In most, if not all, of the previous work on finite element formulation and nonlinear solution procedures, results of geometric nonlinear benchmark problems of shells are presented in the form of load-deflection curves. In this paper, eight sets of popularly employed benchmark problems are identified and their detailed reference solutions are obtained and tabulated. It is hoped that these solutions will form a convenient basis for subsequent comparison and that the tedious yet inaccurate task of reconstructing data points by graphical measurement of previously reported load-deflection curves can be avoided. Moreover, the relative convergent difficulty of the problems are revealed by the number of load increments and the total number of iterations required by an automatic load incrementation scheme for attaining the converged solutions under the maximum loads.

We propose a novel digital switch, the piezoelectronic transistor or PET. Based on properties of known materials, we predict that a nanometer-scale PET can operate at low voltages and relatively high speeds, exceeding the capabilities of any conventional field effect transistor (FET). Depending on the degree to which these attributes can be simultaneously achieved, the device has a broad array of potential applications in digital logic. The PET is a 3-terminal switch in which a gate voltage is applied to a piezoelectric (PE), resulting in expansion compressing a piezoresistive (PR) material comprising the channel, which then undergoes a continuous, reversible insulator-metal transition. The channel becomes conducting in response to the gate voltage. A high piezoelectric coefficient PE, e.g., a relaxor piezoelectric, leads to low voltage operation. Suitable channel materials manifesting a pressure-induced metal-insulator transition can be found amongst rare earth chalcogenides, transition metal oxides, and among others. Mechanical requirements include a high PE/PR area ratio to step up pressure, a rigid surround material to constrain the PE and PR external boundaries normal to the strain axis, and a void space to enable free motion of the component side walls. Using static mechanical modeling and dynamic electro-acoustic simulations, we optimize device structure and materials and predict performance.

Background: Pih1 is an unstable protein and forms an R2TP complex with Rvb1, Rvb2, and Tah1. Results: Pih1 contains two intrinsically disordered regions that mediate different protein-protein interactions within R2TP complex. Conclusion: Pih1 contains an N-terminal Rvb1/Rvb2-binding domain and a C-terminal regulatory domain. Significance: The study provides important insights into the mechanism of intrinsically disordered proteins in protein complex formation.

Abstract

SUMMARYFabric drapes are typical large displacement, large rotation but small strain problems. In particle models for fabric drape simulation, the fabric deformation is characterized by the displacements of the particles distributed over the fabric. In this paper, a new particle model based on the corotational concept is formulated. Under the small membrane strain assumption, the bending energy can be approximated as a quadratic function of the particle displacements that are finite. In other words, the tangential bending stiffness matrix is a constant and only the tangential membrane stiffness matrix needs to be updated after each iteration or step. On the other hand, the requirement on the particle alignment is relaxed by interpolating the particle displacement in a patch of nine particles. To account for the membrane energy, a simple and efficient method similar to the three-node membrane triangular element employing the Green strain measure is adopted. With the present model, the predicted drapes appear to be natural and match our daily perception. In particular, circular clothes and circular pedestal that can only be treated laboriously by most particle models can be conveniently considered.