Onde quasi-TEM des guides cylindriques blindés

tem approximation technique is widely used in the study of waveguides characterized by the fundamental mode without cutoff frequency. It seems that exact justification of this approximation has never been delt with before to his knowledge. Here the author is trying to show the justification for a closed waveguide noting the difference between a quasi-TEM wave and an ordinary tem wave.     

A new sarpedobilin-containing butterflyPapilio graphium stresemani stresemani and its bioecological situation within the species

The doubly cyclized bile pigment sarpedobilin (3) represents a unique case in nature. In spite of being present in trace amounts in many butterfly and moth species containing pterobilin (1) or phorcabilin (2) as the main bilin, this substance occurs as the main pigment in a restricted number of species geographically limited to Southeast Asia. We have isolated and identified sarpedobilin3 (as the dimethyl ester) as the main bile pigment fromPapilio graphium stresemani stresemani (from Ceram island, Indonesia) in the amount of ca. 0.1 mg per individual, double that found inPapilio sar-pedon orP. weiskei. We conclude thatP. sarpedon (and subspecies)P. weis-kei, andP. stresemani represent, in terms of evolution (see article), a group of closely related species. By comparison of colored wing patterns and resistance of the chromoproteins to hydrolysis by MeOH-H₂SO₄,P. stresemani is nearP. weiskei. The bioecological relationships of the three sarpedobilin-containing species is discussed.     

Optical field concentration in low-index waveguides

We present a highly efficient optical field concentrator that is capable of confining optical field in nanometer-thin low-index media with very high optical confinement factor. The structure is made of multiple-layered low-index nanolayers embedded in high-index silicon waveguides. By creating multiple high-index-contrast interfaces, the normal field in the low-index nanolayer regions is significantly enhanced. It subsequently results in a very high optical confinement and power density in these regions. With the help of numerical simulation tools, the guiding and propagating characteristics of the new structure are studied and presented. The optimal structures have demonstrated confinement factors and normalized power densities in the range of 30%-60% and 20-160 /spl mu/m/sup -2/ for the 5-20-nm thin low-index multiple nanolayers.     

Memory Management for Real-Time Java: An Efficient Solution using Hardware Support*

This paper addresses the issue of improving the performance of memory management for real-time Java applications, building upon the real-time specification for Java (RTSJ) from the Real-Time Java Expert Group. In a first step, a collecting dynamic memory solution including both a real-time garbage collector and region-based memory management, is proposed. A thorough analysis of the parameters influencing the performance of write barriers in memory management, together with ways of improvement are then presented. Finally, the implementation of a memory management solution compliant with the RTSJ and integrating the proposed improvements is sketched.     

Creep behavior of adhesives used for external FRP strengthening of RC structures

It is technologically possible to strengthen steel-reinforced concrete structures with externally bonded carbon–epoxy composites. The durability and performance of those reinforcements directly depend on the rheological behavior of the concrete–composite interface. We propose a methodology to evaluate the permissible shear stress of the interface, based on thermo-stimulated tensile shear tests performed on the interface, and taking into account the effects of time and temperature. Four polymers used for bonding were tested and a value for the permissible shear stress is proposed for each strengthening system.     

Influence of clay in limestone fillers for self-compacting cement based composites

High workability together with a good resistance to segregation is needed for cement based composites, specifically fresh self-compacting mortars (SCM); in this prospect, the amount of coarse materials has to be reduced and replaced by fine material. Several limestone fillers are here compared and analysed. These by-products are issued from different industrial sectors, such as the aggregate and lime production industry (quarrying operations) and the ornamental stones industry (sawing operations).Particular attention has been paid to clay content, as consistency of fresh mortars was varying, while other physical characteristics like granulometry remained the same. Relationship between the physico-chemical properties of the fillers and the properties of fresh and hardened mortars are brought forward. Even if it may affect fresh properties of mortars, results clearly show that clay type and content has minor influence than limestone filler itself.     

Error evaluation on experimental stress–strain curve obtained from tube bulging test

To get precise material data for advanced numerical modelling of tube hydroforming process, the tube bulging test is recommended. Stresses and strains in the tube cannot be evaluated easily and several approaches have been proposed. A review is proposed and points out their advantages and drawbacks.     

Steric Crowding Makes Challenging C(sp3)-F Reductive Eliminations Feasible

A high-yielding fluorination of (triphos)Pt-R(+) has been achieved using an array of F(+) sources, with XeF(2) yielding R-F in minutes. The C-F coupling proved to be a stereoretentive process that proceeds via a concerted reductive elimination from a putative dicationic Pt(IV) center. The larger the steric congestion of the (triphos)Pt-C(sp3) (+) complexes, the more efficient the fluorination, seemingly a result of sterically accelerated C-F reductive elimination along with simultaneous deceleration of its competing processes (β-H elimination).