Reproducing kernel Hilbert spaces and variable metric algorithms in PDE constrained shape optimisation

In this paper we investigate and compare different gradient algorithms designed for the domain expression of the shape derivative. Our main focus is to examine the usefulness of kernel reproducing Hilbert spaces for PDE constrained shape optimisation problems. We show that radial kernels provide convenient formulas for the shape gradient that can be efficiently used in numerical simulations. The shape gradients associated with radial kernels depend on a so called smoothing parameter that allows a smoothness adjustment of the shape during the optimisation process. Besides, this smoothing parameter can be used to modify the movement of the shape. The theoretical findings are verified in a number of numerical experiments

Modification of the motion characteristics of a one-mass linear vibratory conveyor

Linear vibratory conveyors are common equipment to convey goods. They are used in different industries such as for example the building, mining and food industry. The systems are often used for the supply of bulk goods into further processing operations. The goods to be conveyed, typically requesting a heavy-duty design of the conveyor and eccentric excitation drives with relatively high torque. Often the motion of these conveyors is not ideal with reference to the conveying process of the bulk goods. Motion speed and amplitude of the goods are not constant and blocking effects as well as separation effects can occur. The target of this article is to determine a dynamic model for the targeted displacement of the centre of elasticity of a one-mass conveyor, enabling an optimal motion of the conveyor by an optimized set of springs, connecting the conveying element to the frame

Two-mass linear vibratory conveyor with reduced vibration transmission to the ground

Linear vibratory conveyors are common equipment to convey goods. They are used in different industries such as for example the building, mining and food industry. The systems are mainly used for the supply of bulk goods into further processing operations. The goods to be conveyed, typically requesting a heavy-duty design of the conveyor and eccentric excitation drives with relatively high torque. A supply of strong vibrations to the floor is an effect, which often is caused by vibratory conveyors. The target of this article is to determine a dynamic model, based on a two-mass absorber system, helping to avoid the transfer of vibrations to the ground. An optimum supply of goods by the same time should be ensured

Feasibility of UV lasing without inversion in mercury vapor

We investigate the feasibility of UV lasing without inversion at a wavelength of $253.7$ nm utilizing interacting dark resonances in mercury vapor. Our theoretical analysis starts with radiation damped optical Bloch equations for all relevant 13 atomic levels. These master equations are generalized by considering technical phase noise of the driving lasers. From the Doppler broadened complex susceptibility we obtain the stationary output power from semiclassical laser theory. The finite overlap of the driving Gaussian laser beams defines an ellipsoidal inhomogeneous gain distribution. Therefore, we evaluate the intra-cavity field inside a ring laser self-consistently with Fourier optics. This analysis confirms the feasibility of UV lasing and reveals its dependence on experimental parameters.Comment: changes were made according to reviewer comments (accepted for publication in JOSA B

Die "Diesel-Debatte" : ökonomische Handlungsempfehlungen an die Politik

Die Diesel-Technologie und die mit ihrer Nutzung verbundenen Belastungen durch lokale und globale Schadstoffemissionen stehen seit längerem im Fokus der umweltpolitischen Diskussion. Mittlerweile sind sogar Fahrverbote für Diesel-Pkw nicht mehr ausgeschlossen. Allerdings sind in der Diesel-Debatte ökonomische Argumente bislang leider nur selten zu hören. Grundsätzlich geht es auch in der Diesel-Debatte darum, wie in Zukunft Wünsche nach Mobilität, Gesundheit und intakter Umwelt bestmöglich erfüllt und miteinander in Einklang gebracht werden können. Die Kernforderung der Ökonomen hierbei ist, dass die Politik negative externe Effekte adressiert und die entsprechenden Aktivitäten – technologieoffen – mit einem Preis versieht. Damit ist aus ökonomischer Perspektive sichergestellt, dass gesellschaftliche Ziele zu geringstmöglichen Kosten für Verbraucher und Industrie erreicht werden. Der vorliegende ZEW Policy Brief betrachtet unterschiedliche negative externe Effekte aus der Nutzung von Verbrennungsmotoren und schlägt für eine Langfriststrategie ökonomische Instrumente vor, um eine Reduktion dieser Effekte zu erreichen

Reproducing kernel Hilbert spaces and variable metric algorithms in PDE constrained shape optimisation

In this paper we investigate and compare different gradient algorithms designed for the domain expression of the shape derivative. Our main focus is to examine the usefulness of kernel reproducing Hilbert spaces for PDE constrained shape optimisation problems. We show that radial kernels provide convenient formulas for the shape gradient that can be efficiently used in numerical simulations. The shape gradients associated with radial kernels depend on a so called smoothing parameter that allows a smoothness adjustment of the shape during the optimisation process. Besides, this smoothing parameter can be used to modify the movement of the shape. The theoretical findings are verified in a number of numerical experiments

ScanComplete: Large-Scale Scene Completion and Semantic Segmentation for 3D Scans

We introduce ScanComplete, a novel data-driven approach for taking an incomplete 3D scan of a scene as input and predicting a complete 3D model along with per-voxel semantic labels. The key contribution of our method is its ability to handle large scenes with varying spatial extent, managing the cubic growth in data size as scene size increases. To this end, we devise a fully-convolutional generative 3D CNN model whose filter kernels are invariant to the overall scene size. The model can be trained on scene subvolumes but deployed on arbitrarily large scenes at test time. In addition, we propose a coarse-to-fine inference strategy in order to produce high-resolution output while also leveraging large input context sizes. In an extensive series of experiments, we carefully evaluate different model design choices, considering both deterministic and probabilistic models for completion and semantic inference. Our results show that we outperform other methods not only in the size of the environments handled and processing efficiency, but also with regard to completion quality and semantic segmentation performance by a significant margin.Comment: Video: https://youtu.be/5s5s8iH0NF

The impact of burden sharing rules on the voluntary provision of public goods

We investigate how burden sharing rules may impact the voluntary provision of a public good which generates heterogeneous benefits to agents. We compare different rule-based contribution schemes that are based on the principle of the smallest common denominator: all agents can suggest a minimum provision level of the public good that is allocated across agents according to some predetermined rule. We find that rule-based contribution schemes significantly increase payoff levels relative to the VCM. Important differences exist between the rules. Contrary to theory predictions, the equal-payoff rule Pareto-dominates all other rules. This also holds relative to a scheme where different types of players separately can determine their minimum contribution levels. Our results lend insights into the efficient institutional design for voluntary private provision of public goods, and how burden sharing rules interact with efficiency when agents are heterogeneous