Robustness and economic measures as control benchmark performance criteria

2002 ◽  
Vol 45 (4-5) ◽  
pp. 117-126 ◽  
Author(s):  
P.A. Vanrolleghem ◽  
S. Gillot
Keyword(s):  
Control Strategies ◽  
Open Loop ◽  
Performance Criteria ◽  
Operating Costs ◽  
Relative Importance ◽  
Cost Index ◽  
Total Cost ◽  
Simple Strategy ◽  
Grey Scale

The objective of this paper was to investigate the usefulness of new multi-criteria measures to evaluate a control strategy through the Benchmark protocol. Using a case study in which respirometry-based control strategies are evaluated, the proposed measures were calculated. An economic index including weighted investment and operating costs (termed Total Cost Index – TCI) appears more powerful than a grey-scale presentation approach. Using the latter approach, it is hard to reflect the relative importance of the criteria investigated, which makes practical decisions rather difficult. In addition, a Robustness Index (RI) is proposed that allows us to evaluate the transferability of control strategies to situations different from the ones defined in the benchmark protocol. Finally, the case study shows that it may be advisable to replace the currently used open loop benchmark reference by a plant in which dissolved oxygen is controlled in all aerated reactors. This quite simple strategy also turned out to be the best one among all evaluated strategies.

Benchmarking of control strategies for ATAD technology: a first approach to the automatic control of sludge treatment systems

2009 ◽  
Vol 60 (2) ◽  
pp. 409-417 ◽  
Author(s):  
J. A. Zambrano ◽  
M. Gil-Martinez ◽  
M. Garcia-Sanz ◽  
I. Irizar
Keyword(s):  
Automatic Control ◽  
Wastewater Treatment Plants ◽  
Control Strategies ◽  
Open Loop ◽  
Operating Costs ◽  
Promising Alternative ◽  
Effluent Quality ◽  
Key Factor ◽  
Simulation Protocol ◽  
Autothermal Thermophilic Aerobic Digestion

Autothermal Thermophilic Aerobic Digestion (ATAD technology) is a promising alternative to conventional digestion systems. Aeration is a key factor in the performance of these kinds of reactors, in relation to effluent quality and operating costs. At present, the realisation of automatic control in ATADs is in its infancy. Additionally, the lack of robust sensors also makes the control of these processes difficult: only redox potential and temperature sensors are reliable for operation in full-scale plants. Based as it is on the existing simulation protocols for benchmarking of control strategies for wastewater treatment plants (WWTP), this paper presents the definition and implementation of a similar protocol but specifically adapted to the needs of ATAD technology. The implemented simulation protocol has been used to validate two different control strategies for aeration (ST1 and ST2). In comparison to an open-loop operation for the ATAD, simulation results showed that the ST1 strategy was able to save aeration costs of around 2–4%. Unlike ST1, ST2 achieved maximum sludge stabilisation but at the expense of higher aeration costs.

scholarly journals Plant Layout Optimization for Chemical Industry Considering Inner Frame Structure Design

2020 ◽  
Vol 12 (6) ◽  
pp. 2476
Author(s):  
Siyu Xu ◽  
Yufei Wang ◽  
Xiao Feng
Keyword(s):  
Special Kind ◽  
Structure Design ◽  
Frame Structure ◽  
Operating Costs ◽  
Plant Layout ◽  
Total Cost ◽  
Four Frames ◽  
Flow Information ◽  
Frame Flow

Plant layout design is a complex task requiring a wealth of engineering experience. A well-designed layout can extraordinarily reduce various costs, so layout study is of great value. To promote the research depth, plenty of considerations have been taken. However, an actual plant may have several frames and how to distribute facilities and determine the location of them in the different frames has not been well studied. In this work, frames are set as a special kind of inner structure and are added into the model to assign facilities into several blocks. A quantitative method for assigning facilities is proposed to let the number of cross-frame connections be minimized. After allocating the facilities into several blocks, each frame is optimized to obtain initial frame results. With designer decisions and cross-frame flow information, the relative locations of frames are determined and then the internal frame layouts are optimized again to reach the coupling optimization between frame and plant layout. Minimizing the total cost involving investment and operating costs is set to be the objective. In the case study, a plant with 138 facilities and 247 material connections is studied. All the facilities are assigned into four frames, and only 17 connections are left to be cross-frame ones. Through the two optimizations of each frame, the length of cross-frame connections reduces by 582.7 m, and the total cost decreases by 4.7 × 105 ¥/a. Through these steps, the idea of frame is successfully applied and the effectiveness of the proposed methodology is proved.

Pollution based real time control strategies for combined sewer systems

1997 ◽  
Vol 36 (8-9) ◽  
pp. 331-336 ◽  
Author(s):  
Gabriela Weinreich ◽  
Wolfgang Schilling ◽  
Ane Birkely ◽  
Tallak Moland
Keyword(s):  
Real Time ◽  
Control Strategies ◽  
Ammonia Nitrogen ◽  
Simple Extension ◽  
Real Time Control ◽  
Time Control ◽  
Sewer Systems ◽  
Receiving Waters ◽  
Tunnel System

This paper presents results from an application of a newly developed simulation tool for pollution based real time control (PBRTC) of urban drainage systems. The Oslo interceptor tunnel is used as a case study. The paper focuses on the reduction of total phosphorus Ptot and ammonia-nitrogen NH4-N overflow loads into the receiving waters by means of optimized operation of the tunnel system. With PBRTC the total reduction of the Ptot load is 48% and of the NH4-N load 51%. Compared to the volume based RTC scenario the reductions are 11% and 15%, respectively. These further reductions could be achieved with a relatively simple extension of the operation strategy.

scholarly journals Optimal placement design for picking and packing in distribution centers

2021 ◽  
Vol 13 (4) ◽  
pp. 168781402110106
Author(s):  
John Rios ◽  
Rodrigo Linfati ◽  
Daniel Morillo-Torres ◽  
Iván Derpich ◽  
Gustavo Gatica
Keyword(s):  
Optimal Allocation ◽  
Programming Model ◽  
Operating Cost ◽  
Nonlinear Integer Programming ◽  
Operating Costs ◽  
Optimal Placement ◽  
Distribution Centers ◽  
Suitable Space ◽  
Efficient Distribution

An efficient distribution center (DC) is one that receives, stores, picks and packs products into new logistics units and then dispatches them to points of sale at the minimal operating cost. The picking and packing processes represent the highest operating cost of a DC, and both require a suitable space for their operation. An effective coordination between these zones prevents bottlenecks and has a direct impact on the DC’s operational results. In the existing literature, there are no studies that optimize the distribution of the picking and packing areas simultaneously while also reducing operating costs. This article proposes an integer nonlinear integer programming model that minimizes order preparation costs. It does so by predicting customer demand based on historical data and defining the ideal area for picking and packing activities. The model is validated through a real case study of seven clients and fifteen products. It achieves a [Formula: see text] reduction in operating costs when the optimal allocation of the picking and packing areas is made.

scholarly journals An integrodifferential approach to modeling, control, state estimation and optimization for heat transfer systems

2016 ◽  
Vol 26 (1) ◽  
pp. 15-30 ◽  
Author(s):  
Andreas Rauh ◽  
Luise Senkel ◽  
Harald Aschemann ◽  
Vasily V. Saurin ◽  
Georgy V. Kostin
Keyword(s):  
Heat Transfer ◽  
Finite Element ◽  
Control Strategies ◽  
Open Loop ◽  
Distributed Parameter ◽  
Dimensional System ◽  
State Equations ◽  
Large Space ◽  
Finite Dimensional ◽  
Spatially Distributed

Abstract In this paper, control-oriented modeling approaches are presented for distributed parameter systems. These systems, which are in the focus of this contribution, are assumed to be described by suitable partial differential equations. They arise naturally during the modeling of dynamic heat transfer processes. The presented approaches aim at developing finite-dimensional system descriptions for the design of various open-loop, closed-loop, and optimal control strategies as well as state, disturbance, and parameter estimation techniques. Here, the modeling is based on the method of integrodifferential relations, which can be employed to determine accurate, finite-dimensional sets of state equations by using projection techniques. These lead to a finite element representation of the distributed parameter system. Where applicable, these finite element models are combined with finite volume representations to describe storage variables that are—with good accuracy—homogeneous over sufficiently large space domains. The advantage of this combination is keeping the computational complexity as low as possible. Under these prerequisites, real-time applicable control algorithms are derived and validated via simulation and experiment for a laboratory-scale heat transfer system at the Chair of Mechatronics at the University of Rostock. This benchmark system consists of a metallic rod that is equipped with a finite number of Peltier elements which are used either as distributed control inputs, allowing active cooling and heating, or as spatially distributed disturbance inputs.

Case study on the implementation of deammonification for the process water treatment of Munich WWTPs

2012 ◽  
Vol 65 (10) ◽  
pp. 1895-1902 ◽  
Author(s):  
Rita Hilliges ◽  
Eberhard Steinle ◽  
Bernhard Böhm
Keyword(s):  
Water Treatment ◽  
Operating Costs ◽  
Process Water ◽  
Second Stage ◽  
Sludge Disposal ◽  
Sludge Digestion ◽  
High Investment ◽  
Flow Treatment

The two-staged WWTP ‘Gut Grosslappen’ has a capacity of 2 mio. PE. It comprises a pre-denitrification in the first stage using recirculation from the nitrifying second stage. A residual post-denitrification in a downstream sand filter is required in order to achieve the effluent standards. Presently the process water from sludge digestion is treated separately by nitrification/denitrification. Due to necessary reconstruction of the biological stages, the process water treatment was included in the future overall process concept of the WWTP. A case study was conducted comparing the processes nitritation/denitrititation and deammonification with nitrification/denitrification including their effect on the operational costs of the planned main flow treatment. Besides the different operating costs the investment costs required for the process water treatment played a significant role. Six cases for the process water treatment were compared. As a result, in Munich deammonification can only be recommended for long-term future developments, due to the high investment costs, compared with the nitritation/denitritation alternative realizable in existing tanks. The savings concerning aeration, sludge disposal and chemicals were not sufficient to compensate for the additional investment costs. Due to the specific circumstances in Munich, for the time being the use of existing tanks for nitritation/denitritation proved to be most economical.

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