Some approximate Godunov schemes to compute shallow-water equations with topography

We study here the computation of shallow-water equations with topography by Finite Volume methods, in a one-dimensional framework (though all methods introduced may be naturally extended in two dimensions). All methods are based on a discretisation of the topography by a piecewise function constant on each cell of the mesh, from an original idea of Le Roux et al. Whereas the Well-Balanced scheme of Le Roux is based on the exact resolution of each Riemann problem, we consider here approximate Riemann solvers. Several single step methods are derived from this formalism, and numerical results are compared to a fractional step method. Some test cases are presented: convergence towards steady states in subcritical and supercritical configurations, occurrence of dry area by a drain over a bump and occurrence of vacuum by a double rarefaction wave over a step. Numerical schemes, combined with an appropriate high-order extension, provide accurate and convergent approximations.     

Integrated Personal Mobility Architecture: A Complete Personal Mobility Solution

The high expectations and demand for users to access the Internet from anywhere at anytime has made user mobility an important part of the design and development of the next generation mobile communications and computing. Traditionally user mobility has been divided into two areas: Terminal Mobility and Personal Mobility. In recent years terminal mobility has focused on the movement of the terminal and developed extensions to IP protocols such as Mobile IP. In contrast, personal mobility has only received limited attention, and is somewhat lagging behind. This research has either focussed on personal mobility in communications or personalisation of operating environments. As a result, to date no framework for providing true personal mobility has emerged. In this paper, we introduce a new personal mobility framework called IPMoA (Integrated Personal Mobility Architecture), which integrates both aspects of personal mobility to provide a complete personal mobility solution, and illustrate the viability of this approach through a proof-of-concept implementation.     

Mixture-proportioning of high-performance concrete

The paper presents a new approach to design concrete mixtures. It is based upon a set of models relating composition and engineering properties of concrete, to be implemented into software, linked with a material database. The principles underlying the various models are summarized, most of which focus on the granular structure of fresh/hardened concrete. A global approach to concrete is promoted, where performance specifications can be formulated in terms of fresh concrete (yield stress, plastic viscosity, slump and air content), hardening concrete (adiabatic temperature rise and autogenous shrinkage) and hardened concrete (compressive strength at any age, tensile strength, elastic modulus, creep and shrinkage). This approach is illustrated through the design of a special high-shrinkage high-performance concrete (HPC) for road application. To date, durability is lacking in the model and requires further research.     

FHCF: A Simple and Efficient Scheduling Scheme for IEEE 802.11e Wireless LAN

The IEEE 802.11e medium access control (MAC) layer protocol is an emerging standard to support quality of service (QoS) in 802.11 wireless networks. Some recent work shows that the 802.11e hybrid coordination function (HCF) can improve significantly the QoS support in 802.11 networks. A simple HCF referenced scheduler has been proposed in the 802.11e which takes into account the QoS requirements of flows and allocates time to stations on the basis of the mean sending rate. As we show in this paper, this HCF referenced scheduling algorithm is only efficient and works well for flows with strict constant bit rate (CBR) characteristics. However, a lot of real-time applications, such as videoconferencing, have some variations in their packet sizes, sending rates or even have variable bit rate (VBR) characteristics. In this paper we propose FHCF, a simple and efficient scheduling algorithm for 802.11e that aims to be fair for both CBR and VBR flows. FHCF uses queue length estimations to tune its time allocation to mobile stations. We present analytical model evaluations and a set of simulations results, and provide performance comparisons with the 802.11e HCF referenced scheduler. Our performance study indicates that FHCF provides good fairness while supporting bandwidth and delay requirements for a large range of network loads. Pierre Ansel received a multidisciplinary in-depth scientific training in different fields such as Pure and Applied Mathematics, Physics, Mechanics, Computer Science and Economics from the Ecole Polytechnique, Palaiseau, France. Then, he joined the Ecole Nationale Superieure des Telecommunications, Paris, France in 2005 where he went further into electronics, databases, computer network security and high speed networks. He received a multidisciplinary master of sciences degree and an additional master of sciences degree in telecommunications in 2005. He did a summer internship in 2003 in INRIA, Sophia Antipolis, France where he worked on the Quality of Service in 802.11 networks at Planete Group, France. Then in 2004, he joined France Telecom R&D, Issy-les-Moulineaux, France to work on Intranet Security issues. He designed a WiFi security supervision architecture based on WiFi Intrusion Detection Sensors. He is currently a French civil servant and belongs to the French Telecommunications Corps. Qiang Ni received the B.Eng., M.Sc. and Ph.D. degrees from Hua Zhong University of Science and Technology (HUST), Wuhan City, China in 1993, 1996 and 1999 respectively. He is currently a faculty member in the Electronic and Computer Engineering Division,School of Engineering and Design, Brunel University, West London, U.K. Between 2004 and 2005 he was a Senior Researcher at the Hamilton Institute, National University of Ireland, Maynooth. From 1999 to 2001, he was a post-doctoral research fellow in the multimedia and wireless communication laboratory, HUST, China. He visited and conducted research at the wireless and networking group of Microsoft Research Asia Lab during the year of 2000. From Sept. 2001 until may 2004, he was a research staff member at the Planète group of INRIA Sophia Antipolis France. Since 2002, he has been active as a voting member at the IEEE 802.11 wireless LAN standard working group. His current research interests include communication protocol design and performance analysis for wireless networks, cross-layer optimizations, vertical handover and mobility management in mobile wireless networks, and adaptive multimedia transmission over hybrid wired/wireless networks. He has authored /co-authored over 40 international journal/conference papers, book chapters, and standard drafts in this field. He is a member of IEEE. E-mail: Qiang.Ni@ieee.org Thierry Turletti received the M.S. (1990) and the Ph.D. (1995) degrees in computer science both from the University of Nice – Sophia Antipolis, France. He has done his PhD studies in the RODEO group at INRIA Sophia Antipolis. During the year 1995–96, he was a postdoctoral fellow in the Telemedia, Networks and Systems group at LCS, MIT. He is currently a research scientist at the Planete group at INRIA Sophia Antipolis. His research interests include multimedia applications, congestion control and wireless networking. Dr. Turletti currently serves on the Editorial Board of Wireless Communications and Mobile Computing.     

Theoretical analysis of a fractal surface radiation

We compare, in this paper, the far field radiated by two fractal distributions of current. The first one is obtained by a fractal cut following the Cantor arrangement, the second one keeps the length of each previous current element, but modifies the distance between the elements which is now taken as a constant. We establish the analytical formulations of the far field at any step n of the Cantor set. Then, we extract the array factor and we analyse and compare the following properties : convergence of the radiation pattern, wide of the main lobe, side lobes level and directivity.     

Identity of identity

Discussing on the subject of Identity, and reaching a common understanding is sometime difficult even between people having a similar background. It represents a formidable challenge when people originate from different disciplines (such as security, law or IT), and when they have totally different backgrounds (such as academics or practitioners). This article presents how FIDIS, a Network of Excellence, is addressing this challenge     

Robust H ∞ static output feedback stabilization of T-S fuzzy systems subject to actuator saturation

This paper proposes a method for designing robust H_?? static output feedback stabilization of Takagi-Sugeno (T-S) fuzzy systems under actuator saturation. In this paper, the input saturation is represented by a polytopic model and the modeling error is assumed a norm-bounded uncertainty. A set invariance condition for robust H_?? static output feedback system under actuator saturation is first established. Then, the estimation of the largest domain of attraction for the system is formulated and solved as a Linear Matrix Inequality (LMI) optimization problem. Two examples are used to demonstrate the effectiveness of the proposed design method.     

Mixing of a self-assembled supramolecular polymer and a covalent polymer in organic solutions

We report on a neutron scattering study of the molecular structure of a self-assembled supramolecular polymer composed of a bicopper complex within a solution of a covalent polymer (atactic polystyrene/trans-decalin). The study is achieved by putting two binary phases in contact and allowing for diffusion of both components in either phase. It is shown that the one-dimensional bicopper filaments are compatible to a high extent with the atactic polymer. These results are discussed in the light of a recently devised encapsulation process of the bicopper filaments within the fibrils of a physical network of isotactic polystyrene.     

Ultrasonic Dispersion of Ceramic Powders

Ultrasonication is very effective in dispersing alumina and barium titanate slurries. When optimum conditions are used, very short durations (2 to 3 min) are enough to achieve well-dispersed, stable suspensions.     

Composition and structure of triacylglycerols in brown adipose tissue of rats fed fish oil

This study examines the incorporation of highly unsaturated n−3 fatty acids (HUFA) into triacylglycerols (TAG) of brown adipose tissue (BAT), and their effect on the positional distribution of saturated (SFA) and of unsaturated (UFA) 16- or 18-carbon fatty acids. To this end, rats were fed a fish oil diet for up to four weeks. The stereospecific analysis of TAG was based on generation ofsn-1,2- andsn-2,3-acylglycerols by Grignard degradation, followed by synthesis of phosphatidic acid and specific hydrolysis with phospholipase A₂. From the end of the first week of fish oil feeding, a steady-state in the fatty acid composition of TAG in BAT was reached. HUFA concentration increased 30-fold, mainly at the expense of n−9 UFA and of SFA. The amount of SFA decreased selectively at position 3, where these fatty acids were progressively replaced by n−3 HUFA. By contrast, the amount of UFA decreased at all positions, and their positional distribution was not affected. About 60% of HUFA was incorporated at position 3. Nearly twice as much 22∶6n−3 was incorporated into TAG than had been previously observed in white adipose tissue (WAT) [Leray, C., Raclot, T., and Groscolas, R. (1993)Lipids 28, 279–284]. At the steady-state, the distribution of HUFA was characterized by high proportions of 22∶6n−3 and 20∶5n−3 in position 3. Moreover, in each position of TAG, a steady level was reached rapidly (within 1 wk). It is concluded that, during fish-oil feeding, fatty acids in TAG of BAT show characteristic time-course changes that lead to a characteristic composition and a tissue-specific positional distribution. This suggests that adipose tissue has its own specificity in controlling the build-up of TAG stores, which is likely to be regulated by the specificity of acylating enzymes as well as molecular rearrangements.