SINGULAB - A Graphical user Interface for the Singularity Analysis of Parallel Robots based on Grassmann-Cayley Algebra

This paper presents SinguLab, a graphical user interface for the singularity analysis of parallel robots. The algorithm is based on Grassmann-Cayley algebra. The proposed tool is interactive and introduces the designer to the singularity analysis performed by this method, showing all the stages along the procedure and eventually showing the solution algebraically and graphically, allowing as well the singularity verification of different robot poses.Comment: Advances in Robot Kinematics, Batz sur Mer : France (2008

Fair Imposition

We introduce a new mechanism-design problem called fair imposition. In this setting a center wishes to fairly allocate tasks among a set of agents whose cost structures are known only to them, and thus will not reveal their true costs without appropriate incentives. The center, with the power to impose arbitrary tasks and payments on the agents, has the additional goal that his net payment to these agents is never positive (or, that it is tightly bounded if a loss is unavoidable). We consider two di#erent notions of fairness that the center may wish to achieve. The central notion, which we call k-fairness, is in the spirit of max-min fairness. We present both positive results (in the form of concrete mechanisms) and negative results (in the form of impossibility theorems) concerning these criteria. We also briefly discuss an alternative, more traditional interpretation of our setting and results, in the context of auctions

The configuration space of an arachnoid mechanism

ABSTRACT. The configuration spaces of arachnoid mechanisms are analyzed in this paper. These mechanisms consist of k branches each of which has an arbitrary number of links and a fixed initial point, while all branches end at one common end-point. It is shown that generically, the configuration spaces of such mechanisms are manifolds, and the conditions for the exceptional cases are determined. The configuration space of planar arachnoid mechanisms having k branches, each with two links is analyzed for both the non-singular and the singular cases

Topological and Kinematic Singularities for a Class of Parallel Mechanisms

We study singularities for a parallel mechanism with a planar moving platform in ℝ(=2,3), with joints which are universal, spherical (spatial case), or rotational (planar case). For such mechanisms, we give a necessary condition for a topological singularity to occur, and describe the corresponding kinematic singularity. An example is provided

Bending Instability of a General Cross Section Thin-Wall Tube for Minimal Radius of Curvature Passage

This paper describes an analytical tool for the design of thin-wall tubes for passage through minimal radius of curvature trajectory. The design is based on a model of thinwall tube buckling under pure bending. An extended analytical solution for general initial cross section is found based on Brazier method by energy theory of elastic stability. The model predicts the critical moment, curvature, flattening, and stress and allows choosing the most suitable cross section shape for a specific purpose. For example, tubes with ocular and rounded-ocular cross sections were found suitable for semiflexible applications such as endoscopy, where they elastically cross a sharp corner

A predictive algorithm using clinical and laboratory parameters may assist in ruling out and in diagnosing MDS

We present a noninvasive Web-based app to help exclude or diagnose myelodysplastic syndrome (MDS), a bone marrow (BM) disorder with cytopenias and leukemic risk, diagnosed by BM examination. A sample of 502 MDS patients from the European MDS (EUMDS) registry (n \gt; 2600) was combined with 502 controls (all BM proven). Gradient-boosted models (GBMs) were used to predict/exclude MDS using demographic, clinical, and laboratory variables. Area under the receiver operating characteristic curve (AUC), sensitivity, and specificity were used to evaluate the models, and performance was validated using 100 times fivefold cross-validation. Model stability was assessed by repeating its fit using different randomly chosen groups of 502 EUMDS cases. AUC was 0.96 (95\ 0.95-0.97). MDS is predicted/excluded accurately in 86\range, 0-1) of less than 0.68 (GBM \lt; 0.68) resulted in a negative predictive value of 0.94, that is, MDS was excluded. GBM ≥ 0.82 provided a positive predictive value of 0.88, that is, MDS. The diagnosis of the remaining patients (0.68 ≤ GBM \lt; 0.82) is indeterminate. The discriminating variables: age, sex, hemoglobin, white blood cells, platelets, mean corpuscular volume, neutrophils, monocytes, glucose, and creatinine. A Web-based app was developed; physicians could use it to exclude or predict MDS noninvasively in most patients without a BM examination. Future work will add peripheral blood cytogenetics/genetics, EUMDS-based prospective validation, and prognostication