Jens Ludwig

Production planning by pinch analysis for biomass use in dynamic and seasonal markets

The planning of production capacity has been extensively discussed in the literature. Seasonal demand of products or seasonal availability of input materials can make the problem even more challenging, due to a constant need for capacity adjustments. For example, the energetic or industrial use of biomass has several distinct characteristics in contrast to conventional chemical processes, such as a time dependent availability of raw materials. Therefore, suitable planning tools are required that take into account the dynamics of the production system (for example, by following the seasons and the yearly changes). Thus a recently proposed heuristic approach for aggregate production planning when facing a seasonal demand is analysed. This method is inspired by the graphical pinch analysis from chemical engineering; it is first illustrated with data from a bicycle company facing seasonal demand showing its plainness and some limitations. Then the transfer to situations with seasonal supplies of input materials is presented, as for biomass use in dynamic and seasonal markets. Using these applications, the simple heuristic, its limits and its benefits are put up for discussion.

Morphology Change and Improved Efficiency in Organic Photovoltaics via Hexa-peri-hexabenzocoronene Templates

The morphology of the active layer in organic photovoltaics (OPVs) is of crucial importance as it greatly influences charge generation and transport. A templating interlayer between the electrode and the active layer can change active layer morphology and influence the domain orientation. A series of amphiphilic interface modifiers (IMs) combining a hydrophilic polyethylene-glycol (PEG) oligomer and a hydrophobic hexabenzocoronene (HBC) were designed to be soluble in PEDOT:PSS solutions, and surface accumulate on drying. These IMs are able to self-assemble in solution. When IMs are deposited on top of a poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate) (PEDOT:PSS) film, they induce a morphology change of the active layer consisting of discotic fluorenyl-substituted HBC (FHBC) and [6,6]-phenyl C61-butyric acid methyl ester (PCBM). However, when only small amounts (0.2 wt %) of IMs are blended into PEDOT:PSS, a profound change of the active layer morphology is also observed. Morphology changes were monitored by grazing incidence wide-angle X-ray scattering (GIWAXS), transmission electron microscopy (TEM), TEM tomography, and low-energy high-angle angular dark-field scanning transmission electron microscopy (HAADF STEM). The interface modification resulted in a 20% enhancement of power conversion efficiency.

Some thoughts on weighting in participatory decision making and e-democracy

Thoughts about possible links between multicriteria decision making and e-democracy are proposed for discussion in this paper. After giving some applications for decision-making tools in e-participation, the idea to use a PROMETHEE tool for weighting votes in public decisions is analysed using an example of urban planning and put forth for discussion. Whereas this idea might seem undemocratic compared to traditional equal consideration, it highlights some drawbacks of local referenda and voting using the internet.

Integrated process design for the inter-company plant layout planning of dynamic mass flow networks. PepOn

Inter-company production networks can improve the resource efficiency of production processes. This book shows the results of the research project Integrated Process Design for the Inter-Company Plant Layout Planning of Dynamic Mass Flow Networks (PepOn). A systematic approach for process design for the best utilisation of process streams based on multiple pinch analyses is proposed for a holistic evaluation of process alternatives and for determining saving potentials for production networks.

Production Planning in Dynamic and Seasonal Markets

In chemical engineering, pinch analysis holds a long tradition as a method for determining optimal target values for heat or mass exchanger networks by calculating an optimal alignment of available flows. A graphical representation of the time-material production relationship derived from the original pinch analysis can be used for aggregate production planning. This can deliver insights in the production planning problem as several production strategies can be compared. The approach is applied to a case study on bicycle coating.