Abstract: A magnetic field generator for MRI comprises a pair of plate yokes opposed to each other with space in between. A magnet is provided in each of the opposed surfaces of the pair of plate yokes. A column yoke is connected to the pair of plate yokes. An enhancing member made of magnetic material and having a curved slant face is provided in an inner surface of the connection between the column yoke and the plate yokes at a place farthest from the magnet. A first bolt of magnetic field adjusting bolts is screwed into the plate yoke, with a tip of the first bolt contacting the enhancing member. A second bolt of the magnetic field adjusting bolts is screwed into the plate yoke, with a tip of the second bolt contacting an upper end face of the column yoke. An engaging portion for engagement of the enhancing member with the yoke may be provided.

Abstract: A plate yoke has an upper surface formed with a projection and a guiding rail. A new magnet block is transported by sliding on the upper surface of the plate yoke, and is bonded side by side with the projection or a magnet block which is already fixed. During the above operation, a magnetic member is held above the plate yoke. Preferably, the new magnet block is transported toward a corner portion, with side surfaces of the magnet block held parallel to a side surface of the projection and a side surface of the guiding rail respectively. When the magnet unit and the column yoke is connected, the column yoke or the magnet unit is lowered so that a guiding rod attached to an end face of the column yoke is inserted into a hole formed in the magnetic unit. Further, the column yoke is guided by a guiding member disposed between a permanent magnet on the plate yoke and a position where the column yoke is to be connected on the plate yoke.

Abstract: A magnetic field generator for an MRI includes a generator main body. The generator main body includes a pair of plate yokes opposed to each other with space in between, a permanent magnet disposed in each of the opposed surfaces of the plate yokes, and a column yoke for magnetically connecting the plate yokes. As a packing member, a shielding member, and if necessary, a stud pin as well as a fixing member are prepared. When packing, the shielding member is attached to the generator main body for shielding an opening. The stud pin may be used for providing a gap between the generator main body and the shielding member. For an open-type generator, the fixing member should preferably be attached to bridge the pair of plate yokes at a middle portion of the opening.

Abstract: An object of the present invention is to provide an MRI magnetic field generator with which the magnetic field uniformity within the imaging field of view of the air gap can be adjusted easily and safely, without having to detach the gradient coils, after the MRI magnetic field generator has been installed with gradient coils already mounted on a pair of magnetic pole pieces. After the holder disk 13 has been placed on and fastened to the base disk 11, the magnetic material pellets or permanent magnet pellets for adjusting the magnetic field uniformity are inserted into the required pits disposed in a specific pattern, and if needed, spacers are placed in the gaps between [the pellets] and the cover disk 14 to position everything, after which the cover disk 14 is screwed on to hold everything together. The resulting shim holder 10 is aligned with and fastened to the gradient coil 6 or its support member.

Abstract: A plate yoke has an upper surface formed with a projection and a guiding rail. A new magnet block is transported by sliding on the upper surface of the plate yoke, and is bonded side by side with the projection or a magnet block which is already fixed. During the above operation, a magnetic member is held above the plate yoke. Preferably, the new magnet block is transported toward a corner portion, with side surfaces of the magnet block held parallel to a side surface of the projection and a side surface of the guiding rail respectively. When the magnet unit and the column yoke is connected, the column yoke or the magnet unit is lowered so that a guiding rod attached to an end face of the column yoke is inserted into a hole formed in the magnetic unit. Further, the column yoke is guided by a guiding member disposed between a permanent magnet on the plate yoke and a position where the column yoke is to be connected on the plate yoke.

Abstract: A magnetic field generating device for use in MRI having a pair of pole pieces opposed at a space to each other and generating a magnetic field in the space, wherein the pole piece has a laminate structure in which a soft ferrite and a magnetic material base are disposed from the side of the space, and a layer of small magnetic permeability and high electric resistance is interposed between the soft ferrite and the magnetic material base. The soft ferrite may be lamination of the soft ferrite and silicon steel sheets. High speed image pick-up at high sensitivity and sharpness is enabled by reducing the eddy current and the remanent magnetism generated in the pole piece by the gradient magnetic field coils.

Abstract: A magnetic field generating apparatus has a permanent magnet arrangement for generating a magnetic field in a magnetic field generating space and a yoke arrangement for forming magnetic circuits for generation of the magnetic field together with the permanent magnet arrangement. The yoke arrangement includes a first pair of yokes arranged facing each other, a second pair of yokes arranged facing each other through which the first pair of yokes are magnetically connected to each other, a third pair of yokes arranged between one end of one of the first pair of yokes and one end of one of the second pair of yokes and between the other end of the one of the first pair of yokes and one end of the other of the second pair of yokes, respectively, and yoke moving units for independently moving the one of the first pair of yokes and each of the second pair of yokes with respect to the third pair of yokes, respectively.

Abstract: A process and apparatus for monitoring the etching ability of an etchant by accurately measuring the etching rate with a relatively simple arrangement. A process and apparatus for monitoring the etching rate is determined by channeling the etchant from an etching tank to a reaction column, subjecting a specimen of the same material as a metal part to be etched in practice to etching with the etchant in the reaction column, collecting hydrogen gas generated during etching of the specimen, measuring the time taken until a predetermined quantity of hydrogen gas is generated, and computing the etching rate from the measured time.

Abstract: An MRI magnet member (e.g., a pole piece or tip) is laminated using relatively large bar-shaped laminations instead of the usual thin sheet material. One or more layers of such bar-shaped laminations are arrayed with small insulating gaps into which a low loss insulating liquid filler material is flowed and then cured to a hardened solid state. This simultaneously produces insulated pole tip laminations which have been robustly integrated together into a unitary structure. The resulting robust laminated pole tip is relatively easy to manufacture and is also capable of withstanding rather large magnetic forces and maintaining relatively uniform magnetic field distribution within an MRI imaging region while yet providing providing sufficient eddy current reduction so as to efficiently permit rapidly changing magnetic gradient coil currents to be established.

Abstract: The concentration of a plating solution in which a workpiece is plated is automatically controlled within a permissible range by replenishing a consumable ingredient to the plating solution in an amount corresponding to the amount of consumption estimated from the surface area of the workpiece for a given plating solution composition under given plating conditions. By measuring the concentration of the consumable ingredient in the plating solution, the replenishment of consumable ingredient is interrupted for a predetermined time or the amount of the consumable ingredient replenished is reduced when the measured concentration is above the permissible range, or the amount of consumable ingredient replenished is increased or a necessary amount of the consumable ingredient is additionally supplied to the plating solution separately from the normal replenishment of consumable ingredient when the measured concentration is below the permissible range.

Abstract: The concentration of a plating solution in which a workpiece is plated is automatically controlled within a permissible range of replenishing a consumable ingredient to the plating solution in an amount corresponding to the amount of consumption estimated from the surface area of the workpiece for a given plating solution composition under given plating conditions. By measuring the concentration of the consumable ingredient in the plating solution, the replenishment of consumable ingredient is interrupted for a predetermined time or the amount of the consumable ingredient replenished is reduced when the measured concentration is above the permissible range, or the amount of consumable ingredient replenished is increased or a necessary amount of the consumable ingredient is additionally supplied to the plating solution separately from the normal replenishment of consumable ingredient when the measured concentration is below the permissible range.

Abstract: In a method for monitoring laser beam welding, a sequential signal representing a laser oscillating wave form is received, light of a predetermined wavelength in the light emitted from the weld zone is received, and the two signals thus received are processed to determine the minimum intensity of the light of the predetermined wavelength and thereby accurately deduce welding beam input and penetration of welding. An apparatus used in practicing the monitoring method includes a monitoring optical fiber for receiving and transmitting the light emitted from a weld being made on a workpiece, an interference filter for selectively passing light of a predetermined wavelength, and a processing device for determining an intensity of the light of the predetermined wavelength.

Abstract: A method for detecting a start point of electroless plating, which comprises the steps of: immersing a couple of metal electrodes in an electroless plating solution; connecting the metal electrodes to a DC power supply to serve as an anode and a cathode, respectively; applying an electric current across the metal electrodes immediately before immersing an object to be electroless plated in the solution thereby causing metal deposition from the solution at the cathode to activate the same; measuring the potential difference between the activated cathode and the object to be plated; and detecting start of the electroless plating of the object from the measured value of the potential difference between the activated cathode and the object. Also disclosed is an apparatus for carrying out the method of the invention.