Visual optimality and stability analysis of 3DCT scan positions

Industrial cone-beam X-Ray computed tomography (CT) systems often face problems due to artifacts caused by a bad placement of the specimen on the rotary plate. This paper presents a visual-analysis tool for CT systems, which provides a simulation-based preview and estimates artifacts and deviations of a specimen's placement using the corresponding 3D geometrical surface model as input. The presented tool identifies potentially good or bad placements of a specimen and regions of a specimen, which cause the major portion of artefacts. The tool can be used for a preliminary analysis of the specimen before CT scanning, in order to determine the optimal way of placing the object. The analysis includes: penetration lengths, placement stability and an investigation in Radon space. Novel visualization techniques are applied to the simulation data. A stability widget is presented for determining the placement parameters' robustness. The performance and the comparison of results provided by the tool compared with real world data is demonstrated using two specimens.     

Ranking kinematics for revising by contextual information

Annals of Mathematics and Artificial Intelligence - Probability kinematics is a leading paradigm in probabilistic belief change. It is based on the idea that conditional beliefs should be...     

Tactile–optical probes for three-dimensional microparts

The dimensional measurement of microsystem components is a field of application that is gaining more and more importance. While optical probing systems offer a number of advantages, their performance is strongly affected by the varying optical properties of the measured surfaces. For this reason, tactile probing systems are essential to many fields of micrometrology. Since conventional tactile probing systems are not suitable for the measurement of microparts, there is a demand for new tactile probing systems that are specifically adapted to the requirements of micrometrology. The tactile–optical Werth Fiber Probe is an established solution within this scope of application. In the present paper, two recent approaches to adding full 3D capabilities to the fiber probe principle are proposed. First prototypes of these sensors are shown and the obtained results are discussed.     

HiL simulation in biomechanics: a new approach for testing total joint replacements

Instability of artificial joints is still one of the most prevalent reasons for revision surgery caused by various influencing factors. In order to investigate instability mechanisms such as dislocation under reproducible, physiologically realistic boundary conditions, a novel test approach is introduced by means of a hardware-in-the-loop (HiL) simulation involving a highly flexible mechatronic test system. In this work, the underlying concept and implementation of all required units is presented enabling comparable investigations of different total hip and knee replacements, respectively. The HiL joint simulator consists of two units: a physical setup composed of a six-axes industrial robot and a numerical multibody model running in real-time. Within the multibody model, the anatomical environment of the considered joint is represented such that the soft tissue response is accounted for during an instability event. Hence, the robot loads and moves the real implant components according to the information provided by the multibody model while transferring back the position and resisting moment recorded. Functionality of the simulator is proved by testing the underlying control principles, and verified by reproducing the dislocation process of a standard total hip replacement. HiL simulations provide a new biomechanical testing tool for analyzing different joint replacement systems with respect to their instability behavior under realistic movements and physiological load conditions.     

Tile-Packing Tomography Is \mathbb{NP}-hard

Discrete tomography deals with reconstructing finite spatial objects from their projections. The objects we study in this paper are called tilings or tile-packings, and they consist of a number of disjoint copies of a fixed tile, where a tile is defined as a connected set of grid points. A row projection specifies how many grid points are covered by tiles in a given row; column projections are defined analogously. For a fixed tile, is it possible to reconstruct its tilings from their projections in polynomial time? It is known that the answer to this question is affirmative if the tile is a bar (its width or height is 1), while for some other types of tiles $\mathbb {NP}$ -hardness results have been shown in the literature. In this paper we present a complete solution to this question by showing that the problem remains $\mathbb {NP}$ -hard for all tiles other than bars.     

Clusteranalyse von Smart-Meter-Daten

The introduction of smart meter technology is a great challenge for the German energy industry. It requires not only large investments in the communication and metering infrastructure, but also a redesign of traditional business processes. The newly incurring costs cannot be fully passed on to the end customers. One option to counterbalance these expenses is to exploit the newly generated smart metering data for the creation of new services and improved processes. For instance, performing a cluster analysis of smart metering data focused on the customers?? time-based consumption behavior allows for a detailed customer segmentation. In the article we present a cluster analysis performed on real-world consumption data from a smart meter project conducted by a German regional utilities company. We show how to integrate a cluster analysis approach into a business intelligence environment and evaluate this artifact as defined by design science. We discuss the results of the cluster analysis and highlight options to apply them to segment-specific tariff design.     

A knowledge-based system for improving the consistency between object models and use case narratives

In today’s systems development environments, object models are playing an increasingly important role in contributing to the agility and flexibility expected of the information systems being built. While current computer-aided software engineering tools can aid in creating object models, they do not provide much support in ensuring that the object models created are consistent with the specifications in use case narratives. This paper presents a methodology and a knowledge-based system to facilitate the verification of consistency of a given object model against a set of use case narratives. The methodology is implemented as a prototype knowledge-based extension to an open source CASE tool. The prototype’s ability to reliably extract relevant information from use case narratives and its role in verifying the consistency of object models have been evaluated using a laboratory experiment. By analyzing use case narratives utilizing natural language processing techniques and applying collaboration patterns and heuristics, this methodology can determine missing and invalid model elements to guide the analyst in creating object models that are consistent with the requirements specified in a set of use case narratives. The results from this design science research indicate that the prototype system can be a useful tool to assist in this process.     

Online scheduling of bounded length jobs to maximize throughput

We consider an online scheduling problem, motivated by the issues present at the joints of networks using ATM and TCP/IP. Namely, IP packets have to be broken down into small ATM cells and sent out before their deadlines, but cells corresponding to different packets can be interwoven. More formally, we consider the online scheduling problem with preemptions, where each job j is revealed at release time r _j , and has processing time p _j , deadline?d _j , and weight w _j . A?preempted job can be resumed at any time. The goal is to maximize the total weight of all jobs completed on time. Our main results are as follows. Firstly, we prove that when the processing times of all jobs are at most k, the optimum deterministic competitive ratio is ??(k/log?k). Secondly, we give a deterministic algorithm with competitive ratio depending on the ratio between the smallest and the largest processing time of all jobs. In particular, it attains competitive ratio 5 in the case when all jobs have identical processing times, for which we give a lower bound of 2.598. The latter upper bound also yields an O(log?k)-competitive randomized algorithm for the variant with processing times bounded by k.