Worcester Polytechnic Institute

About: Worcester Polytechnic Institute is a education organization based out in Worcester, Massachusetts, United States. It is known for research contribution in the topics: Population & Data envelopment analysis. The organization has 6270 authors who have published 12704 publications receiving 332081 citations. The organization is also known as: WPI.

Design‐Sensitivity analysis of Solids Using BEM

Abstract: This paper describes an effective formulation for computing design sensitivities required in the shape optimization of solid objects using the boundary element method (BEM). Implicit differentiation of the discretized boundary integral equations is performed, resulting in a general and efficient analysis technique for design sensitivities of all structural quantities. The numerical integration of kernels is performed, which involves the products of shape functions, fundamental solutions, and their derivatives required for sensitivity calculations. The sensitivities of all components of the boundary stress tensor are obtained without additional numerical integrations. High‐order elements with curved sides are employed for stress and sensitivity analysis. A multizone analysis is implemented and its computational advantages are studied. An approximate method for design sensitivity calculations is also suggested and its performance and computational economy relative to the exact procedure are presented. Compa...

Elastic anisotropy factors for orthorhombic, tetragonal, and hexagonal crystals

Abstract: Elastic anisotropy factors are derived for each of the three modes of propagation from the special in-plane phonon-focusing considerations arising when wave vectors are constrained to the symmetry planes of orthorhombic, tetragonal, and hexagonal crystals. Elastic anisotropy factors for the pure transverse and quasi-transverse modes depend upon the symmetry plane, whereas anisotropy factors for the quasilongitudinal mode depend both upon a symmetry plane and a symmetry axis. These anisotropy factors provide a convenient measure of in-plane phonon focusing.

Porous TiO2/C Nanocomposite Shells As a High-Performance Anode Material for Lithium-Ion Batteries

Abstract: Porous TiO2/C nanocomposite shells with high capacity, excellent cycle stability, and rate performance have been prepared. The synthesis involves coating colloidal TiO2 nanoshells with a resorcinol-formaldehyde (RF) layer with controllable thickness through a sol–gel-like process, and calcining the composites at 700 °C in an inert atmosphere to induce crystallization from amorphous TiO2 to anatase and simultaneous carbonization from RF to carbon. The cross-linked RF polymer contributes to the high stability of the shell morphology and the porous nature of the shells. A strong dependence of the capacity on the amount of incorporated carbon has been revealed, allowing the optimization of the electrode structure for high-rate cell performance.

The origin of hematite nanowire growth during the thermal oxidation of iron

Abstract: a b s t r a c t The oxidation of Fe in pure oxygen between 400 ◦ C and 600 ◦ C has been investigated in order to obtain