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Ranking strategies for stormwater management under uncertainty: Sensitivity analysis
Reda A.L.L.; Beck M.B. (1997)
The disadvantageous consequences of stormwater perturbations of receiving water quality in urban environments can be attenuated by exercising control at various locations across the sewer network, wastewater treatment plant, and the stream itself. As part of a long-standing programme of research on developing an integrated approach to the management and real-time control of water quality in river basins, the paper examines the sensitivity of the associated strategies to model uncertainty. Specifically, results are presented for a case study based on a 10 km stretch of the River Cam as it passes through the city of Cambridge in eastern England. The options for control are restricted to design and operational features of the wastewater treatment facility. Assessment is according to maximum and cumulative values of mass flows of ammonium-N and biochemical oxygen demand, together with the duration of dissolved oxygen concentration below 4.0 gm-3, at the downstream boundary of the system. A straightforward analysis of the sensitivity of these criteria to changes in the parameterization of a model for receiving water quality shows that the ranking of strategies is robust in the face of model uncertainty. Minor differences in ranking occur as a function of whether judgement is based on ammonium-N or the other two attributes of water quality and whether attention is focused on the treatment plant in isolation or performance across the system as a whole. However, such conclusions must be qualified by noting that our analysis has been limited in its scope and elementary in its treatment of uncertainty.The disadvantageous consequences of stormwater perturbations of receiving water quality in urban environments can be attenuated by exercising control at various locations across the sewer network, wastewater treatment plant, and the stream itself. As part of a long-standing programme of research on developing an integrated approach to the management and real-time control of water quality in river basins, the paper examines the sensitivity of the associated strategies to model uncertainty. Specifically, results are presented for a case study based on a 10km stretch of the River Cam as it passes through the city of Cambridge in eastern England. The options for control are restricted to design and operational features of the wastewater treatment facility. Assessment is according to maximum and cumulative values of mass flows of ammonium-N and biochemical oxygen demand, together with the duration of dissolved oxygen concentration below 4.0 gm-3, at the downstream boundary of the system. A straightforward analysis of the sensitivity of these criteria to changes in the parameterisation of a model for receiving water quality shows that the ranking of strategies is robust in the face of model uncertainty. Minor differences in ranking occur as a function of whether judgement is based on ammonium-N or the other two attributes of water quality and whether attention is focused on the treatment plant in isolation or performance across the system as a whole. However, such conclusions must be qualified by noting that our analysis has been limited in its scope and elementary in its treatment of uncertainty.
Environmental benefits of replacing fuel oil by natural gas in the metropolitan region of Sao Paulo - Brazil
Kondo Sohati; de Assuncao Joao Vicente (1998)
The Metropolitan Region of Sao Paulo (Brazil) with a population 16.322 million people (1995 estimate)(2) living a in a area of 8,051 km2 and most of them concentrated in the city of Sao Paulo with 9.8 million people and 4.6 million cars, although with an air quality better than some other Latin American megacities such Mexico and Santiago do Chile is still under an air quality that exceeds the national air quality standards (1, 2, 3). In 2/17/1993 Brazilian Petroleum Company (PETROBRAS) and the Bolivian Petroleum Company (Yacimientos Petroliferos Fiscales Bolivianos - YPFB) signed an agreement to bring natural gas from Bolivia to the south and southeast of Brazil (6). The end of the construction of the gas pipeline will be in 1999, and it will deliver 4 million Nm3/day of natural gas to COMGAS - Sao Paulo State Gas Company. This amount will increase to 8.1 million Nm3/day by the year 2006, that will be sufficient to supply the Sao Paulo Metropolitan Region market need at that time (6). In this study an estimate of the influence in the air quality was performed supposing the substitution of fuel oil by natural gas in industry and also in diesel buses. The results showed that there will be benefits in relation to sulfur dioxide, PM10, greenhouse gases and trace elements, and negligible effects in relation to NOx, NMTOC and carbon monoxide.
ROBUST CONNECTED WORD SPEECH RECOGNITION USING WEIGHTE VITERBI ALGORITHM AND CONTEXT-DEPENDENT TEMPORAL CONSTRAINTS
Yoma N.B.; Ling L.L.; Stump S.D. (1999)
© 1999 6th European Conference on Speech Communication and Technology, EUROSPEECH 1999. All rights reserved.This paper addresses the problem of connected word speech recognition with signals corrupted by additive and convolutional noise. Context-dependent temporal constraints are proposed and compared with the ordinary temporal restrictions, and used in combination with the weighted Viterbi algorithm which had been tested with isolated word recognition experiments in previous papers. Connected-word recognition tests show that the weighted Viterbi algorithm depends on the accuracy of the state duration modelling and the approach here covered can lead to reductions as high as 90 or 95% in the error rate at moderate SNR using spectral subtraction, an easily implemented technique, even with a poor estimation for noise and without using any information about the speaker. It is also shown that the weighting procedure can reduce the error rate when cepstral mean normalization is also used to cancel both additive and convolutional noise.
TEMPORAL CONSTRAINTS IN VITERBI ALIGNMENT FOR SPEECH RECOGNITION IN NOISE
Yoma N.B.; Ling L.L.; Stump S.D. (1999)
© 1999 6th European Conference on Speech Communication and Technology, EUROSPEECH 1999. All rights reserved.This paper addresses the problem of temporal constraints in the Viterbi algorithm using conditional transition probabilities. The results here presented suggest that in a speaker dependent small vocabulary task the statistical modelling of state durations is not relevant if the max and min state duration restrictions are imposed, and that truncated probability densities give better results than a metric previously proposed [1]. Finally, context dependent and context independent temporal restrictions are compared in a connected word speech recognition task and it is shown that the former leads to better results with the same computational load.
Simulation model for real-time decision support in controlling the impacts of storm sewage discharges
Reda A.L.L.; Beck M.B. (1999)
The impacts of combined sewage discharges on river water quality are studied using the MCSTR (Multiple Continuously Stirred Tank Reactor) dynamic model. The potential for applying this model in a real-time context is demonstrated as a tool to support decisions regarding treatment plant operation during storm events, when it is often not possible to sustain full treatment of the incoming sewage flow. Discharges to the River Cam of treated and untreated urban wastewaters from Cambridge and the Cambridge Sewage Works are addressed as a hypothetical case study. Alternative treatment strategies are defined for improving receiving water quality and assessed through simulated water quality downstream of the discharge; the state variables of the model include the concentrations of biochemical oxygen demand, ammoniacal- and nitrate-nitrogen, and dissolved oxygen (chlorophyll-a concentrations are also calculated, but not considered herein). Strategies are assessed and ranked according to the reduction in maximum pollutant concentration (or the increase in minimum concentration, in the case of dissolved oxygen) promoted by each alternative, relative to conventional operation. The consequences of discharging overflows at an alternative position in the river, rather than together with the treatment-plant effluent, are also evaluated. Run times for the MCSTR model are of the order of just a few minutes (at most), thus allowing the potential for its use in real time as decision-support aid.
Continuous attractors in recurrent neural networks and phase space learning
De Oliveira R.; Monteiro L.H.A. (2000)
© 2000 IEEE.Recurrent networks can be used as associative memories where the stored memories represent fixed points to which the dynamics of the network converges. These networks, however, also can present continuous attractors, as limit cycles and chaotic attractors. The use of these attractors in recurrent networks for the construction of associative memories is argued. We provide a training algorithm for continuous attractors and present some numerical results of the learning method which involves genetic algorithms.
The influence of the compaction energy on the SWCC of a residual soil
Marinho F.A.M.; Stuermer M.M. (2000)
The proliferation of the use of the soil water characteristic curve (SWCC) to obtain the unsaturated soil parameters is unavoidable and in some cases desired. However, the complex interrelation between soil water content and soil water suction makes the adequate indirect determination of the unsaturated soil parameters a difficult task. There are many aspect to be considered when using SWCC for predicting mechanical or hydraulic behaviour of the soil. The paper describes a study involving a residual soil of Gneiss, compacted using three different compaction energies. Soil water characteristic curves (SWCC) are obtained with volume measurement during the drying process and the soil suction was obtained using the filter paper method. The filter paper was placed in direct contact with the soil sample. Discussions on the relationship between the compaction energy, SWCC shape and the drying behaviour of the soil samples are given. © 2004 ASCE.
Planning and sustainability - Good and bad practices in Rio, São Paulo and Lisbon
Magalhaes F.; Gallo H.; Da Costa Lobo M. (2000)
Cities are facing major challenges to become sustainable. There are a whole universe of problems pulling in opposite directions: rampant poverty, violence, lack of identity, destruction of cultural heritage and natural values, pollution, traffic, decaying of central areas, among others. Cities are also large consumers of energy and resources. Planning and zoning have an important role to play. This paper present a selection of good and bad practices in three cities of the world - São Paulo, Rio and Lisbon to allow lessons to be learned from the examples. It concludes by discussing possible trends towards helping cities to be more sustainable.
Rapid prototyping
Gomes C.W. (2000)
Rapid prototyping is a quite new technology which started in 1986, and has been growing since then with an average rate of 58% per year, reaching the automobile industry, electronics industry and others that requires plastic injection. This technology has been lately applied in medical areas, in order to make prototype protesys, and even by artists, who found in technology a partner to build their sculptures. By following up projects that required different prototyping processes, the characteristics of each one were raised, getting to know their qualities and limitations. Copyright © 2000 Society of Automotive Engineers, Inc.
Ranking stormwater control strategies under uncertainty: The River Cam case study
Duchesne S.; Beck M.B.; Reda A.L.L. (2001)
Monte Carlo simulations taking uncertainty in model parameters into account were performed on a river water quality model. The simulation results were used to rank wastewater treatment plant control strategies according to their impacts on river water quality. This impact is estimated by the maximum ammonium concentration and by the duration of dissolved oxygen concentration below 4 g/m3 at the downstream boundary of the system. The strategies were classified according to the previous criteria using 4 ranking methods, one of them being based on the concept of stochastic dominance. Results are presented for a case study based on a 10 km stretch of the River Cam as it passes through the city of Cambridge in Eastern England. It was found that ranking was robust in face of uncertainty in the parameter values for the control strategies considered as being superior in terms of river water quality impacts.
Searching for one-dimensional cellular automata in the absence of a priori information
Oliveira G.M.B.; de Oliveira P.P.B.; Omar N. (2001)
© Springer-Verlag Berlin Heidelberg 2001.Various investigations have been carried out on the computational power of cellular automata (CA), with concentrated efforts in the study of onedimensional CA. One of the approaches is the use of genetic algorithms (GA) to look for CA with a predefined computational behavior. We have previously shown a set of parameters that can be effective in helping forecast CA dynamic behavior; here, they are used as an heuristic to guide the GA search, by biasing selection, mutation and crossover, in the context of the Grouping Task (GT) for one-dimensional CA. Since GT is a new task, no a priori knowledge about its solutions is presently available; even then, the incorporation of the parameterbased heuristic entails a significant improvement over the results achieved by the plain genetic search.
Improving genetic search for one-dimensional cellular automata, using heuristics related to their dynamic behavior forecast
Oliveira G.M.B.; De Oliveira P.P.B.; Omar N. (2001)
As part of the comprehensive theme of the relationships between dynamic systems and computational theories, a very active area of research has been the relationships between the generic dynamic behavior of Cellular Automata (CA) and their computational abilities. Various investigations have been carried out on the computational power of CA, with concentrated efforts in the study of one-dimensional CA and their computational abilities. One of the approaches is the use of Genetic Algorithms (GA) to look for CA with a predefined computational behavior. A set of parameters which we have previously shown to be effective in helping forecast CA dynamic behavior, are used here as an auxiliary metric to guide the GA search. To this end, we modified selection, mutation and crossover of a GA, so as to incorporate the heuristic, and obtained very effective results in the evolution search for CA that can solve the so-called Synchronization Task.
The new submillimeter-wave solar telescope
Kaufmann P.; Costa J.E.R.; Gimenez de Castro C.G.; Hadano Y.R.; Kingsley J.S.; Kingsley R.K.; Levato H.; Marun A.; Raulin J.-P.; Rovira M.; Correia E.; Silva A.V.R. (2001)
A new and unique solar submillimeter telescope (SST) was installed in the EI Leoncito site, Argentina Andes. It has a 1.5 m radome-enclosed cassegrain antenna, and arrays of four 212 GHz and two 405 GHz radiometers placed in the focal plane. We present a brief technical description of the system, preliminary results on its performance, the atmospheric opacity measured at the site, and the first detection of solar flare submm-w emissions.
Dynamic behaviour forecast as a driving force in the coevolution of one-dimensional cellular automata
Oliveira G.M.B.; Asakura O.K.N.; De Oliveira P.P.B. (2002)
© 2002 IEEE.Various evolutionary methods have been used to look for cellular automata (CA) with a predefined computational behaviour. The most widely studied CA task is the density classification task (DCT) and the best rule currently known for it was obtained by a coevolutionary genetic algorithm (CGA). Here, we analyse the influence of incorporating a parameter-based heuristic into the coevolutionary search. The results obtained show that the parameters can effectively help a CGA in searching for DCT rules, and suggest that the choice of the amount of bias in the search, allowed for the heuristic, is more sensitive than in previous uses we made of it within standard evolutionary algorithms.
Symmetry detection using global-locally coupled maps
De Oliveira R.; Monteiro L.H.A. (2002)
Symmetry detection through a net of coupled maps is proposed. Logistic maps are associated with each element of a pixel image where the symmetry is intended to be verified. The maps are locally and globally coupled and the reflection-symmetry structure can be embedded in local couplings. Computer simulations are performed by using random gray level images with different image sizes, asymmetry levels and noise intensity. The symmetry detection is also done under dynamic scene changing. Finally the extensions and the adherence of the present model to biological systems are discussed. © Springer-Verlag Berlin Heidelberg 2002.
Multicast routing with quality of service and traffic engineering requirements in the Internet, based on genetic algorithm
De Araujo P.T.; De Oliveira G.M.B. (2002)
© 2002 IEEE.In order to deal with the high computational power required by the QoS routing, the use of genetic algorithm (GA) as a method to obtain the appropriate routes has been presented in various works. The GA discussed in this work was adapted from the model presented by Erdun et al. (2001), that uses bandwidth, delay and cost as metrics to evaluate the routes. Two innovations were incorporated in the GA in order to attend traffic engineering requirements: inclusion of the metric number of steps (or hops) in the route evaluation, and a mechanism to avoid the generation of repeated individuals producing several optimal and sub-optimal routes. In order to test the proposed genetic algorithm, two examples of network topology were used. The results indicate that the GA discussed in this work converges to the global optimal solution, while the implementations discussed in Ravikumar et al. (1998) and Erdun et al. did not reach it. Besides, even in the runs that the GA did not converge to the global optimum, sub-optimal solutions that attend to the constraint delay were obtained with a small increment in the cost.
The concept of partially overlapping multiple beams for spatial determination of solar bursts time transients at submm-IR wavelengths
Kaufmann P.; Melo A.M.; Gimenez de Castro C.G. (2002)
The concept of partially overlapping multiple beams, produced by focal plane arrays in large antennas, has been used successfully at mm-waves to detect instantaneously spatial positions of rapid spikes produced by solar flares. The technique has been used at mm-waves and was recently applied to the Solar Submillimeter-wave Telescope, which operates at 212 and 405 GHz. We present the basic description of the concept and the results obtained. New applications are being considered for shorter submm-IR wavelengths, with the use of focal plane arrays of bolometers, which spatial angular accuracy will strongly depend on the knowledge of the beamshapes of the individual beams produced.
Experimental Demonstration and Numerical Simulation of an Optical Recirculating Loop Operating at 10 Gb/s
Baruh S.; De Barros M.R.X.; Rocha M.D.L.; Horiuchi M.R.; Rosolem J.B.; Arradi R.; Rossi S.M.; Paradisi A.; Rocco Giraldi M.T.M.; Martinez M.A.G. (2003)
We demonstrate an optical recirculating loop as a tool for performance evaluation of cascades of effects or elements in an optical communication system. We describe the critical issues to operate the recirculating loop properly and we present experimental results on the cascading of a dispersive fiber link and an optical amplifier. Additionally, we conduct a numerical simulation of the recirculating loop experimental conditions. Simulation and experimental results are in good agreement.
Simulation Performance of a Sagnac Loop Terahertz Asymmetric Optical Demultiplexer for OTDM Systems
Pereira Jr. A.A.; Martinez M.A.G. (2003)
The aim of this work is to present a customized simulation tool for analysis and design of Sagnac loop TOAD's. Basically, we present a fast and versatile tool to emulate the behavior of some key design parameters like those found on non-linear elements, splitters, fiber delay line among others. After proper optimization, we use two different wavelengths for the control and signal hyperbolic secant pulses. Additionally, a band-pass filter is used to guarantee the transmission of signal pulses only. Furthermore, we analyze a bit to bit all optical demultiplexer, where one channel is extracted from a 64bit frame at 10Gbps transmission rate, and extend the implementation to work at 100Gbps. SNR better than 22dB are achieved with control pulse energy on the order of 200fJ and SOA bias current of 150mA. A degradation of SNR of about 17dB was verified for a variation of splitter coupling factor around 20%.
Curupira: A functional parser for Brazilian Portuguese
Martins R.; Nunes G.; Hasegawa R. (2003)
© Springer-Verlag Berlin Heidelberg 2003.This paper presents the general architecture of Curupira, a generalpurpose robust parser for Brazilian Portuguese (BP). As a former part of a grammar and style checker, Curupira aims at providing the set of all possible syntactic analyses for any sequence of words written in BP irrespective of its meaningfulness and grammaticality. The paper addresses the system features and presents some partial results for a corpus comprising Brazilian newspaper web pages.

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