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A portable vibrating device has two electrical motors each having an axle and a weight element coupled to the axle. The axles couple the electrical motors to the weight elements. The weight elements form a weight unit having a total mass m and having a mass center with an offset r in respect to a rotational axis. The weight units are angularly dispositioned to different angular dispositions for varying the amplitude of vibration according to a desired scheme. The angular disposition is controlled by the rotation of the electrical motors. The device may be able to receive messages and to play the by varying the amplitude of vibration accordingly.

An apparatus and method for force sensing device having a pendulous mechanism proof mass formed in a silicon semiconductor substrate and structured for rotation about an intermediate rotational axis, the proof mass being substantially rectangular in shape with opposing first and second lateral peripheral edges and opposing first and second endwise peripheral edges. A plurality of capacitor comb teeth are formed symmetrically along the opposing first and second endwise peripheral proof mass edges and along the opposing first and second lateral peripheral proof mass edges adjacent to the first and second endwise peripheral edges, and one or more mass reduction apertures are formed in an interior portion of the proof mass on one side of the intermediate hinge axis.

A tactile generator (10) comprises an eccentric mass (16) that imparts a vibration as it rotates about a rotational axis (24). The mass (16) is radially movable with respect to the rotational axis (24) such that the distance between the mass (16) and the axis (24) is variable. Varying the distance of the mass (16) from the axis (24) varies the amount of vibration generated when the mass (16) is rotated. The amount of vibration may be controlled responsive to a detected level of ambient noise.

A vibration-minimizing suspension mechanism for a press roll is provided. The press roll and an opposing roll each having a rotational axis and cooperate to form a press nip adapted to impart a linear load on a fiber web passing therethrough. The linear load is oriented through the rotational axes of the press roll and the opposing roll. As such, the suspension mechanism comprises a suspension arm having opposed ends and a medially-disposed pivot, wherein the press roll is rotatably engaged at the rotational axis thereof with one of the opposed ends of the suspension arm. The suspension arm is further pivotably and adjustably mounted at the pivot so as to allow the pivot to be adjusted in substantially parallel relation to the linear load. The adjustability of the pivot thereby allowing a mounting line along the suspension arm, the mounting line being defined by the pivot and the rotational axis of the press roll, to be maintained in substantially perpendicular orientation to the linear load to thereby minimize vibration in the press roll.

An active type magnetic bearing system includes magnetic bearings (112, 113) for suspending a rotary body (1) to permit it to rotate about its rotational axis. A control system (118) supplies the magnetic bearings (112, 113) with signals to control the radial position of the rotary body, and comprises displace­ment detecting circuits (2, 3, 13, 14) for detecting any displacement of the radial position of the rotary body (1) and a control circuit (118) for producing a control signal which serves to suppress any unstable vibration of the rotary body.

A torsional vibration damping assembly including plates (14,16,18) between which is interposed friction material (30). The plates are held in an assembly and limited against motion by unthreaded reaction pins (38) supported at both ends. The friction material (30) is located radially outwardly of the usual spring assemblies (28) to increase the moment arm over which frictional forces may act. The central plate (16) has a smaller central aperture (22) than the central apertures (20,24) in the adjacent plates and is provided with spline teeth (25) having an axial length substantially no greater than the thickness of the plates (16) so as to allow a coupling (50) to be canted with respect to the rotational axis of the assembly during assembly of a transmission input shaft thereto.

An apparatus (120) for intermittent support of a rotatable shaft (22) comprises an axial collar (120) substantially coaxial with the shaft (22) and fixed thereabout for rubbing contact with the shaft (22) only after the shaft deflects a predetermined amount from its rotational axis (140) to alter the bending mode of the shaft (22) thereby increasing the first order critical speed of the shaft (22) to a level above the maximum speed at which the shaft (22) may be driven to prevent excessive vibration and consequent damage to the shaft (22), associated end couplings (35,56) and housing (78,84,92).

The directional characteristics of second‐order unidirectional microphones Qsee G. M. Sessler and J. E. West, IEEE Trans. Audio Electroacoust. AU‐I9, 19 (1971)] have been considerably improved by alterations in the mechanical design. Relative to the direction of maximum sensitivity at θ = 0° (referred to the rotational axis) the attenuation in the directions of minimum sensitivity at θ = 90°, 180°, 270° now exceeds 20 dB in the midfrequency range.

Vibrational holography was performed on tympanic membranes (TM) in human temporal bones obtained immediately after death. Displacement patterns at the first mode (and also at higher modes) were essentially the same as those found in cats (Khanna et al., 1969). Findings in both species can best be reconciled with the catenary concept of Helmholtz (1868). Owing to the curvature of the TM's surface, a force transformation is brought about between the membrane (larger displacement/lesser force) and the malleus (lesser displacement/larger force). Point‐by‐point comparisons of displacement amplitudes along the manubrium with those in adjacent regions of the posterior quadrant suggested that forces exerted upon the manubrium decrease with distance from the ossicular rotational axis so that FORCE×FORCE ARM≅CONSTANT. The amplitude differences between TM quadrants (Khanna et al., 1969) are explained by the fact that the manubrium and the ossicular rotational axis form an acute angle, open anteriorly (Barany, 1938). Thus, the manubrium appear to rotate around two axes. With frequency, the efficiency of the system varied in a manner resembling the middle‐ear impedance curve. [Supported by NIH grants.]