Analysis of edge impact stresses in composite plates

The in-plane edge impact of composite plates, with or without a protection strip, is investigated. A computational analysis based on the Fast Fourier Transform technique is presented. The particular application of the present method is in the understanding of the foreign object damage problem of composite fan blades. The method is completely general and may be applied to the study of other stress wave propagation problems in a half space. Results indicate that for the protective strip to be effective in reducing impact stresses in the composite the thickness must be equal or greater than the impact contact dimension. Large interface shear stresses at the strip - composite boundary can be induced under impact

The climate change double whammy: Flood damage and the determinants of flood insurance coverage, the case of post-Katrina New Orleans

This paper advances scholarly debate on the contradictions of environmental risk management measures by analyzing the determinants of flood insurance coverage among a sample of 403 residents in New Orleans, a city undergoing rapid transformation due to post-Katrina rebuilding efforts and anthropogenic modifications of climate, hydrology, and ecology. The paper focuses on several predictors including subjective flood risk perception, trust in government officials, sociodemographic characteristics, and experience with flood damage. Using binary logistic regression, the results show that the likelihood of having flood insurance coverage is associated with past flood damage and socioeconomic status. Older people (over age 65) are more likely to have flood insurance than younger residents. Race, gender, trust, and perceived flood risk are not statistically significant predictors of flood insurance. We connect our findings to the paradoxes and conflictual dynamics of flood insurance, a major risk mitigation measure. As we point out, in flood-prone cities like New Orleans, flood insurance operates as a double whammy: uninsured or underinsured homes face pervasive risk of both flooding and rising insurance premiums under the conditions of global climate change

Reentrant Melting of Soliton Lattice Phase in Bilayer Quantum Hall System

At large parallel magnetic field $B_\parallel$, the ground state of bilayer quantum Hall system forms uniform soliton lattice phase. The soliton lattice will melt due to the proliferation of unbound dislocations at certain finite temperature leading to the Kosterlitz-Thouless (KT) melting. We calculate the KT phase boundary by numerically solving the newly developed set of Bethe ansatz equations, which fully take into account the thermal fluctuations of soliton walls. We predict that within certain ranges of $B_\parallel$, the soliton lattice will melt at $T_{\rm KT}$. Interestingly enough, as temperature decreases, it melts at certain temperature lower than $T_{\rm KT}$ exhibiting the reentrant behaviour of the soliton liquid phase.Comment: 11 pages, 2 figure

Remote participation during glycosylation reactions of galactose building blocks: Direct evidence from cryogenic vibrational spectroscopy

The stereoselective formation of 1,2‐cis‐glycosidic bonds is challenging. However, 1,2‐cis‐selectivity can be induced by remote participation of C4 or C6 ester groups. Reactions involving remote participation are believed to proceed via a key ionic intermediate, the glycosyl cation. Although mechanistic pathways were postulated many years ago, the structure of the reaction intermediates remained elusive owing to their short‐lived nature. Herein, we unravel the structure of glycosyl cations involved in remote participation reactions via cryogenic vibrational spectroscopy and first principles theory. Acetyl groups at C4 ensure α‐selective galactosylations by forming a covalent bond to the anomeric carbon in dioxolenium‐type ions. Unexpectedly, also benzyl ether protecting groups can engage in remote participation and promote the stereoselective formation of 1,2‐cis‐glycosidic bonds