On-line estimation of kinetic parameters in anaerobic digestion using observer-based estimators and multiwavelength fluorometry

2006 ◽  
Vol 53 (4-5) ◽  
pp. 77-83 ◽  
Author(s):  
E. Morel ◽  
B. Tartakovsky ◽  
S.R. Guiot ◽  
M. Perrier
Keyword(s):  
Anaerobic Digestion ◽  
Kinetic Parameters ◽  
Time Varying ◽  
State Variables ◽  
Sensor Failure ◽  
Order Model ◽  
Anaerobic Reactor ◽  
First Order ◽  
Kinetic Parameter Estimation ◽  
On Line

Observer-based estimators (OBE) were used for estimation of state variables and kinetic parameters in an anaerobic digestion (AD) process. A simplified first-order model with time-varying kinetic parameters was used to design an OBE for kinetic parameter estimation. This approach was validated on a laboratory-scale anaerobic reactor equipped with a multiwavelength fluorometer for on-line measurements of COD and VFA concentrations in the reactor effluent. The proposed estimators provide continuous adjustment of kinetic parameters and can be used for predictions of state variables between samples acquisition and during sensor failure.

On-line first-order machining error compensation for thin-walled parts considering time-varying cutting condition

2021 ◽  
pp. 1-16
Author(s):  
Xiong Zhao ◽  
Lianyu Zheng ◽  
Yuehong Zhang
Keyword(s):  
Error Compensation ◽  
Compensation Method ◽  
Cutting Condition ◽  
Time Varying ◽  
Machining Error ◽  
Process Step ◽  
Compensation Model ◽  
First Order ◽  
On Line ◽  
Thin Walled

Abstract Mirror error compensation is usually employed to improve the machining precision of thin-walled parts. However, this zero-order method may result in inadequate error compensation, due to the time-varying cutting condition of thin-walled parts. To cope with this problem, an on-line first-order error compensation method is proposed for thin-walled parts. With this context, firstly, the time-varying cutting condition of thin-walled parts is defined with its in-process geometric and physical characteristics. Based on it, a first-order machining error compensation model is constructed. Then, during the process planning, the theory geometric and physical characteristic of thin-walled parts are respectively obtained with CAM software and structure dynamic modification method. After process performing, the real geometric characteristic of thin-walled parts is measured, and it is used to calculate the dimension error of thin-walled parts. Next, the error compensated value is evaluated based on the compensation model, from which, an error compensation plane is constructed to modify the tool center points for next process step. Finally, the machining error is compensated by performing the next process step. A milling test of thin-walled part is employed to verify the proposed method, and the experiment results shown that the proposed method can significantly improve the error compensation effect for low-stiffness structure, and thickness precision of thin-walled parts is improved by 71.4 % compared with the mirror error compensation method after machining.

scholarly journals Kinetics of the thermal decomposition of pine needles

2015 ◽  
Vol 7 (1) ◽  
pp. 5-22 ◽  
Author(s):  
Alok Dhaundiyal ◽  
Jitendra Gangwar
Keyword(s):  
Thermal Decomposition ◽  
Kinetic Parameters ◽  
Pine Needles ◽  
Experimental Results ◽  
Pyrolysis Process ◽  
Order Model ◽  
Exponential Factor ◽  
First Order ◽  
Model Free ◽  
Good Agreement

Abstract A kinetic study of the pyrolysis process of pine needles was examined using a thermogravimetric analyser. The weight loss was measured in nitrogen atmosphere at a purge flow rate of 100 ml/min. The samples were heated over a range of temperature of 19°C–600°C with a heating rate of 10°C/min. The results obtained from the thermal decomposition process indicate that there are three main stages: dehydration, active and passive pyrolysis. The kinetic parameters for the different samples, such as activation energy and pre-exponential factor, are obtained by the shrinking core model (reaction-controlled regime), the model-free, and the first-order model. Experimental results showed that the shrinking model is in good agreement and can be successfully used to understand degradation mechanism of loose biomass. The result obtained from the reaction-controlled regime represented actual values of kinetic parameters which are the same for the whole pyrolysis process; whereas the model-free method presented apparent values of kinetic parameters, as they are dependent on the unknown function ϕ(C), on the sum of the parameters of the physical processes, and on the chemical reactions that happen simultaneously during pyrolysis. Experimental results showed that values of kinetic constant from the first-order model and the SCM are in good agreement and can be successfully used to understand the behaviour of loose biomass (pine needles) in the presence of inert atmosphere. Using TGA results, the simulating pyrolysis can be done, with the help of computer software, to achieve a comprehensive detail of the devolatilization process of different types of biomasses.

scholarly journals Study of Salt Effect on Semi-Continuous Anaerobic Digestion of Food Waste with Modified First-Order Model

2021 ◽  
Vol 701 (1) ◽  
pp. 012032
Author(s):  
X F Li ◽  
T N Hu ◽  
J J Huang ◽  
Y Y Liu ◽  
D P Peng ◽  
...  
Keyword(s):  
Anaerobic Digestion ◽  
Food Waste ◽  
Salt Effect ◽  
Order Model ◽  
First Order

scholarly journals ADM1 modelling of large-scale covered in-ground anaerobic reactor treating sugarcane vinasse

2018 ◽  
Vol 77 (5) ◽  
pp. 1397-1409 ◽  
Author(s):  
Marcelo Leite Conde Elaiuy ◽  
Aiduan Li Borrion ◽  
Davide Poggio ◽  
Julia Anna Stegemann ◽  
Edson Aparecido Abdul Nour
Keyword(s):  
Anaerobic Digestion ◽  
Food Industry ◽  
Large Scale ◽  
Rate Coefficient ◽  
Hydrolysis Rate ◽  
Anaerobic Reactor ◽  
First Order ◽  
Industry Standards ◽  
Scale Reactor ◽  
Sugarcane Vinasse

Abstract In this paper, we demonstrate in a clear procedure the application of the Anaerobic Digestion Model No. 1 (ADM1) to model a large-scale covered in-ground anaerobic reactor (Cigar), processing sugarcane vinasse from a biorefinery in Brazil. The biochemical make-up (carbohydrates, proteins, and lipids) of the substrate was analysed based on the food industry standards. Two distinct subsets of data, based on the sugarcane harvest season for bioethanol and sugar production in 2012 and 2014, were used to direct and cross validate the model, respectively. We fitted measured data by estimating two key parameters against biogas flow rate: the degradation extent (fd) and the first order hydrolysis rate coefficient (khyd). By cross validation we show that the fitted model can be generalised to represent the behaviour of the reactor under study. Therefore, motivated by practical and industrial application of ADM1, for both different reactors types and substrates, we show aspects on the implementation of ADM1 to a specific large-scale reactor for anaerobic digestion of sugarcane vinasse.

scholarly journals ON DISCRETE SAMPLING OF TIME-VARYING CONTINUOUS-TIME SYSTEMS

2009 ◽  
Vol 25 (4) ◽  
pp. 985-994 ◽  
Author(s):  
Peter M. Robinson
Keyword(s):  
Continuous Time ◽  
Time Varying ◽  
Order Model ◽  
First Order ◽  
Continuous Time Systems ◽  
Continuous Time Process ◽  
Time Systems ◽  
Over Time ◽  
Higher Order Models ◽  
Equal Spacing

We consider a multivariate continuous-time process, generated by a system of linear stochastic differential equations, driven by white noise, and involving coefficients that possibly vary over time. The process is observable only at discrete, but not necessarily equally-spaced, time points (though equal spacing significantly simplifies matters). Such settings represent partial extensions of ones studied extensively by A.R. Bergstrom. A model for the observed time series is deduced. Initially we focus on a first-order model, but higher-order models are discussed in the case of equally-spaced observations. Some discussion of issues of statistical inference is included.

scholarly journals Kinetics of Anaerobic Digestion of Unripe Plantain Peels

2020 ◽  
pp. 7-17
Author(s):  
Chinenyenwa Nkeiruka Nweke ◽  
Joseph Tagbo Nwabanne
Keyword(s):  
Anaerobic Digestion ◽  
Hydraulic Retention Time ◽  
Biogas Production ◽  
Growth Yield ◽  
Second Order ◽  
Coefficient Of Determination ◽  
Monod Kinetics ◽  
Order Model ◽  
First Order ◽  
Kinetics Of

This study was carried out to investigate the biogas production obtained from anaerobic digestion of unripe plantain peels (PP) and the kinetics of the digestion process. 400 g of dried and shredded unripe plantain peels were mixed with 200 ml of water and put into 1 L digester and observed for biogas for hydraulic retention time (HRT) of 15 days by the method of downwards displacement. The cumulative biogas volume obtained after digestion was 285 ml. The COD removal efficiency of 72.5% was achieved. The kinetics of PP digestion was evaluated using first order, Monod, Contois and, Grau second-order models. Results showed that the kinetics of anaerobic digestion of PP followed the first-order model with a constant (K) of 0.095 day-1. Monod kinetics was evaluated and the maximum rate of substrate utilization (K), the half velocity constant (KS), endogenous decay coefficient (Kd), biomass growth yield (Y) and, maximum specific microorganism growth rate (µmax) obtained were 0.7615 day-1, 16.20 mg/l, 0.0047 day-1, 0.0112 mgVSS mgCOD-1 and, 0.009 day-1 respectively. These results revealed that inoculation would be required to increase the rate and volume of biogas production. Both first-order and Monod models gave a high coefficient of determination indicating that first order and Monod models can be used to model the digestion of PP. Contois model gave values of µmax and β as 0.011 day-1 and 0.644 mgCOD mgVSS-1 respectively. The result obtained has shown that the digestion of PP did not follow second-order kinetics.

A first-order model of thermal lensing of laser propagation in the eye and implications for laser safety

2005 ◽  
Author(s):  
Robert J. Thomas ◽  
Rebecca L. Vincelette ◽  
Gavin D. Buffington ◽  
Amber D. Strunk ◽  
Michael A. Edwards ◽  
...  
Keyword(s):  
Thermal Lensing ◽  
Order Model ◽  
Laser Safety ◽  
First Order ◽  
Laser Propagation

Evaluation of Kinetic Parameters at the Transport of Indole-3-acetic Acid Through Bulk Liquid Membranes

2017 ◽  
Vol 68 (5) ◽  
pp. 903-907
Author(s):  
Ecaterina Anca Serban ◽  
Ioana Diaconu ◽  
Elena Ruse ◽  
Georgiana Ileana Badea ◽  
Adriana Cuciureanu ◽  
...  
Keyword(s):  
Acetic Acid ◽  
Kinetic Parameters ◽  
Trioctylphosphine Oxide ◽  
Bulk Liquid ◽  
Transport Parameters ◽  
Kinetics Parameters ◽  
First Order ◽  
Phase Concentration ◽  
Feed Phase ◽  
Indole 3 Acetic Acid

Indole-3-acetic acid is a growth phytohormone considered the most important representative of auxin class. This paper presents the assessment of some kinetic parameters in the process of transport of indole-3-acetic acid taking into consideration the kinetic model of consecutive irreversible first order reactions. It was pursued the influence upon the process of parameters such as: feed phase concentration, stripping phase concentration in the presence of two type carriers: tributyl phosphate (TBP) and trioctylphosphine oxide (TOPO). Depending on these transport parameters were calculated kinetics parameters such as: pseudo-first-order apparent membrane entrance and exit rate constants, the maximum flux at the entrance and exit out of the membrane. The highest values of the transport flux is obtained in the presence of carrier trioctylphosphine oxide (TOPO) at the concentration in the feed phase of 10-4 mol/L indole-3-acetic acid and a concentration of 10--2mol/L NaOH in the stripping phase.

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