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  • simulation  (20)
  • Architecture, Civil Engineering, Surveying  (20)
  • 1
    Electronic Resource
    Electronic Resource
    On a stochastic description of the time-space behaviour of extratropical cyclonic precipitation fields (1987)
    Springer
    Stochastic environmental research and risk assessment 1 (1987), S. 37-52 
    Details
    ISSN: 1436-3259
    Keywords: Cyclonic precipitation ; mathematical modeling ; simulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Energy, Environment Protection, Nuclear Power Engineering , Geography , Geosciences
    Notes: Abstract A stochastic description is developed for extratropical cyclonic precipitation fields at synoptic and meso scales as they are typically observed by radars over the Earth. This description attempts to account I) for the synoptic scale behavior of a cyclonic storm (its birth, its synoptic scale motion trajectory, and its dissipation) II) for the synoptic-scale organizational structure of subsynoptic precipitation areas (rainbands, precipitation cores and raincells) within a cyclonic storm; and III) for the behavior of subsynoptic precipitation areas, in terms of their births, their spatial configuration evolutions, their motions, and their deaths (dissipation). The precipitation cores and the raincells are taken as the building blocks of the subsynoptic precipitation, areas within a cyclonic rainfield.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01543908
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  • 2
    Electronic Resource
    Electronic Resource
    A new formulation for the stochastic control of systems with bounded state variables: An application to a single reservoir system (1996)
    Springer
    Stochastic environmental research and risk assessment 10 (1996), S. 167-186 
    Details
    ISSN: 1436-3259
    Keywords: Reservoir stochastic theory ; reliability ; mean ; variance ; indicator function ; storage bounds ; nonlinear programming ; simulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Energy, Environment Protection, Nuclear Power Engineering , Geography , Geosciences
    Notes: Abstract A new formulation is presented for the analysis of reservoir systems synthesizing concepts from the traditional stochastic theory of reservoir storage, moments analysis and reliability programming. The analysis is based on the development of the first and second moments for the stochastic storage state variable. These expressions include terms for the failure probabilities (probabilities of spill or deficit) and consider the storage bounds explicitly. Using this analysis, expected values of the storage state, variances of storage, optimal release policies and failure probabilities — useful information in the context of reservoir operations and design, can be obtained from a nonlinear programming solution. The solutions developed from studies of single reservoir operations on both an annual and monthly basis, compare favorably with those obtained from simulation. The presentation herein is directed to both traditional reservoir storage theorists who are interested in the design of a reservoir and modern reservoir analysts who are interested in the long term operation of reservoirs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01581462
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  • 3
    Electronic Resource
    Electronic Resource
    On the use of Empirical Orthogonal Function (EOF) analysis in the simulation of random fields (1991)
    Springer
    Stochastic environmental research and risk assessment 5 (1991), S. 125-134 
    Details
    ISSN: 1436-3259
    Keywords: Empirical Orthogonal Function analysis ; random fields ; simulation ; non-homogeneous fields
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Energy, Environment Protection, Nuclear Power Engineering , Geography , Geosciences
    Notes: Abstract In several fields of Geophysics, such as Hydrology, Meteorology or Oceanography, it is often useful to generate random fields, displaying the same variabilitity as the observed variables. Usually, these synthetic data are used as forcing fields into numerical models, to test the sensitivity of their outputs to the variability of the inputs. Examples can be found in subsurface or surface Hydrology and in Meteorology with General Circulation Models (GCM). Different techniques have already been proposed, often based on the spectral representation of the random process, with, usually, assumptions of stationarity. This paper suggests that Empirical Orthogonal Function (EOF) analysis, which leads to the decomposition of the covariance kernel on the set of its eigen-functions, is a possible answer to this problem. The convergence and accuracy of the method are shown to depend mainly on the number of EOFs retained in the expansion of the covariance kemel. This result is confirmed by a comparison with the turning band method and a matrix technique. Furthermore, a synthetic example of non-homogencous fields shows the interest of EOF analysis in the direct simulation of such fields.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01543054
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  • 4
    Electronic Resource
    Electronic Resource
    Kernel bandwidth selection for a first order nonparametric streamflow simulation model (1998)
    Springer
    Stochastic environmental research and risk assessment 12 (1998), S. 33-52 
    Details
    ISSN: 1436-3259
    Keywords: Keywords: Streamflow ; simulation ; nonparametric
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Energy, Environment Protection, Nuclear Power Engineering , Geography , Geosciences
    Notes: Abstract A new approach for streamflow simulation using nonparametric methods was described in a recent publication (Sharma et al. 1997). Use of nonparametric methods has the advantage that they avoid the issue of selecting a probability distribution and can represent nonlinear features, such as asymmetry and bimodality that hitherto were difficult to represent, in the probability structure of hydrologic variables such as streamflow and precipitation. The nonparametric method used was kernel density estimation, which requires the selection of bandwidth (smoothing) parameters. This study documents some of the tests that were conduced to evaluate the performance of bandwidth estimation methods for kernel density estimation. Issues related to selection of optimal smoothing parameters for kernel density estimation with small samples (200 or fewer data points) are examined. Both reference to a Gaussian density and data based specifications are applied to estimate bandwidths for samples from bivariate normal mixture densities. The three data based methods studied are Maximum Likelihood Cross Validation (MLCV), Least Square Cross Validation (LSCV) and Biased Cross Validation (BCV2). Modifications for estimating optimal local bandwidths using MLCV and LSCV are also examined. We found that the use of local bandwidths does not necessarily improve the density estimate with small samples. Of the global bandwidth estimators compared, we found that MLCV and LSCV are better because they show lower variability and higher accuracy while Biased Cross Validation suffers from multiple optimal bandwidths for samples from strongly bimodal densities. These results, of particular interest in stochastic hydrology where small samples are common, may have importance in other applications of nonparametric density estimation methods with similar sample sizes and distribution shapes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004770050008
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  • 5
    Electronic Resource
    Electronic Resource
    Stochastic analysis of estuarine hydraulics (1989)
    Springer
    Stochastic environmental research and risk assessment 3 (1989), S. 71-84 
    Details
    ISSN: 1436-3259
    Keywords: Hydraulics ; quasilinearization ; simulation ; stochastic ; estuarine system ; Monte Carlo methods ; random differential equations ; parameter uncertainty
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Energy, Environment Protection, Nuclear Power Engineering , Geography , Geosciences
    Notes: Abstract A new methodology is presented for the solution of the stochastic hydraulic equations characterizing steady, one-dimensional estuarine flow. The methodology is predicated on quasi-linearization, perturbation methods, and the finite difference approximation of the stochastic differential operators. Assuming Manning's roughness coefficient is the principal source of uncertainty in the model, stochastic equations are presented for the water depths and flow rates in the estuarine system. Moment equations are developed for the mean and variance of the water depths. The moment equations are compared with the results of Monte Carlo simulation experiments. The results confirm that for any spatial location in the estuary that (1) as the uncertainty in the channel roughness increases, the uncertainty in mean depth increases, and (2) the predicted mean depth will decrease with increasing uncertainty in Manning'sn. The quasi-analytical approach requires significantly less computer time than Monte Carlo simulations and provides explicit
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01544073
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  • 6
    Electronic Resource
    Electronic Resource
    A model for the generation of simultaneous daily discharges of two rivers at their point of confluence (1990)
    Springer
    Stochastic environmental research and risk assessment 4 (1990), S. 255-276 
    Details
    ISSN: 1436-3259
    Keywords: Stochastic hydrologic process ; daily discharges ; correlated generation ; simulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Energy, Environment Protection, Nuclear Power Engineering , Geography , Geosciences
    Notes: Abstract A geomorphological study at the confluence of the Danube and the Isar in Bavaria required long series of daily discharges in both rivers. A model that generates simultaneous correlated streamflows in both rivers was developed and tested. The model is a modified shot noise model, first developed by Treiber (1975) for a single river, that was adapted to two rivers. It generates correlated pulses of events that produce flow for each river, and these pulses are then convoluted with a river specific systems function. The model, after being calibrated for the two rivers on the basis of 85 years of records, yields artificial series of discharges, in which the statistical properties of the historical records are reproduced. The performance of the model was tested with 20 generated series each 100 years long.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01544081
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  • 7
    Electronic Resource
    Electronic Resource
    Simulation of the time-space evolution of an extratropical cyclonic precipitation field over USA (1988)
    Springer
    Stochastic environmental research and risk assessment 2 (1988), S. 281-294 
    Details
    ISSN: 1436-3259
    Keywords: precipitation field ; stochastic time-space evolution ; simulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Energy, Environment Protection, Nuclear Power Engineering , Geography , Geosciences
    Notes: Abstract The time-space evolution of an extratropical cyclonic precipitation field over U S A is simulated in a stochastic setting as outlined in Kavvas et al. (1988). The birth of a cyclonic storm is characterized by the simultaneous birth of a cyclone center and births of subsynoptic precipitation areas (SPA) at preferred locations around the cyclone center. The precipitation cores and cells which are used as the fundamental building blocks of the SPAs are approximated by circular precipitation areas (CPA) of different sizes. The time space evolution of the precipitation field after the birth is governed by (1) the movement of the synoptic cyclone described by the cyclone center trajectory, (2) independent nonidentically distributed random velocities of the individual CPAs relative to the cyclone center, (3) the births of new CPAs in time and space relative to the cyclone center, (4) the independent evolution in time of the individual spatially uniform intensities of the existing CPAs, (5) the expansion and shrinkage of the existing CPAs in the course of movement and (6) the dissipation (death) of a random number of existing CPAs within the cyclonic system. The computer simulation, the results of which are presented in this paper, successfully reproduced the general mesoscale and synoptic scale features of the radar detected cyclonic rain fields as observed by Austin and Houze (1972), Houze et al. (1976), Hobbs (1978), Hobbs and Locatelli (1978), Houze (1981), Houze and Hobbs (1982) and others.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01544041
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  • 8
    Electronic Resource
    Electronic Resource
    An adaptable microcomputer model for evacuation management (1989)
    Springer
    Fire technology 25 (1989), S. 291-307 
    Details
    ISSN: 1572-8099
    Keywords: evacuation management ; model-based support systems ; simulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying
    Notes: Abstract A simulation method is presented which enables a modeler to identify dangerous bottlenecks for emergency building evacuation and to test the sensitivity of occupant exit behavior to evacuation improvement strategies. The modeling method is tested against landmark evacuation data of Pauls and Jones, and used to predict problems and solutions for a complex evacuation situation involving a large university building with multiple exit choices. Some concluding remarks are addressed to a future research agenda for this method.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01040378
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  • 9
    Electronic Resource
    Electronic Resource
    Simulation assessment of incident detection by cellular phone call-in programs (1999)
    Springer
    Transportation 26 (1999), S. 399-416 
    Details
    ISSN: 1572-9435
    Keywords: cellular telephones ; incident detection ; simulation ; traffic modeling ; wireless communications
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying
    Notes: Abstract This research study was designed to assess by simulation the efficacy of incident detection by cellular phone call-in programs. The assessment was conducted by varying the proportion of drivers with cellular phones on the highway so as to mirror the cellular industry statistics that show a continued growth of ownership of cellular phones in the United States. An analytical model, which combined simulation and the limited field data available in the literature, was used to determine measures of effectiveness of the cellular phone-based detection system. The results showed that a cellular phone detection system offers fast incident detection times and higher detection rates for both shoulder and lane blocking incidents. For example, in moderate traffic flow (i.e. 1,550 vehicles per hour per lane), 90 percent of incidents blocking two lanes were detected in 1.5 minutes when the proportion of drivers with cellular phones was one out of 10 drivers, even with only 20 percent of them willing to report incidents. When the current proportion of cellular ownership, i.e. 1 out of 3, was used in the simulation, the detection time improved to 0.8 minutes. The simulation analysis of incident detection by cellular phones also showed that there is a direct relationship between the probability of detection and the detection time; that is, the specification of a higher detection rate resulted in slower detection times. This is in sharp contrast with the results of field study of automatic incident detection (AID) systems which demonstrated an inverse relationship between probability of detection and detection time.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1005283307060
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  • 10
    Electronic Resource
    Electronic Resource
    Technical Communication: Two-Phase Stochastic Dynamic Programming Model for Optimal Operation of Irrigation Reservoir (1997)
    Springer
    Water resources management 11 (1997), S. 395-406 
    Details
    ISSN: 1573-1650
    Keywords: irrigation reservoirs ; operation ; water deficit ; yield response ; multicrop environment ; stochastic dynamicprogramming ; soil moisture ; water allocation ; simulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Geography
    Notes: Abstract A two-phase stochastic dynamic programming model is developed for optimal operation of irrigation reservoirs under a multicrop environment. Under a multicrop environment, the crops compete for the available water whenever the water available is less than the irrigation demands. The performance of the reservoir depends on how the deficit is allocated among the competing crops. The proposed model integrates reservoir release decisions with water allocation decisions. The water requirements of crops vary from period to period and are determined from the soil moisture balance equation taking into consideration the contribution of soil moisture and rainfall for the water requirements of the crops. The model is demonstrated over an existing reservoir and the performance of the reservoir under the operating policy derived using the model is evaluated through simulation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007914019102
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