ultraviolet waves, because of their short wavelength, have a high energy and considerable damaging effects on surfaces. protection against ultraviolet radiations is one of the finishing treatments done on surfaces exposed to sunlight. the importance of this issue in relation to human health, due to complications such as skin burns and cancer, is doubled. up to now, different materials such as z...

Amodel for torsional vibration of slender thin-walled tubes with constrained-layer dampers is developed. Assuming that the deformation obeys the Saint-Venant hypotheses, we develop a model suitable for prediction of the complex stiffness per unit length in closed, thin-walled tubes whose walls consist of laminated elastic and viscoelastic layers, and formulate a boundary-value problem for the w...

Thin-walled structures have been used in many fields due to their superior mechanical properties. In this paper, two types of hierarchical multi-cell tubes, inspired by the self-similarity Pinus sylvestris, are proposed enhance structural energy absorption performance. The finite element models established validate crashworthiness performance under axial dynamic load. theoretical model mean cru...

The structure and transport properties of pit membranes at the interface between the metaxylem and xylem parenchyma cells and the possible role of these pit membranes in solute transfer to the phloem were investigated. Electron microscopy revealed a fibrillar, almost tubular matrix within the pit membrane structure between the xylem vessels and xylem parenchyma of leaf blade bundles in rice (Or...

The process of freezing of water and blockage of pipes are summarized. Current research on freezing and its applications are briefly reviewed. Design concepts are introduced for doing work by utilizing pressures caused by ice blockage. Several conceptual designs are presented for experimental setups for the isostatic pressurization of thin walled tubes. Potential practical uses of pressures gen...