Multi-agent system architectures for collaborative prognostics

This paper provides a methodology to assess the optimal Multi-Agent architecture for collaborative prognostics in modern fleets of assets. The use of Multi- Agent Systems has been shown to improve the ability to predict equipment failures by enabling machines with communication and collaborative learning capabilities. Di fferent architectures have been postulated for industrial Multi-Agent Systems in general. A rigorous analysis of the implications of their implementation for collaborative prognostics is essential to guide industrial deployment. In this paper, we investigate the cost and reliability implications of using di fferent Multi-Agent Systems architectures for collaborative failure prediction and maintenance optimization in large fleets of industrial assets. Results show that purely distributed architectures are optimal for high-value assets, while hierarchical architectures optimize communication costs for low-value assets. This enables asset managers to design and implement Multi-Agent systems for predictive maintenance that signi ficantly decrease the whole-life cost of their assets.The project that has generated these results has been supported by a la Caixa Fellowship (ID 100010434), with code LCF/BQ/EU17/11590049. This research was partly supported by Siemens Industrial Turbomachinery UK. This research was also partly supported by the Next Generation Converged Digital Infrastructure project (EP/R004935/1) funded by the Engineering and Physical Sciences Research Council and BT. The server used to perform the experiments in this paper was funded by the Centre for Digital Built Britain

An Industrial Multi Agent System for real-time distributed collaborative prognostics

Despite increasing interest, real-time prognostics (failure prediction) is still not widespread in industry due to the di fficulties of existing systems to adapt to the dynamic and heterogeneous properties of real asset fleets. In order to address this, we present an Industrial Multi Agent System for real-time distributed collaborative prognostics. Our system fufil ls all six core properties of Advanced Multi Agent Systems: Distribution, Flexibility, Adaptability, Scalability, Leanness, and Resilience. Experimental examples of each are provided for the case of prognostics using the C-MAPPS engine degradation data set, and data from a fleet of industrial gas turbines. Prognostics are performed using the Weibull Time To Event - Recurrent Neural Network algorithm. Collaboration is achieved by sharing information between agents in the system. We conclude that distributed collaborative prognostics is especially pertinent for systems with presence of sensor faults, limited computing capabilities or significant fleet heterogeneity

Comparison of Agent Deployment Strategies for Collaborative Prognosis

Collaborative prognosis is a technique that enables the industrial assets to learn from similar other assets in a fleet, and improve their data-driven prognosis models. When collabo- rative prognosis is implemented in a computationally distributed framework, each asset is monitored by its corresponding Digital Twin agent. Distributed collaborative prognosis is particularly beneficial for high value assets where the communication and the processing costs are negligible compared to the maintenance costs. This paper analyses the effects of Digital Twin deployment strategies on the effectiveness of predictive maintenance activities relying on distributed collaborative prognosis. Distributed and heterarchical multi-agent system architectures are analysed for large fleets of assets, with varying failure rates and noise levels in the failure data. The results show that no single architecture or deployment strategy can be deemed best across all failure rates and noise levels. The conclusion derived in this paper provides guidance to the asset owners to choose the most suitable combination for a given application.Next Generation Converged Digital Infrastructure project (EP/R004935/1) funded by the Engineering and Physical Sciences Research Council and B

A modified time-of-flight method for precise determination of high speed ratios in molecular beams

Time-of-flight (TOF) is a standard experimental technique for determining, among others, the speed ratio S (velocity spread) of a molecular beam. The speed ratio is a measure for the monochromaticity of the beam and an accurate determination of S is crucial for various applications, for example, for characterising chromatic aberrations in focussing experiments related to helium microscopy or for precise measurements of surface phonons and surface structures in molecular beam scattering experiments. For both of these applications, it is desirable to have as high a speed ratio as possible. Molecular beam TOF measurements are typically performed by chopping the beam using a rotating chopper with one or more slit openings. The TOF spectra are evaluated using a standard deconvolution method. However, for higher speed ratios, this method is very sensitive to errors related to the determination of the slit width and the beam diameter. The exact sensitivity depends on the beam diameter, the number of slits, the chopper radius, and the chopper rotation frequency. We present a modified method suitable for the evaluation of TOF measurements of high speed ratio beams. The modified method is based on a systematic variation of the chopper convolution parameters so that a set of independent measurements that can be fitted with an appropriate function are obtained. We show that with this modified method, it is possible to reduce the error by typically one order of magnitude compared to the standard method

True-to-size surface mapping with neutral helium atoms

Three-dimensional mapping of microscopic surface structures is important in many applications of technology and research, including areas as diverse as microfluidics, MEMS and geoscience. How- ever on the nanoscale, using established techniques for such imaging can be extremely challenging. Scanning helium microscopy (SHeM) is a new technique that uses neutral helium atoms as a probe, enabling completely non-destructive imaging. The technique is broadly applicable and ideal for many otherwise difficult to image materials such as insulators, ultra-thin nano-coatings and biological sam- ples. Here we present a method for implementation and operation of a stereo helium microscope, by applying the photometric stereo method of surface reconstruction to helium microscopy. Four detectors around the sample are typically required, but we show how sample rotation can be used to perform stereo reconstruction with a single detector instrument, or to improve the quality of the reconstructed surface by increasing the number of independent measurements. We examine the quality of the reconstructed surface and show that for low aspect ratio good absolute height is recovered. For features with height/width ∼ 1 the shape of the surface is still recovered well (8% error) despite multiple scattering and masking of the helium beam by surface topography. Therefore it is possible to perform accurate reconstruction of the shape of nanoscale structures with a height to width ratio of at least unity.SM Lambrick acknowledges funding from Mathworks Lt

Zero-order filter for diffractive focusing of de Broglie matter waves

The manipulation of neutral atoms and molecules via their de Broglie wave properties, also referred to as de Broglie matter wave optics, is relevant for several fields ranging from fundamental quantum mechanics tests and quantum metrology to measurements of interaction potentials and new imaging techniques. However, there are several challenges. For example, for diffractive focusing elements, the zero-order beam provides a challenge because it decreases the signal contrast. Here we present the experimental realization of a zero-order filter, also referred to as an order-sorting aperture for de Broglie matter wave diffractive focusing elements. The zero-order filter makes it possible to measure even at low beam intensities. We present measurements of zero-order filtered, focused, neutral helium beams generated at source stagnation pressures between 11 and 81 bars. We show that for certain conditions the atom focusing at lower source stagnation pressures (broader velocity distributions) is better than what has previously been predicted. We present simulations with the software ray-tracing simulation package mcstas using a realistic helium source configuration, which gives very good agreement with our measurements

Operational forecasting of daily summer maximum and minimum temperatures in the Valencia Region

Extreme-temperature events have a great impact on human society. Thus, knowledge of summer temperatures can be very useful both for the general public and for organizations whose workers operate in the open. An accurate forecasting of summer maximum and minimum temperatures could help to predict heatwave conditions and permit the implementation of strategies aimed at minimizing the negative effects that high temperatures have on human health. The objective of this work is to evaluate the skill of the regional atmospheric and modelling system (RAMS) model in determining daily summer maximum and minimum temperatures in the Valencia Region. For this, we have used the real-time configuration of this model currently running at the Centro de Estudios Ambientales de Mediterráneo Foundation. This operational system is run twice a day, and both runs have a 3-day forecast range. To carry out the verification of the model in this work, the information generated by the system has been broken into individual simulation days for a specific daily run of the model. Moreover, we have analysed the summer forecast period from 1 June to 31 August for 2007, 2008, 2009 and 2010. The results indicate good agreement between observed and simulated maximum temperatures, with RMSE in general near 2 °C both for coastal and inland stations. For this parameter, the model shows a negative bias around −1.5 °C in the coast, while the opposite trend is observed inland. In addition, RAMS also shows good results in forecasting minimum temperatures for coastal locations, with bias lower than 1 °C and RMSE below 2 °C. However, the model presents some difficulties for this parameter inland, where bias higher than 3 °C and RMSE of about 4 °C have been found. Besides, there is little difference in both temperatures forecasted within the two daily RAMS cycles and that RAMS is very stable in maintaining the forecast performance at least for three forecast days

Design and prediction performance of Venturi injectors in drip irrigation

[EN] The design and prediction performance of four Venturi injector prototypes have been studied using Computational Fluid Dynamics (CFD) techniques. Results were compared with experimental tests carried out in the laboratory of the Universitat Politecnica de Valencia, Valencia, Spain. The analysed and selected geometries for each prototype were used to simulate the operation without nutrient injection (G1) and with nutrient injection (G2). In first case (G1), the results were presented in the form of pressure profile at the injector axe under different velocities and the pressure distribution in the whole geometry. Additionally, this paper analysed the evolution of pressures and head loss versus main water flow in the different prototypes. The relative error was estimated to compare CFD and experimental results. The second case (G2), the graphical representation for the relations between the nutrient aspiration flow and water main flow were obtained for numerical and experiment approaches. In conclusion, CFD techniques appear as a suitable tool for the analysis of the Venturi injector operation, but its validation with experimental data is recommended.[ES] En la Universitat Politècnica de València, Valencia, España, se ha estudiado el diseño y funcionamiento de cuatro prototipos del inyector Venturi con técnicas de Dinámica de Fluidos Computacional (CFD), comparándo las con ensayos en laboratorio. Para cada prototipo, las geometrías definidas y analizadas han permitido simular el funcionamiento sin (G1) y con inyección (G2) para quimigación. En el caso G1, se presentan los gráficos del perfil de presiones en el eje del inyector para diversas velocidades, así como la distribución del campo de presiones y de la evolución de las diferencias de presión y pérdidas de carga frente al caudal principal. Para comparar los resultados obtenidos con CFD frente al resultado experimental, se calculó el error relativo. En el caso G2, se obtuvo la representación gráfica del el caudal de inyección frente al caudal principal. Las técnicas CFD exigen un buen ajuste del modelo para dar un resultado aceptable. Son interesantes para comparar geometrías, analizar sus variantes, realizar prediseños y aproximar ordenes de magnitud, pero es recomendable su ensayo en laboratorio para validar los resultados.Manzano Juarez, J.; De Azevedo, BM.; Do Bomfim, GV.; Royuela, A.; Palau Estevan, CV.; Viana, TVDA. (2014). Diseño y predicción del funcionamiento de inyectores Venturi en riego localizado. Revista Brasileira de Engenharia Agrícola e Ambiental - Agriambi. 18(12):1209-1217. doi:10.1590/1807-1929/agriambi.v18n12p1209-1217S120912171812Baylar, A., Aydin, M., Unsal, M., & Ozkan, F. (2009). Numerical Modeling of Venturi Flows for Determining Air Injection Rates Using Fluent V6.2. Mathematical and Computational Applications, 14(2), 97-108. doi:10.3390/mca14020097CIPOLLA, E., Silva, F., FILHO, G., & BARROS, R. (2011). Avaliação da Distribuição de Velocidades em Uma Bomba Centrífuga Radial Utilizando Técnicas de CFD. Revista Brasileira de Recursos Hídricos, 16(3), 71-79. doi:10.21168/rbrh.v16n3.p71-79Davis, J. A., & Stewart, M. (2002). Predicting Globe Control Valve Performance—Part I: CFD Modeling. Journal of Fluids Engineering, 124(3), 772-777. doi:10.1115/1.1490108Coutier-Delgosha, O., Fortes-Patella, R., & Reboud, J. L. (2003). Evaluation of the Turbulence Model Influence on the Numerical Simulations of Unsteady Cavitation. Journal of Fluids Engineering, 125(1), 38-45. doi:10.1115/1.1524584Franklin, R. E., & Wallace, J. M. (1970). Absolute measurements of static-hole error using flush transducers. Journal of Fluid Mechanics, 42(1), 33-48. doi:10.1017/s0022112070001052Guo, B., Langrish, T. A. ., & Fletcher, D. F. (2002). CFD simulation of precession in sudden pipe expansion flows with low inlet swirl. Applied Mathematical Modelling, 26(1), 1-15. doi:10.1016/s0307-904x(01)00041-5Hatano, S., Kang, D., Kagawa, S., Nohmi, M., & Yokota, K. (2014). Study of Cavitation Instabilities in Double-Suction Centrifugal Pump. International Journal of Fluid Machinery and Systems, 7(3), 94-100. doi:10.5293/ijfms.2014.7.3.094Lindau, J. W., Kunz, R. F., Boger, D. A., Stinebring, D. R., & Gibeling, H. J. (2002). High Reynolds Number, Unsteady, Multiphase CFD Modeling of Cavitating Flows. Journal of Fluids Engineering, 124(3), 607-616. doi:10.1115/1.1487360Norton, T., Sun, D.-W., Grant, J., Fallon, R., & Dodd, V. (2007). Applications of computational fluid dynamics (CFD) in the modelling and design of ventilation systems in the agricultural industry: A review. Bioresource Technology, 98(12), 2386-2414. doi:10.1016/j.biortech.2006.11.025Palau-Salvador, G., Gonzalez Altozano, P., & Arviza-Valverde, J. (2007). Numerical modeling of cavitating flows for simple geometries using FLUENT V6.1. Spanish Journal of Agricultural Research, 5(4), 460. doi:10.5424/sjar/2007054-269Palau-Salvador, G., González-Altozano, P., & Arviza-Valverde, J. (2007). Three-Dimensional Modeling and Geometrical Influence on the Hydraulic Performance of a Control Valve. Journal of Fluids Engineering, 130(1). doi:10.1115/1.2813131Reader-Harris, M. ., Brunton, W. ., Gibson, J. ., Hodges, D., & Nicholson, I. . (2001). Discharge coefficients of Venturi tubes with standard and non-standard convergent angles. Flow Measurement and Instrumentation, 12(2), 135-145. doi:10.1016/s0955-5986(01)00007-3Singhal, A. K., Athavale, M. M., Li, H., & Jiang, Y. (2002). Mathematical Basis and Validation of the Full Cavitation Model. Journal of Fluids Engineering, 124(3), 617-624. doi:10.1115/1.1486223Sun, Y., & Niu, W. (2012). Simulating the Effects of Structural Parameters on the Hydraulic Performances of Venturi Tube. Modelling and Simulation in Engineering, 2012, 1-7. doi:10.1155/2012/458368Teruel, B. J. (2010). Controle automatizado de casas de vegetação: variáveis climáticas e fertigação. Revista Brasileira de Engenharia Agrícola e Ambiental, 14(3), 237-245. doi:10.1590/s1415-43662010000300001Vortmann, C., Schnerr, G. H., & Seelecke, S. (2003). Thermodynamic modeling and simulation of cavitating nozzle flow. International Journal of Heat and Fluid Flow, 24(5), 774-783. doi:10.1016/s0142-727x(03)00003-1Wei, Q., Shi, Y., Dong, W., Lu, G., & Huang, S. (2006). Study on hydraulic performance of drip emitters by computational fluid dynamics. Agricultural Water Management, 84(1-2), 130-136. doi:10.1016/j.agwat.2006.01.016Xing, T., & Frankel, S. H. (2002). Effect of Cavitation on Vortex Dynamics in a Submerged Laminar Jet. AIAA Journal, 40(11), 2266-2276. doi:10.2514/2.1563Yeoh, G. H., Liu, C., Tu, J., & Timchenko, V. (2012). Computational Fluid Dynamics and Its Applications 2012. Modelling and Simulation in Engineering, 2012, 1-2. doi:10.1155/2012/61061