Browsing NTNU Open by Author "Backi, Christoph Josef"
Now showing items 1-19 of 19
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A comparative study of quality and safety of Atlantic cod (Gadus morhua) fillets during cold storage, as affected by different thawing methods of pre-rigor frozen headed and gutted fish
Roiha, Irja Sunde; Jónsson, Ásbjörn; Backi, Christoph Josef; Lunestad, Bjørn Tore; Karlsdóttir, Magnea (Journal article; Peer reviewed, 2017)BACKGROUND The catch of marine whitefish is typically seasonal, whereas the land‐based processing industry has a need for all‐year stable supply of raw materials. This challenge can be met by applying fish frozen at sea. ... -
A Control- and Estimation-Oriented Gravity Separator Model for Oil and Gas Applications Based upon First-Principles
Backi, Christoph Josef; Grimes, Brian Arthur; Skogestad, Sigurd (Journal article; Peer reviewed, 2018)We introduce a simple model for a gravity separator based on first principles. It can be used for controller design to control the levels of oil, water, and the gas pressure as well as observer design to estimate unmeasurable ... -
A heat equation for freezing processes with phase change: stability analysis and applications
Backi, Christoph Josef; Bendtsen, Jan Dimon; Leth, John; Gravdahl, Jan Tommy (Journal article, 2016)In this work, the stability properties as well as possible applications of a partial differential equation (PDE) with state-dependent parameters are investigated. Among other things, the PDE describes freezing of foodstuff, ... -
Combined state and parameter estimation for not fully observable dynamic systems
Backi, Christoph Josef; Gravdahl, Jan Tommy; Skogestad, Sigurd (Journal article, 2020)In this paper, a simple, yet novel method for state estimation and parameter identification for dynamic systems is presented. Apart from providing estimates of non-measurable state variables, the algorithm is also capable ... -
Development and assessment of novel technologies improving the fishing operation and on board processing with respect to environmental impact and fish quality (DANTEQ)
Aursand, Ida Grong; Digre, Hanne; Ladstein, Jarle; Kyllingstad, Lars Tandle; Erikson, Ulf Gøran; Tveit, Guro Møen; Backi, Christoph Josef; Reite, Karl Johan (Research report, 2015)Bærekraftig høsting av villfanget fisk er en av de viktigste utfordringene i det globale bildet når det gjelder å skaffe tilstrekkelige mengder fisk. Det ligger et stort potensial i å høste fisk på en bedre måte. Norge er ... -
Effects of controlled thawing media temperatures on quality and safety of pre-rigor frozen Atlantic cod (Gadus morhua)
Roiha, Irja Sunde; Tveit, Guro Møen; Backi, Christoph Josef; Jónsson, Ásbjörn; Karlsdóttir, Magnea; Lunestad, Bjørn Tore (Journal article; Peer reviewed, 2018)Novel strategies for thawing of pre-rigor frozen Atlantic cod (Gadus morhua) in water with air circulation, applying different and controlled temperatures are presented. After thawing (day 0) and after six days of storage ... -
Estimation of inner-domain temperatures for a freezing process
Backi, Christoph Josef; Bendtsen, Jan Dimon; Leth, John; Gravdahl, Jan Tommy (Journal article; Peer reviewed, 2014)In this paper a state observer for a distributed parameter system (DPS) with nonconstant parameter functions is presented. The DPS describes the freezing of foodstuff in vertical plate freezers and is a nonlinear heat ... -
Improved PI control for a surge tank satisfying level constraints
Reyes Lua, Adriana; Backi, Christoph Josef; Skogestad, Sigurd (Journal article; Peer reviewed, 2018)This paper considers the case of averaging level control, where the main objective is to reduce flow variations by using varying liquid levels. However, to avoid overfilling or emptying the tank, the liquid level needs to ... -
Modeling of Freezing of Fish by Vertical Plate Freezers
Backi, Christoph Josef; Gravdahl, Jan Tommy (Proceedings of the 17th Nordic Process Control Workshop;, Chapter, 2012) -
Modeling, Estimation and Control of Freezing and Thawing Processes: Theory and Applications
Backi, Christoph Josef (Doctoral thesis at NTNU;2015:323, Doctoral thesis, 2015)Fisheries and aquaculture are very important sectors in the Norwegian industry. Fish and its by-products are considered wholesome foodstuff and are popular especially due to their nutritional value. Therefore, consumer ... -
Nonlinear modeling and control for an evaporator unit
Backi, Christoph Josef (Journal article; Peer reviewed, 2018)This article presents a nonlinear modeling approach describing the enthalpy dynamics between the inlet of the economizer and the outlet of the evaporator in a once-through boiler. The model is used to design an LQG controller ... -
Nonlinear observer design for a Greitzer compressor model
Backi, Christoph Josef; Gravdahl, Jan Tommy; Grøtli, Esten Ingar (Chapter, 2013)In this paper two different observers for a nonlinear compressor model have been developed and compared: A nonlinear observer based on a circle criterion design and an Extended Kalman Filter. Both of these observers ... -
Optimal boundary control for the heat equation with application to freezing with phase change
Backi, Christoph Josef; Gravdahl, Jan Tommy (Chapter, 2013)In this paper an approach for optimal boundary control of a parabolic partial differential equation (PDE) is presented. The parabolic PDE is the heat equation for thermal conduction. A technical application for this is the ... -
Optimal boundary control of a contact thawing process for foodstuff
Backi, Christoph Josef; Leth, John; Gravdahl, Jan Tommy (Journal article, 2016)In this work an approach for thawing blocks of foodstuff, in particular fish, is introduced. The functional principle is based on plate freezer technology, which has been used in industry for decades. The aim of this work ... -
Simple method for parameter identification of a nonlinear Greitzer compressor model
Backi, Christoph Josef; Gravdahl, Jan Tommy; Skogestad, Sigurd (Journal article; Peer reviewed, 2018)This work introduces a simple method to estimate state variables and identify parameters of a nonlinear dynamic Greitzer compressor model. The observer is based upon an extended Kalman filter, which estimates the dynamic ... -
Slug handling with a virtual harp based on nonlinear predictive control for a gravity separator
Backi, Christoph Josef; Krishnamoorthy, Dinesh; Skogestad, Sigurd (Journal article; Peer reviewed, 2018)This paper presents a nonlinear model predictive control approach for a three-phase gravity separator model. The aim of the controller is to dampen slug-induced, oscillatory disturbances in the inflow to the gravity ... -
Stability properties of a heat equation with state-dependent parameters and asymmetric boundary conditions
Backi, Christoph Josef; Bendtsen, Jan Dimon; Leth, John; Gravdahl, Jan Tommy (Journal article; Peer reviewed, 2015)In this work the stability properties of a partial differential equation (PDE) with statedependent parameters and asymmetric boundary conditions are investigated. The PDE describes the temperature distribution inside ... -
The nonlinear heat equation with state-dependent parameters and its connection to the Burgers’ and the potential Burgers’ equation
Backi, Christoph Josef; Bendtsen, Jan Dimon; Leth, John; Gravdahl, Jan Tommy (Journal article; Peer reviewed, 2014)In this work the stability properties of a nonlinear partial differential equation (PDE) with state dependent parameters is investigated. Among other things, the PDE describes freezing of foodstuff, and is closely related ... -
Virtual inflow estimation with simplified tuning using cascaded and Kalman-like least squares observers
Backi, Christoph Josef; Skogestad, Sigurd (Journal article; Peer reviewed, 2018)Multiphase metering is often unavailable, unreliable or expensive, which makes model-based, virtual monitoring a cheap and reliable alternative in order to obtain information about e.g. the inflows to a device. This paper ...