We investigated the feasibility of designing an Anger-logic PET detector module using large-area high-gain avalanche photodiodes (APDs) for a brain-dedicated PET/MRI system. Using Monte Carlo simulations, we systematically optimized the detector design with regard to the scintillation crystal, optical diffuser, surface treatment, layout of large-area APDs, and signal-to-noise ratio (SNR, define...

This paper uses airflow modeling and particle-tracking methodologies to compare the risk of contaminant deposition on an operating room (OR) surgical site and back table for different ventilation systems. The ventilation system designs considered incorporated commonly used diffuser types, in particular, conventional, laminar, nonaspirating, and displacement diffuser types. Further, a range of d...

This study presents a thermodynamic model for determining the entrainment ratio and double choke limiting pressure of supersonic ejectors within the context of heat driven refrigeration cycles, with and without droplet injection, at the constant area section of the device. Input data include the inlet operating conditions and key geometry parameters (primary throat, mixing section and diffuser ...

Most multi-phase pumps used in crude oil production have been developed to satisfy certain pressure specifications. In the design of these pumps, the flow characteristics of the posterior stage are different from those of the prior stage. For this reason, the design of the second stage needs to be supplemented. To optimize performance in this stage, multi-objective optimization to simultaneousl...

A variety of different types of actuators have been previously investigated as flow control devices. Potential applications include the control of boundary layer separation in external flows, as well as jet engine inlet and diffuser flow control. The operating principles for such devices are typically based on either mechanical deflection of control surfaces (which include MEMS flap devices), m...

Measurements of the time-varying flow in a centrifugal blood pump operating as a left ventricular assist device (LVAD) are presented. This includes changes in both the pump flow rate as a function of the left ventricle contraction and the interaction of the rotating impeller and fixed exit volute. When operating with a pulsing ventricle, the flow rate through the LVAD varies from 0-11 L/min dur...

Coupling model for two-dimensional mixed-compression supersonic inlet with Mach number of 2.5 at design point and pulse detonation combustor was established, three working schemes were designed to investigate multi cycle process by using unsteady numerical simulation chemical reaction. The results show that the following two measurements can both restrain back-propagating compression wave broad...

Rapid changes in the performance-related parameters of a pump during its startup operation lead to large pressure fluctuations and structural vibrations it. In view these problems, this study investigates evolution cavitation characteristics under centrifugal startup. We use finite volume method simulate dynamic process. To characterize acceleration, we assume that rotational speed rate flow ar...

The radiometric calibration for the reflective solar bands (RSB) of the Visible Infrared Imaging Radiometer Suite (VIIRS) on board the Suomi National Polar-orbiting Partnership (SNPP) platform has reached a mature stage after four years since its launch. The characterization of the vignetting effect of the attenuation screens, the bidirectional reflectance factor of the solar diffuser, the degr...

We develop a reduced order model for large-scale unsteadiness (vortex shedding) in a two-dimensional diffuser and study the mechanisms of active flow separation control. This model can estimate the vortex shedding frequency for inviscid flows by accounting for the accumulated vorticity flux in the diffuser. The model can also predict the stagnation pressure loss, which consists of two parts: A ...