Abstract: Particulate material suspended in a fluid is separated and recycled by means of an ultrasonic resonance wave. In a preferred embodiment, the ultrasonic resonance field is generated within a multilayered composite resonator system including a transducer, the suspension and a mirror parallel to each other. Dimensions and frequencies resonant to the whole system but not exciting Eigen-frequencies of transducer and mirror itself are chosen so that thermal dissipation is minimized. Generally, the process is suitable for all kinds of particles (solid, liquid or gaseous disperse phases) especially for hydrosols (particles in water) and for separation of biological particles such as mammalian, bacterial and plant cells or aggregates. Specialized applications in biotechnology are described including an acoustic filter for mammalian cell bioreactors or the selective retention of viable cells relative to nonviable cells.

Abstract: Particulate material suspended in a fluid is separated and recycled by means of an ultrasonic resonance wave. In a preferred embodiment, the ultrasonic resonance field is generated within a multilayered composite resonator system including a transducer, the suspension and a mirror parallel to each other. Dimensions and frequencies resonant to the whole system but not exciting Eigen-frequencies of transducer and mirror itself are chosen so that thermal dissipation is minimized. Generally, the process is suitable for all kinds of particles (solid, liquid or gaseous disperse phases) especially for hydrosols (particles in water) and for separation of biological particles such as mammalian, bacterial and plant cells or aggregates. Specialized applications in biotechnology are described including an acoustic filter for mammalian cell bioreactors or the selective retention of viable cells relative to non-viable cells.

Abstract: Method and apparatus for separating particles (1) which are dispersed in a dispersion medium, whereby an ultrasonic standing wave (3) is generated by means of a composite resonator in a vessel (8) containing dispersion (2), the frequency of said wave preferably being in the neighborhood of the characteristic frequency (f.sub.o). In order to achieve, a better separation of the particles it is provided that the amplitudes (V) of the sound particle velocity which appear in the sound field are chosen slightly smaller than the upper threshold amplitude (V.sub.max), and that pressure forces on the dispersed particles (1), which result from the acoustic stream of the dispersion medium caused by applied sound, are equivalent to the longitudinal holding forces of the dispersed particles (1) in the areas of the antinodes (11) and nodes (12), and furthermore that the frequency by means of which the composite resonator is driven is as precisely as possible tuned to one of the resonant frequencies (f.sub.n).

Abstract: The invention relates to a device for recognizing the impact site (29, 37) of a charge carrier beam on a target. This device has two position-sensitive detectors (22, 23) above the target which have a given distance from each other and from the target and on which via imaging systems (24, 25) the impact site (29, 37) of the charge carrier beam is imaged by means of X-rays. The output signals of these detectors (22, 23) are placed on a special evaluation device which determines all three spatial coordinates of the impact site (29, 37) of the charge carrier beam.

Abstract: The invention concerns apparatus for detecting the position of incidence (2) of a beam (1) of charge carriers on a target (3) wherein X-rays (4) starting from the position of incidence (2) are detected by detector (7) connected to an analyzing circuit (9) An imaging system (5, 50; 10, 11, 12) is provided which can cover all the positions (P.sub.1 . . . P.sub.8) that the positions of incidence (2) can take up and projects them on the sensing surface of a position-sensitive detector (7), wherein the projected coordinates (x', y') are directly proportional to the coordinates (x, y) of the position of incidence (2). In addition, a filter (6) highly transparent to the X-ray radiation range emitted from the position of incidence (2) is arranged between the target surface (3) and the position-sensitive sensor (7). The position-sensitive detector (7) emits electric signals which depend from the coordinates (x, y) of the position of incidence (FIG. 1).

Abstract: The invention relates to a system for determining the current thickness of changing coatings of a material on a substrate, using an electrically excitable, mechanically vibratable element (2) having at least one pronounced resonant frequency, which is excited to a steady vibration by an oscillator circuit (1) at a resonant frequency, and which is covered by the material in the same manner as the substrate. A signal (U.sub.D) is produced which depends on the damping caused by the coating of the vibratable element (2). This signal (U.sub.D) is compared with a known critical value signal (U.sub.DE) whereby it is possible to indicate when the vibratable element (2), which can be coated with the material only to a certain degree, must be replaced with a new vibratable element (FIG. 2).

Abstract: A piezoelectric resonator, particularly for pressure, acceleration, temperature and load transducers, consisting of a resonator core having holding discs on its opposite sides, said holding discs being formed of solid body layers, said layers consisting alternatively of materials having strongly different acoustic impedance for unit cross-sectional area.