An Interdisciplinary Approach for the Assessment and Implementation of Resilient and Flexible Water Supply Infrastructure under Changing or Instable Conditions

In case of demographic changes or emergencies pipeline bound infrastructure like gas or water is specifically challenged. Then, the advantages of decentralized infrastructure should be considered: Minimization of asset bound funds; flexibility; resilience; response capacity. A research project at the Federal Armed Forces University together with the Brazilian utility company COPASA, the process engineering company Grünbeck and the ICT company Phönix focused on: A procedure for successful decentralized water infrastructure implementation; a new operation scheme; related pilot tests. To describe the local situation the Open System of Boundaries is created comprising 13 interdisciplinary groups and 68 subgroups. To describe water supply systems the Open System of Attributes is created comprising 15 groups and 64 subgroups. An Attributes Profile which fits into the Boundaries Profile makes a resilient decentralized application more likely. For Minas Gerais, Brazil, i.e. for instable conditions the Boundaries Profile and the Attributes Profile of a decentralized SCADA equipped water treatment plant are compiled. Results of on-site tests are discussed. Recommendations for decentralized water supply under instable conditions are given. The application of standardized SCADA equipped treatment plants is suggested with remote supervision from one control centre

Robust Decentralized Abstractions for Multiple Mobile Manipulators

This paper addresses the problem of decentralized abstractions for multiple mobile manipulators with 2nd order dynamics. In particular, we propose decentralized controllers for the navigation of each agent among predefined regions of interest in the workspace, while guaranteeing at the same time inter-agent collision avoidance and connectivity maintenance for a subset of initially connected agents. In that way, the motion of the coupled multi-agent system is abstracted into multiple finite transition systems for each agent, which are then suitable for the application of temporal logic-based high level plans. The proposed methodology is decentralized, since each agent uses local information based on limited sensing capabilities. Finally, simulation studies verify the validity of the approach.Comment: Accepted for publication in the IEEE Conference on Decision and Control, Melbourne, Australia, 201

Approximate Decentralized Bayesian Inference

This paper presents an approximate method for performing Bayesian inference in models with conditional independence over a decentralized network of learning agents. The method first employs variational inference on each individual learning agent to generate a local approximate posterior, the agents transmit their local posteriors to other agents in the network, and finally each agent combines its set of received local posteriors. The key insight in this work is that, for many Bayesian models, approximate inference schemes destroy symmetry and dependencies in the model that are crucial to the correct application of Bayes' rule when combining the local posteriors. The proposed method addresses this issue by including an additional optimization step in the combination procedure that accounts for these broken dependencies. Experiments on synthetic and real data demonstrate that the decentralized method provides advantages in computational performance and predictive test likelihood over previous batch and distributed methods.Comment: This paper was presented at UAI 2014. Please use the following BibTeX citation: @inproceedings{Campbell14_UAI, Author = {Trevor Campbell and Jonathan P. How}, Title = {Approximate Decentralized Bayesian Inference}, Booktitle = {Uncertainty in Artificial Intelligence (UAI)}, Year = {2014}

Plug-and-Play Decentralized Model Predictive Control

In this paper we consider a linear system structured into physically coupled subsystems and propose a decentralized control scheme capable to guarantee asymptotic stability and satisfaction of constraints on system inputs and states. The design procedure is totally decentralized, since the synthesis of a local controller uses only information on a subsystem and its neighbors, i.e. subsystems coupled to it. We first derive tests for checking if a subsystem can be plugged into (or unplugged from) an existing plant without spoiling overall stability and constraint satisfaction. When this is possible, we show how to automatize the design of local controllers so that it can be carried out in parallel by smart actuators equipped with computational resources and capable to exchange information with neighboring subsystems. In particular, local controllers exploit tube-based Model Predictive Control (MPC) in order to guarantee robustness with respect to physical coupling among subsystems. Finally, an application of the proposed control design procedure to frequency control in power networks is presented.Comment: arXiv admin note: text overlap with arXiv:1210.692

Efficiency evaluation for pooling resources in health care: An interpretation for managers

Subject/Research problem\ud Hospitals traditionally segregated resources into centralized functional departments such as diagnostic departments, ambulatory care centres, and nursing wards. In recent years this organizational model has been challenged by the idea that higher quality of care and efficiency in service delivery can be achieved when services are organized around patient groups. Examples are specialized clinics for breast cancer patients and clinical pathways for diabetes patients. Hospitals are grappling more and more with the question, should we become more centralized to achieve economies of scale or more decentralized to achieve economies of focus. In this paper service and patient group characteristics are examined to determine conditions where a centralized model is more efficient and conversely where a decentralized model is more efficient.\ud Research Question\ud When organizing hospital capacity what service and patient group characteristics indicate that efficiency can be gained through economies of scale vs. economies of focus?\ud Approach\ud Using quantitative models from the Queueing Theory and Simulation disciplines the performance of centralized and decentralized hospital clinics are compared. This is done for a variety of services and patient groups. \ud Result\ud The study results in a model measuring the tradeoffs between economies of scale and economies of focus. From this model “rules of thumb” for managers are derived.\ud Application\ud The general results support strategic planning for a new facility at the Netherlands Cancer Institute - Antoni van Leeuwenhoek Hospital. A model developed during this study is also applied in the Chemotherapy Department of the same hospital.\u