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This article deals with the regulation of water flow in open-channels modelled by Saint-Venant equations. By means of a Riemann invariants approach, we deduce stabilizing control laws for a single horizontal reach without friction. The stability condition is extended to a general class of hyperbolic systems which can describe canal networks with more general topologies. A control law design based on this condition is illustrated with a simple case study: two reaches in cascade. The proof of the main stability theorem is based on a previous result from Li Ta-tsien concerning the existence and decay of classical solutions of hyperbolic systems.

This paper deals with the regulation of water flow and level in water-ways made up of channels separated by spillways. This control problem is solved by using boundary control based on Riemann invariants. The control performance is illustrated with an experiment for the Sambre river.

This paper deals with the regulation of water flow in open-channels modelled by Saint-Venant equations. A previous Lyapunov design of stabilizing controllers for a single reach is extended to the case of multi-reach channels.

We retrospectively investigated the fate of bone auto- and allografts in 64 patients who underwent a tibial tubercle elevation with bone graft. Half of them received an autograft and the other half, an allograft that had been processed and freeze-dried. The two groups had similar preoperative characteristics concerning age, sex and pathology. Roentgenograms were reviewed by three independent observers and scored for fusion, resorption and collapse. Clinical charts were analysed for different variables. The overall radiological score for both groups did not differ statistically. Comparison of graft fixation with one or two screws demonstrated more bone resorption in the case of a single-screw fixation. In such a case, the occurrence of a preoperative tubercle fracture had a significant adverse influence, due to a less stable fixation. From the clinical charts review, only the mean stay at hospital was significantly shorter when an allograft was performed. A bone allograft appears to be suitable to maintain an osteotomy but requires a more careful surgical technique fixation to obtain a similar result to an autograft.

The article is concerned with the design of boundary control laws for stabilizing systems of 2 /spl times/ 2 first order quasi-linear hyperbolic PDEs. A new graph representation of such systems represents the interactions between the characteristic curves and the boundary control laws, the invariant graph, is introduced. The structure of the invariant graph is used to design stabilizing control laws and an analytical stability condition is given.

The paper deals with the stabilization of distributed hyperbolic systems. It describes a generic method for building Lyapunov function candidates based on entropies. The method is illustrated with a case-study.

We consider a tank containing fluid. The tank is subjected to a one-dimensional horizontal move and the motion of the fluid is described by shallow water equations. By means of a Lyapunov approach, we deduce the control laws to stabilize the state of the fluid-tank system. The control law is an output feedback where the output is given by the trajectory of the tank and the level of the fluid at the boundary of the tank. Although global asymptotic stability is yet to be proved, we numerically simulate the system and observe the stabilization.

This case report describes the evolution of postfractural axial bone deviations that occurred in a child with hepatic osteodystrophy due to an Alagille Syndrome. Postfractural bone deformities in children trend to spontaneous correction if there is a remaining growth potential. In case of severe hepatic osteodystrophy correlated by liver transplantation, we have observed spontaneous correction of a posttraumatic valgus deformity of the leg, as well as worsening of a diaphyseal femoral bowing. We tried to explain this apparently paradoxal evolution.Andrea St. is born in 1984 with multiple malformations corresponding to Alagille Syndrome: ductulus paucity, pulmonary arterial hypoplasia, posterior embryotoxin and "butterfly vertebrae". She has developed a cholostatic icterial and a portal hypertension due to a hepatic cirrhosis which needed an hepatic transplantation at the age of 8 years. Before her transplantation, Andrea St developed postfractural axial bone deviations. At the age of 7 years, she had a tibia valgum of 20 degrees and a femoral bowing of 50 degrees. With the normalization of the metabolism due to the hepatic transplantation, the osteopenia as well the tibia valgum of 20 degrees has been corrected spontaneously up to 8 degrees and there was a worsening of the femoral bowing up to 50 degrees.The physiopathology of the hepatic osteodystrophy is not yet perfectly known. Treatment with Vitamin D and Calcium doesn't seem to prevent hepatic osteodystrophy. Salter reported that postfractural bone angulation in children will spontaneously correct itself if on one hand it is not far from the growth cartilage and on the other hand if it is in the same mobility plane than the adjacent articulation. Postfractural diaphyseal bone deformities tend to correct spontaneously if the angulation is less than 20 to 30 degrees. Concerning fractures of the proximal tibia in children, they develop frequently a progressive tibia valgum deformity, even if the fracture was not primary displaced. However we know that all proximal tibial fractures in children don't give residual valgus deformities, and that several postfractural tibia valgum correct spontaneously. This has been explained by a temporary growth acceleration of the medial part of the proximal tibial growth plate. In this case, the femoral bowing worsened. This is explained by the mediodiaphyseal location of the deformation, and the importance of the bone deviation much bigger than the threshold of 20 to 30 degrees that may not be overtaken to hope a spontaneous correction. The evolution of the proximal metaphyseal tibial fracture consisted firstly in a progressive valgus deformation that resolved spontaneously after hepatic transplantation.

Our experience with the bone banking methodology that we have used over the last years is reported. The technical and investigational aspects of the procurement, storage and treatment of the donor bone and related tissues are presented. For different purposes, we have prepared sterile and nonsterile procured implants. Appropriate donor selection and sterility controls remain the two major concerns of bone banking activities.