Numerical Behaviour of Composite K-Joints Subjected to Combined Loading and Corrosive Environment

[EN] Concrete filled steel tubular (CFST) truss structures have been adopted in various infrastructures worldwide for past several decades. Application of CFST truss is more prevalent especially in areas where harsh marine condition with chloride corrosion limits the design life of structures. Design of joints is one of the most complicated issues in CFST truss structures; and it becomes more critical when corrosion causes section loss in the outer steel tube. Improved designs in terms of economy and durability need to be suggested based on rational research on composite K-joints in corrosive environment, whilst such research is very limited up until now. This paper thus attempts to study the behaviour of circular concrete filled steel tubular (CFST) K-joints under combined effect of long-term loading and corrosion. A finite element analysis (FEA) model is presented and verified against existing test results. The model is then utilized to perform mechanism analysis of CFST K-joints under varying loading and corrosion situations. Failure modes, detailed propagation of yield and stress distribution between the core concrete in chord and the tubular steel is investigated, based on which a favourable mode of failure is suggested in terms of maximum joint capacity. Finally, a full range analysis of the load-deformation characteristics is carried out for various corrosion situations, with the corresponding joint strength as well as ductility predicted.Saleh, S.; Hou, C.; Han, L.; Hua, Y. (2018). Numerical Behaviour of Composite K-Joints Subjected to Combined Loading and Corrosive Environment. En Proceedings of the 12th International Conference on Advances in Steel-Concrete Composite Structures. ASCCS 2018. Editorial Universitat Politècnica de València. 557-564. https://doi.org/10.4995/ASCCS2018.2018.6974OCS55756

Low-lying excited states quantum entanglement and continuous quantum phase transitions: The criticality of a one-dimensional deconfined critical point

From the perspective of low-lying excited states, we study the deconfined quantum critical point (DQCP) in a one-dimensional quantum spin chain by means of the entanglement entropy and fidelity. Our results show that there is a close connection between the reconstruction of low-lying excitation spectra and the DQCP. The precise position of the critical point and its continuous nature is indicated by the singular behavior of the entanglement and fidelity of the first-excited state. Furthermore, compared with the Berezinskii-Kosterlitz-Thouless type phase transitions, which also go beyond the scope of Landau-Ginzburg-Wilson paradigm, we attempt to reveal the essence of different types of symmetries on both sides of the DQPT from different manifestations of entanglement singularity

Effects of Fatty Acid Treatments on the Dexamethasone-Induced Intramuscular Lipid Accumulation in Chickens

BACKGROUND: Glucocorticoid has an important effect on lipid metabolism in muscles, and the type of fatty acid likely affects mitochondrial utilization. Therefore, we hypothesize that the different fatty acid types treatment may affect the glucocorticoid induction of intramuscular lipid accumulation. METHODOLOGY/PRINCIPAL FINDINGS: The effect of dexamethasone (DEX) on fatty acid metabolism and storage in skeletal muscle of broiler chickens (Gallus gallus domesticus) was investigated with and without fatty acid treatments. Male Arbor Acres chickens (31 d old) were treated with either palmitic acid (PA) or oleic acid (OA) for 7 days, followed by DEX administration for 3 days (35-37 d old). The DEX-induced lipid uptake and oxidation imbalance, which was estimated by increased fatty acid transport protein 1 (FATP1) expression and decreased carnitine palmitoyl transferase 1 activity, contributed to skeletal muscle lipid accumulation. More sensitive than glycolytic muscle, the oxidative muscle in DEX-treated chickens showed a decrease in the AMP to ATP ratio, a decrease in AMP-activated protein kinase (AMPK) alpha phosphorylation and its activity, as well as an increase in the phosphorylation of mammalian target of rapamycin (mTOR) and ribosomal p70S6 kinase, without Akt activation. DEX-stimulated lipid deposition was augmented by PA, but alleviated by OA, in response to pathways that were regulated differently, including AMPK, mTOR and FATP1. CONCLUSIONS: DEX-induced intramuscular lipid accumulation was aggravated by SFA but alleviated by unsaturated fatty acid. The suppressed AMPK and augmented mTOR signaling pathways were involved in glucocortcoid-mediated enhanced intramuscular fat accumulation

Trajectory tracking and traction coordinating controller design for lunar rover based on dynamics and kinematics analysis

Trajectory tracking control is a necessary part for autonomous navigation of planetary rover and traction coordinating control can reduce the forces consumption during navigation. As a result, a trajectory tracking and traction coordinating controller for wheeled lunar rover with Rocker Bogie is proposed in the paper. Firstly, the longitudinal dynamics model and the kinematics model of six-wheeled rover are established. Secondly, the traction coordinating control algorithm is studied based on sliding mode theory with improved exponential approach law. Thirdly, based on kinematics analysis and traction system identification, the trajectory tracking controller is designed using optimal theory. Then, co-simulations between ADAMS and MATLAB/Simulink are carried out to validate the proposed algorithm, and the simulation results have confirmed the effectiveness of path tracking and traction mobility improving

Flat-Band Enhanced Antiferromagnetic Fluctuations and Unconventional Superconductivity in Pressurized CsCr3_3Sb5_5

The interrelationship between flat bands and correlated phenomena such as unconventional superconductivity stands as an intriguing subject in condensed matter physics. Here, by first-principles calculations and random phase approximation analyses, we investigate the electronic structure, superconducting instability, as well as roles of the incipient flat bands in kagome superconductor CsCr$_3$Sb$_5$. Our calculations reveal strong antiferromagnetic spin fluctuations in CsCr$_3$Sb$_5$, which mediates two sets of spin-singlet superconducting orders with $s_{\pm}$- and ($d_{xy}$, $d_{x^2-y^2}$)-wave symmetries. Under the dominance of local Coulomb interactions, the unoccupied incipient flat bands are shown to be crucial for the momentum dependence of spin fluctuations and thus the superconductivity. Our further analyses unveil a sublattice-momentum-coupling-driven mechanism for this momentum-dependent enhancement of the fluctuations, which provides us a new perspective for future studies of geometrically frustrated systems