Bounded shear stress in masonry-like bodies

In the paper, a hyperelastic material with limited tensile and compressive strength is considered. In addition, the maximum value of the tangential component of the stress that can be attained on each plane depends on the intensity of the normal component. Previously formulated for the plane case, the constitutive equation of this material is now extended to three-dimensional bodies, constituting henceforth a generalization of the well-known model of masonry-like materials. The proposed constitutive law has been implemented in the finite element code MADY and has been applied to the study of masonry panels under different load conditions.     

A study of some parameters relevant to the response of harwell PMMA dosimeters to gamma and electron irradiation

The effects on the radiation response of Harwell polymethylmethacrylate (PMMA) dosimeters of dose-rate, radiation type, temperature during irradiation and post-irradiation storage, and post-irradiation stability, are of importance to the operators of commercial irradiation facilities.

This paper describes recent studies of the effects of some of these parameters on the radiation response of Harwell Red 4034, Amber 3042, and Gammachrome YR Perspex dosimeters, and provides data on batch to batch variation and shelf-life.     

Adam-Gibbs model for the supercooled dynamics in the ortho-terphenyl ortho-phenylphenol mixture

Dielectric measurements of the alpha-relaxation time were carried out on a mixture of ortho-terphenyl (OTP) with ortho-phenylphenol, over a range of temperatures at two pressures, 0.1 and 28.8 MPa. These are the same conditions for which heat capacity, thermal expansivity, and compressibility measurements were reported by Takahara et al. [S. Takahara, M. Ishikawa, O. Yamamuro, and T. Matsuo, J. Phys. Chem. B 103, 3288 (1999)] for the same mixture. From the combined dynamic and thermodynamic data, we determine that density and temperature govern to an equivalent degree the variation of the relaxation times with temperature. Over the measured range, the dependence of the relaxation times on configurational entropy is in accord with the Adam-Gibbs model, and this dependence is invariant to pressure. Consistent with the implied connection between relaxation and thermodynamic properties, the kinetic and thermodynamic fragilities are found to have the same pressure independence. In comparing the relaxation properties of the mixture to those of neat OTP, density effects are stronger in the former, perhaps suggestive of less efficient packing.     

Microwave accelerated steam distillation of essential oil from lavender: A rapid, clean and environmentally friendly approach

A new process design and operation for microwave accelerated steam distillation (MASD) of essential oils was developed. A packed bed of lavender flowers (Lavandula angustifolia Mill., Lamiaceae) sits above the steam source generated by microwave heating. Only steam passes through it without the boiling water mixing with vegetable raw material, as is the case in hydro-distillation. MASD has been compared with a conventional technique, steam distillation (SD), for the extraction of essential oil from lavender flowers. Extraction of essential oils from lavender with MASD was better than SD in terms of energy saving, rapidity (10 min versus 90 min), product yield, cleanliness and product quality.     

Normal elastic and elastoplastic materials: from a comprehensive approach a mixed method for masonry

Meccanica - The article deals with materials with a constraint on the stress, which must belong to a closed and convex subset of the space of the second order tensors, called stress range. With...     

Equilibrated divergence measure stress tensor fields for heavy masonry bodies

In this paper we study the equilibrium problem of rectangular panels made of no-tension material under gravity and undergoing a vertical load distributed on their top and a horizontal load distributed on a lateral side. Equilibrated and negative semi-definite stress fields are presented which are tensor-valued measure whose distributional divergence is a vector-valued measure. Then, for a fixed vertical load, the maximum value of the lateral load which is compatible with the equilibrium of the panel is determined.     

Ti掺杂对α″-Fe16N2相稳定性的影响

研究了掺杂Ti对α″-Fe₁₆N₂相稳定性的影响，发现适量Ti掺杂有利于α″-Fe₁₆N₂相的形成．理论分析表明，掺杂适量Ti元素后含Ti的α″-(Fe,Ti)₁₆N₂相的生成焓降低，使α″相的稳定性提高，也使α″相更易制备．Ti浓度为3—15at％的(FeTi)-N薄膜具有高饱和磁化强度，μ₀M_s=2.3—2.5T． 关键词：