A composite ply failure model based on continuum damage mechanics

A material model including the failure behaviour is derived for a thin unidirectional (UD) composite ply. The model is derived within a thermodynamic framework and the failure behaviour is modelled using continuum damage mechanics. The following features describe the model: (i) The ply is assumed to be in a plane state of stress. (ii) Three damage variables associated with the stress in the fibre-, transverse and shear directions, respectively, are used. (iii) The plastic behaviour of the matrix material is modelled. (iv) The difference in the material response in tensile and compressive loading is modelled. (v) Rate dependent behavior of plasticity and damage (i.e. strength) is modelled.     

Robustness of transitions in switched linear systems

A robustness problem for transitions in switched linear systems is considered in this paper. The specific problem is to estimate the size of the image when a subset of an affine subspace is mapped by an uncertain system to another affine subspace. It is assumed that the system dynamics is linear and that the uncertainty and the disturbances are characterized by integral quadratic constraints (IQC). The estimates can be obtained by solving a special affinely parameterized linear quadratic optimal control problem. The results are applied to the problem of verifying robustness of oscillations in a switched linear system. In particular, sufficient conditions are given, which ensure that there remains a periodic solution when the system is perturbed by a Lipschitz continuous nonlinearity. Copyright © 2005 John Wiley & Sons, Ltd.     

Robustness of trajectories with finite time extent

The problem of estimating perturbation bounds of finite trajectories is considered. The trajectory is assumed to be generated by a linear system with uncertainty characterized in terms of integral quadratic constraints. It is shown that such perturbation bounds can be obtained as the solution to a nonconvex quadratic optimization problem, which can be addressed using Lagrange relaxation. The result can be used in robustness analysis of hybrid systems and switched dynamical systems.     

Diagnostic protein marker patterns in squamous cervical cancer

Purpose: Cervical cancer is the second most prevalent malignancy of women. Our aim was to identify additional marker protein patterns for objective diagnosis of squamous cervical cancer (SCC). Experimental design: Collected tissue biopsies of SCC, squamous vaginal cancer (SVC), normal cervical and vaginal mucosa were subjected to 2‐DE, SameSpot analysis, MALDI‐TOF‐MS protein identification, and analysis of the expression of selected proteins by immunohistochemistry. Results: In 148 protein spots selected by the difference in expression 99 proteins were identified. A differential protein pattern for SCC was, e.g. over‐expressed (OE) eukaryotic translation initiation factor 3‐2β, neutrophil cytosolic factor 2, annexin A6 (ANXA6), for SVC it was OE cathepsin D, γ‐catenin, RAB2A, for both cancers it was OE apolipoprotein E, tropomyosin 3, HSPA8, and underexpressed cytokeratin 13, osteoglycin. In SCC nuclear expression of neutrophil cytosolic factor 2, PRDX2, HSP27 (nine of ten cases), ANXA6 (nine of ten cases) was observed while tropomyosin 4 was expressed only in two of ten cases. There was 81.1% (43/53) agreement between the expression of protein spots and the immune expression of proteins ( www.proteinatlas.org ). Conclusions and clinical relevance: SCC is characterized by specific tissue marker protein patterns that allow objective detection of the disease. They can become a basis for objective automated cytology‐based screening and improve current diagnostics of SCC.     

Buckling of Long Orthotropic Plates Including Higher-Order Transverse Shear

The problem of buckling of long orthotropic plates under combined in-plane loading is considered. An approximate analytical solution is presented. The concept of a mixed Rayleigh-Ritz method is used considering higher-order shear deformations. The achieved load function of the half-buckling wavelength and the inclination of the nodal lines are minimized via a simplex search method. For low transverse shear stiffnesses the model predicts buckling coefficients under in-plane shear load that are of the same order of magnitude as those resulting from a uniaxial compressive load. For a thin plate, the critical shear load is larger by 42% compared to the uniaxial case. The model also suggests that for highly anisotropic materials, such as paper, the critical load solution is still influenced by the shear deformation effect at width-to-thickness ratios above 100.     

Preparation of gold catalysts for glucose oxidation

The investigations focused on the influence of doping an alumina support with different base metal oxides on the catalytic performance of gold catalysts to oxidize glucose to gluconic acid. Sodium oxide and calcium oxide strongly enhanced the reaction rate for catalysts prepared by both the deposition–precipitation and incipient wetness method. Urea was used as the precipitation agent in the former. The total selectivity of the catalysts was not influenced by the dopants. TEM analysis revealed very small gold particles of less than 2 nm for sodium doped catalysts prepared by the two methods.     

Research Opportunities on the Low Temperature Microgravity Physics Facility on the International Space Station

The Low Temperature Microgravity Physics Facility (LTMPF) is a state-of-the-art facility for long duration science investigations whose objectives can only be achieved in microgravity and at low temperature. LTMPF consists of two reusable, cryogenic facilities with self-contained electronics, software and communication capabilities. The Facility will be first launched by Japanese HIIA Rocket in 2004 with at least five months cryogen lifetime on the Japanese Experiment Module Exposed Facility (JEM EF) of the International Space Station (ISS). Future missions will be launched and retrieved by the Space Shuttle. A number of high precision sensors of temperature, pressure and capacitance will be available, which can be further tailored to accommodate a wide variety of low temperature experiments. This paper will describe the LTMPF and its goals and design requirements. Currently there are six candidate experiments in the flight definition phase to fly on LTMPF. Future candidate experiments will be selected through the NASA Research Announcement(NRA) process. Opportunities for utilization and collaboration with international partners will also be discussed.     

Measuring incident radiant heat flux using the plate thermometer

This paper shows that the plate thermometer as described in the fire resistance test standards ISO 834-1 and EN 1363-1 can be used for measuring incident radiant flux under ambient conditions as an alternative to water cooled total flux heat metres (HFMs). Measurements with a plate thermometer mounted in the cone calorimeter and exposed to different heat flux levels were analysed as well as simultaneous measurements with total HFMs and plate thermometers in large scale tests. It is shown how the incident radiant flux to a target can be derived from measurements with total HFMs and plate thermometers, respectively, and how well these two methods match. The plate thermometer is therefore deemed to be a practical alternative for measuring thermal conditions including incident radiant heat flux particularly under field conditions. It is, however, recommended that the plate thermometer should be modified when used under ambient conditions to reduce errors.