Abstract: Disclosed is a method for characterising an object, comprising: emission of ultrasonic waves that enter an object by passing through an external interface, then reflect off an internal interface, then exit the object by passing through the external interface again, the ultrasonic waves comprising first waves having a mode that varies according to a first variation during their propagation in the object, and second waves having a mode that varies according to a second variation during their propagation in the object; reception of echo signals comprising first signals representing echoes of the first waves, and second signals representing echoes of the second waves, construction of a plurality of images showing the object, the plurality of images being constructed from the echo signals, under the assumption that two characteristics of the object are equal to two candidate values, and comprising a first image constructed from the first signals, and a second constructed from the second signals; construction of a

Abstract: The invention relates to a method for characterising bone, the method comprising the steps of receiving (102) ultrasonic wave echo signals transmitted into a body, determining (104) a speed of sound in the body's non-bone biological tissue, locating (106) a first demarcation curve between non-bone biological tissue and bone in an image of the body constructed during said determining step, and determining (108) a speed of sound in bone. The steps of determining speed include constructing images from the signals, and a metric calculation indicative of a focus quality in the constructed images.

Abstract: The invention relates to a method for characterising bone, the method comprising the steps of receiving (102) ultrasonic wave echo signals transmitted into a body, determining (104) a speed of sound in the body's non-bone biological tissue, locating (106) a first demarcation curve between non-bone biological tissue and bone in an image of the body constructed during said determining step, and determining (108) a speed of sound in bone. The steps of determining speed include constructing images from the signals, and a metric calculation indicative of a focus quality in the constructed images.

Abstract: The invention concerns a method for detecting a fatigue undergone on at least one specific location of a hydraulic unit (10), the method being characterized in that the fatigue undergone on the at least on specific location is detected by at least one fatigue indicator (F) said at least one fatigue indicator arranged for being remotely queried via wirings or via a wireless connection.

Abstract: The invention concerns a method for starting a hydroelectric turbine (10) provided with a runner (6) mechanically coupled to a shaft line (8), a distributor (4) comprising leak tight guide vanes to control a flow of water to said runner, a spiral case (12) for supplying water to said runner, said spiral case comprising a duct connected to a main inlet valve (14), the method comprising: a) a step of balancing pressures on both sides of said main inlet valve (14), and of at least partially opening said main inlet valve (14), while the leak-tight guide vanes of the distributor (4) are closed, water pressurized at an upstream level being present in said spiral case and at said distributor (4); b) then a step of opening the leak-tight guide vanes of the distributor (4).

Abstract: This method for stabilizing the rotation speed of a hydraulic machine having S-characteristic and comprising a distributor (9) is adapted to modify a water flow, so that the machine can be coupled to a grid. The method comprises the steps of calculating an orientation of the distributor (9); and orienting the distributor according to the calculated orientation. The method further comprises the steps of providing an electric torque to the machine so as to reach a target speed.

Abstract: A watertight enclosure for the underwater confinement of a device includes a set of ellipsoidal modules juxtaposed in a watertight manner and internally delimiting at least one volume receiving the device. It has been found that producing a watertight enclosure by means of juxtaposed ellipsoidal modules enables a total weight saving of the order of one third compared to a cylindrical envelope.

Abstract: The disclosure relates to an acoustic method and device for localized, contactless, measurement of elastic and dissipative non-linearities and dynamic non-linear viscoelasticity in a medium subjected to a low-frequency acoustic stress and probed by ultrasonic pulses or wave trains.

Abstract: The disclosure relates to an acoustic method and device for localized, contactless, measurement of elastic and dissipative non-linearities and dynamic non-linear viscoelasticity in a medium subjected to a low-frequency acoustic stress and probed by ultrasonic pulses or wave trains.