Non-centralized predictive control for drinking-water supply systems

The final publication is available at link.springer.comThis book presents a set of approaches for the real-time monitoring and control of drinking-water networks based on advanced information and communication technologies. It shows the reader how to achieve significant improvements in efficiency in terms of water use, energy consumption, water loss minimization, and water quality guarantees. The methods and approaches presented are illustrated and have been applied using real-life pilot demonstrations based on the drinking-water network in Barcelona, Spain. The proposed approaches and tools cover: - decision-making support for real-time optimal control of water transport networks, explaining how stochastic model predictive control algorithms that take explicit account of uncertainties associated with energy prices and real demand allow the main flow andpressure actuators—pumping stations and pressure regulation valves—and intermediate storage tanks to be operated to meet demand using the most sustainable types of source and with minimum electricity costs; - decision-making support for monitoring water balance and distribution network quality in real time, implementing fault detection anddiagnosis techniques and using information from hundreds of flow,pressure, and water-quality sensors together with hydraulic and quality-parameter-evolution models to detect and locate leaks in the network, possible breaches in water quality, and failures in sensors and/or actuators; - consumer-demand prediction, based on smart metering techniques, producing detailed analyses and forecasts of consumption patterns,providing a customer communications service, and suggesting economic measures intended to promote more efficient use of water at the household level. Researchers and engineers working with drinking-water networks will find this a vital support in overcoming the problems associated with increased population, environmental sensitivities and regulation, aging infrastructures, energy requirements, and limited water sources.Peer ReviewedPostprint (author's final draft

Comparison between sampled-data control, deadband control and model-based event-triggered control

Abstract: This paper investigates the stability as well as communication properties of sampleddata control and two event-triggered control schemes: deadband control and model-based eventtriggered control. After proposing a uniform representation, these schemes are compared by deriving approximation error bounds with respect to the behavior of the continuous-time statefeedback loop and by specifying lower bounds on the minimum inter-sampling times. The results show that, under the conditions derived in this paper, the model-based approach guarantees the best stability and communication properties which is also demonstrated by a numerical example

Making big steps in trajectories

We consider the solution of initial value problems within the context of hybrid systems and emphasise the use of high precision approximations (in software for exact real arithmetic). We propose a novel algorithm for the computation of trajectories up to the area where discontinuous jumps appear, applicable for holomorphic flow functions. Examples with a prototypical implementation illustrate that the algorithm might provide results with higher precision than well-known ODE solvers at a similar computation time

Discrete-State Abstractions of Nonlinear Systems Using Multi-resolution Quantizer

Abstract. This paper proposes a design method for discrete abstrac-tions of nonlinear systems using multi-resolution quantizer, which is ca-pable of handling state dependent approximation precision requirements. To this aim, we extend the notion of quantizer embedding, which has been proposed by the authors ’ previous works as a transformation from continuous-state systems to discrete-state systems, to a multi-resolution setting. Then, we propose a computational method that analyzes how a locally generated quantization error is propagated through the state space. Based on this method, we present an algorithm that generates a multi-resolution quantizer with a specified error precision by finite refine-ments. Discrete abstractions produced by the proposed method exhibit non-uniform distribution of discrete states and inputs.

Electron dynamics in planar radio frequency magnetron plasmas: II. Heating and energization mechanisms studied via a 2d3v particle-in-cell/Monte Carlo code

The present work investigates electron transport and heating mechanisms using an (r, z) particle-in-cell (PIC) simulation of a typical rf-driven axisymmetric magnetron discharge with a conducting target. It is shown that for the considered magnetic field topology the electron current flows through different channels in the (r, z) plane: a ``transverse'' one, which involves current flow through the electrons' magnetic confinement region (EMCR) above the racetrack, and two ''longitudinal'' ones. Electrons gain energy from the electric field along these channels following various mechanisms, which are rather distinct from those sustaining dc-powered magnetrons. The longitudinal power absorption involves mirror-effect heating (MEH), nonlinear electron resonance heating (NERH), magnetized bounce heating (MBH), and the heating by the ambipolar field at the sheath-presheath interface. The MEH and MBH represent two new mechanisms missing from the previous literature. The MEH is caused by a reversed electric field needed to overcome the mirror force generated in a nonuniform magnetic field to ensure sufficient flux of electrons to the powered electrode, and the MBH is related to a possibility for an electron to undergo multiple reflections from the expanding sheath in the longitudinal channels connected by the arc-like magnetic field. The electron heating in the transverse channel is caused mostly by the essentially collisionless Hall heating in the EMCR above the racetrack, generating a strong ExB azimuthal drift velocity. The latter mechanism results in an efficient electron energization, i.e., energy transfer from the electric field to electrons in the inelastic range. Since the main electron population energized by this mechanism remains confined within the discharge for a long time, its contribution to the ionization processes is dominant

Institutional Innovations for Building Impact-oriented Agricultural Research, Knowledge and Development Institutions

The central development question in African agriculture is how to catalyze a more competitive, equitable and sustainable agricultural growth within the context of smallholder production systems, inefficient agricultural marketing, inefficient investments by private sector amidst degradation prone natural resources base (Lynam and Blackie, 1994; IAC, 2004; World bank, 2006 ). Concerted scholarly analyses of Science and Technology (S&T) strategies have given birth to Integrated Agricultural Research for Development (IAR4D) an organizing concept of the Innovation Systems Approach (ISA) as the promise holder. It is hypothesized that the generation, diffusion and application of impactful innovations critically depend on systemic integration of knowledge systems that promote communication, interaction and cooperation between agricultural research, education, extension, farmers, private sector and policy regulatory systems. This paper examines how the different institutional innovations arising from various permutations of linkages and interactions of ARD organizations (national, international advanced agricultural research centres and universities) influenced the different outcomes in addressing identified ARD problems. A multi-institutional, multi-disciplinary phased Participatory Action Research approach was used to pool knowledge to address outstanding and emerging challenges in three countries (DRC, Rwanda and Uganda) with 2, 16 and 24 years out of conflict, respectively) of the Lake Kivu Pilot Learning Site. A landmark institutional innovation was the participatory establishment of twelve (12) Innovation Platforms as tools for pooling knowledge across the agricultural business, education, research and extension systems. The knowledge “pool” was to generate, diffuse and apply innovations to reduce transactions costs and create value chain based “win-win” situations. A number of innovations (e.g. International Public Goods-IPGs, market binding contracts, registered brands and/or certification processes, diversity, density and quality of networks/collective action, bulking centres, ICT application and depth of knowledge pools) were initiated. There were major breakthroughs which included bringing on board non-traditional private sector and policy maker partners, overcoming the predominant “farmer handout syndrome”, building consensus and addressing common interest challenge. Making markets work, bringing various stakeholders including universities to the community and vice-versa, appreciation of indigenous knowledge system, propelling collective soil and water conservation and demand/utilization of technologies hitherto on-shelf were other very significant breakthroughs. Sustainable operations of the Innovation Systems knowledge “pool” nurturing institutional learning were ensured through the availability of a “functional body”. The body undertook the social enterprise of organizing farmers and traders, facilitating/brokering ARD organization linkages by using multi-media to build social capital to overcome emergent knowledge, credit, market, technology and resource degradation challenges under different policy regulatory systems

Tobacco industry globalization and global health governance: : towards an interdisciplinary research agenda

Shifting patterns of tobacco production and consumption, and the resultant disease burden worldwide since the late twentieth century prompted efforts to strengthen global health governance through adoption of the Framework Convention on Tobacco Control. While the treaty is rightfully considered an important achievement, to address a neglected public health issue through collective action, evidence suggests that tobacco industry globalization continues apace. In this article we provide a systematic review of the public health literature and reveal definitional and measurement imprecision, ahistorical timeframes, transnational tobacco companies and the state as the primary units and levels of analysis, and a strong emphasis on agency as opposed to structural power. Drawing on the study of globalization in international political economy and business studies, we identify opportunities to expand analysis along each of these dimensions. We conclude that this expanded and interdisciplinary research agenda provides the potential for fuller understanding of the dual and dynamic relationship between the tobacco industry and globalization. Deeper analysis of how the industry has adapted to globalization over time, as well as how the industry has influenced the nature and trajectory of globalization, is essential for building effective global governance responses

Multicriterion structure/control design for optimal maneuverability and fault tolerance of flexible spacecraft

A multicriterion design problem for optimal maneuverability and fault tolerance of flexible spacecraft is considered. The maneuverability index reflects the time required to perform rest-to-rest attitude maneuvers for a given set of angles, with the postmaneuver spillover within a specified bound. The performance degradation is defined to reflect the maximum possible attitude error after maneuver due to the effect of faults. The fault-tolerant design is to minimize the worst performance degradation from all admissible faults by adjusting the design of the spacecraft. It is assumed that admissible faults can be specified by a vector of real parameters. The multicriterion design for optimal maneuverability and fault tolerance is shown to be well defined, leading to a minimax problem. Analysis for this nonsmooth problem leads to closed-form expressions of the generalized gradient of the performance degradation function with respect to the fault parameters and structural design variables. Necessary and sufficient conditions for the optimum are derived, and the closed-form expressions of the generalized gradients are applied for their interpretation. The bundle method is applicable to this minimax problem. Approximate methods which efficiently solve this minimax problem with relatively little computational difficulties are presented. Numerical examples suggest that it is possible to improve the fault tolerance substantially with relatively little loss in maneuverability.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/45242/1/10957_2005_Article_BF02191852.pd

Principles, design and processes of integrated agricultural research for development: experiences and lessons from LKPLS under the SSACP

With increasing recognition holding the promise of overcoming the outstanding problems faced byAfrican agriculture, IAR4D faces the danger of being ‘blurred’ by past approaches and falling short of its potential to deliver the desired impacts in diverse multi-stakeholder, biophysical, socio- economic, cultural, technological and market contexts unless its actualisation and working is clearly understood. In this paper, we present the conceptualisation and principles of and knowledge-based experiences and lessons from the implementation of the sub-Saharan Africa Challenge Programme (SSACP) in the Lake Kivu Pilot Learning Site (LKPLS). The presentation covers the formation and facilitation of IPs for the actualisation of IAR4D to evolve mechanisms for the early recognition of interlinked issues in natural resource management, productivity and value addition technologies, markets, gender and policy arrangements. These have autonomously triggered flexible, locally directed interactions to innovate options from within or outside their environment for resolving the challenges, and have moved along a new institutional and technological change trajectory. Emerging lessons point to the endowment of IP members with selfhelp knowledge interactions, training in IAR4D, quality of facilitation and research to be key determinants of the power behind of self-regulating mechanisms