A contribution to collision-free trajectory planning for handling systems in varying environments

In highly flexible and complex handling systems the risk of collision of moving machine components is continuously increasing. When, for example, several robots share the same workspace and the environment in the workspace is changing due to the operation, the robot trajectories can no longer be planned in advance without the risk of collision. The objective of this paper is the collision-free motion planning of handling system manipulators from the start to the end position within a changing environment. For this purpose, the trajectories on the control system have to be planned during the operating time most efficiently depending on the current state of a varying environment. This paper describes a new approach for trajectory planning based on curve shortening flows combined with potential fields. The functional capability of the method will be demonstrated initially on a simple robot kinematics with two degrees of freedom.     

Modeling kinetic processes controlling hydrogen and acetate concentrations in an aquifer-derived microcosm

Groundwater contaminants may degrade via fermentation to intermediate species, which are subsequently consumed by terminal electron-accepting processes (TEAPs). A numerical model of an aquifer-derived laboratory microcosm is developed to simulate the dynamic behavior of fermentation and respiration in groundwater by coupling microbial growth and substrate utilization kinetics with a formulation that also includes aqueous speciation and other geochemical reactions including surface complexation, mineral dissolution, and precipitation. The model is used to test approaches that currently make use of H2(aq) to diagnose prevalent TEAPs in groundwater. Competition between TEAPs is integral to the conceptual model of the simulation, and the results indicate that competitive exclusion is significant but with some overlap found in the temporal sequence of TEAPs. Steady-state H2(aq) concentrations observed during different TEAPs do not differ significantly. The results are not consistent with previous applications of the partial equilibrium approach since most TEAP redox pairs exhibit free energies that suggest a particular process is able to proceed, yet observations here show that this process does not proceed.     

Smart consumer load balancing: state of the art and an empirical evaluation in the Spanish electricity market

The basis of an efficient functioning of a power grid is an accurate balancing of the electricity demand of all the consumers at any instant with supply. Nowadays, this task involves only the grid operator and retail electricity providers. One of the facets of the Smart Grid vision is that consumers may have a more active role in the problem of balancing demand with supply. With the deployment of intelligent information and communication technologies in domestic environments, homes are becoming smarter and able to play a more active role in the management of energy. We use the term Smart Consumer Load Balancing to refer to algorithms that are run by energy management systems of homes in order to optimise the electricity consumption, to minimise costs and/or meet supply constraints. In this work, we analyse different approaches to Smart Consumer Load Balancing based on (distributed) artificial intelligence. We also put forward a new model of Smart Consumer Load Balancing, where consumers actively participate in the balancing of demand with supply by forming groups that agree on a joint demand profile to be contracted in the market with the mediation of an aggregator. We specify the business model as well as the optimisation model for load balancing, showing the economic benefits for the consumers in a realistic scenario based on the Spanish electricity market.     

3D deep X-ray lithography for producing a multi-channel Fourier transform interferometer

We introduce a modified LIGA process architecture to manufacture a static lamellar grating Fourier-transform spectrometer invented by Moser and Möller (European patent EP 0 765 488 B1, 1994). Such spectrometers hold unique advantages over common Michelson-type FTIRs including high time resolution, speed, compactness, and robustness. To cope with the spectrometer’s demand for precise high-aspect-ratio micro-fabrication, we present a modified LIGA process which enhances the X-ray lithography by means of a moving mask technique (Heussler and Moser Lithography method and apparatus PCT/SG2011/000376, 2011). The technique relies on independently moving multiple masks stacked on top of each other during the lithographic step and thus allows to locally vary the deposited dose in a positive tone photoresist. First manufacturing results as well as a performance test of a prototype spectrometer are reported.     

Bio-ethanol production by fermentation of ricotta cheese whey as an effective alternative non-vegetable source

The aim of the present paper is to investigate the feasibility of bio-ethanol production by batch fermentation of ricotta cheese whey (“Scotta”), a dairy industry waste characterized by lactose concentration ranging from 4.5% to 5.0% (w/w) and, with respect to traditional (raw) whey, by much lower protein content. Scotta, therefore, could represent an effective non-vegetable source for renewable energy production. The microrganism used to carry out the fermentation processes was the yeast Kluyveromyces marxianus. Preliminary experiments, performed in aerobic conditions on different volumes of scotta, have shown the actual growth of the yeast. The subsequent fermentation experiments were carried out, in anaerobic conditions, on three different substrates: scotta, raw cheese whey and deproteinized whey. The experimental data have demonstrated the process feasibility: scotta is an excellent substrate for fermentation and exhibits better performance with respect to both raw cheese whey and deproteinized whey. Complete lactose consumption, indeed, was observed in the shortest time (13 h) and with the highest ethanol yield (97% of the theoretical value).     

A Framework for the Verification of Certifying Computations

Formal verification of complex algorithms is challenging. Verifying their implementations goes beyond the state of the art of current automatic verification tools and usually involves intricate mathematical theorems. Certifying algorithms compute in addition to each output a witness certifying that the output is correct. A checker for such a witness is usually much simpler than the original algorithm—yet it is all the user has to trust. The verification of checkers is feasible with current tools and leads to computations that can be completely trusted. We describe a framework to seamlessly verify certifying computations. We use the automatic verifier VCC for establishing the correctness of the checker and the interactive theorem prover Isabelle/HOL for high-level mathematical properties of algorithms. We demonstrate the effectiveness of our approach by presenting the verification of typical examples of the industrial-level and widespread algorithmic library LEDA.     

Autonomous stair-climbing with miniature jumping robots.

The problem of vision-guided control of miniature mobile robots is investigated. Untethered mobile robots with small physical dimensions of around 10 cm or less do not permit powerful onboard computers because of size and power constraints. These challenges have, in the past, reduced the functionality of such devices to that of a complex remote control vehicle with fancy sensors. With the help of a computationally more powerful entity such as a larger companion robot, the control loop can be closed. Using the miniature robot's video transmission or that of an observer to localize it in the world, control commands can be computed and relayed to the inept robot. The result is a system that exhibits autonomous capabilities. The framework presented here solves the problem of climbing stairs with the miniature Scout robot. The robot's unique locomotion mode, the jump, is employed to hop one step at a time. Methods for externally tracking the Scout are developed. A large number of real-world experiments are conducted and the results discussed.