Efficient, small-scale fixed-pitch rotor blades are essential for miniature rotorcraft. Extremely thin blade sections are required for highly efficient rotor performance that leads to acceptable mission endurance. Such rotor blades are difficult to manufacture from sufficiently rigid material to avoid significant torsional deformation in operating conditions. In practice, it is necessary to tra...

For a hyponormal operator, C. R. Putnam’s inequality gives an upper bound on the norm of its self-commutator. In the special case of a Toeplitz operator with analytic symbol in the Smirnov space of a domain, there is also a geometric lower bound shown by D. Khavinson (1985) that when combined with Putnam’s inequality implies the classical isoperimetric inequality. For a nontrivial domain, we co...

ABSTRACT: In this study, large-deformation and small-strain elasto-plastic analysis of space frames with symmetric cross sections and semi-rigid connections are presented. The effect of axial forces on the bending moment and lateral buckling are included. However, axial-torsional and warping effects are omitted. The Eulerian equations for a beam-column with finite rotation taking into account b...

The peptide-based porous 3D framework, ZnCar, has been synthesized from Zn(2+) and the natural dipeptide carnosine (β-alanyl-L-histidine). Unlike previous extended peptide networks, the imidazole side chain of the histidine residue is deprotonated to afford Zn-imidazolate chains, with bonding similar to the zeolitic imidazolate framework (ZIF) family of porous materials. ZnCar exhibits permanen...

In this work, an analytical study on the bending stiffnesses of corrugated board has been performed. Formulations to calculate the bending stiffnesses D11, D22, D12, and D66 of the equivalent plate representing the corrugated board have been established, and then compared to expressions suggested by other investigators. Several methods for modeling the shape of the corrugated orthotropic medium...

Highly anisotropic microtubules (MTs) immersed in cytosol are a central part of the cytoskeleton in eukaryotic cells. The dynamic behaviors of an MT-cytosol system are of major interest in biomechanics community. Such a solid-fluid system is characterized by a Reynolds number of the order 10(-3) and a slip ionic layer formed at the MT-cytosol interface. In view of these unique features, an orth...

Bacterial flagella assume different helical shapes during the tumbling phase of a bacterium but also in response to varying environmental conditions. Force-extension measurements by Darnton and Berg explicitly demonstrate a transformation from the coiled to the normal helical state (N.C. Darnton, H.C. Berg, Biophys. J. 92, 2230 (2007)). We here develop an elastic model for the flagellum based o...

The Trp RNA-binding protein (TRAP) has a toroidal topology and a perfect 11-fold symmetry, which makes it an excellent candidate for a vibrational study of elastic properties. Normal mode analysis in combination with correlation matrix calculations was used to detect collective low-frequency motions in TRAP. The results reveal the presence of highly correlated modes at the lower end of the spec...

In this paper we derive the general equilibrium equations of a polymer chain with a noncircular cross section by the variation of the free energy functional. From the equilibrium equation of the elastic ribbon we derive analytically the equilibrium conformations both of the helical ribbons and the twisted ribbons. We find that the pitch angle of the helical ribbons depends on the ratio of the t...

The present paper treats the problem of finding the asymptotic bounds for the globally optimal locations of orthogonal stiffeners minimizing the compliance of a rectangular plate in elastostatic bending. The essence of the paper is the utilization of a method of analysis of orthogonally stiffened rectangular plates first presented by Mazurkiewicz in 1962, and obtained herein in a closed form fo...