil compression under stacking loads. On the basis of the calculated results, engineering safety and stability were evaluated, and a guide for the design and construction was proposed.
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Jung, Dong Won. "Investigation on Variation of Bow Defect in Roll Forming Process". Key Engineering Materials 729 (febbraio 2017): 80–85. http://dx.doi.org/10.4028/www.scientific.net/kem.729.80.
Testo completoAbstract (sommario):
Roll forming is a kind of plastic forming process in which a steel strip is bent by several sets of rolls gradually into the desired shape. The products are cold roll forming steels with various sections. Roll forming is one of the most widely used processes in the world for forming metal. Roll forming is a complex deformation process, which involves large displacement, finite strain and the problems of contact and friction between strip and rolls. This process exhibits obvious geometry, physical and boundary nonliterary. The complex processes contain many aspects such as geometry, kinematics and dynamics, etc. The forming process involves not only transverse bending, but also other additional deformations. In this paper, a group of simulations have been established with ABAQUS software to studying about the spring back and bow defect in the roll forming process. At last, experiments have been accomplished to verify the simulation results. The simulations based on the ABAQUS software calculate the spring back angles and bow displacements. The bow displacement of the roll forming process is considered relate to many factors include inner distance between stands, gaps of the rolls, channel width, the material of the sheet, sheet thickness and so on.To verify the bow displacement in roll forming process, 9 groups of simulations were set up use Taguchi method to figure out the influence on bow displacement of every factor. The longitudinal strain also has been learned in the present study.
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Katona, Tamás János, László Tóth e Erzsébet Győri. "Fault Displacement Hazard Analysis Based on Probabilistic Seismic Hazard Analysis for Specific Nuclear Sites". Applied Sciences 11, n. 15 (3 agosto 2021): 7162. http://dx.doi.org/10.3390/app11157162.
Testo completoAbstract (sommario):
Permanent ground displacements/deformations caused by earthquakes can seriously challenge the safety of the nuclear power plants. The state-of-the-art hazard analysis methods provide a fault displacement hazard curve, i.e., the annual probability of given measure of displacement will be exceeded. The evaluation of ground displacement hazard requires great effort, empirical evidence, and sufficient data for the characterization of the fault activity and capability to cause permanent surface displacement. There are practical cases when the fault at the site area revealed to be active, and, despite this, there are no sufficient data for the evaluation of permanent ground displacements hazard and for judging on the safety significance of permanent ground displacement. For these cases, a methodology is proposed that is based on the seismotectonic modelling and results of the probabilistic seismic hazard analysis. The method provides conservative assessment of the annual probability of fault displacement that allows the decision whether permanent displacement hazard is relevant to nuclear power plant safety. The feasibility and applicability of the method is demonstrated for the Paks site, Hungary.
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Zhang, Xiaoshuang, Xiuchuan Zhang e Yunshan Han. "A Case Study on Field Monitoring Analysis of Deep Foundation Pit in Soft Soils". Advances in Civil Engineering 2019 (2 maggio 2019): 1–10. http://dx.doi.org/10.1155/2019/9342341.
Testo completoAbstract (sommario):
Field monitoring in the process of excavation of foundation pit is an important measure to reduce the risk. This paper describes a case study of the filed monitoring data during the process of deep foundation pit excavation in soft soil areas. The displacements of the diaphragm wall top were analysed and found that the horizontal displacement showed the convex shape, while the vertical displacement showed the concave shape. Based on the field monitoring data, the deformation mode of lateral displacement of the diaphragm wall belonged to the composite mode. The relationship between maximum lateral displacement and excavation depth showed a strong linear correlation. The horizontal displacements of bracing pillar decreased with the increasing of bracing stiffness, while the effect of bracing stiffness on vertical displacements of bracing pillar could be ignored. The settlement profile computed using the method of Hsieh and Ou was in good agreement with the field observations and better described the development trend of the ground surface settlement. The ratio of the maximum ground surface settlement (δvm) to the maximum lateral displacement of the diaphragm wall (δhm) was in the range of 0.74∼0.88, belonging to the range of 0.5∼1.0 proposed by Hsieh and Ou. This paper provides a reference basis and related guidance for similar projects.
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Aburatani, Hideaki. "Drive of Piezoelectric Actuators Using an Electrical Depoling Process". International Journal of Automation Technology 5, n. 4 (5 luglio 2011): 601–5. http://dx.doi.org/10.20965/ijat.2011.p0601.
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In conventional drives of piezoelectric actuators, the piezoelectricity of the material itself has not been controlled electrically. A newly-developed electrical depoling process is proposed and applied to piezoelectric actuators in this study. Selectable piezoelectric and non-piezoelectric responses of the piezoelectric element can be obtained using the electrical depoling process. A piezoelectric unimorph and a gripper consisting of two unimorphs are chosen to demonstrate the drive of piezoelectric actuators using electrical depoling. It is shown that displacement is not induced in the electrically depoled samples until the applied field exceeds the critical value. From the electric field dependence of induced displacement, conflicts among ferroelectric domains during polarization switching are suggested to be the origin of the electrically depoled state. It is also demonstrated that electrically depoled piezoelectric ceramics exhibit digital-like displacements. Potential uses for the drive of piezoelectric actuators that use the electrical depoling is also discussed.
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Koole, R., G. Voorhout e H. A. W. Hazewinkel. "Mandibular Coronoid Process Displacement: Signs, Causes, Treatment". Veterinary and Comparative Orthopaedics and Traumatology 06, n. 01 (1993): 29–35. http://dx.doi.org/10.1055/s-0038-1633143.
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SummaryOpen-mout h locking due to lateral impingement of the mandibular coronoid process, lateral to the zygomatic arch, is described in five dogs and one cat. In order to elucidate the underlying cause of this abnormality, radiographs of temporomandibular joints of forty dogs, as well as the case history of a human patient, are compared. Three possible aetiologies are given, namely, flattening of the zygomatic arch, aberrant architecture of the condylar aspects, or contracture of the pterygoid muscle. An effective surgical treatment to prevent recur-rence of coronoid impingement was achieved by ostectomy of the locking part of the coronoid process.Unilateral protrusion of the mandible is described as a veterinary and comparative abnormality in five dogs, a cat and a woman. For the impingement of the coronoid process lateral of the zygomatic arch causing open-mouth locking in the animals, three aetiologies and an effective ostectomy of the coronoid process are given.
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Yang, Zhenqing, Changjin Shao, Guanggang Zhou e Chao Qiu. "Modeling non-aqueous phase liquid displacement process". Petroleum Science 4, n. 3 (agosto 2007): 40–46. http://dx.doi.org/10.1007/s12182-007-0007-8.
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Kawaguchi, Masami. "Sequential polymer adsorption: competition and displacement process". Advances in Colloid and Interface Science 32, n. 1 (giugno 1990): 1–41. http://dx.doi.org/10.1016/0001-8686(90)80010-w.
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Takushima, Shigeru, Nobuhiro Shinohara, Daiji Morita, Hiroyuki Kawano, Yasuhiro Mizutani e Yasuhiro Takaya. "In-Process Height Displacement Measurement Using Crossed Line Beams for Process Control of Laser Wire Deposition". International Journal of Automation Technology 15, n. 5 (5 settembre 2021): 715–27. http://dx.doi.org/10.20965/ijat.2021.p0715.
Testo completoAbstract (sommario):
We propose the use of the line section method with crossed line beams for the process control of laser wire deposition. This method could be used to measure the height displacement in front of a laser spot when the processing direction changes. In laser processing, especially laser deposition of metal additive manufacturing, the laser process control technique that controls the processing parameters based on the measured height displacement in front of a laser processing spot is indispensable for high-accuracy processing. However, it was impossible to measure the height displacement in front of a processing laser spot in a processing route in which the processing direction changes as the measurement direction of the conventional light-section method comprising the use of a straight-line beam is restricted although the configuration is simple. In this paper, we present an in-process height displacement measurement system of the light-section method using two crossed line beams. This method could be used to measure the height displacement in a ±90° direction by projecting two crossed line beams from the side of a laser processing head with a simple configuration comprising the addition of one line laser to the conventional light-section method. The height displacement can be calculated from the projected position shift of the line beams irrespective of the measurement direction by changing the longitudinal position on the crossed line beams according to the measurement direction. In addition, the configuration of our proposed system is compact because the imaging system is integrated into the processing head. We could measure the height displacement at 2.8–4 mm in front of a laser processing spot according to the measurement direction by reducing the influence of intense thermal radiation. Moreover, we experimentally evaluated the height displacement measurement accuracy for various measurement directions. Finally, we evaluated continuous deposition in an “L” shape wherein the deposition direction was changed while using a laser wire direct energy deposition machine for the laser process control based on the in-process height displacement measurement result. We achieved highly accurate continuous deposition at the position wherein the processing direction changes despite the acceleration and deceleration of the stage by laser process control.
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Rosen, Mary Ellen, Christopher P. Grant e J. C. Dallon. "Mean square displacement for a discrete centroid model of cell motion". PLOS ONE 16, n. 12 (20 dicembre 2021): e0261021. http://dx.doi.org/10.1371/journal.pone.0261021.
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The mean square displacement (MSD) is an important statistical measure on a stochastic process or a trajectory. In this paper we find an approximation to the mean square displacement for a model of cell motion. The model is a discrete-time jump process which approximates a force-based model for cell motion. In cell motion, the mean square displacement not only gives a measure of overall drift, but it is also an indicator of mode of transport. The key to finding the approximation is to find the mean square displacement for a subset of the state space and use it as an approximation for the entire state space. We give some intuition as to why this is an unexpectedly good approximation. A lower bound and upper bound for the mean square displacement are also given. We show that, although the upper bound is far from the computed mean square displacement, in rare cases the large displacements are approached.
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Zhang, Sheng, Yang Qiao e Hong-Bao Zhao. "The crack opening displacement of rock fracture process zone". Thermal Science 23, n. 3 Part A (2019): 1479–86. http://dx.doi.org/10.2298/tsci180913214z.
Testo completoAbstract (sommario):
The original displacement value of fracture process zone can be obtained by digital image correlation technology. According to the virtual crack model, the formula to obtain the opening displacement is given in the experiment. Basing on the damage Mechanics theory and the actual deformation characteristics of fracture process zone, the traditional opening displacement distribution function of fracture process zone is modified by defining the wave coefficient and the damage factor of the horizontal elastic modulus. The measured opening displacement is compared with the opening displacement of the traditional theoretical function and modified function, and the results show that the opening displacement is non-linear fluctuation characteristic distribution influenced by damage. The revise distribution function not only reflects the overall growth trend of the opening displacement, but also reflects the local fluctuation characteristics. It has an important theoretical significance for understanding the non-linear characteristics of rock fracture process.
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Guo, Xiangying, Changkun Li, Zhong Luo e Dongxing Cao. "Modal Parameter Identification of Structures Using Reconstructed Displacements and Stochastic Subspace Identification". Applied Sciences 11, n. 23 (2 dicembre 2021): 11432. http://dx.doi.org/10.3390/app112311432.
Testo completoAbstract (sommario):
A method of modal parameter identification of structures using reconstructed displacements was proposed in the present research. The proposed method was developed based on the stochastic subspace identification (SSI) approach and used reconstructed displacements of measured accelerations as inputs. These reconstructed displacements suppressed the high-frequency component of measured acceleration data. Therefore, in comparison to the acceleration-based modal analysis, the operational modal analysis obtained more reliable and stable identification parameters from displacements regardless of the model order. However, due to the difficulty of displacement measurement, different types of noise interferences occurred when an acceleration sensor was used, causing a trend term drift error in the integral displacement. A moving average low-frequency attenuation frequency-domain integral was used to reconstruct displacements, and the moving time window was used in combination with the SSI method to identify the structural modal parameters. First, measured accelerations were used to estimate displacements. Due to the interference of noise and the influence of initial conditions, the integral displacement inevitably had a drift term. The moving average method was then used in combination with a filter to effectively eliminate the random fluctuation interference in measurement data and reduce the influence of random errors. Real displacement results of a structure were obtained through multiple smoothing, filtering, and integration. Finally, using reconstructed displacements as inputs, the improved SSI method was employed to identify the modal parameters of the structure.
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Nakhodchi, S., Andrew Hodgkins, Robert Moskovic, David John Smith e Peter E. J. Flewitt. "Fracture Process Zones in Polygranular Graphite in Bending". Key Engineering Materials 452-453 (novembre 2010): 93–96. http://dx.doi.org/10.4028/www.scientific.net/kem.452-453.93.
Testo completoAbstract (sommario):
The formation of fracture process zones in polygranular reactor core moderator graphites subjected to four-point bending has been investigated. The three-dimensional digital image correlation technique has been combined with resistance strain gauge measurements to evaluate, both the localised and the global displacements during testing. The non-linear load-displacement characteristics prior to peak load are correlated with the localised displacements which can extend up to ~3mm (process zone) from the tensile surface of the specimen. At peak load a macro-crack propagates rapidly along an irregular path controlled by the direction of the applied tensile load and the microstructure of the graphite. These cracks arrest prior to complete separation of the specimen. Localised tensile process zones extend for distances of up to ~3mm ahead of the tips of these cracks.
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Malarski, Ryszard. "A concept for the examination of reference points stability in horizontal control networks". Reports on Geodesy and Geoinformatics 101, n. 1 (1 giugno 2016): 60–69. http://dx.doi.org/10.1515/rgg-2016-0022.
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Abstract This paper presents a concept for the identification of stable reference points used in horizontal control networks, which is based on the lengths of apparent displacement vectors and their mean errors. These vectors and their mean errors are obtained during the process of calculating displacements with free adjustment conditions. It will be shown that the influence of the apparent displacement vectors has a significant effect on the calculation of results. The identification of stable points, using the proposed method, is an integral part of the adjustment process and allows for the interrogation the influence of individual point inclusion or deletion from the reference database, on the values of displacements of controlled points. A detailed process of stable reference points identification is presented using the example of a linear-angular network for a barrage.
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He, Cheng Zhong, e Wei Liang Chen. "The Dynamic Analysis of Gantry Crane Girder under Lifting Process". Advanced Materials Research 823 (ottobre 2013): 29–32. http://dx.doi.org/10.4028/www.scientific.net/amr.823.29.
Testo completoAbstract (sommario):
In order to get the displacement response curve of the Gantry Crane Girder under three stage of lifting process, the vibration differential equation and displacement response expression were deduced, combining with the actual case, the displacement response expression and displacement response curve were deduced in the load duration time 0.8 s and 0.2 s. The results show that: the lifting process is an important factor affecting the structural vibration; Displacement peak and load duration time are inversely proportional; Increase the load duration time can reduce the vibration of the structure.
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Elashmawy, M., A. Alghamdi e I. Badawi. "Investigation of the Effect of Pipeline Size on the Cross Flow Injection Process". Engineering, Technology & Applied Science Research 6, n. 3 (12 giugno 2016): 1023–28. http://dx.doi.org/10.48084/etasr.727.
Testo completoAbstract (sommario):
Injection pumps constitute an essential component for many industrial applications. The main focus of this study is to predict the effect of the size of the pipeline on the cross flow injection process. A test-rig was designed, built and equipped with three different pipelines, 1½", ¾" and ½" diameters. Comparison was made under constant line pressure of 40-bar and line flow rate of 5 liter/min, with a fixed injection pump rotational speed of 100 rpm. The main parameter tested was the injection dose capacity at different pump displacements. Cross flow mixing process is also theoretically studied using 3D-CFD analysis to show the injection cross flow behavior for the same geometry and parameters used for experimental test. Results show that increasing the size of the pipeline increases injection pump doses ability. This effect is insignificant at lower injection pump displacements, while the effect of the size of the pipeline becomes dominant when increasing the displacement. By changing the size of the pipeline from ½" to 1½" diameter injection pump dose capacity increases by 3.24% at 100% pump displacement. Selecting larger pipe sizes for injection ports is recommended whenever possible.
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Lu, Ye, Yun Jiang e Xiaoyong Wang. "Investigation of soil displacements caused by the press-in process for close-ended model piles using an imaging technique". Acta Geotechnica Slovenica 17, n. 2 (2020): 2–15. http://dx.doi.org/10.18690/10.18690/actageotechslov.17.2.2-15.2020.
Testo completoAbstract (sommario):
In recent years, installing piles using the press-in method has gained popularity in urban areas. However, pushing piles into the ground squeezes the surrounding soils and consequently causes a disturbance or even damage to the underground structures and facilities close by. In order to investigate the squeezing effect incurred by press-in piling, a series of model tests were performed. The soil displacement field was captured using a non-contact technique called digital image correlation (DIC), and the horizontal soil stresses were measured by mini pressure cells. Analyses of the soil displacement fields showed that the pile press-in process caused different soil displacement paths at different depths and locations. The development of horizontal soil stresses correlated well with the horizontal and vertical displacements. A thin disturbance layer could be observed along the pile-soil interface and it was about 7.4-11.1 D50 in thickness (D50, median particle size). At the end, the soil displacements caused by pushing the model pile with different pile shoes were analyzed and compared, and the analyses showed that a greater shoe angle resulted in greater disturbance to the surrounding soils. However, the influence of the pile shoe angle became less substantial with the increase of the pile penetration depth.
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Peng, Wen Fei, Si Jia Jiao, Xue Dao Shu e Kang Sheng Zhang. "Study of the Metal Flow Law on Cross Wedge Rolling Asymmetric Shaft". Applied Mechanics and Materials 184-185 (giugno 2012): 501–4. http://dx.doi.org/10.4028/www.scientific.net/amm.184-185.501.
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Finite element model of Cross wedge rolling asymmetric shaft is established, contrasting with symmetrical rolling, the axial relative displacement of weak-side and strong-side’s metal in asymmetric cross wedge rolling is analyzed. The results show that: axial relative displacement asymmetrical rolling on the weak-side undergo the process of “increase-decrease-unchangeableness” and axial non-uniform deformation increases; axial relative displacements on the strong-side undergo the process of “decrease- unchangeableness” and axial non-uniform deformation decreases. The results provide a theoretical basis for the cross wedge rolling asymmetric shaft parts.
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Iván Vergara, Jorge, Hans Gundermann e Héctor González. "The displacement process of aymara language in Chile". Journal of Historical Archaeology & Anthropological Sciences 5, n. 4 (21 luglio 2020): 124–32. http://dx.doi.org/10.15406/jhaas.2020.05.00226.
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Irwin, D. D., e J. P. Batycky. "The Successive Displacement Process: Oil Recovery During Blowdown". SPE Reservoir Engineering 12, n. 04 (1 novembre 1997): 240–45. http://dx.doi.org/10.2118/36719-pa.
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Zha, Hongyuan, e Zhenyue Zhang. "The arnoldi process, short recursions, and displacement ranks". Linear Algebra and its Applications 249, n. 1-3 (dicembre 1996): 169–88. http://dx.doi.org/10.1016/s0024-3795(97)82725-5.
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Cowie, Patience A., e Zoe K. Shipton. "Fault tip displacement gradients and process zone dimensions". Journal of Structural Geology 20, n. 8 (agosto 1998): 983–97. http://dx.doi.org/10.1016/s0191-8141(98)00029-7.
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Eckerd, Adam, Yushim Kim e Heather Campbell. "Gentrification and Displacement: Modeling a Complex Urban Process". Housing Policy Debate 29, n. 2 (26 novembre 2018): 273–95. http://dx.doi.org/10.1080/10511482.2018.1512512.
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Wu, Xiu Gen, Bai Lin Zheng, Peng Fei He e Shu Guang Liu. "The Behavior of Column during Constrained Buckling Process". Applied Mechanics and Materials 166-169 (maggio 2012): 385–91. http://dx.doi.org/10.4028/www.scientific.net/amm.166-169.385.
Testo completoAbstract (sommario):
The elastic Euler buckling of an inextensible column is confined in a plane, and subject to fixed end displacement, in the presence of rigid, frictionless side-walls which constrain overall lateral displacements. The whole deflection is divided into some typical columns because of the symmetry. The governing equations of constrained buckling mode and deflection about axial load are deduced, based on linearized differential equation of beam. Point and line contact models are introduced to describe the behavior of the column in constrained buckling process, including load capacity, buckling wave and reaction force. The analysis on the deflection of column is helpful to the research about possible post-buckling paths.
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Ahmed, Mohd, Devinder Singh, Saeed AlQadhi e Nabil Ben Kahla. "L2-Norm Based a Posteriori Error Estimates of Compressible and Nearly-Incompressible Elastic Finite Element Solutions". Applied Sciences 12, n. 8 (15 aprile 2022): 3999. http://dx.doi.org/10.3390/app12083999.
Testo completoAbstract (sommario):
The displacement and stress-based error estimates in a posteriori error recovery of compressible and nearly-incompressible elastic finite element solutions is investigated in the present study. The errors in the finite element solutions, i.e., in displacement and stress, at local and global levels are computed in L2-norm of quantity of interest, namely, displacements and gradients. The error estimation techniques are based on the least square fitting of higher order polynomials to stress and displacement in a patch comprising of node/elements surrounding and including the node/elements under consideration. The benchmark examples of compressible and incompressible elastic bodies, with known solutions employing triangular discretization schemes, are implemented to measure the finite element errors in displacements and gradients. The mixed formulation involving displacement and pressure is used for incompressible elastic analysis. The performance of error estimation is measured in terms of convergence properties, effectivity and mesh required for predefined precision. The error convergence rate, in FEM original solution, recovered solution using displacement recovery-based and stress-based error recovery technique for stresses, are obtained as (1.9714, 2.8999, and 2.5018) and (0.9818, 1.7805, and 1.4952) respectively for compressible and incompressible self-loaded elastic plate benchmark example using higher order triangular elements. It is concluded from the study that displacement fitting technique for extracting higher order derivatives shows a very effective technique for recovery of compressible and nearly-incompressible finite element analysis errors.
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Zhang, Dingli, Liqiang Cao, Jianbo Fei, Huangcheng Fang, Lin Yu e Xuefei Hong. "Movements and Its In-Process Control of Ground and Built Structures due to Tunnelling in Urban Areas". Advances in Civil Engineering 2022 (29 gennaio 2022): 1–13. http://dx.doi.org/10.1155/2022/4255280.
Testo completoAbstract (sommario):
Tunnelling-induced environmental responses including ground movements and deformation of the environmental structures are the two prominent issues needed to be carefully disposed in urban areas. This paper tries to develop a theoretical framework to evaluate and control the environmental deformation to avoid two disasters including ground collapse and structural failure. According to the mechanical responses of the ground due to tunnelling, the urban ground in China can be roughly divided into three types including composite multilayered ground, highly water-bearing ground, and mixed rock ground. The displacements of ground and environmental structures due to tunnelling in multilayered ground are emphatically discussed in view of its largest proportion distribution. The cumulative and mutational characteristics of the displacements are considered, which can be the main basis for distinguishing the occurrence of two types of disasters. Based on the development of the displacements, the three-stage evolution model of disaster is established. Combined with the existing displacement and degeneration of the ground and structures and the safety factor, the displacement control standards can be eventually determined. The theoretical framework of in-process control is established which is based on the prediction, measurement, and control standards of the displacements. In the framework, the prediction model can be modified in time, and the tunnelling parameters can be adjusted synchronously. The current research is successfully applied in the Qinghuayuan Tunnel Project.
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He, Cheng Zhong, e Xi Zhi Zhou. "The Dynamic Analysis of Portal Crane with Self-Funnel under Unloading Process". Advanced Materials Research 740 (agosto 2013): 249–53. http://dx.doi.org/10.4028/www.scientific.net/amr.740.249.
Testo completoAbstract (sommario):
In order to get the displacement response curve of the Portal Crane under four phase of unloading process, the vibration system was built, the vibration differential equation and displacement response expression were deduced, combining with the actual case, the displacement response expression and displacement response curve were deduced in the open grab time 1.5 s and 4 s. The results show that: the unloading process is an important factor affecting the structural vibration; Displacement peak and open grab time are inversely proportional; Increase the open grab time can reduce the vibration of the structure.
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Liang, Cai Ping, e Yong Bing Li. "Study on the Thermal Expansion Displacement during Spot Welding Depending on the Multi-Physical Coupling Finite Element Model". Advanced Materials Research 941-944 (giugno 2014): 2007–11. http://dx.doi.org/10.4028/www.scientific.net/amr.941-944.2007.
Testo completoAbstract (sommario):
An incremental and thermal electro-mechanical coupled finite element model has been presented in this study for predicting spot nugget size, gap between workpieces, and thermal expansion displacement during spot welding process. Approximate temperature dependent material properties, including physical and mechanical properties, have been considered. The spot nugget shape and the thermal expansion displacement were obtained by simulation. The solutions showed that the displacement of workpieces was directly related to the quality of solder joints and can be as a monitoring parameter of spot weld quality. These calculations provide a theoretical reference for nugget quality monitoring and forecasting by electrode expansion displacements.
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Zhang, Yanrong, Kai Wu, Chao Yu, Shuang Zhang e Xiaopei Cai. "Application of Statistical Process Control for Structural Health Monitoring of a High-Speed Railway Track System". Applied Sciences 12, n. 12 (14 giugno 2022): 6046. http://dx.doi.org/10.3390/app12126046.
Testo completoAbstract (sommario):
To make full use of the massive monitoring data accumulated in China high-speed railways, an improved statistical process control (SPC) framework was introduced to analyze the discontinuous monitoring data of the track system on a high-speed railway elevated station. Multilinear regression models and time series difference equation (TSDE) models were first developed to separate common-cause variations in the monitoring data. Then, individual control charts, moving range control charts, and exponentially weighted moving average control charts were constructed to detect special-cause variations. Results showed that the variations of girder displacement and track slab–girder relative displacements mainly resulted from temperature effects and linear trends related with material damages. Moreover, visible serial dependence was found in the regression model residuals, which could be effectively captured by the TSDE model. Numerous outliers were detected at the measuring points of rail–track slab displacement 15 and track slab–girder relative displacement 17 by more than three control charts, implying higher sensitivity to special causes. With respect to the special causes triggering the anomalous responses of local and overall track systems, sixteen and twenty-eight significant special events were detected, respectively.
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Peng, Shoujian, Xinrui Zhang, Xiaojun Tang, Jiang Xu, Feng Jiao e Meixin He. "Experimental Investigation of Non-Linear Seepage Characteristics in Rock Discontinuities and Morphology of the Shear Section in the Shear Process". Processes 10, n. 12 (7 dicembre 2022): 2625. http://dx.doi.org/10.3390/pr10122625.
Testo completoAbstract (sommario):
Considering the increasing frequency of geological disasters related to groundwater activities, it is important to study the relationship between geological dislocation and groundwater flow for the safety assessment of engineering rock mass stability. To elucidate the non-linear seepage characteristics at rock discontinuities during shearing, a custom-made device was used to conduct seepage tests at discontinuities that exhibit varying undulation angles and different shear displacements. The results show that as the shear displacement increases, the shear stress at a structural plane involving different undulation angles fluctuates with an increasing trend. Based on an identical shear displacement condition, the shear strengths of the structural planes increase as the undulation angle increases, and this enhances the shear expansion. Concerning an identical fluctuation angle and hydraulic gradient, the seepage flow at a structural plane increases as the shear displacement increases. By contrast, both the linear term coefficient a and non-linear term coefficient b in the Forchheimer fitting equation decrease as the shear displacement increases. In addition, the critical Reynolds number initially increases, followed by stabilisation as the shear displacement increases, and this number varies between 9.65 and 1758.52. The shear fracture morphology of the structural plane exhibits obvious anisotropy. During shearing, the roughness coefficient decreases in all but the vertical direction. The dominant seepage channel is perpendicular to the shear direction. The findings can provide a valuable reference for the stability research and analysis of rock slopes with structural planes.
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Xu, Jiancong, Yu Jiang e Chengbin Yang. "Landslide Displacement Prediction during the Sliding Process Using XGBoost, SVR and RNNs". Applied Sciences 12, n. 12 (14 giugno 2022): 6056. http://dx.doi.org/10.3390/app12126056.
Testo completoAbstract (sommario):
In order to promptly evacuate personnel and property near the foot of the landslide and take emergency treatment measures in case of sudden danger, it is very necessary to select suitable forecasting methods for conduct short-term displacement predictions in the slope-sliding process. In this paper, we used Python to develop the landslide displacement-prediction method based on the eXtreme Gradient Boosting (XGBoost) algorithm, and optimized the hyperparameters through a genetic algorithm to solve the problem of insufficient short-term displacement-prediction accuracy for landslides. We compared the deviation, relative error (RE) and median of RE of predicted values obtained using XGBoost, SVR and RNNs, and the actual value of landslide displacement. The results show that the accuracies of slope displacement prediction using XGBoost and SVR are very high, and that using RNNs is very low during the sliding process. For large displacement values and small numbers of samples, the displacement-prediction effect of XGBoost algorithm is better than that of SVR and RNNs in the sliding process of landslide. There are generally only fewer data samples collected during the landslide sliding process, so RNNs is not suitable for displacement prediction in this scenario. If the number of data samples is large enough, using RNNs to predict the long-term displacement of the slope may also have a much higher accuracy.
36
Yu, Jiayong, Zhen Fang, Xiaolin Meng, Yilin Xie e Qian Fan. "Measurement of Quasi-Static and Dynamic Displacements of Footbridges Using the Composite Instrument of a Smartstation and an Accelerometer: Case Studies". Remote Sensing 12, n. 16 (15 agosto 2020): 2635. http://dx.doi.org/10.3390/rs12162635.
Testo completoAbstract (sommario):
Monitoring the dynamic responses of bridge structures has received considerable attention. It is important to synchronously measure both the quasi-static and dynamic displacements of bridge structures. However, the traditional accelerometer method cannot capture the quasi-static displacement component, although it can detect the dynamic displacement component. To this end, a novel composite instrument of a smartstation was proposed to monitor vibration displacements of footbridges. Full-scale experiments were conducted on a footbridge to validate the feasibility of the composite instrument-based monitoring method. A Chebyshev filter and wavelet algorithms were developed to process the composite instrument measurements. It was concluded that the measurement noise of the composite instrument was mainly distributed in a frequency range of 0–0.1 Hz. In two case studies with displacement peaks of 5.7–10.0 mm and 1.3– 2.5 mm, the composite instrument accurately identified the quasi-static and dynamic displacements. The composite instrument will be a potential tool for monitoring structural dynamics because of its enhanced overall performance.
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Sun, Lianwei, Zhong-chao Li e Rong-zhu Liang. "Simplified Analytical Method for Predicting the Lateral Ground Displacements due to Shield Tunnelling". Advances in Civil Engineering 2021 (21 giugno 2021): 1–10. http://dx.doi.org/10.1155/2021/5524557.
Testo completoAbstract (sommario):
Earth pressure balance or slurry shield tunnelling will squeeze the subsoils and lead to lateral outward ground displacement. However, current methods to estimate the shield tunnelling-induced ground displacements generally use the methods based on the face unsupported tunnelling (e.g., New Austrian tunnelling and open shield excavation), which cannot predict the lateral ground movement due to shield tunnelling. In this paper, a novel simplified analytical method is proposed to predict the ground lateral displacement during the shield advancing process. The key shield tunnelling operation factors, including the additional pressure of cutter head, the friction forces around shield body, the back-fill grouting pressure, and the soil volume loss are all considered. The lateral ground displacements induced by the four former factors are calculated by using Mindlin’s solutions. The soil volume loss-induced lateral ground displacement is calculated by employing the expression introduced by Pinto and Whittle. Combining with the displacement obtained from all the factors, the analytical method for lateral ground displacement induced by shield tunnelling is obtained. The applicability of the proposed analytical approach is verified with three well-documented case histories involving slurry shield and EPB shield machines.
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Chen, Hong Niao, Ray Kai Leung Su e Jia Jian Chen. "Study on Fracture Properties of Mortar Based on Electronic Speckle Pattern Interferometry". Materials Science Forum 893 (marzo 2017): 405–9. http://dx.doi.org/10.4028/www.scientific.net/msf.893.405.
Testo completoAbstract (sommario):
With high resolution, electronic speckle pattern interferometry (ESPI) technique can be useful in measuring full-filed deformation of laboratory specimens. In this study, ESPI was applied to measure the full-field displacements of mortar beam subjected to three-point bend. Load-displacement curves measured by ESPI were compared to that measured by clip gauge and LVDTs. Satisfactory agreement was observed in all the comparisons, demonstrating the effectiveness and accuracy of ESPI measurement. Furthermore, load versus crack tip opening displacement curve was obtained from ESPI results. Finally, extent of the fracture process zone and neutral axis of the mortar beam were analyzed based on full-filed displacement contour measured by ESPI.
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Ahmad, Mahmood, Maaz Amjad, Ramez Al-Mansob, Paweł Kamiński, Piotr Olczak, Beenish Khan e Arnold Alguno. "Prediction of Liquefaction-Induced Lateral Displacements Using Gaussian Process Regression". Applied Sciences 12, n. 4 (14 febbraio 2022): 1977. http://dx.doi.org/10.3390/app12041977.
Testo completoAbstract (sommario):
During severe earthquakes, liquefaction-induced lateral displacement causes significant damage to designed structures. As a result, geotechnical specialists must accurately estimate lateral displacement in liquefaction-prone areas in order to ensure long-term development. This research proposes a Gaussian Process Regression (GPR) model based on 247 post liquefaction in-situ free face ground conditions case studies for analyzing liquefaction-induced lateral displacement. The performance of the GPR model is assessed using statistical parameters, including the coefficient of determination, coefficient of correlation, Nash–Sutcliffe efficiency coefficient, root mean square error (RMSE), and ratio of the RMSE to the standard deviation of measured data. The developed GPR model predictive ability is compared to that of three other known models—evolutionary polynomial regression, artificial neural network, and multi-layer regression available in the literature. The results show that the GPR model can accurately learn complicated nonlinear relationships between lateral displacement and its influencing factors. A sensitivity analysis is also presented in this study to assess the effects of input parameters on lateral displacement.
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Chen, Ruijun, e Daniel F. Baldwin. "Displacement Theory for Fixturing Design of Thin Flexible Circuit Board Assembly". Journal of Electronic Packaging 123, n. 4 (1 novembre 2000): 388–93. http://dx.doi.org/10.1115/1.1371926.
Testo completoAbstract (sommario):
The compliant nature of flexible substrates subject to assembly forces can result in severe misregistration of the component leads and substrate bond pads, leading to assembly process defects. Specially dedicated tooling for fixturing thin flexible substrates in standard surface mount assembly equipment is gaining importance. This paper focuses on developing a theoretical foundation for implementing Smart Tooling of fixturing thin flexible substrates. The primary goals are to determine the impact of fixturing tooling on assembly process quality, to develop a displacement theory to predict transverse displacements, and to analyze the optimum perimeter fixturing configuration. The predictive capabilities of the transverse displacement model are verified.
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Zabulionis, Darius, Ona Lukoševičienė, Rimantas Kačianauskas, Liudas Tumonis e Romualdas Kliukas. "Stochastic Lattice Modelling of the Force-Displacement and Cracking Behaviour of the Steel Reinforced Tie". Mathematical Problems in Engineering 2019 (10 aprile 2019): 1–17. http://dx.doi.org/10.1155/2019/6340656.
Testo completoAbstract (sommario):
The stochastic modelling of the microcracking and the force-displacement behaviour of the tensile steel reinforced tie using the lattice model is presented in the current article. The three-dimension problem of the modelling of the tie is reduced to the two-dimensional so as the main stiffness parameters of the concrete and the reinforcement of the two-dimensional model would be the same as for the three-dimensional. The concrete and steel obey the Hook law. All elastic constants, as well as dimensions of the tie, were assumed as the deterministic quantities except for the critical concrete tensile strains which were treated as a two-dimensional stationary uncorrelated truncated Gaussian random field. The discrete element approach and the explicit integration scheme have been used for the modelling. The estimations of the main parameters of the force-displacement behaviour stochastic process and other statistical indexes were obtained using 72 realization of the force-displacement behaviour of a chosen model. Extra two stochastic realizations of the two different models, as well as three deterministic models, were modelled to compare stochastic and deterministic behaviour of the force-displacement behaviour. The analysis showed that the force-displacement behaviour of the tie under tensile force cannot be treated as a Gaussian stochastic process when the p value is 0.05 at the small displacements and within the interval when the cracking of the concrete is very intensive. However, at the bigger displacements, when the cracking becomes less intensive, the tensile force can be treated as a Gaussian random variable.
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Ocheje, Paul D. "Legalizing Displacement". Journal of Asian and African Studies 32, n. 1-2 (1997): 120–33. http://dx.doi.org/10.1163/15685217-90007286.
Testo completoAbstract (sommario):
As developments in Nigeria have demonstrated, law and the legal order can be manipulated in order to sustain the state and a section of the society at the expense of the general public. This process was imposed on the people of Nigeria under the guise of promoting development. Although development projects have been elaborately supported by the law, the effect on the welfare of the people has been largely negative. Rather than promoting progress, projects have led to the displacement of vast numbers of Nigerians from their familiar habitat. Law and the legal order have been used by the state to sustain itself at the expense of the people and therefore have had the effect of perpetuating injustice. As this situation makes clear, law can be an agent of both progress and retrogression, depending on whether the state is oriented towards protecting the people in general or in promoting the interests of a particular class. The Nigerian state has clearly had the latter objective in mind.
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Pan, Wen Jun, Xian Guo Ye e Lei Chang. "Application of QR Method for Analysis of Spatial-Mega Frame Structure". Advanced Materials Research 243-249 (maggio 2011): 6049–52. http://dx.doi.org/10.4028/www.scientific.net/amr.243-249.6049.
Testo completoAbstract (sommario):
With the generalized displacement parameters of spline knots chosen as basic unknowns, the node displacement functions of spatial mega frames were built up, then element node displacements could be expressed by these parameters. New stiffness equation of spatial mega frame was deduced according to energy variational principle. The nodal displacement and nodal forces were worked out by the displacement parameters of spline knots. Process of block assembling for spline-discretization matrix was introduced briefly. One spatial mega frame was calculated by QR method and different finite element softwares. Comparation among the results and those of references proves that QR method is exactly an economical, effective and reliable method for computation of spatial mega frames. It provides a new approach for simplified calculation to spatial mega structures, so has good theoretical and practical value.
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Pender, Daniel. "Suspensory Tethers and Critical Point Membrane Displacement in Endolymphatic Hydrops". International Archives of Otorhinolaryngology 22, n. 03 (25 luglio 2017): 214–19. http://dx.doi.org/10.1055/s-0037-1604474.
Testo completoAbstract (sommario):
Introduction Grossly displaced membranes are characteristic of endolymphatic hydrops. The process whereby physiological membrane displacement becomes pathological may be mediated by stress, but the membrane biomechanics underlying this transition are unclear. Objective This study seeks to determine the role of suspensory tethers during pressure-induced membrane displacement in the generation of the membranous lesions seen in this disease entity using a biomechanical model approach. Methods The location of membrane suspensory tethers was identified histologically. The influence of tethers on model membrane configuration during displacement was assessed graphically. The relationship of membrane configuration during displacement to curvature radius was quantified trigonometrically. The relationship of curvature radius to stress susceptibility was determined mathematically. The net effect of suspensory tethers on membrane stress levels for various degrees of membrane distention and displacement was then calculated numerically. Results In the inferior labyrinth, suspensory tethers are found to occur on the membranes' boundaries. Such tethering is found to impose a biphasic effect on membrane curvature with increasing degrees of displacement. As a consequence, tensile stress susceptibility is found to decline with initial membrane displacement to a critical point nadir beyond which stress then increases monotonically. No such effect was found for the superior labyrinth. Conclusion Boundary tethers in the inferior labyrinth are associated with significant tensile stress reductions until a critical point of membrane displacement is reached. Displacements short of the critical point may be physiological and even reversible, whereas such displacements beyond the critical point are apt to be overtly hydropic and irreversible.
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Wang, Zhi-Feng, Xing-Bin Peng, Yong Liu, Wen-Chieh Cheng, Ya-Qiong Wang e Chao-Jun Wu. "Evaluation of Ground Displacements Caused by Installing Jet Grouted Columns Using Machine Learning Methods". Advances in Civil Engineering 2020 (21 settembre 2020): 1–11. http://dx.doi.org/10.1155/2020/8857293.
Testo completoAbstract (sommario):
During the jet grouting process, large volumes of high pressurized fluids injected into the soils will cause significant ground displacements, which may bring harmful impacts on surrounding environment. Therefore, it is essential to provide an accurate estimation of the ground displacement in the design stage. Based on multiple nonlinear regression (MNLR) and support vector regression (SVR), the prediction approaches are established, respectively. The column radius (Rc), Young’s modulus (E), and distance from column center to target point (LOA) are selected as the input parameters, while the displacement of target point A at the radial direction (δA) is taken as the output parameter. Comparisons results on the prediction performance of ground displacements indicate that the MNLR-based approach has a better prediction effect. The design charts of the MNLR-based approach for predicting the ground displacement are created, which will be helpful for the practicing engineers to get a quick estimation.
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Adamcová, Dana, Stanislav Bartoň, Piotr Osinski, Grzegorz Pasternak, Anna Podlasek, Magdalena Daria Vaverková e Eugeniusz Koda. "Analytical Modelling of MSW Landfill Surface Displacement Based on GNSS Monitoring". Sensors 20, n. 21 (22 ottobre 2020): 5998. http://dx.doi.org/10.3390/s20215998.
Testo completoAbstract (sommario):
Displacements of landfills play an important role in the reclamation process and geotechnical safety improvement of such sites. Landfill settlements are defined as a vertical displacement of waste body due to compression, degradable nature of the waste, and creep phenomenon of the waste particles. Waste composition is more diverse than natural soil. Thus, it has to be properly placed and compacted since the landfill body will continuously settle down. Several models of the landfill displacement estimation have already been developed. The aim of the present study was: (i) to review the methods of landfill settlements computation and (ii) to propose the model allowing landfill body displacements simulation based on monitoring datasets applying a Global Navigation Satellite Systems (GNSS) measurement. The new model employs Gauss-Newton iteration and Runge-Kutta methods to estimate landfill surface displacements. The objectives were to analyse and mathematically describe the landfill body displacements. The GNSS geodetic survey and computations allowed concluding that the landfill body has been transformed over the years. The results revealed that the curves of waste displacement are in agreement with the measured total displacement of the landfill, and all curves corresponding to waste displacement are perpendicular to the active edge of the landfill. In the period of a maximum of 4.5 years after the waste deposition with a layer of up to 16.2 m thickness, the phenomenon of expansion was observed, which then disappears, and more settlement occurs due to the gravity of upper layers. The analysed landfill as a whole does not experience significant displacements. Neither of the slope failures are observed, even for large inclination.
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Li, Yinshan, Xinye Li, Chen Xie e Shuhao Huo. "Explicit Solution to Large Deformation of Cantilever Beam by Improved Homotopy Analysis Method II: Vertical and Horizontal Displacements". Applied Sciences 12, n. 5 (28 febbraio 2022): 2513. http://dx.doi.org/10.3390/app12052513.
Testo completoAbstract (sommario):
Explicit solutions to vertical and horizontal displacements are derived for large deformation of a cantilever beam under point load at the free end by an improved homotopy analysis method (IHAM). Quadratic and cubic nonlinear differential equations are adopted to construct more proficient nonlinear equations for vertical and horizontal displacements respectively combined with their currently available nonlinear displacement equations. Higher-order nonlinear iterative homotopy equations are established to solve the vertical and horizontal displacements by combining simultaneous equations of the constructed nonlinear equations and the auxiliary linear equations. The convergence range of vertical displacement is extended by the homotopy-Páde approximation. The explicit solutions to the vertical and horizontal displacements are in favorable agreements with the respective exact solutions. The convergence ranges for a relative error of 1% by the improved homotopy analysis method for vertical and horizontal displacements increases by 60% and 7%, respectively. These explicit formulas are helpful in practical engineering design for very slender structures, such as high-rise buildings and long bridges.
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Khalili, Khalil, S. Ehsan Eftekhari Shahri, Parviz Kahhal e M. Soheil Khalili. "Wrinkling Study in Tube Hydroforming Process". Key Engineering Materials 473 (marzo 2011): 151–58. http://dx.doi.org/10.4028/www.scientific.net/kem.473.151.
Testo completoAbstract (sommario):
Tube Hydroforming Process (THF) is heavily affected by the pressure-displacement diagram, and adjustment of the raw tube. Three common defects of the process are bursting, buckling and wrinkling. In this work, the leading conditions to wrinkling defect have been studied. Proper criteria are required to predict wrinkling condition, and to quantify wrinkling when subjected to various pressure-displacement diagrams. A variety of criteria have been presented by researchers, most of which are suitable to a specific geometry. In current work, two criteria are considered namely, the strain difference and the radius velocity. At first an accurate FEM (Finite Element Model) model of the process have been established and validated. Then based on a number of experiments with different diagram, the process have been simulated and analyzed. According to experiments imbalances between pressure and displacement, improper sitting of tube in the die, poor vacation of the tube and the existence of external tiny particle inside the die, are the reason of wrinkling criterion in the tube. The Response Surface Method (RSM) has been used to model the responses from the finite element analysis. The behavior of the process has been predicted using this model.
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Zhan, Feng Lin, e Ping Ye. "ANSYS Simulating Analysis of a 3D High-Temperature Stope Reinforced in Advance with Fully Grouted Cable Bolts". Applied Mechanics and Materials 170-173 (maggio 2012): 525–28. http://dx.doi.org/10.4028/www.scientific.net/amm.170-173.525.
Testo completoAbstract (sommario):
By using ANSYS, 3D high-temperature stope models based on the in-situ experiment of reinforcement with fully grouted cable bolts in the test stope hangingwall of Dongxiang Copper Mine are established and analyzed. Results show that both displacements of ground surface and stope hangingwall are in their allowable scopes. The surrounding rock rising displacement caused by heated rock expansion can partly or fully offset the subsidence displacement caused by gravity. Hangingwall rising displacement occurs if stope temperature is equal to or greater than 100°C. Mining is safe if stope temperature is equal to or less than 500°C. The stope hangingwall anchoring parameters can meet the requirements of surrounding rock stability in the process of extraction.
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Egermann, Patrick, Michel Robin, Jean-Marc N. Lombard, Cyrus A. Modavi e Mohammed Z. Kalam. "Gas Process Displacement Efficiency Comparisons on a Carbonate Reservoir". SPE Reservoir Evaluation & Engineering 9, n. 06 (1 dicembre 2006): 621–29. http://dx.doi.org/10.2118/81577-pa.
Testo completoAbstract (sommario):
Summary Secondary- and tertiary-recovery processes based on gas injection can extend the life of waterflooded reservoirs by maximizing the oil recovery. However, the injection strategy needs to be studied carefully to optimize the overall sweep efficiency. In particular, the impact of possible water blocking on the recovery has to be addressed. For that purpose, a series of experiments was performed under reservoir conditions on a carbonate rock type to compare the displacement efficiencies of a secondary gas injection, a tertiary gas injection, and a simultaneous water-alternating-gas (SWAG) injection. The experiments were carried out on composite cores consisting of several carefully selected reservoir core plugs of the chosen rock type. The operating pressure was lower than the minimum miscible pressure (MMP) and reflected the current reservoir pressure. Phase exchanges were monitored continually during the hydrocarbon recovery, including the chromatographic analysis of the produced gas. The final oil recovery resulting from the three types of experiments was very good [approximately 90% original oil in place (OOIP) at surface conditions after 6 pore-volume (PV) injection] and quite similar within the expected experimental error, regardless of the sequence of gas injection. The low remaining oil saturation (ROS) values observed were consistent with competing processes of both viscous displacement of oil by gas and phase exchanges occurring between oil and gas. Because of the nature of the injected gas (rich gas from the first separation stage), a condensing/vaporizing process had to be considered. The SWAG injection speeds up the oil recovery by mobility control of the water phase. This enhances the sweep efficiency by viscous drive. A water-blocking effect was found to be negligible because it could be anticipated due to wettability consideration. The influence of the fluid description (equation of state, or EOS) and the three-phase relative permeability model on the simulation results was studied. An excellent agreement between simulation and production data was obtained with both gas/oil relative permeability data measured at ambient conditions on a restored composite core and an appropriate EOS (with seven pseudos). The condensing/vaporizing process that strips the intermediate compounds from the oil phase to the gas phase was properly taken into account with this appropriate EOS. The influence of the three-phase permeability model (either "geometrical construction" or Stone1) on the results was found to be small. Introduction For enhanced oil recovery (EOR) purposes, miscible or immiscible hydrocarbon gas injections have been applied successfully in many oil reservoirs throughout the world (Thomas et al. 1994; Lee et al. 1988). Compared to water injection, gas injection is associated with higher microscopic displacement efficiency due to the low value of the interfacial tension (IFT) between the oil and gas phases. IFT tends toward zero when miscibility is reached, which means that the oil recovery can be total in the swept area. Even when miscibility is not reached, the mass-transfer mechanisms that occur between oil and gas phases lead to low IFT values when compared to waterflooding. Even under those conditions, regarding remaining oil-saturation values, gas injection appears to be an interesting recovery process.