Abstract: The present invention discloses a crack-resistant ultra-high performance concrete (UHPC) for underground engineering in water-rich strata, preparation method, and application thereof, belonging to the technical field of building materials. The concrete is prepared from the following raw materials in parts by weight: 550-650 parts of cement, 140-180 parts of fly ash, 120-150 parts of silica fume, 200-300 parts of calcined shield tunnel slag, 30-50 parts of micron-scale magnesium oxide, 30-50 parts of nano-scale magnesium oxide, 30-50 parts of rheology-modifying material, 800-1000 parts of lightweight aggregate, 4-8 parts of water reducer, and 50-200 parts of water. The rheology-modifying material has a fluidity ratio of 106%. The present invention incorporates calcined shield tunnel slag, micron/nano-scale magnesium oxide, and lightweight aggregate into the UHPC, which effectively suppresses shrinkage and reduces crack formation.

Abstract: The present disclosure provides a vertically retractable magnet field assembly for a Magnetic Imaging Resonance (MRI) system. The assembly can move from an upward raised position to a downward retracted position, and vice versa. The assembly includes a magnet configured with a bore for imaging a body portion of a subject. The bore defines an inner surface of the magnet and extends along a longitudinal axis of the magnet. The magnet includes at least one flux generating element disposed within the magnet and oriented such that each of the at least one flux generating element surrounds the bore. Each of the at least one flux generating element is configured to generate a magnetic field for magnetizing the body portion positioned within the bore to generate a visual representation of an anatomy of the body portion.

Abstract: The present disclosure provides a magnet assembly for a Magnetic Resonance Imaging (MRI) system. The assembly includes a yoke having a frame member movably positioned by a magnet movement unit. A first arm extends laterally from a first end of the frame member and includes a first magnet-pole assembly having a first central axis. A second arm extends laterally from a second end of the frame member and includes a second magnet-pole assembly. The second magnet-pole assembly includes a second central axis and configured to orient towards with the first magnet-pole assembly while maintaining a gap therebetween, for positioning a body portion for magnetization. A first and a second clamp member are each mounted about a peripheral side surface of the magnet-pole assemblies, respectively. The clamp members are configured to attenuate a leakage flux emanating from the magnet pole assemblies.

Abstract: The present disclosure provides a vertically retractable magnet field assembly for a Magnetic Imaging Resonance (MRI) system. The assembly can move from an upward raised position to a downward retracted position, and vice versa. The assembly includes a magnet configured with a bore for imaging a body portion of a subject. The bore defines an inner surface of the magnet and extends along a longitudinal axis of the magnet. The magnet includes at least one flux generating element disposed within the magnet and oriented such that each of the at least one flux generating element surrounds the bore. Each of the at least one flux generating element is configured to generate a magnetic field for magnetizing the body portion positioned within the bore to generate a visual representation of an anatomy of the body portion.

Abstract: The present disclosure provides a magnet assembly for a Magnetic Resonance Imaging (MRI) system. The assembly includes a yoke having a frame member movably positioned by a magnet movement unit. A first arm extends laterally from a first end of the frame member and includes a first magnet-pole assembly having a first central axis. A second arm extends laterally from a second end of the frame member and includes a second magnet-pole assembly. The second magnet-pole assembly includes a second central axis and configured to orient towards with the first magnet-pole assembly while maintaining a gap therebetween, for positioning a body portion for magnetization. A first and a second clamp member are each mounted about a peripheral side surface of the magnet-pole assemblies, respectively. The clamp members are configured to attenuate a leakage flux emanating from the magnet pole assemblies.

Abstract: A MRI quadrature coil for imaging a human shoulder has a first coil shaped to conform to the top of the shoulder and a second coil adapted to encircle the shoulder. The second coil has a magnetic axis generally orthogonal to that of the first coil.