Building a mechanistic biogeochemical reaction network for upscaling: Characterization of mass transport limitation between regions of hydrolysis and methanogenesis

In this study, we aim to validate the reaction network with an idealized experiment. We want to show that 1) rate controlling parameters are identifiable from the measured data by inverse modeling, and 2) that this network is able to predict the measured emissions in the experiment given the initial conditions. In the experiment, cabbage is used...

A generic transport-reactive model for simulating microbially influenced mineral precipitation in porous medium

The spatial and temporal distribution of precipitated minerals is one of the key factors governing various processes in the sub-surface environment, including microbially influenced corrosion (MIC) (Huang, 2002), bio-cementation (van Paassen et al., 2010) and sediment diagenesis (Paraska et al., 2014). The mineral precipitation not only affects...

Investigating the impact of process parameters on aeration of MSW via a mechanistic biogeochemical reaction model

The aim of our study is to investigate previously mentioned aspects with scenario analyses via a mechanistic biogeochemical reaction network model that contains the emission controlling reactions. In order to find such a network, we apply the gray modeling toolbox developed by van Turnhout et al. (2015) on a measured dataset used in the study of...

Water balance modeling for estimation of residence time of water in a full-scale landfill using a data-assimilation approach

In order to develop novel approaches for reducing the after-care of Municipal Solid Waste (MSW) sanitary landfills methods are required with which we can quantify the emission potential present in waste bodies. Currently full-scale experiments are being prepared at three Dutch landfills based on enhanced infiltration by irrigation and leachate...

Gray box modelling of MSW biodegradation; Revealing its dominant (bio)chemical mechanism

Gray box modeling of MSW degradation: Revealing its dominant (bio)chemical mechanism

In this paper we present an approach to describe organic degradation within immobile water regions of Municipal Solid Waste (MSW) landfills which is best described by the term “gray box” model. We use a simplified set of dominant (bio)chemical and physical reactions and realistic environmental conditions. All equations, relationships and...

Gray box modeling of MSW degradation: Revealing its dominant (bio)chemical mechanism

Quantification of (bio)geochemical heterogeneous activity in full-scale landfills (abstract)

The main focus of this paper is the assessment of landfill leachate/gas emissions and longterm prediction of these emissions. Due to variation in environmental conditions, like rainfall events, leachate concentrations are very dynamic on a short-time scale. The measured concentrations in the leachate oscillate between maximum and minimum...

Grey box modeling of municipal solid waste

Landfill emission quantification: Improvement in measurement and modelling approaches to asses (long-term) emissions and stabilization

Poster

Finding order in the design landscape of simple optical systems

Contrary to the frequent tacit assumption that the local minima of a merit function are points scattered more or less randomly over the design landscape, we have found that, at least for simple imaging systems (doublets with three and triplets with five variables) all design shapes we have observed thus far form a strictly ordered set of points,...

Predictability and unpredictability in optical system optimization

Local optimization algorithms, when they are optimized only for speed, have in certain situations an unpredictable behavior: starting points very close to each other lead after optimization to different minima. In these cases, the sets of points, which, when chosen as starting points for local optimization, lead to the same minimum (the so...

Practical guide to saddle-point construction in lens design

Saddle-point construction (SPC) is a new method to insert lenses into an existing design. With SPC, by inserting and extracting lenses new system shapes can be obtained very rapidly, and we believe that, if added to the optical designer’s arsenal, this new tool can significantly increase design productivity in certain situations. Despite the...

Looking for order in the optical design landscape

In present-day optical system design, it is tacitly assumed that local minima are points in the merit function landscapewithout relationships between them. We will show however that there is a certain degree of order in the design landscapeand that this order is best observed when we change the dimensionality of the optimization problem and when...

Generating saddle points in the merit function landscape of optical systems

Finding multiple local minima in the merit function landscape of optical system optimization is a difficult task, especially for complex designs that have a large number of variables. We discuss here a method that enables a rapid generation of new local minima for optical systems of arbitrary complexity. We have recently shown that saddle points...

Saddle points in the merit function landscape of systems of thin lenses in contact

The merit function landscape of systems of thin lenses in contact, which are perhaps the simplest possible types of optical systems, shows remarkable regularities. It is easier to understand how the optimization parameter space of these simple systems is divided into basins of attraction for the various local minima if one focuses on the (Morse...