Abstract: Apparatus is provided in which flow to be monitored actuates a device to move past a sensing electrode, causing changes of a capacitive sensing impedance in series with an impedance transformation device. The sensing electrode is at the high-impedance level of the impedance transformation device. Only a small fraction of the stray capacitance of circuit wiring, etc., which is connected at the low-impedance level of the impedance transformation device is reflected as a dulling shunt across the sensing capacitance.

Abstract: Radio frequency pulses are repeatedly applied to a sample including a fluid portion positioned in a static magnetic field, so that spins of the sample are put into the steady-state free precession state so as to generate an FID signal just after the radio frequency pulse and generate a time-reversed FID signal just before the next radio frequency pulse. Both of the signals generated thus are detected and are subjected to image reconstruction process to image the fluid portion of the sample.

Abstract: An MRI imaging device has a cylindrical magnet configuration, gradient coils and an Rf coil. The magnet has a primary and a secondary electromagnet on the same longitudinal center axis but spaced apart along the axis. Each electromagnet is a coil located within a flux guiding member preferably having a cylindrical structure closed at one end. The electromagnets provide a static magnetic field having substantial homogeneity in a central air gap A.sub.G extending from within the primary electromagnet coil axially beyond the primary coil toward the secondary electromagnet coil.

Abstract: A magnetic resonance system employs a sequence of radio frequency pulses and magnetic field gradients to detect and measure the spin-relaxation time T.sub.1 of a selected portion of a sample. Spin-lattice relaxation times are determined by first inverting longitudinal spin magnetization and then detecting the recovery of this magnetization with a series of detection radio frequency pulses. The inversion pulse is applied to the entire sample, but the detection pulses are applied to selected portions of the sample. Each detection pulse is applied in a unique location of the sample, thereby increasing the accuracy of the measurement and permitting the use of multiple detection pulses after a single inversion pulse.

Abstract: An EPR imager and spectrometer includes pulse generating system for generating broadband pulses having an RF carrier frequency that is not highly absorbed by biological samples. The pulse generating system includes up and down chirp convertors for frequency modulating a carrier frequency pulse and compressing the frequency modulated pulse to form a broadband excitation pulse of high energy. Such a machine could form the basis of a clinical imaging device capable of high sensitivity to free radical species in human patients.

Abstract: The present invention is a method to rapidly determine the fluid-flow permeability of porous media with nuclear magnetic resonance (NMR). The method can be applied to measurements of permeability in fluid-saturated earth formations using NMR logging tools.

Abstract: A slice selective excitation method of nuclear spins in an MRI apparatus comprising applying a first gradient magnetic field (B+G.sub.s1) to a patient in a predetermined direction, exciting nuclear spins in a first slice selection region of the patient by a first radio frequency pulse, applying then a second gradient magnetic field (B+G.sub.s2) different from the first gradient magnetic field (B+G.sub.s1) in the predetermined direction, exciting a second slice selection region overlapping at least partially with the first slice selection region by irradiating thereto a second radio frequency pulse so as to excite once again the nuclear spin excited by the first radio frequency pulse, and generating NMR signals effective for image reconstruction from only the overlapping portion of the slice selection regions.

Abstract: A nuclear magnetic resonance imaging system with the intercom facility in which the disturbing and potentially harmful large noise due to the application of the reading gradient field pulses can be reduced at the exterior of the examination room. In the system, a connection between the microphone and the loudspeaker for transmitting the sounds generated inside the examination room to the exterior of the examination room is controlled according to the pulse sequence specified by the sequence controller such that the microphone and the loudspeaker are disconnected whenever the application of the reading gradient field pulse takes place.

Abstract: An improved magnetic field generating device for use with a medical nuclear magnetic resonance tomographic device (MRI). The device comprises a magnetic circuit formed of a pair of magnetic pole pieces connected by yoke members in opposite relationship with each other leaving a space sufficient to accommodate therebetween an object receiving a medical inspection. According to the present invention, a super-conductive coil is wound around one of the pairs of magnetic pole pieces and the dimensional relationship between the two magnetic pole pieces is varied in a variety of ways to reduce the magnetic field imbalance, with the advantages that the magnetic flux distribution becomes highly uniform throughout the space between the pair of magnetic pole pieces, the patient entering the space has no oppressive sensation and the manufacturing cost can be reduced to a considerable degree.

Abstract: An MRI system has a magnet configuration that provides access for a surgeon or other personnel to perform procedures on a patient under support of real time MRI image. The magnet system uses a plurality of C-shape solenoidal magnets oriented to form an imaging volume in a central region of the magnets so that the magnetic flux from each magnet contributes to the magnetic field in the imaging volume. The configuration provides a high strength field in the imaging volume. The MRI system has a gradient coil for providing a magnetic field gradient in the imaging volume and an Rf coil for providing an Rf signal in the imaging volume. Preferably, the Rf coil also receives NMR signals from a specimen in the imaging volume.

Abstract: A flow meter apparatus for measuring the mass flow rate of a fluid using the Coriolis principle. A single straight flow conduit is employed which is vibrated in a radial-mode of vibration. Coriolis forces are thereby produced along the walls of the flow conduit which deform the conduit's cross-sectional shape as a function of mass flow rate. Additional embodiments are disclosed employing vibration of selected portions of the flow conduit walls. In addition, a method is described to determine the pressure and the density of a fluid by simultaneously vibrating a flow conduit in two modes of vibration and thereby determining pressure and density based on changes in each frequency.

Abstract: In nuclear magnetic resonance spectroscopy spatial localization of the output signal is achieved by using gradient magnetic fields and radio-frequency inversion pulses to define slices through a sample from which a signal is obtained. The use of intersecting slices allows the field of view to be reduced to the region of intersection to study a localized volume of interest in the sample. Conventionally, three orthogonal gradient magnetic fields can be defined by energizing successively three gradient magnetic field coils. With the present invention combinations of the gradient magnetic field coils are energized simultaneously to allow the field of view to be more closely conformed to a described volume of interest. This simultaneous energization allows the field of view to be rotated relative to the axes of the coils and/or allows non-orthogonal intersecting slices to be defined to alter the shape of the field of view at the intersection of the slices.

Abstract: The invention concerns a method for adjusting the desired current values of shim coils of a tesseral harmonic (off axis) shim system in order, in particular in the center of the shim system, to produce as homogeneous a magnetic field as possible. Utilizing a minimal number of measuring points and appropriate linear combinations of the corresponding measurement values with and without switching on the corresponding shim coil, a simple, systematic and reliable measurement method is introduced which does not require any iterative procedure. The method can be used by itself or the desired current values can serve as starting values for a further shimming procedure.

Abstract: In an inspection apparatus using nuclear magnetic resonance (NMR), a spatial distribution of homogeneity of a static magnetic field can be quickly measured even when a heterogeneous object is inspected, by measuring simultaneously phase data and a transverse relaxation time at the same spatial position of the heterogeneous object, removing the difference of a phase term due to a chemical shift by anticipating components at that position and obtaining only the phase data resulting from static magnetic field inhomogeneity.

Abstract: Apparatus for analysis of flowing streams of liquids, flowable solids or mixed liquids and solids by nuclear magnetic resonance techniques. The apparatus is sufficiently small, economical and easy to operate so that it is useful for making measurements in applications such as the production of foods and the like.

Abstract: An NMR imaging apparatus includes an excitation coil with a plurality of conductive elements extending between two spaced-apart end loops to form conventional "birdcage" coil. A shield is provided to reduce interference between the excitation coil and gradient field coils. The shield comprises a first electrically conductive section having an open ring with a gap therein and a plurality of first members extending from the ring with each member terminating at a remote end. A capacitor is connected across the gap in the ring. A second electrically conductive section has another ring from which a like plurality of second members extend with each one terminating at a remote end. The remote end of each second member is spaced from a remote end of a corresponding one of the first members and a capacitor is connected across those remote ends.

Abstract: A borehole logging tool comprises a Nuclear Magnetic Resonance (NMR) tool and is pulsed according to a selected sequence. An interpretation is performed which involves a singular value decomposition and compression of data obtained by the tool. The compressed data is then subjected to a nonegative, linear least square fit to obtain a distribution function. The distribution function is used in determining bound fluid volume, unbound fluid volume, total porosity, spin-lattice relaxation time, spin-spin relaxation time, and mean relaxation time using only the pulse NMR tool.

Abstract: In known magnetic resonance devices shimming is applied on the basis of maps of field inhomogeneities obtained from two images of a slice of an object by formation of a ratio image thereof. This ratio image is processed in order to obtain shimming information. These known methods are time-consuming and cumbersome. The invention proposes a fast and simple shimming method which utilizes only one measuring sequence or a few measuring sequences. The shimming gradient (-dG) is determined from a time shift between an anticipated temporal position (t1) and a measured temporal position (t1') of a maximum of an echo resonance signal (ec) produced by the measuring sequence.

Abstract: Slaved radio frequency field and light polarization magnetometer. The polarization direction (P) is slaved perpendicular to the field (Bo) to be measured, as well as the radio frequency field (Brf). Application to the measurement of weak magnetic fields such as the geomagnetic field.

Abstract: In a method for the generation of a nuclear magnetic resonance (NMR) spectrum from a measuring volume, which is exposed to a highly homogeneous stationary magnetic field B.sub.0, a radio frequency (RF)-pulse is irradiated in a first run into the measuring volume in order to excite the concerned nuclear spins; at least one magnetic gradient field G is switched, for example for selecting a certain slice from the measuring volume and after switching off the magnetic gradient field G, a first data set is recorded which contains the observable measuring signals from the measuring volume, subsequently the method is repeated in a second run with a magnetic gradient field -G which has the opposite polarity to the magnetic gradient field G, whereas the remaining experimental parameters of the first run are maintained, wherein after switching off the magnetic gradient field -G a second data set is recorded and added to the first data set.