Article
Generation of diurnal variation for influent data for dynamic simulation.
Institute of Sanitary Engineering and Water Pollution Control, University of Natural Resources and Applied Life Sciences, Vienna BOKU, Muthgasse 18, A1190 Vienna, Austria.
Water Science & Technology (Impact Factor: 1.1). 02/2008; 57(9):14836. DOI:10.2166/wst.2008.228 Source: PubMed

Conference Proceeding: Dosimetric analysis of ruthenium106 ophthalmic applicators for the treatment of retinoblastoma and ocular melanoma
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ABSTRACT: Treatment of retinoblastoma dates back to the first reported (and unsuccessful) enucleation in 1767. Over 200 years later, enucleation is a far more humane and common procedure, yet brachytherapy is often the treatment of choice for small to mediumsize tumors offering both functionpreservation and good survivalrates (usually employing Co<sup>60</sup>, Ir<sup>192</sup> and I<sup>125</sup>). Use of Ru<sup>106</sup>/Rh<sup>106</sup>(T<sub>½</sub>=1 y; a˜Emax=3.54 MeV) for ocular applicators offers the dosimetric advantage of more rapid dose falloff and reduced risk of cataracts and optic nerve injury. Ru<sup>106</sup>/Rh<sup>106</sup> plaques are therefore suitable for treatment of small tumors, especially in pediatric patients where radiation sensitivity of retinoblastoma is well documented. The authors present dose measurements and MonteCarlo simulation of the dose distribution for a 14 mm applicator, and compare them with I<sup>125</sup> plaques. Depth dose and transverse profile distributions were calculated via numerical integration. Beta dose as a function of radial distance from a point source was obtained from the beta dose kernels of Simpkin and Mackie, which are applicable to several beta isotopes and energies. The authors assumed the source was uniformly distributed over the applicatorsurface, which was divided into approximately 10<sup>6</sup> segments. Numerical integration of the kernel was performed over a 1 mm dosegrid. Measurements were performed using both Scanditronix `stereotacticfield diode' in water phantom, and radiochromic film in water equivalent phantom. Manufacturer specifications are based on measurements with a relatively large detector, and thus have a ±30% uncertainty. In contrast, both measurements as well as the Monte Carlo simulation are in good agreement, and clinically usableEngineering in Medicine and Biology Society, 2000. Proceedings of the 22nd Annual International Conference of the IEEE; 02/2000  [show abstract] [hide abstract]
ABSTRACT: Activated Sludge Models are widely used for simulationbased evaluation of wastewater treatment plant (WWTP) performance. However, due to the high workload and cost of a measuring campaign on a fullscale WWTP, many simulation studies suffer from lack of sufficiently long influent flow rate and concentration time series representing realistic wastewater influent dynamics. In this paper, a simple phenomenological modelling approach is proposed as an alternative to generate dynamic influent pollutant disturbance scenarios. The presented set of models is constructed following the principles of parsimony (limiting the number of parameters as much as possible), transparency (using parameters with physical meaning where possible) and flexibility (easily extendable to other applications where long dynamic influent time series are needed). The proposed approach is subdivided in four main model blocks: 1) model block for flow rate generation, 2) model block for pollutants generation (carbon, nitrogen and phosphorus), 3) model block for temperature generation and 4) model block for transport of water and pollutants. The paper is illustrated with the results obtained during the development of the dynamic influent of the Benchmark Simulation Model no. 2 (BSM2). The series of simulations show that it is possible to generate a dry weather influent describing diurnal flow rate dynamics (low rate at night, high rate during day time), weekend effects (with different flow rate during weekends, compared to weekdays), holiday effects (where the wastewater production is assumed to be different for a number of weeks) and seasonal effects (with variations in the infiltration and thus also the flow rate to the WWTP). In addition, the dry weather model can be extended with a rain and storm weather generator, where the proposed phenomenological model can also mimic the “first flush” effect from the sewer network and the influent dilution phenomena that are typically observed at fullscale WWTPs following a rain event. Finally, the extension of the sewer system can be incorporated in the influent dynamics as well: the larger the simulated sewer network, the smoother the simulated diurnal flow rate and concentration variations. In the discussion, it is pointed out how the proposed phenomenological models can be expanded to other applications, for example to represent heavy metal or organic micropollutant loads entering the treatment plant.Environmental Modelling and Software 01/2011; · 3.48 Impact Factor
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