On the effect of debonding on the overall behavior of composite materials

The present paper is an investigation of the effects of debonding on some of the basic properties of composite materials. In the adopted debonding model, the tractions and normal displacements are continuous at the interfaces, but there exists a jump in the tangential displacement, proportional to the corresponding shear traction. The consequences of such interface conditions on the inverse relation between the effective moduli and compliances are studied. By means of a simple example of a laminated medium, it is shown that the inverse relation ceases to be valid in this composite as the degree of debonding increases. This phenomenon is explained by investigating the rate of decay of end effects, and thus the applicability of Saint-Venant principle, in a laminated composite with debonding.     

Single sample modal identification of a nonstationary stochastic process

Gauss-Markov processes excited by nonstationary noises are encountered in the modeling of vibrating systems. We prove that the classical instrumental variable method, as well as the Ho-Kalman realization algorithm, for identifying the pole part (modal characteristics) of the model, are consistent when used on a single sample of the (nonstationary) signal.     

Metastasis of malignant melanoma of the nasal mucosa to the small intestine

Malignant melanoma of the mucous membranes is rare and has a very poor prognosis. When localized in the nose, the tumor becomes apparent late in the course of the disease with nasal obstruction and epistaxis. Distant metastases are uncommon, but any organ of the body can be involved. A case of a malignant melanoma of the nasal mucosa with metastasis to the small intestine is presented, and the natural history of the metastatic disease is discussed.     

The nonlinear lamb problem

The two-dimensional problem of finite amplitude wave propagation in a nonlinear half-space excited by a normal and tangential time-dependent line loads is considered. A numerical scheme is developed and applied. The reliability of the numerical procedure is examined in some special cases by comparison with the corresponding analytical solutions which can be deduced for those cases. Vertical and horizontal displacements in the nonlinear half-space are presented and compared with the behavior of those obtained in the corresponding linear problem. It is noted that the symmetry of the horizontal displacements and the antisymmetry of the vertical displacements which are present in the linear halfspace for the case of tangential loading are completely destroyed in the nonlinear problem and that significant vertical displacements are obtained at stations beneath the load.     

Urinary excretion of vanilmandelic acid in the glossalgia syndrome

Under observation there were 78 patients aged 41 to 70 years suffering from the glossalgia syndrome, as well as 25 clinically healthy subjects. An activation of the sympathoadrenal system was revealed in the patients. This was ascertained on the basis of the data on vanillylmandelic acid excretion with the urine. The excretion of that acid is known to be dependent on the intensity of the paraesthesias, the duration of the ailment and the character of concurrent visceral diseases. The results obtained are regarded as evidences of the participation of the vegetative nervous system in the mechanism of the glossalgia syndrome development.     

Isolation and partial characterization of (PAF) platelet-activating-factor

Platelet-activating-factor is a new mediator of anaphylaxis released in numerous mammalian species from basophils and mastocytes by antigens, anti-IgE antiserum, ionophore A 23187, C3a, C5a and neutrophil cationic protein. It is probably a lyso-1-phosphatidylcholine, as evidenced by structural studies isomg phospholipases. It may explain the involvement of platelets in immunopathology.     

A Jordan control canonical form for singular systems

A canonical form for controllable singular systems modulo restricted system equivalence is presented. The canonical form respects the decomposition of the singular system into a regular and an impulsive part. The construction is based on Popov's control canonical form and on the Jordan canonical form recently developed by Hinrichsen and Prätzel-Wolters. Continuity properties are analysed and the cellular partition of the orbit space induced by the canonical form is briefly discussed.     

Hybrid dynamical systems theory and the Signal language

The logic and synchronization characteristics of general dynamical systems called hybrid dynamical systems (HDS) are studied. The theory is related to discrete event dynamical system theory, but handles numerics as well as symbolics. It is supported by the programming language Signal and a mathematical model of general implicit dynamical systems. The core of the theory is the notion of HDS resolution which is based on a coding of any HDS into a dynamic graph which consists of a skew product of a polynomial dynamical system on the finite field of integers modulo 3 (to describe the transitions of the underlying automation) and directed graphs (to describe how data dependencies dynamically evolve). The resolution algorithms are based on the study of this dynamical system     

A SAXS study of the structure of gels formed by mixtures of polyoxyalkylene triblock copolymers

Small‐angle X‐ray scattering was used to characterise aqueous micellar gels of triblock copolymers E₁₃₇S₁₈E₁₃₇, E₈₂S₉E₈₂, E₇₆S₅E₇₆, E₆₂P₃₉E₆₂, and of two mixtures: E₁₃₇S₁₈E₁₃₇ and E₆₂P₃₉E₆₂ (Mix 1) and E₈₂S₉E₈₂ and E₆₂P₃₉E₆₂ (Mix 2), each 50/50 wt%. E = oxyethylene, CH₂CH₂O; S = oxyphenylethylene, OCH₂CH(C₆H₅); and P = oxypropylene, OCH₂CH(CH₃). Within the concentration and temperature ranges investigated (30–40 wt% copolymer, 20–80 °C), spherical micelles of copolymers E₁₃₇S₁₈E₁₃₇, E₈₂S₉E₈₂ and E₆₂P₃₉E₆₂ packed into body‐centred cubic (BCC) structures. Gels of E₇₆S₅E₇₆ were stable only at high concentrations and low temperatures, and a 70 wt% copolymer solution at T = 30 °C formed a hexagonal gel consistent with cylindrical micelles. It is likely that the mixed copolymers would form two distributions of micelles, and more complex structures were expected. However, gels of Mix 2 had well‐ordered BCC structures, while the less ordered gels of Mix 1 were also best characterised as BCC. Copyright © 2006 Society of Chemical Industry