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Your search keyword '"Jeppesen, Martin"' showing total 16 results
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16 results on '"Jeppesen, Martin"'

1. Quantum Annealing Continuous Optimisation in Renewable Energy

Author

Sharabiani, Mansour T. A., Jakobsen, Vibe B., Jeppesen, Martin, and Mahani, Alireza S.

Subjects
Quantum Physics, Mathematics - Optimization and Control
Abstract

Renewable energy optimisation poses computationally-intensive challenges. Yet, often the continuous nature of the decision space precludes the use of many emerging, non-von-Neumann computing platforms such as quantum annealing, which are limited to discrete problems. We propose Quantum Annealing Continuous Optimisation (QuAnCO), a Trust Region (TR)-based algorithm, where the TR Newton sub-problem is transformed into Quadratic Unconstrained Binary Optimisation (QUBO), thereby allowing the use of Ising solvers such as D-Wave's quantum annealer. This transformation to QUBO is done by 1) using a hyper-rectangular shape for the TR, 2) discrete representation of each continuous dimension using an interval-bounded integer, and 3) binary encoding of the resulting bounded integers. We tackle a real-world challenge of optimising the biomass mix selection for Nature Energy, the largest biogas producer in Europe, thus providing evidence of feasibility and performance advantage in using QuAnCO in green energy production, and beyond., Comment: 35 pages, 13 figures, 2 tables

Published
2021

7. Continuous recycling of enzymes during production of lignocellulosic bioethanol in demonstration scale

Author

Haven, Mai Østergaard, Lindedam, Jane, Jeppesen, Martin D., Elleskov, Michael, Rodrigues, Ana Cristina, Gama, Miguel, Jørgensen, Henning, Felby, Claus, Haven, Mai Østergaard, Lindedam, Jane, Jeppesen, Martin D., Elleskov, Michael, Rodrigues, Ana Cristina, Gama, Miguel, Jørgensen, Henning, and Felby, Claus

Abstract

Recycling of enzymes in production of lignocellulosic bioethanol has been tried for more than 30 years. So far, the successes have been few and the experiments have been carried out at conditions far from those in an industrially feasible process. Here we have tested continuous enzyme recycling at demonstration scale using industrial process conditions (high dry matter content and low enzyme dosage) for a period of eight days. The experiment was performed at the Inbicon demonstration plant (Kalundborg, Denmark) capable of converting four tonnes of wheat straw per hour. 20% of the fermentation broth was recycled to the hydrolysis reactor while enzyme dosage was reduced by 5%. The results demonstrate that recycling enzymes by this method can reduce overall enzyme consumption and may also increase the ethanol concentrations in the fermentation broth. Our results further show that recycling fermentation broth also opens up the possibility of lowering the dry matter content in hydrolysis and fermentation while still maintaining high ethanol concentrations.

Published
2015

11. The effect of moving heat sources upon the stratification in rooms ventilated by displacement ventilation

Author

Brohus, Henrik, Balling, H., and Jeppesen, Martin Dan

Subjects
Computer simulated person, Movements, CFD, Bacterial transport, Operating room, Contaminant transport
Abstract

The influence of persons movements on contaminant transport during an orthopedic surgical operation is examined. Orthopedic surgical operations require an ultra clean environment usually provided by a LAF device (laminar airflow). During hip replacements bone cement is sometimes applied. Due to practical reasons cement mixing is performed outside the LAF area. During the cement transport from the mixing location to the surgeon there is a potential risk of bacterial transport to the clean zone. This phenomenon is examined by smoke visualization and computational fluid dynamics (CFD). The movements are modeled by CFD using distributed momentum sources as well as a turbulent kinetic energy source. A significant risk of contaminant transport from the less clean zone to the ultra clean zone is found. The results indicate that it is possible to simulate the influence of movements using a relatively simple CFD model that considers the significant influence of a transient phenomenon in an approximate way. Udgivelsesdato: OCT The influence of persons movements on contaminant transport during an orthopedic surgical operation is examined. Orthopedic surgical operations require an ultra clean environment usually provided by a LAF device (laminar airflow). During hip replacements bone cement is sometimes applied. Due to practical reasons cement mixing is performed outside the LAF area. During the cement transport from the mixing location to the surgeon there is a potential risk of bacterial transport to the clean zone. This phenomenon is examined by smoke visualization and computational fluid dynamics (CFD). The movements are modeled by CFD using distributed momentum sources as well as a turbulent kinetic energy source. A significant risk of contaminant transport from the less clean zone to the ultra clean zone is found. The results indicate that it is possible to simulate the influence of movements using a relatively simple CFD model that considers the significant influence of a transient phenomenon in an approximate way.

Published
2006

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