State Observer for Optimal Control using White-box Building Models

In order to improve the energy efficiency of buildings, optimal control strategies, such as model predictive control (MPC), have proven to be potential techniques for intelligent operation of energy systems in buildings. However, in order to perform well, MPC needs an accurate controller model of the building to make correct predictions of the building thermal needs (feedforward) and the algorithm should ideally use measurement data to update the model to the actual state of the building (feedback). In this paper, a white-box approach is used to develop the controller model for an office building, leading to a model with more than 1000 states. As these states are not directly measurable, a state observer needs to be developed. In this paper, we compare three different state estimation techniques commonly applied to optimal control in buildings by applying them on a simulation model of the office building but fed with real measurement data. The considered observers are stationary Kalman Filter, time-varying Kalman Filter, and Moving Horizon Estimation. Summarizing the results, all estimators can achieve low output estimation error, but on the other hand only Moving Horizon Estimation is capable to keep the state trajectories within the limits thanks to the constraints at expenses of the computational time. As a first step towards real implementation of white-box MPC, in this paper, we have compared different state estimation techniques commonly applied to optimal control in buildings. We selected three different state observers available from the literature and compared their estimation error and robustness against initial conditions and noise in a numerical case study by using a virtual test bed model of a real building

Analytical solution for optimal mass flow rate in primary circuit of ground-coupled heat pump systems

Ground source heat pump (GSHP) systems extract heat or cold from the ground by circulating a heat carrier uid (HCF) in a ground heat exchanger and inject this energy in buildings. This paper shows that there exists an optimal HCF ow rate which minimizes the energy use of such systems. The paper proposes an analytical solution for the optimal ow rate as a function of measurable variables, system parameters and data that can easily be derived from manufacturer data sheets. The analytical solution is validated using a detailed simulation model representing an existing GSHP system of 99 boreholes with a depth of 30m

hybridGEOTABS project : MPC for controlling the power of the ground by integration

GEOTABS is an acronym for a GEOthermal heat pump combined with a Thermally Activated Building System (TABS). GEOTABS combines the use of geothermal energy, which is an almost limitless and ubiquitous energy source, with radiant heating and cooling systems, which can provide very comfortable conditioning of the indoor space. GEOTABShybrid refers to the integration of GEOTABS with secondary heating and cooling systems and other renewable and residual energy sources (R2ES), offering a huge potential to meet heating and cooling needs in office buildings, elderly care homes, schools and multi-family buildings throughout Europe in a sustainable way. Through the use of Model Predictive Control (MPC), a new control-integrated building design procedure and a readily applicable commercial system solution in GEOTABShybrid, the overall efficiency of heating and cooling will be significantly improved in comparison to current best practice GEOTABS systems and its competitiveness will be strengthened. The present paper is the first of a series that first introduces the hybridGEOTABS project and then specifically focuses on the control-related aspects of the hybridGEOTABS solution, the MPC, providing some interesting insights of its potential development

Development and validation of a full-time-scale semi-analytical model for the short- and long-term simulation of vertical geothermal bore fields

This paper presents the development and validation of a full-time-scale semi-analytical bore field simulation model. The model allows for the simulation of bore fields comprised of arbitrarily positioned boreholes while accounting for both short-term transient thermal effects within the boreholes and long-term thermal interactions in the bore field. The g-function of the bore field, obtained from the finite line source solution, is corrected to account for the cylindrical geometry of the boreholes and coupled to a thermal resistances and capacitances model of the borehole interior, thereby extending the scope of g-functions to short time scales. Additionally, an improved load aggregation scheme for ground thermal response calculations allows the model to be used with variable simulation time steps. The complete model is validated using a combination of analytical, experimental and field monitored data to verify both its short-term and long-term behaviour. The model is implemented using the Modelica language as part of an implementation in the open-source buildings simulation library IBPSA

Comparison of Model Predictive Control performance using grey-box and white box controller models

Model predictive control (MPC) for building climate control has received increasing attention the last decade. Its large scale implementation is, however, still hampered by the difficulty of obtaining accurate but computationally efficient multi-zone building controller models. This paper compares an existing grey-box approach with a novel white-box approach to obtain a controller model of the building envelope and it compares the performance achieved by using these two approaches. The comparison is made for an existing office building, which is currently controlled using a grey-box MPC [1].  The building envelope and its heating, cooling and air conditioning systems  (HVAC) are modelled using the Modelica building energy simulation library IDEAS. The model is validated using measurement data from the real building. This detailed simulation model is composed of discretised partial differential equations, ordinary differential equations and algebraic equations. The model is therefore too complex to be used as controller model for MPC. Two MPC approaches are compared. On the one hand, the white-box controller model is obtained by linearizing the building envelope part of the simulation model and by pre-computing model inputs such as solar gains through each window [2]. The method generates a linear state space model, which produces very similar temperatures as the original non-linear model. On the other hand, the grey-box identification method that was used to obtain the current controller model, is also applied to the detailed simulation model. Both white-box and grey-box MPC are applied to the detailed simulation model. The dynamics of the HVAC systems are not included in the MPC model but the efficiencies, constraints, cost function and boundary conditions are included. The energy use, the achieved thermal zone comfort and the prediction performance are compared. Finally, a new grey-box model is identified with operation data of the real building and the multi-step ahead prediction performance of the white-box and of both the grey-box models obtained with the simulation data and obtained with the measured data is computed for the real building using the measurement data and the weather forecast, which are used by the current MPC implementation.  [1] Zdenek Vana, Jiri Cigler, Jan Siroky, Eva Zacekova, Lukas Ferkl. Model-based energy efficient control applied to an office building. J. Process Control (2014).  [2] Picard, D., Jorissen, F., and Helsen, L. 2015. Methodology for Obtaining Linear State Space Building Energy Simulation Models. In 11th International Modelica Conference, pages 51–58, Paris

Strain localization and anisotropic correlations in a mesoscopic model of amorphous plasticity

A mesoscopic model for shear plasticity of amorphous materials in two dimensions is introduced, and studied through numerical simulations in order to elucidate the macroscopic (large scale) mechanical behavior. Plastic deformation is assumed to occur through a series of local reorganizations. Using a discretization of the mechanical fields on a discrete lattice, local reorganizations are modeled as local slip events. Local yield stresses are randomly distributed in space and invariant in time. Each plastic slip event induces a long-ranged elastic stress redistribution. Rate and thermal effects are not discussed in the present study. Extremal dynamics allows for recovering many of the complex features of amorphous plasticity observed experimentally and in numerical atomistic simulations in the quasi-static regime. In particular, a quantitative picture of localization, and of the anisotropic strain correlation both in the initial transient regime, and in the steady state are provided. In addition, the preparation of the amorphous sample is shown to have a crucial effect of on the localization behavior

Marking techniques in the Marbled Newt (Triturus marmoratus): PIT-Tag and tracking device implant protocols

Individual marking has become essential for studying population dynamics and ecological requirements. However, marking small-bodied species such as amphibians is becoming a challenge in the last decades. Amphibian surveys may require to mark manually individuals, using toe clipping, polymers and pigments, or passive integrated transponders (PIT-tags). Even if ethics committees have recently recommend avoiding toe clipping in amphibians, the use of PIT-tags led to controversial results because low tag retention reported in some studies. Here, we describe a protocol of potentially life-long PIT-tag marking in a protected species, the marbled newt Triturus marmoratus. In addition, we also detailed a second procedure of surgery for the implantation of transmitters needed in radio-tracking surveys. During both procedures, we found that the newt phase (either aquatic or terrestrial) strongly affected the anesthesia duration. Indeed, newts in aquatic phase were more quickly anesthetized than newts under terrestrial phase. We then recommend to pay attention of this physiological particularity when performing this kind of procedure. Improving our knowledge on ecological requirements and population dynamics of this species is crucial for management and conservation plans, and could be extended to other large newts

Marking techniques in the Marbled Newt (<em>Triturus marmoratus</em>): PIT-Tag and tracking device implant protocols

Individual marking has become essential for studying population dynamics and ecological requirements. However, marking small-bodied species such as amphibians is becoming a challenge in the last decades. Amphibian surveys may require to mark manually individuals, using toe clipping, polymers and pigments, or passive integrated transponders (PIT-tags). Even if ethics committees have recently recommend avoiding toe clipping in amphibians, the use of PIT-tags led to controversial results because low tag retention reported in some studies. Here, we describe a protocol of potentially life-long PIT-tag marking in a protected species, the marbled newt Triturus marmoratus. In addition, we also detailed a second procedure of surgery for the implantation of transmitters needed in radio-tracking surveys. During both procedures, we found that the newt phase (either aquatic or terrestrial) strongly affected the anesthesia duration. Indeed, newts in aquatic phase were more quickly anesthetized than newts under terrestrial phase. We then recommend to pay attention of this physiological particularity when performing this kind of procedure. Improving our knowledge on ecological requirements and population dynamics of this species is crucial for management and conservation plans, and could be extended to other large newts

Snow accumulation and ablation measurements in a midlatitude mountain coniferous forest (Col de Porte, France, 1325&thinsp;m altitude): the Snow Under Forest (SnoUF) field campaign data set

Forests strongly modify the accumulation, metamorphism and melting of snow in midlatitude and high-latitude regions. Recently, snow routines in hydrological and land surface models were improved to incorporate more accurate representations of forest snow processes, but model intercomparison projects have identified deficiencies, partly due to incomplete knowledge of the processes controlling snow cover in forests. The Snow Under Forest (SnoUF) project was initiated to enhance knowledge of the complex interactions between snow and vegetation. Two field campaigns, during the winters 2016–2017 and 2017–2018, were conducted in a coniferous forest bordering the snow study at Col de Porte (1325 m a.s.l., French Alps) to document the snow accumulation and ablation processes. This paper presents the field site, the instrumentation and the collection and postprocessing methods. The observations include distributed forest characteristics (tree inventory, lidar measurements of forest structure, subcanopy hemispherical photographs), meteorology (automatic weather station and an array of radiometers), snow cover and depth (snow pole transect and laser scan) and snow interception by the canopy during precipitation events. The weather station installed under dense canopy during the first campaign has been maintained since then and has provided continuous measurements throughout the year since 2018. Data are publicly available from the repository of the Observatoire des Sciences de l'Univers de Grenoble (OSUG) data center at https://doi.org/10.17178/SNOUF.2022 (Sicart et al., 2022).</p

Immunodeficiency, auto-inflammation and amylopectinosis in humans with inherited HOIL-1 and LUBAC deficiency

We report the clinical description and molecular dissection of a new fatal human inherited disorder characterized by chronic auto-inflammation, invasive bacterial infections and muscular amylopectinosis. Patients from two kindreds carried biallelic loss-of-expression and loss-of-function mutations in HOIL1, a component the linear ubiquitination chain assembly complex (LUBAC). These mutations resulted in impairment of LUBAC stability. NF-κB activation in response to interleukin-1β (IL-1β) was compromised in the patients’ fibroblasts. By contrast, the patients’ mononuclear leukocytes, particularly monocytes, were hyperresponsive to IL-1β. The consequences of human HOIL-1 and LUBAC deficiencies for IL-1β responses thus differed between cell types, consistent with the unique association of auto-inflammation and immunodeficiency in these patients. These data suggest that LUBAC regulates NF-κB-dependent IL-1β responses differently in different cell types