Biologically-Inspired Control for a Planetary Exploration Tensegrity Robot

Tensegrity structures are becoming increasingly popular as mechanical structures for robots. Their inherent compliance makes them extremely robust to environmental disturbances, and their design allows them to have a high strength-to-weight ratio whilst being lightweight compared to traditional robots. For these reasons they would be of interest to the aerospace industry, particularly for planetary exploration. However, being such compliant structures thanks to their network of elastic elements also means that their control is not an easy task. Relying solely on traditional control strategies to generate efficient locomotion would surely be near impossible due to the complex oscillatory motions and nonlinear interactions of its members. The goal of this project was to use bio-inspired control techniques to generate locomotion for a tensegrity icosahedron, namely the SUPERball project of the Intelligent Robotics Group of NASA Ames Research Center

Don't be scared: insert a mesh!

Mesh repair is now the gold standard technique of repair on incisional hernias. Infection of the mesh is a challenging complication of this type of repair. The risk of mesh infection has been shown to be greater in case of complicated hernia. We present the case of a 64 years old female who presented with an incarcerated incisional hernia with bowel infarction. Treated with a non absorbable mesh repair, she developed mesh infection. The infection was successively treated with simple drainage. This case and review of relevant literature seem to be an indication that mesh repair could still be considered in cases of complicated hernia. Simple drainage usually helps manage the cases of mesh infection

Segmentation and along-strike asymmetry of the passive margin in Socotra, eastern Gulf of Aden: Are they controlled by detachment faults?

International audienceOn the island of Socotra, the southern passive margin of the Gulf of Aden displays along its strike two different types of asymmetric structures. Western Socotra is made up of a series of southward tilted blocks bounded by consistently northward dipping normal faults. Eastern Socotra consists of a broad asymmetric anticline with a steep northern limb and a gently dipping southern limb. A zone of NE-SW striking strike- slip and normal faults separates the two areas. The overall structure is interpreted as representing two rift segments separated by a transfer zone. The along-strike juxtaposition of crustal-scale asymmetric structures on the southern margin of the Gulf of Aden is complemented by the asymmetry of the conjugate margins on either side of the gulf. Whereas the western Socotra margin is narrow and characterized by oceanward dipping normal faults, the conjugate Oman margin is broader and dominated by horsts and graben. Considering that asymmetric structures in the upper crust are often associated with synthetic shear zones at deeper ductile levels, we propose that the western and eastern Socotra margin segments were controlled at depth by two detachment faults with opposite dips and senses of shear. The normal faults of western Socotra would sole out into a top-to-the-north ductile shear zone, whereas the asymmetric anticline of eastern Socotra would be associated with a top-to-the-south detachment fault

Formation of oligopeptides in high yield under simple programmable conditions

Many high-yielding reactions for forming peptide bonds have been developed but these are complex, requiring activated amino-acid precursors and heterogeneous supports. Herein we demonstrate the programmable one-pot dehydration–hydration condensation of amino acids forming oligopeptide chains in around 50% yield. A digital recursive reactor system was developed to investigate this process, performing these reactions with control over parameters such as temperature, number of cycles, cycle duration, initial monomer concentration and initial pH. Glycine oligopeptides up to 20 amino acids long were formed with very high monomer-to-oligomer conversion, and the majority of these products comprised three amino acid residues or more. Having established the formation of glycine homo-oligopeptides, we then demonstrated the co-condensation of glycine with eight other amino acids (Ala, Asp, Glu, His, Lys, Pro, Thr and Val), incorporating a range of side-chain functionality

Construction of Design Aids for Biaxial Bending of Long Rectangular Reinforced Concrete Columns

This study presents a refined approach to the analysis and design of rectangular tied reinforced concrete columns subjected to axial thrust and biaxial bending. One of the several techniques for the design of concrete columns currently in use is thoroughly examined, organized into a logical procedure and converted into graphical form to be used as design aids. Due to the character of the resulting charts the scope of this study is limited to the construction and illustration of design charts only so far as to convey the process by which they were formulated. It is intended for the future that a complete set of design charts be constructed for use over a large range of design parameters to serve as functional design aids for the structural engineer.Architectural Engineerin

Towards Formally Verified Optimizing Compilation in Flight Control Software

International audienceThis work presents a preliminary evaluation of the use of the CompCert formally specified and verified optimizing compiler for the development of level A critical flight control software. First, the motivation for choosing CompCert is presented, as well as the requirements and constraints for safety-critical avionics software. The main point is to allow optimized code generation by relying on the formal proof of correctness instead of the current un-optimized generation required to produce assembly code structurally similar to the algorithmic language (and even the initial models) source code. The evaluation of its performance (measured using WCET) is presented and the results are compared to those obtained with the currently used compiler. Finally, the paper discusses verification and certification issues that are raised when one seeks to use CompCert for the development of such critical software

Formally verified optimizing compilation in ACG-based flight control software

International audienceThis work presents an evaluation of the CompCert formally specified and verified optimizing compiler for the development of DO-178 level A flight control software. First, some fundamental characteristics of flight control software are presented and the case study program is described. Then, the use of CompCert is justified: its main point is to allow optimized code generation by relying on the formal proof of correctness and additional compilation information instead of the current un-optimized generation required to produce predictable assembly code patterns. The evaluation of its performance (measured using WCET and code size) is presented and the results are compared to those obtained with the currently used compiler

Étude métallographique de deux masses de fer brut et de deux bandages de roues gallo-romains d’Alésia

L’étude métallographique de deux masses de fer brut et de deux bandages de roues en fer, provenant de l’agglomération gallo-romaine d’Alésia, découverts lors des fouilles conduites par É. Espérandieu en 1913, apporte des informations significatives sur les techniques de mise en forme et de fabrication de ces types de mobilier, dans la mesure où les découvertes de ces objets sont peu fréquentes et leur étude encore plus rare. Les deux blocs de fer, d’aspect massif (une douzaine de kg chacun) et de forme grossièrement parallélépipédique, et dont les surfaces conservent des empreintes d’outils ayant servi à leur mise en forme, représentent des demi-produits encore relativement bruts parvenant dans l’agglomération pour l’alimentation des ateliers de travail du fer que les fouilles ont mis au jour en de nombreux endroits. Les deux bandages de roue, fabriqués à partir de segments assemblés par soudure, et qui n’ont à l’évidence pas été utilisés, renvoient de manière explicite à une activité de charronnerie, dont témoignent peut-être d’autres indices archéologiques. Leur découverte dans la même cave que les blocs de fer brut, parmi de nombreux autres objets et outils, peut faire penser à un dépôt ou à un stock en relation avec un atelier de forge. À titre d’hypothèse comparative, l’utilisation de plusieurs de ces masses de fer brut a été nécessaire pour élaborer chacun de ces bandages.The metallographic analysis of two masses of pig iron and two iron wheel bands – all from the Gallo-Roman agglomeration of Alésia, and discovered during excavations conducted by É. Espérandieu in 1913 – has contributed useful information on the techniques of the shaping and manufacture of these objects insofar as such objects are infrequently found and their study even rarer. The two iron blocks, each weighing about 12 kg and roughly parallelopipedal, and whose surfaces are marked by the tools used in their shaping, are relatively unfinished products discovered in the agglomeration that supplied the ironworking workshops. The two wheel bands are made from welded sections and seem never to have been used. They are explicit indications of a wheelwrighting activity, which other archaeological evidence may support. Their discovery in the same cellar as the iron blocks, along with many other objects and tools, is suggestive of a storeroom or the stock of a forge. A comparative hypothesis might be considered in which many of these iron blocks were required to produce each of the wheel bands.Die metallographische Untersuchung von zwei eisernen Radreifen aus der gallo-römischen 1913 von É. Espérandieu entdeckten Siedlung Alésias liefert Informationen über die Bearbeitungs- und Herstellungstechniken dieser Gegenstände, deren Bedeutung auf der Seltenheit der Entdeckung solcher Artefakte und deren noch selteneren Untersuchung beruht. Die Oberflächen der beiden massiven grob parallelflachen Eisenbarren (jeweils an die 12 kg) weisen Werkzeugspuren auf, die von ihrer Bearbeitung zeugen. Es handelt sich um unbearbeitete Halbfabrikate, die nach Alésia eingeführt wurden, um die an zahlreichen Stellen nachgewiesenen Eisenwerkstätten zu beliefern. Die beiden aus verschiedenen Segmenten zusammengeschweißten offensichtlich nie benutzten Radreifen weisen eindeutig auf eine Wagnerei, der möglicherweise noch weitere archäologische Funde zugeordnet werden können. Ihre Entdeckung in demselben Keller wie die Roheisenblöcke mit zahlreichen anderen Gegenständen und Werkzeugen lässt an das Depot oder Warenlager einer Schmiede denken. Es wird die Hypothese aufgestellt, dass für die Herstellung jedes Radreifens mehrere dieser Eisenblöcke benötigt wurden