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Hanlong Liu - One of the best experts on this subject based on the ideXlab platform.
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Finite element analyses of negative skin friction on a single pile
Acta Geotechnica, 2012Co-Authors: Jinyuan Liu, Hongmei Gao, Hanlong LiuAbstract:This paper presents finite element analyses of negative skin friction on a single pile under various conditions. Negative skin friction is a common problem if a pile is designed in a highly compressible soil. There are two most important parameters in estimating the load caused by negative skin friction: (1) the distribution and magnitude of skin friction and (2) the location of the neutral plane. The neutral plane is the location where the pile and soil settle the same amount or have no relative displacement. Negative skin friction is a very complex phenomenon influenced by many factors. In this paper, a two-dimensional axisymmetric model is built in the finite element program, ABAQUS. The model is first verified with a known case history. A systematic parametric analysis is performed to investigate the influence on both the neutral plane and the magnitude and distribution of negative skin friction along the pile length of various influencing factors, including the Consolidation Time, the properties of pile/soil interface, the lateral earth pressure coefficient, pile-soil limiting displacement, the intensity of surcharge, and soil stiffness. Based on the analyses, it is found that the location of the neutral plane is significantly influenced by the Consolidation Time and the stiffness of bearing layer. The distribution and magnitude of negative skin friction is influenced mainly by the pile/soil interface, soil compressibility, and the surcharge intensity. Based on the field measurements from literature and this investigation, a simple design procedure is proposed for estimating the pile load caused by negative skin friction.
Chaoxiong Ye - One of the best experts on this subject based on the ideXlab platform.
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working memory capacity affects trade off between quality and quantity only when stimulus exposure duration is sufficient evidence for the two phase model
Scientific Reports, 2019Co-Authors: Chaoxiong Ye, Qianru Xu, Tengfei Liang, Yin ZhangAbstract:The relation between visual working memory (VWM) capacity and attention has attracted much interest. In this study, we investigated the correlation between the participants' VWM capacity and their ability to voluntarily trade off the precision and number of items remembered. The two-phase resource allocation model proposed by Ye et al. (2017) suggests that for a given set size, it takes a certain amount of Consolidation Time for an individual to control attention to adjust the VWM resources to trade off the precision and number. To verify whether trade-off ability varies across VWM capacity, we measured each individual's VWM capacity and then conducted a colour recall task to examine their trade-off ability. By manipulating the task requirement, participants were instructed to memorise either more colours in a low-precision way or fewer colours in a high-precision way. We conducted two experiments by adjusting stimulus duration to be longer than predicted critical value (Experiment 1) and duration shorter than predicted critical value (Experiment 2). While the results of Experiment 1 showed a positive correlation between the VWM capacity and trade-off ability, the results of Experiment 2 showed a lack of such correlation. These results are consistent with the prediction from the two-phase model.
Mohammed Saedi Jami - One of the best experts on this subject based on the ideXlab platform.
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constant pressure expression of power law non newtonian fluid solid mixture
Journal of The Taiwan Institute of Chemical Engineers, 2019Co-Authors: Masashi Iwata, Takayuki Shimo, Takanori Tanaka, Mohammed Saedi JamiAbstract:Abstract Expression of non-Newtonian fluid/solid mixture is often encountered in the fields of polymer and food industries. However, a reliable method for the design of the expression process has not been established. In this study, we conducted expression experiments of power law non-Newtonian fluid/solid mixture under constant pressure condition. The basic Consolidation equation was derived by combining the fundamental equation for power law non-Newtonian flow through the cake with the equation of continuity and solved numerically using the Runge–Kutta method. The progress of the expression is represented by an average Consolidation ratio Uc. The agreement between calculated and experimental Uc was satisfactory when the creep deformation of the material was taken into consideration. It was also elucidated that the Consolidation Time required for attaining a certain degree of primary Consolidation depends on the (N + 1)/N-th power of the total volume of the solid material ω0, where N is the flow behavior index of the squeezed liquid. On the other hand, the creep constants B, the ratio of creep deformation to the total deformation, and η, a measure of the rate of creep deformation, both were found to be ω0-independent parameters, supporting the validity of the assumption made in the theoretical derivation.
Hueiwen Chang - One of the best experts on this subject based on the ideXlab platform.
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secondary compression behavior in one dimensional Consolidation tests
Journal of GeoEngineering, 2012Co-Authors: Toshihiko Takeda, Motohiro Sugiyama, Masaru Akaishi, Hueiwen ChangAbstract:One-dimensional Consolidation analysis is described for predicting the Consolidation Time curves of clay exhibiting secondary compression during primary Consolidation. The constitutive soil model is based on the equation governing the secondary compression rate of the decrease in void ratio. This model uses four parameters, namely, Cc, * c C , Cα and * v c , that can be easily determined or assumed from incremental loading (IL) oedometric Consolidation tests. In order to be certain of the correct proposed soil model, the Consolidation Time curves observed in oedometer specimens are compared against those predicted by the analysis. A satisfactory agreement between the computed behaviors and oedometer observations would indicate the correct assumption. In addition, it is shown that the void ratio rate ( s e�) due to secondary compression during primary Consolidation varies by approximately 10 2~3 Times as much as its final value before the application of the next loading increment.
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initial rates of secondary compression in one dimensional Consolidation analysis
Proceedings of the School of Engineering of Tokai University, 2010Co-Authors: Toshihiko Takeda, Motohiro Sugiyama, Masaru Akaishi, Hueiwen ChangAbstract:The finite difference analysis of one-dimensional Consolidation of clays, exhibiting large amounts of secondary compression during primary Consolidation, provide fairly good predictions of the Consolidation-Time curve for oedometer specimens with different heights. Some parameters including the initial rate of secondary compression defined by primary Consolidation in this analysis have been assumed to avoid experimental difficulty. The trial and error calculation procedure was therefore used where the calculated Consolidation-Time curves fit the observed ones. Finally, it is emphasized that the assumption for unknown secondary compression behaviors during primary Consolidation has a predominant influence on the Consolidation-Time curve.
Matija Krkovic - One of the best experts on this subject based on the ideXlab platform.
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management of post traumatic femoral defects with a monorail external fixator over an intramedullary nail
European Journal of Orthopaedic Surgery and Traumatology, 2021Co-Authors: James Zhang, Andrew Kailin Zhou, Matija KrkovicAbstract:Purpose The management of limb-length discrepancy secondary to traumatic femoral bone loss poses a unique challenge for surgeons. The Ilizarov technique is popular, but is associated with long external fixator Time and many complications. This retrospective study assessed outcomes of post-traumatic femoral defects managed by monorail external fixation over an intramedullary nail. Methods Eight patients were included from October 2015 to May 2019 with post-traumatic femoral defects that underwent treatment with monorail fixator-assisted intramedullary nailing. Primary outcome was Time to bone union and bone results according to ASAMI classification. Secondary outcomes were lengthening index, Consolidation Time and index, external fixator index (EFI), Time to partial weight bearing(PWB) and full weight bearing (FWB), and complications. Patient reported outcome measures including EQ-5D-5L, SF-36, Oxford knee scores (OKS), and Oxford hip scores (OHS) were recorded after recovery. Results Mean follow-up Time was 227 weeks. Average bone defect size was 9.69 cm. Average Consolidation Time and index were 11.35 months and 1.24 months/cm, respectively. Mean lengthening and external fixator index were 20.2 days/cm and 23.88 days/cm, respectively. On average, patients achieved FWB and bone union 56.25 weeks and 68.83 weeks after bone transport initiation, respectively. Two patients had docking site non-union, five patients had pin site infections, and two patients had osteomyelitis. EQ-5D-5L and EQ-VAS scores were compared to UK population norms (p = 0.104, p = 0.238, respectively). Average OKS was 32.17 and OHS was 34.00. Conclusion Monorail external fixation over an intramedullary nail is an effective option for post-traumatic femoral defects, reducing external fixator Time and returning patients' quality of life to a level comparable with the normal population.
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Bone transport with magnetic intramedullary nails in long bone defects
European Journal of Orthopaedic Surgery & Traumatology, 2020Co-Authors: Selina Summers, Matija KrkovicAbstract:Background This study describes the outcomes of internal bone transport with magnetic nails in five cases of traumatic segmental femoral bone defects. Methods Five patients with open fracture of the femur and diaphyseal bone loss were included between May 2018 and August 2020. The mean femoral defect was 8.7 cm (range 5.6–16.0). Intervention We used plate-assisted bone segment transport (PABST) with PRECICE magnetic nails. Results All five patients have fully consolidated. The mean Consolidation Time and index were 7.5 months and 0.8 mo/cm, respectively. The mean follow-up was 21.3 months. The main complications were reduced knee ROM, mild varus deformity and plate bending. Post-operative SF-36, Oxford Knee scores and ED-5Q-5L scores were also compiled for four of five patients. SF-36 and Oxford Knee scores were reported without pre-injury data for comparison. ED-5Q-5L index and VAS were compared UK population norm and were both found to be statistically insignificant ( p = 0.071 and p = 0.068, respectively). Conclusion Bone transport with magnetic nails has the capacity to obtain good functional recovery in long bone defects despite variable outcome pictures. In response to variable outcome reporting in the literature, we propose a standard reporting template for future studies to facilitate more rigorous analyses.