585 research outputs found
Modelling and Validation of 3D FEM for Laterally Loaded Single Pile
At present, researchers are increasingly in favour of Three-Dimensional Finite Element Method (3D FEM) during design process to better understand ground mechanisms and soil-structure interactions. Subsequently, it is essentially a back-analysis modelling procedure for applications in design and post-construction or failure investigation. This research aims to use 3D FEM to validate laterally loaded single pile response. Two different case studies are selected, Firstly, a published case study comparing the p-y method and finite element method for the behaviour of single pile subjected to the horizontal forces is investigated. The second case is one of published centrifuge data and finite element method for the behaviour of pile behind retaining wall subjected to excavation-induced soil movement. Through comparison with the results from case studies, 3D FEM is in good agreement with the general trend observed in field or centrifuge measurements and gives better validation or prediction of lateral deflection characteristics compared to other conventional methods
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Non peer reviewe
Simulation of the deflected cutting tool trajectory in complex surface milling
Since industry is rapidly developing, either locally
or globally, manufacturers witness harder challenges due to
the growing competitivity. This urges them to better consider the four factors linked to production and output: quality, quantity, cost and price, quality being of course the most important factor which constitutes their main concern. Efforts will be concentrated—in this research—on improving the quality and securing more accuracy for a machined surface in ball-end milling. Quality and precision are two essential criteria in industrial milling. However, milling errors and imperfections, duemainly to the cutting tool deflection, hinder the full achieving of these targets. Our task, all along this paper, consists in studying and realizing the simulation of the deflected cutting tool trajectory, by using the methods which are available. In a future stage, and in the frame of a deeper
research, the simulation process will help to carry out the
correction and the compensation of the errors resulting from
the tool deflection. The corrected trajectory which is obtained by the method mirror will be sent to the machine. To achieve this goal, the next process consists—as a first step—in selecting a model of cutting forces for a ball-end mill. This allows to define—later on—the behavior of this tool, and the emergence of three methods namely the analytical model, the finite elements method, and the experimental method. It is possible to tackle the cutting forces simulation, all along the tool trajectory, while this latter is carrying out the sweeping of the part to be machined in milling and taking into consideration the cutting conditions, as well as the geography of the workpiece. A simulation of the deflected cutting tool trajectory dependent on the cutting forces has been realized
Phase Stability of Lead Phosphate Apatite PbCu(PO)O, PbCu(PO)(OH), and PbCu(PO)
Recently, Cu-substituted lead apatite LK-99 was reported to have
room-temperature ambient-pressure superconductivity. Here we utilize density
functional theory (DFT) total energy and harmonic phonon calculations to
investigate the thermodynamic and dynamic stability of two lead phosphate
apatites in their pure and Cu-substituted structures. Though
Pb(PO)O and Pb(PO)(OH) are found to be
thermodynamically stable (i.e., on the T=0K ground state convex hull), their
Cu-substituted counterparts are above the convex hull. Harmonic phonon
calculations reveal dynamic instabilities in all four of these structures.
Oxygen vacancy formation energies demonstrate that the addition of Cu dopant
substituting for Pb increases the likelihood of the formation of oxygen
vacancies on the anion site. We propose a new possible phase in this system,
PbCu(PO), where two monovalent Cu atoms are substituted for two
Pb(1) atoms and the anion oxygen is removed. We also propose several reaction
pathways for PbCu(PO)O and PbCu(PO), and found that
both of these two structures are likely to be synthesized under a 1:1 ratio of
reactants PbSO and CuP. Our work provides a thorough foundation for
the thermodynamic and dynamic stabilities of LK-99 related compounds and we
propose several possible novel synthesis reaction pathways and a new predicted
structure for future studies
Regulation of Adipose Tissue Stromal Cells Behaviors by Endogenic Oct4 Expression Control
BACKGROUND: To clarify the role of the POU domain transcription factor Oct4 in Adipose Tissue Stromal Cells (ATSCs), we investigated the regulation of Oct4 expression and other embryonic genes in fully differentiated cells, in addition to identifying expression at the gene and protein levels. The ATSCs and several immature cells were routinely expressing Oct4 protein before and after differentiating into specific lineages. METHODOLOGY/PRINCIPAL FINDINGS AND CONCLUSIONS: Here, we demonstrated the role of Oct4 in ATSCs on cell proliferation and differentiation. Exogenous Oct4 improves adult ATSCs cell proliferation and differentiation potencies through epigenetic reprogramming of stemness genes such as Oct4, Nanog, Sox2, and Rex1. Oct4 directly or indirectly induces ATSCs reprogramming along with the activation of JAK/STAT3 and ERK1/2. Exogenic Oct4 introduced a transdifferentiation priority into the neural lineage than mesodermal lineage. Global gene expression analysis results showed that Oct4 regulated target genes which could be characterized as differentially regulated genes such as pluripotency markers NANOG, SOX2, and KLF4 and markers of undifferentiated stem cells FOXD1, CDC2, and EPHB1. The negatively regulated genes included FAS, TNFR, COL6A1, JAM2, FOXQ1, FOXO1, NESTIN, SMAD3, SLIT3, DKK1, WNT5A, BMP1, and GLIS3 which are implicated in differentiation processes as well as a number of novel genes. Finally we have demonstrated the therapeutic utility of Oct4/ATSCs were introduced into the mouse traumatic brain, engrafted cells was more effectively induces regeneration activity with high therapeutic modality than that of control ATSCs. Engrafted Oct4/ATSCs efficiently migrated and transdifferentiated into action potential carrying, functionally neurons in the hippocampus and promoting the amelioration of lesion cavities
Performance studies of the Belle II Silicon Vertex Detector with data taken at the DESY test beam in April 2016
Belle II is a multipurpose detector currently under construction which will be operated at the next generation B-factory SuberKEKB in Japan. Its main devices for the vertex reconstruction are the Silicon Vertex Detector (SVD) and the Pixel Detector (PXD). In April 2016 a sector of the Belle II SVD and PXD have been tested in a beam of high energetic electrons at the test beam facility at DESY Hamburg (Germany). We report here the results for the hit efficiency estimation and the measurement of the resolution for the Belle II silicon vertex etector. We find that the hit efficiencies are on average above 99.5% and that the measured resolution is within the expectations
Performance studies of the Belle II Silicon Vertex Detector with data taken at the DESY test beam in April 2016
Belle II is a multipurpose detector currently under construction which will be operated at the next generation B-factory SuberKEKB in Japan. Its main devices for the vertex reconstruction are the Silicon Vertex Detector (SVD) and the Pixel Detector (PXD). In April 2016 a sector of the Belle II SVD and PXD have been tested in a beam of high energetic electrons at the test beam facility at DESY Hamburg (Germany). We report here the results for the hit efficiency estimation and the measurement of the resolution for the Belle II silicon vertex etector. We find that the hit efficiencies are on average above 99.5% and that the measured resolution is within the expectations
The Belle II SVD detector
The Silicon Vertex Detector (SVD) is one of the main detectors in the Belle II experiment at KEK, Japan. In combination with a pixel detector, the SVD determines precise decay vertex and low-momentum track reconstruction. The SVD ladders are being developed at several institutes. For the development of the tracking algorithm as well as the performance estimation of the ladders, beam tests for the ladders were performed. We report an overview of the SVD development, its performance measured in the beam test, and the prospect of its assembly and commissioning until installation
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