TY  - CHAP
A1  - Müller, Tim M.
A1  - Schmitt, Andreas
A1  - Leise, Philipp
A1  - Meck, Tobias
A1  - Altherr, Lena
A1  - Pelz, Peter F.
A1  - Pfetsch, Marc E.
T1  - Validation of an optimized resilient water supply system
T2  - Uncertainty in Mechanical Engineering
N2  - Component failures within water supply systems can lead to significant performance losses. One way to address these losses is the explicit anticipation of failures within the design process. We consider a water supply system for high-rise buildings, where pump failures are the most likely failure scenarios. We explicitly consider these failures within an early design stage which leads to a more resilient system, i.e., a system which is able to operate under a predefined number of arbitrary pump failures. We use a mathematical optimization approach to compute such a resilient design. This is based on a multi-stage model for topology optimization, which can be described by a system of nonlinear inequalities and integrality constraints. Such a model has to be both computationally tractable and to represent the real-world system accurately. We therefore validate the algorithmic solutions using experiments on a scaled test rig for high-rise buildings. The test rig allows for an arbitrary connection of pumps to reproduce scaled versions of booster station designs for high-rise buildings. We experimentally verify the applicability of the presented optimization model and that the proposed resilience properties are also fulfilled in real systems.
KW  - Optimization
KW  - Mixed-integer nonlinear programming
KW  - Water distribution system
KW  - Resilience
KW  - Validation
Y1  - 2021
SN  - 978-3-030-77255-0
SN  - 978-3-030-77256-7
U6  - http://dx.doi.org/10.1007/978-3-030-77256-7_7
N1  - Proceedings of the 4th International Conference on Uncertainty in Mechanical Engineering (ICUME 2021), June 7–8, 2021
SP  - 70
EP  - 80
PB  - Springer
CY  - Cham
ER  - 
TY  - CHAP
A1  - Meck, Marvin M.
A1  - Müller, Tim M.
A1  - Altherr, Lena
A1  - Pelz, Peter F.
T1  - Improving an industrial cooling system using MINLP, considering capital and operating costs
T2  - Operations Research Proceedings 2019
N2  - The chemical industry is one of the most important industrial sectors in Germany in terms of manufacturing revenue. While thermodynamic boundary conditions often restrict the scope for reducing the energy consumption of core processes, secondary processes such as cooling offer scope for energy optimisation. In this contribution, we therefore model and optimise an existing cooling system. The technical boundary conditions of the model are provided by the operators, the German chemical company BASF SE. In order to systematically evaluate different degrees of freedom in topology and operation, we formulate and solve a Mixed-Integer Nonlinear Program (MINLP), and compare our optimisation results with the existing system.
KW  - Engineering optimisation
KW  - Mixed-integer programming
KW  - Industrial optimisation
KW  - Cooling system
KW  - Process engineering
Y1  - 2020
SN  - 978-3-030-48438-5 (Print)
SN  - 978-3-030-48439-2 (Online)
U6  - http://dx.doi.org/10.1007/978-3-030-48439-2_61
N1  - Annual International Conference of the German Operations Research Society (GOR), Dresden, Germany, September 4-6, 2019.
SP  - 505
EP  - 512
PB  - Springer
CY  - Cham
ER  - 
TY  - JOUR
A1  - Müller, Tim M.
A1  - Leise, Philipp
A1  - Lorenz, Imke-Sophie
A1  - Altherr, Lena
A1  - Pelz, Peter F.
T1  - Optimization and validation of pumping system design and operation for water supply in high-rise buildings
JF  - Optimization and Engineering
N2  - The application of mathematical optimization methods for water supply system design and operation provides the capacity to increase the energy efficiency and to lower the investment costs considerably. We present a system approach for the optimal design and operation of pumping systems in real-world high-rise buildings that is based on the usage of mixed-integer nonlinear and mixed-integer linear modeling approaches. In addition, we consider different booster station topologies, i.e. parallel and series-parallel central booster stations as well as decentral booster stations. To confirm the validity of the underlying optimization models with real-world system behavior, we additionally present validation results based on experiments conducted on a modularly constructed pumping test rig. Within the models we consider layout and control decisions for different load scenarios, leading to a Deterministic Equivalent of a two-stage stochastic optimization program. We use a piecewise linearization as well as a piecewise relaxation of the pumps’ characteristics to derive mixed-integer linear models. Besides the solution with off-the-shelf solvers, we present a problem specific exact solving algorithm to improve the computation time. Focusing on the efficient exploration of the solution space, we divide the problem into smaller subproblems, which partly can be cut off in the solution process. Furthermore, we discuss the performance and applicability of the solution approaches for real buildings and analyze the technical aspects of the solutions from an engineer’s point of view, keeping in mind the economically important trade-off between investment and operation costs.
KW  - Technical Operations Research
KW  - MINLP
KW  - MILP
KW  - Experimental validation
KW  - Pumping systems
Y1  - 2020
U6  - http://dx.doi.org/10.1007/s11081-020-09553-4
SN  - 1573-2924
VL  - 2021
IS  - 22
SP  - 643
EP  - 686
PB  - Springer
ER  - 
TY  - CHAP
A1  - Müller, Tim M.
A1  - Altherr, Lena
A1  - Leise, Philipp
A1  - Pelz, Peter F.
T1  - Optimization of pumping systems for buildings: Experimental validation of different degrees of model detail on a modular test rig
T2  - Operations Research Proceedings 2019
N2  - Successful optimization requires an appropriate model of the system under consideration. When selecting a suitable level of detail, one has to consider solution quality as well as the computational and implementation effort. In this paper, we present a MINLP for a pumping system for the drinking water supply of high-rise buildings. We investigate the influence of the granularity of the underlying physical models on the solution quality. Therefore, we model the system with a varying level of detail regarding the friction losses, and conduct an experimental validation of our model on a modular test rig. Furthermore, we investigate the computational effort and show that it can be reduced by the integration of domain-specific knowledge.
KW  - Experimental validation
KW  - MINLP
KW  - Engineering optimization
KW  - Water supply system
KW  - Network design
Y1  - 2020
SN  - 978-3-030-48438-5
U6  - http://dx.doi.org/10.1007/978-3-030-48439-2_58
N1  - Annual International Conference of the German Operations Research Society (GOR), Dresden, Germany, September 4-6, 2019
SP  - 481
EP  - 488
PB  - Springer
CY  - Cham
ER  - 
TY  - CHAP
A1  - Müller, Tim M.
A1  - Altherr, Lena
A1  - Ahola, Marja
A1  - Schabel, Samuel
A1  - Pelz, Peter F.
ED  - Rodrigues, H. C.
T1  - Multi-Criteria optimization of pressure screen systems in paper recycling – balancing quality, yield, energy consumption and system complexity
T2  - EngOpt 2018 Proceedings of the 6th International Conference on Engineering Optimization
N2  - The paper industry is the industry with the third highest energy consumption in the European Union. Using recycled paper instead of fresh fibers for papermaking is less energy consuming and saves resources. However, adhesive contaminants in recycled paper are particularly problematic since they reduce the quality of the resulting paper-product. To remove as many contaminants and at the same time obtain as many valuable fibres as possible, fine screening systems, consisting of multiple interconnected pressure screens, are used. Choosing the best configuration is a non-trivial task: The screens can be interconnected in several ways, and suitable screen designs as well as operational parameters have to be selected. Additionally, one has to face conflicting objectives. In this paper, we present an approach for the multi-criteria optimization of pressure screen systems based on Mixed-Integer Nonlinear Programming. We specifically focus on a clear representation of the trade-off between different objectives.
Y1  - 2019
SN  - 978-3-319-97773-7
U6  - http://dx.doi.org/10.1007/978-3-319-97773-7_105
N1  - EngOpt 2018 Proceedings of the 6th International Conference on Engineering Optimization. 17-19 September 2018. Lisboa, Portugal
PB  - Springer International Publishing
CY  - Basel
ER  - 
TY  - CHAP
A1  - Müller, Tim M.
A1  - Altherr, Lena
A1  - Ahola, Marja
A1  - Schabel, Samuel
A1  - Pelz, Peter F.
T1  - Optimizing pressure screen systems in paper recycling: optimal system layout, component selection and operation
N2  - Around 60% of the paper worldwide is made from recovered paper. Especially adhesive contaminants, so called stickies, reduce paper quality. To remove stickies but at the same time keep as many valuable fibers as possible, multi-stage screening systems with several interconnected pressure screens are used. When planning such systems, suitable screens have to be selected and their interconnection as well as operational parameters have to be defined considering multiple conflicting objectives. In this contribution, we present a Mixed-Integer Nonlinear Program to optimize system layout, component selection and operation to find a suitable trade-off between output quality and yield.
KW  - Mixed-integer nonlinear problem
KW  - MINLP
KW  - Process engineering
KW  - Paper recycling
KW  - Multi-criteria optimization
Y1  - 2018
SN  - 978-3-030-18499-5
U6  - http://dx.doi.org/10.1007/978-3-030-18500-8_44
SP  - 355
EP  - 361
PB  - Springer
CY  - Cham
ER  - 
TY  - JOUR
A1  - Rösch, C.
A1  - Kratz, F.
A1  - Hering, T.
A1  - Trautmann, S.
A1  - Umanskaya, N.
A1  - Tippkötter, Nils
A1  - Müller-Renno, C.M.
A1  - Ulber, R.
A1  - Hannig, M.
A1  - Ziegler, C.
T1  - Albumin-lysozyme interactions: cooperative adsorption on titanium and enzymatic activity
JF  - Colloids and Surfaces B: Biointerfaces
N2  - The interplay of albumin (BSA) and lysozyme (LYZ) adsorbed simultaneously on titanium was analyzed by gel electrophoresis and BCA assay. It was found that BSA and lysozyme adsorb cooperatively. Additionally, the isoelectric point of the respective protein influences the adsorption. Also, the enzymatic activity of lysozyme and amylase (AMY) in mixtures with BSA was considered with respect to a possible influence of protein-protein interaction on enzyme activity. Indeed, an increase of lysozyme activity in the presence of BSA could be observed. In contrast, BSA does not influence the activity of amylase.
Y1  - 2016
U6  - http://dx.doi.org/10.1016/j.colsurfb.2016.09.048
VL  - 149
IS  - 1
SP  - 115
EP  - 121
PB  - Elsevier
CY  - Amsterdam
ER  -