33 research outputs found
Wind-tunnel study of block 259 building, Houston
No full textCER78-79JEC-JAP-AK18.Prepared for Colaco Engineers, Inc.Includes bibliographical references (pages 32-33).January 1979
A Monte Carlo Simulation Study on Adsorption of Nitrogen Oxides (NOx) in zeolites
No full textNitrogen oxides (NOx) are significant sources of air pollution. Nitrogen oxides like Nitric oxide (NO) and Nitrogen dioxide (NO2) are mainly responsible for the acid rain and smog. Nitrous oxide (N2O), also known as the laughing gas, is the major greenhouse gas that is responsible for the ozone layer's damage in the troposphere. According to the Environmental Protection Agency (EPA) report, one pound of N2O is 300 times more potent greenhouse gas than one pound of CO2. The significant emitters of Nitrogen oxides (NOx) are automobiles, agricultural sources, thermal power plants, and chemical processes like Nitric acid production plants, paint manufacturing, etc. This study mainly focuses on the tail gas emitted from the Nitric acid production facility. The tail gas emitted during the HNO3 production consists of almost 2% of O2, 200-400 ppm of NO2, and NO, whereas 800 ppm of N2O. As N2O is the most emitted gas from the Nitric acid production facility, it is followed by NO2 and NO, so it is essential to reduce these pollutants from the tail gas. Selective catalytic reduction (SCR) is a well-known technique currently involved in reducing NOx via the adsorption process from the Nitric acid production facility. But the costs involved in these methods are quite high. Nanoporous materials like zeolite exhibit uniform pore size and high thermal stability are said to be the promising adsorbents of NOx. The availability of a large number of zeolites makes it impossible to identify the proper zeolite for NOx adsorption experimentally. In such situations, molecular simulations are a powerful tool that can help identify the perfect zeolite. The time and cost involved in the process of molecular simulations are very low. In this work, Monte Carlo simulations involving reaction ensemble are implemented to obtain the equilibrium composition of NOx components at desired operating conditions in the Brick molecular simulation package. This is followed by Grand Canonical Monte Carlo simulations (GCMC) and Reactive Grand Canonical Monte Carlo simulations (RXMC-GCMC) for pure and quaternary NOx gas mixture adsorption in five different zeolites (FAU, FER, MOR, MFI, and TON) using simulation package RASPA. The composition results from the reaction ensemble are validated with the composition results obtained using the Gibbs minimization technique in the MATLAB model, and the results are in good agreement. The quaternary gas mixture adsorption results in five different frameworks from RXMC-GCMC simulations are then validated in Ideal adsorbed solution theory in the Python model, and the results are in good agreement at the given operating conditions. </p
Scade 6: from a Kahn Semantics to a Kahn Implementation for Multicore
No full textInternational audienceSCADE is an environment for developing critical embedded software that is used for more than twenty years in various application domains like avionics, nuclear plants, transportation, automotive. It comes with a language and a code generator which complies with the highest safety standards like DO-178C, IEC 61508, EN 50128, IEC 60880 and ISO 26262. The language has been founded on the pioneering work by Caspi and Halbwachs on Lustre. In 2008, a major revision of the language and compiler, named 'Scade 6', was released. One of its novelty was a smooth integration of the traditional data-flow style of Lustre with control-structures inspired from those of Esterel and SyncCharts, with static/dynamic semantics and a compilation inspired from Lucid Synchrone. In particular, it relies on four dedicated type systems-typing, clock calculus, causality analysis, initialization analysis-and a compilation through source-to-source transformations into a minimal clocked data-flow language, based on a Kahn semantics, that is translated to imperative code. One ongoing work is the generation of code for multi-core architectures. Because of the intrinsic deterministic parallelism of Scade, we propose a solution that relies on annotations that specify what must be executed concurrently but do not change the semantics. The paper is a survey of past to ongoing work on Scade 6 language definition and implementation
Sources of Macroeconomic Imbalances in the World Economy: A Simulation Approach
No full textThis paper uses a global macroeconomic simulation model to identify the factors that have contributed to global trade and financial imbalances in the 1980s. After investigating the properties of monetary and fiscal policies in the model, we examine whether the budgetary shifts in the OECD economies in the 1980s can account for the bulk of trade and exchange rate movements. Our conclusions are mixed. The combination of sharply higher fiscal deficits in the United States and sharply reduced deficits in Japan goes far to explain the movements of the trade balances and exchange rates of the two economies. However, the drop in the dollar vis-a-vis the Yen since late 1985 is not well explained by the model. We also investigate the prospects for a reduction of the U.S. trade deficits if U.S. budget deficits are in fact reduced, as well as the possible role for Japanese monetary and fiscal policies in reducing the trade imbalances of the two countries.
Aspects of approximate optimisation: overcoming the curse of dimensionality and design of experiments
No full textCoupling optimisation algorithms to Finite Element Methods (FEM) is a very promising way to achieve optimal metal forming processes. However, many optimisation algorithms exist and it is not clear which of these algorithms to use. This paper investigates the sensitivity of a Sequential Approximate Optimisation algorithm (SAO) proposed in [1-4] to an increasing number of design variables and compares it with two other algorithms: an Evolutionary Strategy (ES) and an Evolutionary version of the SAO (ESAO). In addition, it observes the influence of different Designs Of Experiments used with the SAO. It is concluded that the SAO is very capable and efficient and its combination with an ES is not beneficial. Moreover, the use of SAO with Fractional Factorial Design is the most efficient method, rather than Full Factorial Design as proposed in [1-4]
Mechanochemical synthesis of phthalimides with crystal structures of intermediates and products
No full textA series of phthalimides have been successfully synthesized in the solid state by grinding (or kneading) of substituted phthalic anhydride and aniline derivatives. Selected products and intermediates were crystallized and characterized by crystallography leading to a potential rationale for the solid-state reactivity that suggests that co-crystals could serve as intermediates. This journal is</p
Building a Hybrid Systems Modeler on Synchronous Languages Principles
No full textInternational audienceHybrid systems modeling languages that mix discrete and continuous time signals and systems are widely used to develop Cyber-Physical systems where control software interacts with physical devices. Compilers play a central role, statically checking source models, generating intermediate representations for testing and verification, and producing sequential code for simulation and execution on target platforms.This paper presents a novel approach to the design and implementation of a hybrid systems language, built on synchronous language principles and their proven compilation techniques. The result is a hybrid systems modeling language in which synchronous programming constructs can be mixed with Ordinary Differential Equations (ODEs) and zero-crossing events, and a runtime that delegates their approximation to an off-the-shelf numerical solver.We propose an ideal semantics based on non standard analysis, which defines the execution of a hybrid model as an infinite sequence of infinitesimally small time steps. It is used to specify and prove correct three essential compilation steps: (1) a type system that guarantees that a continuous-time signal is never used where a discrete-time one is expected and conversely; (2) a type system that ensures the absence of combinatorial loops; (3) the generation of statically scheduled code for efficient execution.Our approach has been evaluated in two implementations: the academic language Zélus, which extends a language reminiscent of Lustre with ODEs and zero-crossing events, and the industrial prototype Scade Hybrid, a conservative extension of Scade 6
