Publications

Improving Stability of Electronically Controlled Pressure 1 Reducing Valves
Improving Stability of Electronically Controlled Pressure 1 Reducing Valves Tomasz Janus; Bogumil Ulanicki 9 This paper explains the root cause of instabilities which tend to arise in pressure reducing 10 valves (PRVs) under low flow conditions. It was found that the loss of stability in PRVs is a direct 11 result of an increase in the static valve/network gain as the valve position gets smaller, thus making 12 pressure changes more sensitive to valve position adjustments. If the valve controller is tuned at 13 medium valve openings characteristic of normal operating conditions, the increased gain at low 14 valve openings can cause the control system to be too aggressive in its valve position adjustments 15 leading to oscillations. The manuscript provides a mathematical derivation of the gain equation 16 for a simplified pipe-PRV-pipe model. The obtained gain equation curve is then used to derive the 17 formula for a gain compensator whose purpose is to keep the static gain constant across an entire 18 range of permitted valve openings. A simplified network transient model is then used to recreate a 19 real-life PRV instability event and show the remedial effects of the gain compensator. The file attached to this record is the author's final peer reviewed version.
Canonical Variable Analysis and Long Short-term Memory for Fault Diagnosis and Performance Estimation of a Centrifugal Compressor
Canonical Variable Analysis and Long Short-term Memory for Fault Diagnosis and Performance Estimation of a Centrifugal Compressor Li, Xiaochuan; Duan, Fang; Mba, David; Bennett, Ian; Loukopoulosa, Panagiotis Centrifugal compressors are widely used for gas lift, re-injection and transport in the oil and gas industry. Critical compressors that compress flammable gases and operate at high speeds are prioritized on maintenance lists to minimize safety risks and operational downtime hazards. Identifying incipient faults and predicting fault evolution for centrifugal compressors could improve plant safety and efficiency and reduce maintenance and operation costs. This study proposes a dynamic process monitoring method based on canonical variable analysis (CVA) and long short-term memory (LSTM). CVA was used to perform fault detection and identification based on the abnormalities in the canonical state and the residual space. In addition, CVA combined with LSTM was used to estimate the behavior of a system after the occurrence of a fault using data captured from the early stages of deterioration. The approach was evaluated using process data obtained from an operational industrial centrifugal compressor. The results show that the proposed method can effectively detect process abnormalities and perform multi-step-ahead prediction of the system’s behavior after the appearance of a fault. The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link
Hydraulic modelling for pressure reducing valve controller design addressing disturbance rejection and stability properties
Hydraulic modelling for pressure reducing valve controller design addressing disturbance rejection and stability properties Janus, Tomasz; Ulanicki, Bogumil Pressure reducing valves (PRVs) are widely used in water distribution systems to reduce excess pressure caused by variations in terrain elevation or by excessive pumping. The fundamental role of a PRV is to maintain a desired outlet pressure irrespectively of hydraulic conditions in the water distribution network (WDN). Unfortunately, even a stable PRV can exhibit poor disturbance rejection resulting in variations of outlet pressure around the setpoint due to randomly varying demands. The aim of this paper is to better understand this phenomenon and to develop models which would facilitate designing effective controllers considering the stability and disturbance rejection issues Open Access article
Integrating water, waste, energy, transport and ICT aspects into the smart city concept
Integrating water, waste, energy, transport and ICT aspects into the smart city concept Strzelecka, A.; Ulanicki, Bogumil; Koops, Stef; Koetsier, Laurence; van Leeuwen, Kees; Elelman, Richard The paper presents the partial results of the EU BlueSCities project [1]. The project is developing the methodology for the integration of the water and waste sectors within the ’Smart Cities and Communities’ concept to compliment other priority areas such as energy, transport and Information and mmunication Technologies (ICT). The project has developed the City Blueprint Framework or water and waste and the City Amberprint Framework for energy, transport and ICT. Open Access article
Water Distribution Systems
Water Distribution Systems Ulanicki, Bogumil Water is the source of life. Its global importance is beyond question. It is essential for all human settlements, including cities. Water influences our social, economic, political and cultural lives. Above all, it is a human right, as recognised by the United Nations back in 2010. The 2015 Sustainable Development Goal (SDG) of Clean Water and Sanitation aims to ensure access to water and sanitation for all, as part of an international effort to fight inequalities and tackle climate change. In order to quench the growing thirst of our planet, we need to manage water intelligently, certainly more intelligently than we have done to date. Water is an irreplaceable resource for society, but it is only renewable if well managed. We need to be open to innovation with regard to water management, especially in our cities - the urban areas which are home to an ever-increasing majority of the world’s population. In order to foster innovation and achieve its acceptance by society, scientific and technological knowledge must not only be generated but also communicated in a way that can be understood by all citizens. What must follow is an open public debate in which the priorities of our political agendas are established. And what better way to facilitate such a debate than through art? Through the passage of time, the role of water as the principal ingredient of life has been reflected in the world of art. It is the one element that has dominated human civilisation. Observing man’s perception of water through the eyes of the artist allows us to appreciate a simple truth, too often forgotten, hich is that we simply would not exist without water. The Urban Water Atlas for Europe reveals the new, pioneering concept of Sci-Art Water Diplomacy. This concept first appeared in a pilot scheme in Jordan which led to the exhibition “Science and Art in Water – Water through the eyes of Jordanian children”, organised under the auspices of the Jordanian Minister for Education by the European Commission’s science and knowledge service (the Joint Research Centre) and the partners of the Horizon 2020 Project, BlueSCities. Schoolchildren from different countries were encouraged to consider the water problems facing their region and to describe their personal feelings through drawings. The children’s thought-provoking, yet innocent images called on society to progress towards a more ecological, more sustainable and more peaceful future, perhaps far more effectively than any scientific treatise. The dramatic results of this exercise laid the philosophical basis for the Urban Water Atlas for Europe The Atlas gathers best practices of urban water management, and demonstrates how cities are addressing issues by endeavouring to become not only smart, but also resilient to the water challenges that lie ahead. The multisector collaboration involved in preparing the Atlas helped show local politicians the necessity for cities and towns to convert supranational intentions into feasible regional and local realities with regard to water and climate resilience, whilst demonstrating the advantages of an inter-municipal partnership based on trust and experience. The Atlas thus shows the way towards a new and even stronger European ideal. We hope it will be a source of inspiration for you all.
Integrated benchmark simulation model of an immersed membrane bioreactor
Integrated benchmark simulation model of an immersed membrane bioreactor Janus, Tomasz; Ulanicki, Bogumil This paper presents a new integrated model of an immersed membrane bioreactor (iMBR)for wastewater treatment. The model is constructed out of three previously published sub-models describing the bioreactor, the membrane, and the interface between them. Thebioreactor submodel extends a conventional activated sludge model with soluble and boundbiopolymers which have been found to cause irreversible and reversible fouling. The mem-brane model describes fouling as a function of biopolymer concentrations, permeate flow,and shear stresses on the membrane surface. The interface describes the dependency ofoxygen transfer rate on suspended solids concentrations and calculates shear stresses onthe membrane surface from air-scour rates. The paper serves three purposes. First, the inte-grated model is simulated on a plant layout of a previously published MBR benchmark modelwhich did not consider any interactions between the submodels. Hence, this paper presentsa new and upgraded MBR benchmark model. Secondly, the simulation results showcase howsimulations with an integrated model can be used to optimise plant performance and min-imise energy consumption. Finally, the paper introduces new measures of fouling whichcan be used for benchmarking different MBR plant layouts and control strategies. The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link.
The Chebyshev spectral element approximation with exact quadratures
The Chebyshev spectral element approximation with exact quadratures Li, Yibiao; Li, X. K. A new Chebyshev spectral element method has been developed in this paper, in which exact quadratures are used to overcome a shortfall of the Gauss–Chebyshev quadrature in variational spectral element projections. The method is validated with the Stokes and the Cauchy–Riemann problems. It is shown that an enhancement of the approximation convergence rate is attained, and numerical accuracy is much better than that from the Gauss–Lobatto–Legendre spectral element method.
Wind Tunnel Manoeuvre Rig: A Multi-DOF Test Platform for Model Aircraft
Wind Tunnel Manoeuvre Rig: A Multi-DOF Test Platform for Model Aircraft Araujo-Estrada, Sergio A.; Gong, Zheng; Lowenberg, M. H.; Neild, Simon; Goman, M. (Mikhail G.) This paper presents recent progress in the development of a novel multi-degree-of-freedom dynamic manoeuvre rig aimed at investigation of aircraft model nonlinear and time dependent aerodynamics in the wind tunnel. The purpose and characteristics of the rig are first described, along with a description of the data acquisition, processing and presentation system. The dynamic manoeuvre rig capabilities are demonstrated via a series of experiments involving a wind tunnel model aircraft in a closed section low-speed wind tunnel. First, an experiment illustrating low-speed wind tunnel aerodynamic model identification is presented. Then, examples of experiments involving real-time control of the rig/aircraft model are shown; these are evaluated in terms of testing productivity with a focus on the development and design of aircraft control laws.
Positivity-Preserving Runge-Kutta Discontinuous Galerkin Method on Adaptive Cartesian Grid for Strong Moving Shock
Positivity-Preserving Runge-Kutta Discontinuous Galerkin Method on Adaptive Cartesian Grid for Strong Moving Shock Liu, Jianming; Qiu, Jianxian; Goman, M. (Mikhail G.); Li, X. K.; Liu, Meilin In order to suppress the failure of preserving positivity of density or pressure, a positivity-preserving limiter technique coupled with h-adaptive Runge-Kutta discontinuous Galerkin (RKDG) method is developed in this paper. Such a method is implemented to simulate flows with the large Mach number, strong shock/obstacle interactions and shock diffractions. The Cartesian grid with ghost cell immersed boundary method for arbitrarily complex geometries is also presented. This approach directly uses the cell solution polynomial of DG finite element space as the interpolation formula. The method is validated by the well documented test examples involving unsteady compressible flows through complex bodies over a large Mach numbers. The numerical results demonstrate the robustness and the versatility of the proposed approach.
Interface model between the bioreactor and the membrane in a membrane bioreactor for wastewater treatment.
Interface model between the bioreactor and the membrane in a membrane bioreactor for wastewater treatment. Janus, Tomasz; Ulanicki, Bogumil This paper proposes a structure of an integrated mathematical model of a membrane bioreactor (MBR) and describes the links between two main parts of a MBR model: the bioreactor and the membrane. In case of an immersed MBR three types of links are considered: a relationship between specific cake resistance (SCR) and extracellular polymeric substances (EPS) in the bioreactor, a relationship between air scour rate and shear stresses on the membrane surface, and a relationship between concentration of soluble microbial products (SMP) in the bioreactor and rate of pore constriction. While SMP concentration features directly in the equations of pore constriction, EPS are assumed to affect SCR which in turn has an effect on cake filtration. The relationship between EPS and SCR is described with a linear algebraic equation. Shear stresses on the membrane surface are calculated as a function of air scour rate with a one- imensional slug flow model.

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