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ABSTRACT This study develops an efficient numerical homogenisation approach for meso-scale concrete samples with randomly generated and packed aggregates and pores. A simple algorithm is devised to discretize samples into [...]

ABSTRACT A procedure for generating two-dimensional heterogeneous meso-scale concrete samples is developed, in which the multi-phasic features including the shape, size, volume fraction and spatial distribution of aggregates and pores [...]

ABSTRACT This paper presents an analytical solution for predicting the full-range mechanical behaviour of grouted rockbolts in tension based on a realistic tri-linear bond-slip model with residual bond strength at [...]

Abstract The technique of bonding fibre reinforced polymer (FRP) composites to the tension face or sides of reinforced concrete (RC) beams has become very popular for strengthening or retrofitting purposes. [...]

Plasma disruption in tokamak experiments is a challenging issue that causes damage to the device. Reliable prediction methods are needed, but the lack of full understanding of plasma disruption limits the effectiveness of physics-driven methods. Data-driven methods based on supervised learning are commonly used, and they rely on labelled training data. However, manual labelling of disruption precursors is a time-consuming and challenging task, as some precursors are difficult to accurately identify. The mainstream labelling methods assume that the precursor onset occurs at a fixed time before disruption, which leads to mislabeled samples and suboptimal prediction performance. In this paper, we present disruption prediction methods based on anomaly detection to address these issues, demonstrating good prediction performance on J-TEXT and EAST. By evaluating precursor onset times using different anomaly detection algorithms, it is found that labelling methods can be improved since the onset times of different shots are not necessarily the same. The study optimizes precursor labelling using the onset times inferred by the anomaly detection predictor and test the optimized labels on supervised learning disruption predictors. The results on J-TEXT and EAST show that the models trained on the optimized labels outperform those trained on fixed onset time labels.

• User-defined element subroutines (UEL and VUEL) are developed in ABAQUS for the scaled boundary finite element method (SBFEM) for general stress analysis. • The ease-of-use and acceptability of the SBFEM are increased. • The developed UEL and VUEL are successfully validated by a few 2D and 3D problems for homogeneous and heterogeneous solids. • The results are compared favourably with FEM simulations in terms of accuracy and degrees of freedom. User-defined element subroutines (UEL and VUEL) in Fortran are developed in ABAQUS, to implement the Scaled Boundary Finite Element Method (SBFEM), for general static and elastodynamic stress analyses of solids. The purposes are twofold: to increase the ease-of-use and acceptability of this relatively new numerical method; and to combine advantages of both the SBFEM and ABAQUS, namely, the former's semi-analytical solutions and flexibility in domain discretization, and the latter's powerful linear and nonlinear solvers and pre/post-processing modules, for modelling complicated problems with higher accuracy and fewer degrees of freedom than the traditional FEM. Using the developed UEL and VUEL, a few 2D and 3D problems, including homogeneous solids with and without cracks, composites with inclusions of random shapes, XCT-image converted concrete mesoscale models, are simulated. The results are compared favourably with FEM simulations in terms of accuracy and degrees of freedom. [ABSTRACT FROM AUTHOR]

Via examining the option prices of seven actively traded stocks (IWM, MDY, QQQQ, SPY, GOOG, MSFT, QCOM, etc.) with a phenomenological approach, we report two important discoveries in this paper. We introduce the dimensionless parameters to express the relationships among them. The first one is that, for a given day, the option prices of a stock as a function of strike prices with the same expiry date can be empirically fitted by very simple elementary functions of the underlying security, the at-the-money (ATM) prices, and one fitting parameter. The second discovery is that, for a given day, the ATM price with various expiry dates can be empirically fitted to a power-law function of the time interval from the given day to the option expiry day. The application of these discoveries is briefly discussed.

Abstract: This paper presents an extension of the recently-developed finite element–scaled boundary finite element (FEM–SBFEM) coupled method to model multiple crack propagation in concrete. The concrete bulk and fracture process zones are modelled using SBFEM and nonlinear cohesive interface finite elements (CIEs), respectively. The CIEs are automatically inserted into the SBFEM mesh as the cracks propagate. The algorithm previously devised for single crack propagation is augmented to model problems with multiple cracks and to allow cracks to initiate in an un-cracked SBFEM mesh. It also addresses crack propagation from one subdomain into another, as a result of partitioning a coarse SBFEM mesh, required for some mixed–mode problems. Each crack in the SBFEM mesh propagates when the sign of the Mode-I stress intensity factor at the crack tip turns positive from negative. Its propagation angle is determined using linear elastic fracture mechanics criteria. Three concrete beams involving multiple crack propagation are modelled. The predicted crack propagation patterns and load–displacement curves are in good agreement with data reported in literature. [Copyright &y& Elsevier]

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Two different kinds of pits in InGaN/GaN MQWs were observed. They are generated by In atoms in the InGaN quantum well layers migrating in opposite directions, which may imply different mechanisms for the pit formation.

A comparative investigation on the possibility of hydroxyapatite (HA) coating and pure Ti column to form biological sealing with skin tissue was completed in this study. HA coating and pure Ti column were percutaneously implanted in the tibia of rabbits. Compared with titanium (Ti) implant, HA coating forms epithelial sealing with skin tissue at 6 weeks postoperatively, while the Ti implant may loosen from the implanted site and be lost. The Ti column loosing rate at this time was 50%. However, once the Ti implant becomes fixed with the bone tissue, it can form epithelial sealing with skin tissue just like the HA coating, at 8 weeks postoperatively. At 8 weeks postoperatively, the epithelial sealing is not destroyed in spite of the fact that the HA coating is biodegraded. Our results show that the HA coating can become fixed with the bone faster than the Ti, which is beneficial for epithelial sealing formation. The main role of HA coating for epithelial sealing is beneficial for sealing at the initial period after it is implanted.

On the basis of the Meissner effect and the London theory of superconductivity, we theoretically studied the interaction between a magnetic point dipole and a superconducting sphere. Furthermore, the force acting on the tip of a magnetic force microscope from a superconducting sphere was derived on the basis of the London theory of superconductivity. For a micro-system, we derived an analytical expression of the repelling forces as a function of the London penetration depth λ(T) and suggest an experimental method to measure λ(T) as a function of temperature T. From the model study, we show the invalidity of the frequency used image method for some superconductor-magnet systems.

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Background. We hypothesize that total parenteral nutrition (TPN) induces anorexia by an increase in anorexigenic cytokines (factors with central action via the hypothalamus) and tested this hypothesis by measuring changes in food intake and cytokines in response to TPN. Methods. Fischer rats with an internal jugular catheter and ad libitum food received saline solution for 10 days. On day 11, rats were randomized to TPN (G:F:AA=50:30:20) for 4 days (days 11 through 14); control rats received on saline solution for 5 days. On day 14, one half of the TPN group was switched back to saline solution for 1 day. Daily food intake was measured. On day 14 in one half of all rats and on day 15 in the remaining, tumor necrosis factor (TNF)-@a and interleukin (IL)-1@a were measured in plasma and cerebrospinal fluid (CSF). Spontaneous in vitro TNF-@a and IL-1@a were also measured in peripheral blood mononuclear cells. Results. With TPN, an 80% decrease (p<0.01) in food intake occurred; plasma TNF-@a increased (78+/-9 pg/ml vs undetectable; p<0.001), and IL-1@a was undetectable. Spontaneous in vitro TNF-@a and IL-1@a production were unchanged. Stoppage of TPN led to return toward normal of food intake and plasma TNF-@a. TNF-@a and IL-1@a in CSF were undetectable in both groups during and after TPN. Conclusion. Increase in plasma TNF-@a with no increase in CSF-TNF-@a during TPN, when food intake decreased, suggests an association between TPN and TNF-@a but not necessarily cause and effect.

Background. With the onset of eating, the associated rise of dopamine in the lateral hypothalamus (LHA-DA) is thought to regulate quantity of food consumed per meal. Early release of LHA-DA induced by eating is facilitated by oronasal stimulation; we propose that the subsequent LHA-DA response induced by nutrients in the portal vein is dampened by the innervated liver. This was tested by measuring LHA-DA in normal rats: during parenteral feeding to bypass oronasal stimulation, while eating during parenteral feeding, and while eating only. Methods. Rats had either total liver denervation or sham operation, with placement of a jugular vein catheter and LHA-DA microdialysis cannula. After a 3-week recovery period total liver denervated rats were randomized to parenterally fed, food only, and parenteral plus food groups each with sham-operated controls in which LHA-DA was measured. Results. No difference in LHA-DA release in food only groups occurred between total liver denervated or sham-operated rats. A significantly higher rise in LHA-DA was observed in total liver denervated versus sham-operated rats in parenterally fed (129%+/-4% versus 116%+/-2%; p<0.05) and parenteral plus food (151%+/-4% versus 134%+/-4%; p<0.05) groups. Conclusions. In total liver denervation versus sham operation, an increase in LHA-DA release occurs during parenteral feeding and eating during parenteral feeding, suggesting that innervated liver inhibits LHA-DA release.

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