FlowMate: scalable on-line flow clustering

We design and implement an efficient on-line approach, FlowMate, for clustering flows (connections) emanating from a busy server, according to shared bottlenecks. Clusters can be periodically input to load balancing, congestion coordination, aggregation, admission control, or pricing modules. FlowMate uses in-band (passive) end-to-end delay measurements to infer shared bottlenecks. Delay information is piggybacked on feedback from the receivers, or, if impossible, TCP or application round-trip time estimates are used. We simulate FlowMate and examine the effects of network load, traffic burstiness, network buffer sizes, and packet drop policies on clustering correctness, evaluated via a novel accuracy metric. We find that coordinated congestion management techniques are more fair when integrated with FlowMate. We also implement FlowMate in the Linux kernel v2.4.17 and evaluate its performance on the Emulab testbed, using both synthetic and tcplib-generated traffic. Our results demonstrate that clustering of medium to long-lived flows is accurate, even with bursty background traffic. Finally, we validate our results on the Internet Planetlab testbed.     

Metal-Assisted Oxidative Cyclization of Arylamidrazones I. Synthesis of 3-Acetyl-1,4-dihydro-1-phenyl-1,2,4-benzotriazine

In the presence of RuCl₃, N-phenylamidrazone underwent oxidative cyclization into 1,4-dihydro-1-phenyl-1,2,4-benzotriazine, the structure of which is established by spectral and X-ray diffraction data.     

Analysis of electromagnetic wave propagation in complex dielectric materials with uncertainty

We consider the propagation of high frequency electromagnetic pulses in complex materials with nonlinear polarization. The physical problem is modeled by Maxwell’s equations in variational form, and well-posedness results are established with respect to probability distributions on the polarization parameters (in a Prohorov metric sense).     

Synthesis and characterization of MFe2O4 sulfur nanoadsorbents

Nanoparticles of ferrites (Fe₃O₄, NiFe₂O₄, CuFe₂O₄, and MnFe₂O₄) were prepared by a reverse (water/oil) microemulsion method. The microemulsion system consisted of cetyltrimethylammonium bromide, 1-butanol, cyclohexane, and a metal salt solution. The procedure was carried out using aqueous ammonia as the coprecipitating agent. Nanosized particles were characterized by thermal analysis, X-ray diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy, and pyridine adsorption. The NiFe₂O₄ sample exhibited narrow mesoporous pore size distribution and high surface area ≈233 m²/g. It achieved good adsorption activity towards the dibenzothiophene (DBT) compound (166.3 μmol/g of DBT adsorbent). The structural properties obtained were very interesting for potential applications in the desulfurization process in petroleum refining.     

Project of an internal target for the antiproton ring at FAIR

The case of the internal target for the hyper-nuclear experiment of the PANDA (antiproton Annihilation at Darmstadt) Collaboration at the High Energy Storage Ring of Facility for Antiproton and Ion Research is illustrated. After a discussion of the problems arising from the interaction of a solid internal target with an antiproton beam, the design of material, shape and sizes of a target satisfying the experimental requirements is presented. The techniques used to produce a prototype of this target are illustrated. Then the results of the tests performed on the prototype for investigating the properties (purity, radiation hardness, structure modifications after shaping) are reported and the plan of the future activity is pointed out.     

The effect of chloride concentration and pH on pitting corrosion of AA7075 aluminum alloy coated with phenyltrimethoxysilane

The effect of chloride ion concentration and pH of solution on the corrosion behavior of aluminum alloy AA7075 coated with phenyltrimethoxysilane (PTMS) immersed in aqueous solutions of NaCl is reported. Potentiodynamic polarization, linear polarization, open circuit potential, and weight loss measurements were performed. The surface of samples was examined using SEM and optical microscopy. Elemental characterization of the coating by secondary ion mass spectrometry indicates an intermediate layer between coating and aluminum alloy surface. The corrosion behavior of the aluminum alloy AA7075 depends on chloride concentration and pH of solution. In acidic or neutral solutions, general and pitting corrosion occur simultaneously. On the contrary, exposure to alkaline solutions results in general corrosion only. Results further reveal that aluminum alloy AA7075 is susceptible to pitting corrosion in all chloride solutions with concentrations between 0.05 M and 2 M NaCl; an increase in the chloride concentration slightly shifted both the pitting and corrosion potentials to more active values. Linear polarization resistance measurements show a substantially improved corrosion resistance value in case of samples coated with PTMS as compared to uncoated samples in both neutral (pH = 7), acidic (pH = 0.85 and 3), and alkaline chloride solutions (pH = 10 and 12.85). The higher corrosion resistance of the aluminum alloy coated with PTMS can be attributed to the hydrophobic coating which acts as a barrier and prevents chloride ion penetration and subsequent reaction with the aluminum alloy.     

Douglas algebras which are invariant under the Bourgain map

Part of this work was done while the second author was visiting the University of Georgia, Athens/Georgia, USA.