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Full-Text Articles in Mechanical Engineering

High Temperature Heat Exchanger Annual Report, Anthony Hechanova Sep 2008

High Temperature Heat Exchanger Annual Report, Anthony Hechanova

Publications (NSTD)

Objectives

• Identify candidate materials for heat exchanger components.

• Test candidate materials for heat exchanger components.

• Design critical components in the interface between the reactor and hydrogen production plant and within the sulfur iodine thermochemical process.

• Fabricate prototypical components.

• Test prototypical components.


Knowledge-Based Information Resource Management System For Materials Of Sodium-Cooled Fast Reactor, Sean Hsieh Jan 2008

Knowledge-Based Information Resource Management System For Materials Of Sodium-Cooled Fast Reactor, Sean Hsieh

Reactor Campaign (TRP)

In the development of advanced fast reactors, materials and coolant/material interactions pose a critical barrier for higher temperature and longer core life designs. For advanced burner reactors (sodium cooled) such as EBR-II and FFTF, experience has shown that the qualified structural materials and fuel cladding severely limits the economic performance. In other liquid metal cooled reactor concepts, advanced materials and better understanding and control of coolant and materials interactions are necessary for realizing the potentials.

Liquid sodium has been selected as the primary coolant candidate for Gen. IV nuclear energy systems. Global Nuclear Partnership (GNEP) Advanced Burned Reactor (ABR ...


Correlation Of Tellurium Inclusions And Carrier Lifetime In Detector Grade Cadmium Zinc Telluride, Ezzat S. Elshazly, Gary C. Tepper Jan 2008

Correlation Of Tellurium Inclusions And Carrier Lifetime In Detector Grade Cadmium Zinc Telluride, Ezzat S. Elshazly, Gary C. Tepper

Mechanical and Nuclear Engineering Publications

Carrier lifetimes and telluriuminclusion densities in detector grade cadmiumzinc telluride crystals grown by the high pressure Bridgman method were optically measured using pulsed laser microwavecavity perturbation and infrared microscopy. Excess carriers were produced in the material using a pulsed laser with a wavelength of 1064 nm and pulse width of 7 ns, and the electronic decay was measured at room temperature. Spatial mapping of lifetimes and defect densities in cadmiumzinc telluride was performed to determine the relationship between telluriumdefect density and trapping. A strong correlation was found between the volume fraction of telluriuminclusions and the carrier trapping time.


Electrokinetic Separation Of Co-Solutes Into Bimodal Fibers By Electrospinning, Chunya Wu, Shinobu Nagata, Gary C. Tepper, James T. Mcleskey Jr. Jan 2008

Electrokinetic Separation Of Co-Solutes Into Bimodal Fibers By Electrospinning, Chunya Wu, Shinobu Nagata, Gary C. Tepper, James T. Mcleskey Jr.

Mechanical and Nuclear Engineering Publications

Composite and chemically/physically distinct fibers of sodium poly[2-(3-thienyl)-ethoxy-4-butylsulfonate] (PTEBS) and polyethylene oxide (PEO) were formed by electrospinning from a homogeneous aqueous solution containing PTEBS and PEO co-solutes. Composite nanofibers of diameter of ∼60nm were electrospun from an aqueous solution. The addition of ammonium hydroxide (NH4OH) to the water solution resulted in “bimodal” electrospun fibers consisting of distinct large diameter white PEO fiber segments and small diameter black PTEBS fiber segments. The optical absorptionspectrum of the composite PTEBS/PEO nanofibers did not exhibit the characteristic peak around 460nm, which is present in the bulk spectrum.


The Dissipated Power In Atomic Force Microscopy Due To Interactions With A Capillary Fluid Layer, Nicole N. Hashemi, M.R. Paul, H. Dankowicz, W. Jhe Jan 2008

The Dissipated Power In Atomic Force Microscopy Due To Interactions With A Capillary Fluid Layer, Nicole N. Hashemi, M.R. Paul, H. Dankowicz, W. Jhe

Nastaran Hashemi

We study the power dissipated by the tip of an oscillating micron-scale cantilever as it interacts with a sample using a nonlinear model of the tip-surface force interactions that includes attractive, adhesive, repulsive, and capillary contributions. The force interactions of the model are entirely conservative and the dissipated power is due to the hysteretic nature of the interaction with the capillary fluid layer. Using numerical techniques tailored for nonlinear and discontinuous dynamical systems we compute the exact dissipated power over a range of experimentally relevant conditions. This is accomplished by computing precisely the fraction of oscillations that break the fluid ...


The Nonlinear Dynamics Of Tapping Mode Atomic Force Microscopy With Capillary Force Interactions, Nicole N. Hashemi, H. Dankowicz, M.R. Paul Jan 2008

The Nonlinear Dynamics Of Tapping Mode Atomic Force Microscopy With Capillary Force Interactions, Nicole N. Hashemi, H. Dankowicz, M.R. Paul

Nastaran Hashemi

We study the nonlinear dynamics of a tapping mode atomic force microscope with tip-surface interactions that include attractive, repulsive, and capillary force contributions using numerical techniques tailored for hybrid or discontinuous dynamical systems that include forward-time simulation with event handling and numerical pseudo-arclength continuation. We find four branches of periodic solutions that are separated by windows of complex and irregular dynamics. The branches of periodic solutions end where the cantilever comes into grazing contact with event surfaces in state space, corresponding to the onset of capillary interactions and the onset of repulsive forces associated with contact. These windows of irregular ...


Modeling And Design Algorithms For Electromagnetic Pumps, Daniel P. Cook, Yitung Chen, Jian Ma Jan 2008

Modeling And Design Algorithms For Electromagnetic Pumps, Daniel P. Cook, Yitung Chen, Jian Ma

Reactor Campaign (TRP)

Electromagnetic (EM) induction pumps are used extensively in current and proposed nuclear power systems and industrial molten metal transfer operations. Although the Magnetohydrodynamic (MHD) theory that underlies the operation of these types of pumps has been studied extensively in the past few decades, the design of specific EM pumping systems for specific flow cases requires computational tools and expertise, which is lacking in the U.S. However, for the past two years, researchers at UNLV have been utilizing the TC-1 liquid metal loop system at UNLV and an Annular Linear Induction Pump (ALIP) to drive the liquid metal and to ...


Thermal Transient Flow Rate Sensor For High Temperature Liquid Metal Cooled Nuclear Reactor, Yingtao Jiang, Jian Ma Jan 2008

Thermal Transient Flow Rate Sensor For High Temperature Liquid Metal Cooled Nuclear Reactor, Yingtao Jiang, Jian Ma

Reactor Campaign (TRP)

In nuclear power plants and accelerator driven systems (ADS) for nuclear waste treatment, it is important to monitor the coolant flow rate in the reactor core and pipe-line. In such a strong irradiation, high pressure, and temperature environment, the existing flow measurement techniques (such as Electromagnetic flow meters, Ultrasonic flow meters, Turbine flow meters, etc.) are not accurate and reliable.

The measurement of flow rates (mass flow rates or volume flow rate) plays a notable role in monitoring and controlling the experimental conditions. The bulk flow rates can be obtained through direct methods, which measure the amount of discharged fluids ...


Knowledge-Based Information Resource Management System For Materials Of Sodium-Cooled Fast Reactor, Sean Hsieh Jan 2008

Knowledge-Based Information Resource Management System For Materials Of Sodium-Cooled Fast Reactor, Sean Hsieh

Reactor Campaign (TRP)

In the development of advanced fast reactors, materials and coolant/ material interactions pose a critical barrier for higher temperature and longer core life designs. For sodium-cooled fast reactors (SFRs) such as the Experimental Breeder Reactors in Idaho and the Fast Flux Test Facility in Hanford, experience has shown that qualified structural materials and fuel cladding severely limits their economic performance.

Liquid sodium has been selected as the primary coolant candidate for the Advanced Burner Reactor (ABR) of the Global Nuclear Partnership (GNEP). Materials improvement has been identified as a major thrust to improve fast reactor economics. Researchers from universities, national ...