The effect of irregular surface roughness on the frictional resistance of ships

The Methanizer: A Small Scale Biogas Reactor for a Restaurant

The purpose of this study is to determine the technical and economic feasibility of a smallscale bioreactor called the Methanizer for a restaurant. The bioreactor converts organic waste produced by the restaurant into methane. This methane can be used to power the restaurant’s cooking stoves. The system proposed is a double-tank, batch-fed...

The methanizer: A small scale biogas reactor for a restaurant

The purpose of this study is to determine the technical and economic feasibility of a smallscale bioreactor called the Methanizer for a restaurant. The bioreactor converts organic waste produced by the restaurant into methane. This methane can be used to power the restaurant’s cooking stoves. The system proposed is a double-tank, batch-fed...

Continuous Surrogate-Based Optimization Algorithms Are Well-Suited for Expensive Discrete Problems

One method to solve expensive black-box optimization problems is to use a surrogate model that approximates the objective based on previous observed evaluations. The surrogate, which is cheaper to evaluate, is optimized instead to find an approximate solution to the original problem. In the case of discrete problems, recent research has...

Illuminance Flow Estimation by Regression

We investigate the estimation of illuminance flow using Histograms of Oriented Gradient features (HOGs). In a regression setting, we found for both ridge regression and support vector machines, that the optimal solution shows close resemblance to the gradient based structure tensor (also known as the second moment matrix). Theoretical results...

Illuminance flow over anisotropic surfaces with arbitrary viewpoint

The theory of illuminance flow estimation by structure tensors is generalized for oblique viewing of anisotropic texture. An added benefit is that the theory predicts the behavior of unsupervised illuminant tilt estimators. The previous theory is refined with general matrix formulations and compacted by exploiting general properties of the...

Optimal design of the annular groove phase mask central region

Vortex phase masks have been shown to be an efficient means to reduce the blinding stellar light in high-contrast imaging instruments. Once placed at the focal plane of the telescope, the helical phase ramp of a vortex phase mask diffracts the light of a bright on-axis source outside the re-imaged telescope pupil, while transmitting the light...

Benchmarking surrogate-based optimisation algorithms on expensive black-box functions

Surrogate algorithms such as Bayesian optimisation are especially designed for black-box optimisation problems with expensive objectives, such as hyperparameter tuning or simulation-based optimisation. In the literature, these algorithms are usually evaluated with synthetic benchmarks which are well established but have no expensive objective...