Shields

About: Shields is a research topic. Over the lifetime, 1456 publications have been published within this topic receiving 10896 citations.

Design of Light Multi-layered Shields for Use in Diagnostic Radiology and Nuclear Medicine via MCNP5 Monte Carlo Code

Abstract: Introduction Lead-based shields are the most widely used attenuators in X-ray and gamma ray fields. The heavy weight, toxicity and corrosion of lead have led researchers towards the development of non-lead shields. Materials and Methods The purpose of this study was to design multi-layered shields for protection against X-rays and gamma rays in diagnostic radiology and nuclear medicine. In this study, cubic slabs composed of several materials with high atomic numbers, i.e., lead, barium, bismuth, gadolinium, tin and tungsten, were simulated, using MCNP5 Monte Carlo code. Cubic slabs (30×30×0.05 cm3) were simulated at a 50 cm distance from the point photon source. The X-ray spectra of 80 kVp and 120 kVp were obtained, using IPEM Report 78. The photon flux following the use of each shield was obtained inside cubic tally cells (1×1×0.5 cm3) at a 5 cm distance from the shields. The photon attenuation properties of multi-layered shields (i.e., two, three, four and five layers), composed of non-lead radiation materials, were also obtained via Monte Carlo simulations. Results Among different shield designs proposed in this study, the three-layered shield, composed of tungsten, bismuth and gadolinium, showed the most significant attenuation properties in radiology, with acceptable shielding at 140 keV energy in nuclear medicine. Conclusion According to the results, materials with k-edges equal to energies common to diagnostic radiology can be proper substitutes for lead shields.

Method and System for Deployed Shielding Against Ballistic Threats

Abstract: A system (100) shields field-deployable equipment from effects of nearby multi-directional threats, the equipment including or being mounted in association with a sensor unit (110) having at least one sensor operable to detect the motion of an in-flight projectile and to generate a nearby impact point determination. Shields (130) are mounted in spaced relationship with the equipment and adapted to be moved from a first position wherein the equipment is fully exposed to a second position wherein the equipment is at least partially shielded, and a control unit (150) is coupled to the shields and is responsive to detection of an in flight projectile prior to nearby impact for moving at least one of the shields from the first position to the second position.

Analysis of solar-radiation shields for temperature control of space vehicles subjected to large changes in solar energy

Abstract: : An analysis was made of a passive temper tur co rol system for a space vehicle subjected to variable solar energy. This system effectively isolates the capsule from the incident solar energy by the use of solar-radiation shields. The desired temperature level of the capsule could then be maintained by a constant internal heat load. The alysis was developed on the basis of diffusely refl cting isoth rm l urfaces and permits evaluation of the temperatures of various shield-capsule configurations. Several shield-capsule configurations were studi d and parameters were established which indicate the important criteria for achieving the desired temperature control. The effects of specularly reflecting (instead of diffusely reflecting) surfaces and the effects of shield thermal conductivity on capsule temperature were also studied. Results from these studies were applied to the single-shield, conical-capsule configuration and it was found that these effects did not significantly alter the magnitude of temperature control achieved. (Author)

Composite shield structure and perpendicular magnetic recording head

Abstract: PROBLEM TO BE SOLVED: To provide a perpendicular magnetic recording head capable of improving a magnetic field gradient while maintaining sufficient magnetic field intensity in use of a high recording density and a narrow track width. SOLUTION: A main recording magnetic pole 20 having a magnetic pole tip 20t in ABS, and a shield structure 100 formed around the same, are included. This shield structure 100 includes a leading shield 22, a trailing shield 21, two side shields 23 and 24 which are partial side shields, magnetic couplers 25 and 28 for magnetically coupling together the leading shield 22 and the two side shields 23 and 24, and magnetic couplers 26 and 27 for magnetically coupling together the trailing shield 21 and the two side shields 23 and 24. Magnetic potential of the leading shield 22, the trailing shield 21, and the two side shields 23 and 24 is optimized. COPYRIGHT: (C)2009,JPO&INPIT

Omnibearing magnetic screen reactor

Abstract: The utility model belongs to a reactor structure which is suitable for the magnetic core reactor The utility model is characterized in that the both ends of a coil are provided with the magnetic shields; the silicon steel sheets which form the magnetic shields are divided into a plurality of groups with a non-permeability magnetic material, and are integrally bound with the adhesive agent; one side of each the magnetic shield is welded with the silicon steel sheets with a nonmagnetic steel plate; any two of the flabellate cakes which form an iron-core cake are divided by an insulation layer The utility model has the advantages of small magnetic-leakage loss, low total loss, high operational reliability, etc