8 research outputs found
On-line hydraulic state prediction for water distribution systems
World Environmental and Water Resources Congress 2009: Great Rivers Proceedings of World Environmental and Water Resources Congress 2009 May 17â21, 2009 Kansas City, MissouriThis paper describes and demonstrates a method for onâline hydraulic state prediction in urban water networks. The proposed method uses a PredictorâCorrector (PC) approach in which a statistical dataâdriven algorithm is applied to estimate future water demands, while near realâtime field measurements are used to correct (i.e., calibrate) these predicted values onâline. The calibration problem is solved using a modified Least Squares (LS) fit method. The objective function is the minimization of the leastâsquares of the differences between predicted and measured hydraulic parameters (i.e., pressure and flow rates at several system locations), with the decision variables being the consumers' water demands. The aâpriori estimation (i.e., prediction) of the values of the decision variables, which improves through experience, facilitates a better convergence of the calibration model and provides adequate information on the system's hydraulic state for real time optimization. The proposed methodology is demonstrated on a prototypical municipal water distribution system
Comment on âA variable rate coefficient chlorine decay modelâ
We commend Jonkergouw et al. (1) for adopting the goal of\ud
developing a chlorine decay model that is practical for â...day-to-day water distribution network modelling purposes and chlorine dosing optimisation studiesâ in the sense that the model coefficients are independent of loading conditions\ud
(initial and rechlorination doses)
Outcome in patient-specific PEEK cranioplasty: A two-center cohort study of 40 implants
The best material choice for cranioplasty following craniectomy remains a subject to discussion. Complication rates after cranioplasty tend to be high. Computer-assisted 3-dimensional modelling of polyetheretherketone (PEEK) was recently introduced for cranial reconstruction. The aim of this study was to evaluate patient- and surgery-related characteristics and risk factors that predispose patients to cranioplasty complications. This retrospective study included a total of 40 cranial PEEK implants in 38 patients, performed at two reference centers in the Netherlands from 2011 to 2014. Complications were registered and patient- and surgery-related data were carefully analysed. The overall complication rate of PEEK cranioplasty was 28%. Complications included infection (13 %), postoperative haematoma (10 %), cerebrospinal fluid leak (2.5 %) and wound-related problems (2.5 %). All postoperative infections required removal of the implant. Nonetheless removed implants could be successfully re-used after re-sterilization. Although overall complication rates after PEEK cranioplasty remain high, outcomes are satisfactory, as our results compare favourably to recent literature reports on cranial vault reconstructio