133 research outputs found
Jean-Baptiste Bélanger, hydraulic engineer, researcher and academic
Jean-Baptiste BÉLANGER (1790-1874) worked as a hydraulic engineer at the beginning of his career. He developed the backwater equation to calculate gradually-varied open channel flow properties for steady flow conditions. Later, as an academic at the leading French engineering schools (Ecole Centrale des Arts et Manufactures, Ecole des Ponts et Chaussées, and Ecole Polytechnique), he developed a new university curriculum in mechanics and several textbooks including a seminal text in hydraulic engineering. His influence on his contemporaries was considerable, and his name is written on the border of one of the four facades of the Eiffel Tower. BÉLANGER's leading role demonstrated the dynamism of practicing engineers at the time, and his contributions paved the way to many significant works in hydraulics
Transient Gas Flow in a Porous Column
Implicit techniques have been used in fluid flow computations for many years. Such techniques generally permit large time steps to be used in the calculation and are unconditionally stable-a distinct advantage over explicit techniques. The most commonly used implicit technique is the alternating direction implicit (ADI) method of Peaceman and Rachford [l]. 2 ADI has been used quite successfully in both two and threedimensional viscous flow and heat transfer problems. ADI splits the equation into a sequence of multidimensional equations, each of which is solved by the inversion of a tridiagonal matrix. Hence, in two-dimensional problems, the equation is solved in one direction (row) as a tridiagonal matrix and then solved in the other direction (column) as a tridiagonal matrix with the updated values from the first direction solution. The strongly implicit procedure (SIP) is a fully implicit technique that does not require the equation to be split as in ADI. SIP has been used by Stone [2] and Weinstein, et al. [3] in calculating transport in both two and three dimensions. Bozema
Competition and Market Strategies in the Swiss Fixed Telephony Market - An Estimation of Swisscom's Dynamic Residual Demand Curve
Competition and Market Strategies in the Swiss Fixed Telephony Market. An estimation of Swisscom’s dynamic residual demand curve.
Fixed telephony has long been a fundamentally important market for European telecommunications operators. The
liberalisation and the introduction of regulation in the end of the 1990s, however, allowed new entrants to compete
with incumbents at the retail level. A rapid price decline and a decline in revenues followed. Increased retail
competition consequently led a number of national regulators to deregulate this market. In 2013, however, many
European countries (including Switzerland) continued to have partially binding retail price regulation. More than a
decade after liberalisation and the introduction of wholesale and retail price regulation, sufficient data is available to empirically measure the success of regulation and assess its continued necessity. This paper develops a market
model based on a generalised version of the traditional “dominant firm – competitive fringe” model allowing the
incumbent also more competitive conduct than that of a dominant firm. A system of simultaneous equations is
developed and direct estimation of the incumbent‟s residual demand function is performed by instrumenting the
market price by incumbent-specific cost shifting variables as well as other variables. Unlike earlier papers that
assess market power in this market, this paper also adjusts the market model to ensure a sufficient level of
cointegration and avoid spurious regression results. This necessitates introducing intertemporal effects. While the
incumbent's conduct cannot be directly estimated using this framework, the concrete estimates show that residual
demand is inelastic (long run price elasticity of residual demand of -0.12). Such a level of elasticity is, however, only compatible with a profit maximising incumbent in the case of largely competitive conduct (conduct parameter below
0.12 and therefore close to zero). It is therefore found that the Swiss incumbent acted rather competitively in the
fixed telephony retail market in the period under review (2004-2012) and that (partial) retail price caps in place can no longer be justified on the basis of a lack of competition
Syndromics: A Bioinformatics Approach for Neurotrauma Research
Substantial scientific progress has been made in the past 50 years in delineating many of the biological mechanisms involved in the primary and secondary injuries following trauma to the spinal cord and brain. These advances have highlighted numerous potential therapeutic approaches that may help restore function after injury. Despite these advances, bench-to-bedside translation has remained elusive. Translational testing of novel therapies requires standardized measures of function for comparison across different laboratories, paradigms, and species. Although numerous functional assessments have been developed in animal models, it remains unclear how to best integrate this information to describe the complete translational “syndrome” produced by neurotrauma. The present paper describes a multivariate statistical framework for integrating diverse neurotrauma data and reviews the few papers to date that have taken an information-intensive approach for basic neurotrauma research. We argue that these papers can be described as the seminal works of a new field that we call “syndromics”, which aim to apply informatics tools to disease models to characterize the full set of mechanistic inter-relationships from multi-scale data. In the future, centralized databases of raw neurotrauma data will enable better syndromic approaches and aid future translational research, leading to more efficient testing regimens and more clinically relevant findings
Perturbation and numerical study of double-diffusive dissipative reactive convective flow in an open vertical duct containing a non-darcy porous medium with robin boundary conditions
A mathematical model for thermosolutal convection flow in an open two-dimensional vertical channel containing a porous medium saturated with reactive Newtonian fluid is developed and studied. Robin boundary conditions are prescribed, and a first-order homogenous chemical reaction is considered. The Darcy–Forchheimer model is used to simulate both the first- and second-order porous mediums’ drag effects. For the general non-Darcy-case, a numerical solution is presented using the Runge–Kutta quadrature and a shooting method. The influences of thermal (0≤λ1≤15) and solute Grashof numbers (0≤λ2≤20) , Biot numbers (1≤Bi1≤10,Bi2=10) , Brinkman number (0≤Br≤0.5) , first-order chemical reaction parameter (2≤α≤8) , porous medium parameter (2≤σ≤8) and Forchheimer (inertial drag) parameter (0≤I≤12) on the evolutions of velocity, temperature and concentration (species) distributions are visualized graphically. Nusselt number and skin friction at the walls are also computed for specific values of selected parameters. The study is relevant to the analysis of geothermal energy systems with chemical reaction
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