Constraint programming for optimal design of architectures for water distribution tanks and reservoirs: a case study

Sustav za raspodjelu vode je bitna komponenta svakog gradskog infrastrukturnog sustava. Njegov je projekt uglavnom težak zadatak zbog postojanja nekoliko složenih međusobno povezanih parametara. Između ostalih, neki parametri koji se moraju proučiti su potražnja za vodom, potrebni tlak, topografija, lokacija resursa, pouzdanost sustava, i korištenje energije. U ovom smo radu usmjereni na postojeći slučaj sustava za distribuciju vode s ciljem smanjenja troškova instaliranja zadovoljavanjem zahtjeva toga sustava. Problem rješavamo primjenom najnovijih metoda Programiranja Ograničenja kombiniranih s Analizom Intervala u svrhu preciznog baratanja s trajnim varijablama odluka. Eksperimentalni rezultati pokazuju da je predloženi pristup izvediv i globalni optimum postignut u svim slučajevima i u zadovoljavajućem vremenu.A water distribution system is an essential component of any urban infrastructure system. Its design is commonly a hard task mainly due to the presence of several complex interrelated parameters. Among others, some parameters to study are the water demand, pressure requirements, topography, location of resources, system reliability, and energy uses. In this paper, we focus on a real case of water distribution system in order to minimize installation costs by satisfying the given system requirements. We solve the problem by using state-of-the-art Constraint Programming techniques combined with Interval Analysis for rigorously handling continuous decision variables. Experimental results demonstrate the feasibility of the proposed approach, where the global optimum is reached in all instances and in reasonable runtime

CONSTRAINT PROGRAMMING FOR OPTIMAL DESIGN OF ARCHITECTURES FOR WATER DISTRIBUTION TANKS AND RESERVOIRS: A CASE STUDY

Original scientific paper A water distribution system is an essential component of any urban infrastructure system. Its design is commonly a hard task mainly due to the presence of several complex interrelated parameters. Among others, some parameters to study are the water demand, pressure requirements, topography, location of resources, system reliability, and energy uses. In this paper, we focus on a real case of water distribution system in order to minimize installation costs by satisfying the given system requirements. We solve the problem by using state-of-the-art Constraint Programming techniques combined with Interval Analysis for rigorously handling continuous decision variables. Experimental results demonstrate the feasibility of the proposed approach, where the global optimum is reached in all instances and in reasonable runtime. Keywords: constraint programming, optimization, water distribution Programiranje ograničenja za optimalni projekt arhitekture spremišta i rezervoara za distribuciju vode: analiza slučaja Izvorni znanstveni članak Sustav za raspodjelu vode je bitna komponenta svakog gradskog infrastrukturnog sustava. Njegov je projekt uglavnom težak zadatak zbog postojanja nekoliko složenih međusobno povezanih parametara. Između ostalih, neki parametri koji se moraju proučiti su potražnja za vodom, potrebni tlak, topografija, lokacija resursa, pouzdanost sustava, i korištenje energije. U ovom smo radu usmjereni na postojeći slučaj sustava za distribuciju vode s ciljem smanjenja troškova instaliranja zadovoljavanjem zahtjeva toga sustava. Problem rješavamo primjenom najnovijih metoda Programiranja Ograničenja kombiniranih s Analizom Intervala u svrhu preciznog baratanja s trajnim varijablama odluka. Eksperimentalni rezultati pokazuju da je predloženi pristup izvediv i globalni optimum postignut u svim slučajevima i u zadovoljavajućem vremenu

Predicting the Viability of Fish Populations in a Modified Riverine Environment

Riverine fishes evolved to life in a highly variable, flow-driven environment. During the two past centuries, large rivers have been substantially altered by human activities. This has resulted in declines of fish populations that depend on the large river environment. The research described here uses models to evaluate the effects of human activities on the viability of fish populations in rivers. I focused on five modifications of the river environment associated with impoundment: (1) seasonal allocation of river flow; (2) diversion of river flow; (3) fragmentation of the river habitat by dams; (4) conversion of free-flowing river to reservoir habitat; and (5) alteration of migration patterns. To understand the role of flow regulation on chinook salmon (Oncorhynchus tshawytscha) recruitment, I developed an individual-based model to predict recruitment as a function of seasonal flow patterns in the Tuolumne River, California. I used simulated annealing to find flow patterns that maximize chinook recruitment under wet and dry hydrologic conditions. As water availability increased, I found that the optimal flow pattern shifted from allocating low flows uniformly across seasons to a pattern with high spring flows. When I considered a new objective: maximizing the variance of spawning times among recruits, the optimal flow regime called for a winter pulse in flow just before the peak spawning date for the minority (late-fall) run. To evaluate the recovery options for chinook salmon in the Tuolumne River, Ideveloped an age-based model to conduct a population viability analysis (PVA). I developed a flow-dependent spawner-recruitment relationship from the recruitment model. Its shape depended on the flow regime, suggesting that such relationships are not fixed properties of species, but depend on environmental conditions. The PVA model suggested that recovery, in the absence of straying, would be enhanced most by significantly reducing ocean harvest, followed by reduced diversion of water from the river. For white sturgeon (Acipenser transmontanus) populations in the Snake River, Idaho a main concern is habitat fragmentation by dams resulting in smaller, isolated populations. Simulation experiments to evaluate the effects of fragmentation suggested that population viability was higher when dams were spaced widely enough apart to retain free-flowing habitat. A simulation experiment to evaluate the effects of altered migration patterns associated with impoundment showed that both the likelihood of persistence and the genetic diversity among white sturgeon populations were enhanced by balanced upstream and downstream migration rates. Models that simulate the responses of fish populations to modified river habitat do not consider the potential for an evolutionary response. I designed a PVA model simulating the genetic basis of age at maturity for individual fish. Simulated individual variation in this trait lead to increased population viability only when the variation was heritable and subjected to an altered selective regime. The results support the idea that predicting population viability depends on estimating the potential for evolution in fitness-related traits for populations exposed to anthropogenic changes in the environment that impose strong, directional selective forces

The determination of petroleum reservoir fluid properties : application of robust modeling approaches.

Doctor of Philosophy in Chemical Engineering. University of KwaZulu-Natal, Durban 2016.Abstract available in PDF file

Experimental and Theoretical Analysis of Pressure Coupled Infusion Gyration for Fibre Production

In this work, we uncover the science of the combined application of external pressure, controlled infusion of polymer solution and gyration in the field of nanofiber preparation. This novel application takes gyration-based method into another new arena through enabling the mass production of exceedingly fine (few nanometres upwards) nanofibres in a single step. Polyethylene oxide (PEO) was used as a model polymer in the experimental study, which shows the use of this novel method to fabricate polymeric nanofibres and nanofibrous mats under different combinations of operating parameters, including working pressure, rotational speed, infusion rate and collection distance. The morphologies of the nanofibres were characterised using scanning electron microscopy, and the anisotropy of alignment of fibre was studied using two dimensional fast Fourier transform analysis. A correlation between the product morphology and the processing parameters is established. The response surface models of the experimental process were developed using the least squares fitting. A systematic description of the PCIG spinning was developed to help us obtain a clear understanding of the fibre formation process of this novel application. The input data we used are the conventional mean of fibre diameter measurements obtained from our experimental works. In this part, both linear and nonlinear fitting formats were applied, and the successes of the fitted models were mainly evaluated using Adjusted R2 and Akaike Information Criterion (AIC). The correlations and effects of individual parameters and their interactions were explicitly studied. The modelling results indicated the polymer concentration has the most significant impact on fibre diameters. A self-defined objective function was studied with the best-fitted model to optimise the experimental process for achieving the desired nanofibre diameters and narrow standard deviations. The experimental parameters were optimised by several algorithms, and the most favoured sets of parameters recommended by the non-linear interior point methods were further validated through a set of additional experiments. The results of validation indicated that pressure coupled infusion gyration offers a facile way for forming nanofibres and nanofibre assemblies, and the developed model has a good prediction power of experimental parameters that are possible to be useful for achieving the desirable PEO nanofibres