Abstract: A coil arrangement for producing a static magnetic field comprising a central coil and two outer coils disposed on opposite sides of the central coil. The positions and dimensions of the coils are so selected that each term contained in the Taylor series of the function of the magnetic field in the axial direction (z axis) of the coil arrangement in minimized. The current density in the central portion of the central coil is made to be higher than at other portions. The inventive coil arrangement is smaller in size, lighter in weight, and consumers a smaller amount of power than the prior art for the same magnetic strength and with a better homogeneous magnetic field.

Abstract: A gas sensor and a method for detecting a small amount of a gas such as CO contained in air entering a space between electrodes ionized by a radiation source. At least one radiation source is provided for ionizing at least a part of the space between the electrodes disposed so as to oppose each other and a radio d/x of a distance d cm between the electrodes to a field strength x V/cm of the ionized space is set to be 0.4 or more so as to obtain a change in the ionic current sufficient to realize gas sensing based on the formation of cluster ions within the ionized space.

Abstract: An NMR imaging domain is required to have a uniform distribution of static magnetic field. However, it is very difficult to generate a uniform magnetic field for an entire imaging domain, which is usually a spherical domain. The invention advantageously, exploits the requirement that to obtain imaging the static magnetic field need only be uniform as the slicing part. Thus, sufficient uniformity of static magnetic field is obtained in the invention by providing one or more shim coils to a static magnetic field generating coil and selectively controlling current to be applied to each shim coil in relation to data defining the imaging domain.

Abstract: In a nuclear magnetic resonance imaging device, a pulse sequence is selected and a variance or standard deviation of a calculated image for T1, T2, .rho. is determined as a function of scan parameters from the theoretical equation of signal intensity in the pulse sequence and the variance in the values for T1, T2, .rho. to be measured and the original image. Scan parameters, with which the total sum of variance or standard deviation of the calculated image takes a minimum value, are determined as optimum values. An image is obtained from the optimum scan parameters to obtain a plurality of original images. A calculated image for T1, T2, .rho. is determined, based on the original images, whereby a calculated image of high quality is simultaneously obtained.

Abstract: An NMR imaging apparatus which generates NMR signals cleared of foreign noises by adding a noise detecting coil, for detecting mainly the foreign noises, to an intrinsic detecting coil for detecting the NMR signals and by producing a difference from the outputs of the two detecting coils. As a result, the foreign noises can be eliminated simply and effectively without requiring expensive shielded rooms.

Abstract: The static magnetic fields of an NMR imaging apparatus should be maintained constant in intensity in order to obtain satisfactory NMR images. Coils used to generate the static magnetic fields, and the supporting frames therefor, are subject to heat expansion due to changes in the temperature, which causes fluctuations in the intensity of the generated static magnetic fields. In the invention, the temperatures of the coils, frames, atmosphere and cooling water, and the amount of cooling water, are detected, and the energizing current for the static magnetic field coils is selectively controlled, based on the detected quantities, to thereby maintain constant the intensity of the generated static magnetic fields.

Abstract: An NMR data processing method for use with an NMR tomograph, wherein signals, located in a period before and after an NMR signal to be sampled and containing substantially none of the NMR signal component, are measured as offset data for each view, so that even the offset slightly fluctuating in the view can be corrected for the NMR signal, on the basis of that data.

Abstract: In an examination method and apparatus utilizing nuclear magnetic resonance, high frequency pulses for producing nuclear magnetic resonance are applied by successively imposing a first 90.degree. pulse, a first 180.degree. pulse, a second 90.degree. pulse, and a second 180.degree. pulse substantially immediately after the second 90.degree. pulse, and a next pulse sequence is initiated upon elapse of a wait time after the second 180.degree. pulse has been applied. The wait time is rendered much shorter than the conventional prior art wait times for high speed scanning operation, by forcibly aligning magnetization M first with the direction of a -Z direction axis and then with the direction of a +Z direction axis, using the second 90.degree. pulse and the second 180.degree. pulse. By applying a number of first 180.degree. pulses, a number of nuclear magentic resonance signals are produced for additionally shortening the overall measurement time.

Abstract: After spins in a subject being examined have been selectively excited, the application of gradient magnetic fields is interrupted to produce an FID signal. The intensity of the primary magnetic field is determined based on the central frequency of the Fourier spectrum of the FID signal, i.e., the Larmor frequency. The primary magnetic field is controlled or the observed data is corrected, according to the measured value of the primary magnetic field intensity.

Abstract: A coil assembly comprises four coils for generating a static magnetic field in an NMR imaging apparatus, wherein the dimensions of the coils are selected so that the flatness of the cross section of the coils, the current turns ratio, and the radius ratio, are within certain limits. The assembly so constructed produces highly uniform magnetic field, is small in size, and light-weight, and consumes a lower amount of power, and can be manufactured inexpensively.

Abstract: An examination method and apparatus utilizes a nuclear magnetic resonance technique in which the body of a subject to be examined is placed in a uniform static magnetic field and subjected to an electromagnetic wave having a frequency which induces nuclear magnetic resonance, a magnetic field is also applied to the subject body to specify an area of the body from which nuclear magnetic resonance (NMR) signals are radiated, and such nuclear magnetic resonance signals from the specified body area are received. A first 90.degree. pulse as the electromagnetic wave is applied to the body to excite the same, and then a 180.degree. pulse is applied to the body to produce an echo signal. A second 90.degree. pulse is to the body when the echo signal is maximum to thereby allow a magnetization to return to a state of thermal equilibrium. The foregoing sequence of the steps is repeated at prescribed intervals.

Abstract: Disclosed herein is an improved composite-type heat-system fire sensing device consisting essentially of a differential sensing element and constant-temperature sensing element, capable respectively of actuating a pair of electric contacts. These two type of sensing elements used in customary devices are difficult to assemble and to adjust. There are also serious problems for production and wider utilization of the sensing device. Further, the elements lack practical utilizability as well as reliability. The sensing device of this invention overcomes the abovementioned problems of the customary devices by effecting sensitivity matching of different operation characteristics of the two sensing elements, and makes it possible to optionally and freely adjust the sensitivity of the sensing device as required in accordance with the conditions of the place of installation of the sensing device so as to ensure a higher reliability and wider application of the sensing device.