Finite Element Investigation on Load Carrying Capacity of Corroded RC Beam Based on Bond-Slip

The finite element (FE) investigation on the load carrying capacity of corroded RC beam is carried out based on the bond-slip between the steel bars and concrete. In the numerical simulation, several FE models of RC simply supported beam with different corrosion ratios were built using ANSYS. In these FE models, element of Solid65 was used to simulate concrete, element of Link8 was used for bars and element of Combin39 was adopted to simulate the bond and bond-slip between bars and concrete. The effect of corrosion ratio on bonding force between bars and concrete was simulated by adjusting the parameter of Combin39. Besides, the reduction of bars section area and decrease of bars yielding stress were also considered for calculating the load carrying capacity of corroded RC beam with different corrosion ratios. The results show that as the corrosion ratio increases the stiffness of corroded beam would decrease, slip between bars and concrete would be larger and ductile failure of RC beam would turn to brittle failure. The load carrying capacity of corroded RC beam would obviously deteriorate and descending speed is the fastest when the corrosion rate falls in the range of 4%-7%

Asymptotic preserving and uniformly unconditionally stable finite difference schemes for kinetic transport equations

In this paper, uniformly unconditionally stable first and second order finite difference schemes are developed for kinetic transport equations in the diffusive scaling. We first derive an approximate evolution equation for the macroscopic density, from the formal solution of the distribution function, which is then discretized by following characteristics for the transport part with a backward finite difference semi-Lagrangian approach, while the diffusive part is discretized implicitly. After the macroscopic density is available, the distribution function can be efficiently solved even with a fully implicit time discretization, since all discrete velocities are decoupled, resulting in a low-dimensional linear system from spatial discretizations at each discrete velocity. Both first and second order discretizations in space and in time are considered. The resulting schemes can be shown to be asymptotic preserving (AP) in the diffusive limit. Uniformly unconditional stabilities are verified from a Fourier analysis based on eigenvalues of corresponding amplification matrices. Numerical experiments, including high dimensional problems, have demonstrated the corresponding orders of accuracy both in space and in time, uniform stability, AP property, and good performances of our proposed approach

Description of the newly observed Ξc0\Xi_c^{0} states as molecular states

Very recently, three new structures $\Xi_c(2923)^0$, $\Xi(2938)^0$, and $\Xi(2964)^0$ at the invariant mass spectrum of $\Lambda_c^{+}K^{-}$ observed by the LHCb Collaboration triggers a hot discussion about their inner structure. In this work, we study the strong decay mode of the newly observed $\Xi_c$ assuming that the $\Xi_c$ is a $\bar{D}\Lambda-\bar{D}\Sigma$ molecular state. With the possible quantum numbers $J^p=1/2^{\pm}$ and $3/2^{\pm}$, the partial decay widths of the $\bar{D}\Lambda-\bar{D}\Sigma$ molecular state into the $\Lambda_c^{+}K^{-}$, $\Sigma_c^{+}K^{-}$,and $\Xi_c^{+}\pi^{-}$ final states through hadronic loop are calculated with the help of the effective Lagrangians. By comparison with the LHCb observation, the current results of total decay width support the $\Xi(2923)^0$ as $\bar{D}\Lambda-\bar{D}\Sigma$ molecule while the decay width of the $\Xi_c(2938)^0$ and $\Xi(2964)^0$ can not be well reproduced in the molecular state picture. In addition, the calculated partial decay widths with $S$ wave $\bar{D}\Lambda-\bar{D}\Sigma$ molecular state picture indicate that allowed decay modes, $\Xi_c^{+}\pi^{-}$, may have the biggest branching ratios for the $\Xi_c(2923)$. The experimental measurements for this strong decay process could be a crucial test for the molecule interpretation of the $\Xi_c(2923)$.Comment: arXiv admin note: text overlap with arXiv:1002.0218 by other author

Anti-jamming of Inverse Synthetic Aperture Radar based on Slope-varying Linear Frequency Modulation Signal

Deceptive jamming technology against inverse synthetic aperture radar is matured now, which is meaningful in military application. But the research on anti-jamming technology for inverse synthetic aperture radar (ISAR) is still not a mature technology. Through the analysis on the theory of deceptive jamming technology against ISAR, a new method for anti-jamming against ISAR based on linear frequency modulation signals frequency slope-varying is presented. The false target echo energy is suppressed due to frequency modulation slope mis-matching. Doppler domain averaging is adopted for improving the quality of the ISAR image, which helps automatic target recognition. Simulation result based on simulating data shows the validity of the new algorithm.Defence Science Journal, 2009, 59(5), pp.537-544, DOI:http://dx.doi.org/10.14429/dsj.59.155

CROSS CULTURAL VARIATION OF QUESTIONING IN NEWS INTERVIEWS – A CASE OF POST-QUESTION ELABORATION IN CHINESE NEWS INTERVIEWS

Questioning practice in news interviews has long been a central concern in the current studies of media discourse analysis in terms of its role in maintaining journalistic neutralism. Questions are usually structured into two forms: simple and complex one. In western news interviews, prefatory statements in complex questions are suffi ciently examined in previous studies. Drawing on Conversation Analysis as methodology, this paper examines the questioning practice of English news interviews (i.e., Dialogue) aired in Chinese context and captures the post-question elaboration as a noticeable variant particularity in questioning practice in Chinese news interviews. Post-question elaborations are recognized in terms of the formal features in question design and their functions in the interviewer-interviewee interaction and further categorized into three types: fi rst, post-question elaboration being evaded; second, post-question elaboration being answered along with the question; third, post-question elaboration being answered with question itself being evaded. This analysis reveals that post-question elaborations appear mostly to be associated with the informational contents negatively implicated in the question design and serve not only to contextualize the question itself but also to justify the act of questioning on the part of the interviewer