This paper describes a statistical image reconstruction method for x-ray CT that is based on a physical model that accounts for the polyenergetic x-ray source spectrum and the measurement nonlinearities caused by energy-dependent attenuation. Unlike our earlier work, the proposed algorithm does not require pre-segmentation of the object into the various tissue classes (e.g., bone and soft tissu...

A procedure for efficient three-dimensional nonlinear time-history analysis of steel framed buildings is derived. It incorporates two types of nonlinear beam elements—the plastic hinge type and the elastofiber type—and nonlinear panel zone elements to model yielding and strain-hardening in moment-frames. Floors and roofs of buildings are modeled using 4-node elastic diaphragm elements. The proc...

As emerging advanced construction materials, strain hardening cementitious composites (SHCCs) have seen increasing field applications recently to take advantage of its unique tensile strain hardening behavior, yet existing uniaxial tensile tests are relatively complicated and sometime difficult to implement, particularly for quality control purpose in field applications. This paper presents a n...

The x-ray attenuation values of brain studied with computed tomography (CT) are strikingly affected by the ages of the subjects. Premature neonates, for example, may have brain attenuation values 20-30 H below adult values. These lower attenuation values for developing compared with adult brain can be ascribed partly to machine-related effects (beam-hardening, adult algorithms, scanning geometr...

For the investigation of the dynamics of heavy-ion beams penetrating hot dense plasma at the Z6 area at GSI an experimental setup was developed, which allows for diagnosing a directly laser-heated plasma target, and measuring the charge state and energy loss of an ion beam after / in it [1, 2]. The varying energy loss of the ion beam in the target (solid—plasma—vacuum) is determined in a TOFlik...

Space missions require extremely high reliable components that must guarantee correct functionality without incurring in catastrophic effects. When electronic devices are adopted in space applications, radiation hardened technology should be mandatorily adopted. In this paper we propose a novel method for analyzing the sensitivity with respect to Single Event Latch-up (SEL) in radiation hardene...

Radiation-hard ionization chambers were tested using an intense electron beam from the accelerator test facility (ATF) at the Brookhaven National Laboratory (BNL). The detectors were designed to be used as the basic element for monitoring muons in the Main Injector Neutrino beamline (NuMI) at the Fermi National Accelerator Laboratory (FNAL). Measurements of linearity of response, voltage depend...

 Abstract—Imaging in the presence of prosthetic implants presents a notoriously difficult challenge to CT reconstrucion. Such hardware is made of alloys that are highly attenuating (e.g., Co-Cr-Mo) and impart severe degradation in image quality due to photon starvation, beam hardening, etc. An important clinical example is in the proliferation of total knee replacement, increasing the need for...