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Infiltration Heat Recovery in Building Walls: Computational Fluid Dynamics Investigations Results
Conventional calculations of heating (and cooling) loads for buildings assume that conduction heat loss (or gain) through walls is independent of air infiltration heat loss (or gain). During passage through the building envelope, infiltrating air substantially exchanges heat wall insulation leading to partial recovery of heat conducted through the wall. The Infiltration Heat Recovery (IHR) factor was introduced to quantify the heat recovery and correct the conventional calculations. In this study, Computational Fluid Dynamics was used to calculate infiltration heat recovery under a range of idealized conditions, specifically to understand factors that influence it, and assess its significance in building heat load calculations. This study shows for the first time the important effect of the external boundary layers on conduction and infiltration heat loads. Results show (under the idealized conditions studied here) that (1) the interior details of the wall encountered in the leakage pa th (i.e., insulated or empty walls) do not greatly influence the IHR, the overall relative location of the cracks (i.e., inlet and outlet locations on the wall) has the largest influence on the IHR magnitude, (2) external boundary layers on the walls substantially contribute to IHR and (3) the relative error in heat load calculations …
Date:
August 5, 2002
Creator:
Abadie, Marc O.; Finlayson, Elizabeth U. & Gadgil, Ashok J.
Object Type:
Report
System:
The UNT Digital Library
Neutral Kaon Interferometry in Au+Au collisions at sqrt(s_NN) =200 GeV
We present the first statistically meaningful results fromtwo-K0s interferometry in heavy-ion collisions. A model that takes theeffect of the strong interaction into account has been used to fit themeasured correlation function. The effects of single and coupled channelwere explored. At the mean transverse mass m_T = 1.07 GeV, we obtain thevalues R = 4.09 +- 0.46 (stat.) +- 0.31 (sys) fm and lambda = 0.92 +-0.23 (stat) +- 0.13 (sys), where R and lambda are the invariant radiusand chaoticity parameters respectively. The results are qualitativelyconsistent with m_T systematics established with pions in a scenariocharacterized by a strong collective flow.
Date:
August 5, 2006
Creator:
Abelev, B. I.; Adams, J.; Aggarwal, M. M.; Ahammed, Z.; Amonett, J.; Anderson, B. D. et al.
Object Type:
Article
System:
The UNT Digital Library
Seeing the Nature of the Accelerating Physics: It's a SNAP
For true insight into the nature of dark energy, measurements of the precision and accuracy of the Supernova/Acceleration Probe (SNAP) are required. Precursor or scaled-down experiments are unavoidably limited, even for distinguishing the cosmological constant. They can pave the way for, but should not delay, SNAP by developing calibration, refinement, and systematics control (and they will also provide important, exciting astrophysics).
Date:
August 5, 2005
Creator:
Albert, J.; Aldering, G.; Allam, S.; Althouse, W.; Amanullah, R.; Annis, J. et al.
Object Type:
Report
System:
The UNT Digital Library
A Metadata Approach to Preservation of Digital Resources: The University of North Texas Libraries' Experience
Article discussing metadata approaches to preservation of digital resources and the experiences of the University of North Texas (UNT) Libraries.
Date:
August 5, 2002
Creator:
Alemneh, Daniel Gelaw; Hastings, Samantha Kelly & Hartman, Cathy Nelson
Object Type:
Article
System:
The UNT Digital Library
The SPARX Project: R & D Activity Towards X-Rays FEL Sources
SPARX is an evolutionary project proposed by a collaboration among ENEA-INFN-CNR-Universita di Roma Tor Vergata aiming at the construction of a FELSASE X-ray source in the Tor Vergata Campus. The first phase of the SPARX project, funded by Government Agencies, will be focused on R&D activity on critical components and techniques for future X-ray facilities as described in this paper.
Date:
August 5, 2005
Creator:
Alesini, D.; Bellaveglia, M.; Bertolucci, S.; Biagini, M. E.; Boni, R.; Boscolo, M. et al.
Object Type:
Article
System:
The UNT Digital Library
Timpson & Tenaha News (Timpson, Tex.), Vol. 19, No. 30, Ed. 1 Thursday, August 5, 2004
Weekly newspaper from Timpson, Texas that includes local, state, and national news along with advertising.
Date:
August 5, 2004
Creator:
Alexander, Nancy
Object Type:
Newspaper
System:
The Portal to Texas History
Low Mach Number Modeling of Type Ia Supernovae
We introduce a low Mach number equation set for the large-scale numerical simulation of carbon-oxygen white dwarfs experiencing a thermonuclear deflagration. Since most of the interesting physics in a Type Ia supernova transpires at Mach numbers from 0.01 to 0.1, such an approach enables both a considerable increase in accuracy and savings in computer time compared with frequently used compressible codes. Our equation set is derived from the fully compressible equations using low Mach number asymptotics, but without any restriction on the size of perturbations in density or temperature. Comparisons with simulations that use the fully compressible equations validate the low Mach number model in regimes where both are applicable. Comparisons to simulations based on the more traditional an elastic approximation also demonstrate the agreement of these models in the regime for which the anelastic approximation is valid. For low Mach number flows with potentially finite amplitude variations in density and temperature, the low Mach number model overcomes the limitations of each of the more traditional models and can serve as the basis for an accurate and efficient simulation tool.
Date:
August 5, 2005
Creator:
Almgren, Ann S.; Bell, John B.; Rendleman, Charles A. & Zingale,Michael
Object Type:
Article
System:
The UNT Digital Library
Accretion onto the first stellar mass black holes
The first stars, forming at redshifts z > 15 in minihalos with M {approx} 10{sup 5-6} M{sub {circle_dot}} may leave behind remnant black holes, which could conceivably have been the 'seeds' for the supermassive black holes observed at z {approx}< 7. We study remnant black hole growth through accretion, including for the first time the radiation emitted due to accretion, with adaptive mesh refinement cosmological radiation-hydrodynamical simulations. The effects of photo-ionization and heating dramatically affect the large-scale inflow, resulting in negligible mass growth. We compare cases with accretion luminosity included and neglected to show that accretion radiation drastically changes the environment within 100 pc of the black hole, increasing gas temperatures by an order of magnitude. Gas densities are reduced and further star formation in the same minihalo is prevented for the two hundred million years we followed. Without radiative feedback included most seed black holes do not gain mass as efficiently as has been hoped for in previous theories, implying that black hole remnants of Pop III stars in minihalos are not likely to be miniquasars. Most importantly, however, our calculations demonstrate that if these black holes are indeed accreting close to the Bondi-Hoyle rate with ten percent radiative …
Date:
August 5, 2009
Creator:
Alvarez, Marcelo A.; Wise, John H. & Abel, Tom
Object Type:
Article
System:
The UNT Digital Library
Secret Sessions of Congress: A Brief Historical Overview
None
Date:
August 5, 2003
Creator:
Amer, Mildred L.
Object Type:
Report
System:
The UNT Digital Library
Through Weld Inspection of Wrought Stainless Steel Piping Using Phased-Array Ultrasonic Probes.
A study was conducted to assess the ability of phased-array ultrasonic techniques to detect and accurately determine the size of flaws from the far-side of wrought austenitic piping welds. Far-side inspections of these welds are currently performed on a “best effort” basis and do not conform to ASME Code Section XI Appendix VIII performance demonstration requirements. For this study, four circumferential welds in 610mm diameter, 36mm thick ASTM A-358, Grade 304 vintage austenitic stainless steel pipe were examined. The welds were fabricated with varied welding parameters; both horizontal and vertical pipe orientations were used, with air and water backing, to simulate field welding conditions. A series of saw cuts, electro-discharge machined (EDM) notches, and implanted fatigue cracks were placed into the heat affected zones of the welds. The saw cuts and notches range in depth from 7.5% to 28.4% through-wall. The implanted cracks ranged in depth from 5% through wall to 64% through wall. The welds were examined with two phased-array probes, a 2.0 MHz transmit-receive longitudinal wave array and a 2.0 MHz transmit-receive shear wave array. These examinations showed that both phased-array transducers were able to detect and accurately length-size, but not depth size, all of the notches and …
Date:
August 5, 2004
Creator:
Anderson, Michael T.; Cumblidge, Stephen E. & Doctor, Steven R.
Object Type:
Article
System:
The UNT Digital Library
Altus Times (Altus, Okla.), Vol. 106, No. 108, Ed. 1 Thursday, August 5, 2004
Daily newspaper from Altus, Oklahoma that includes local, state, and national news along with advertising.
Date:
August 5, 2004
Creator:
Andrews, Mike
Object Type:
Newspaper
System:
The Gateway to Oklahoma History
Altus Times (Altus, Okla.), Vol. 107, No. 107, Ed. 1 Friday, August 5, 2005
Daily newspaper from Altus, Oklahoma that includes local, state, and national news along with advertising.
Date:
August 5, 2005
Creator:
Andrews, Mike
Object Type:
Newspaper
System:
The Gateway to Oklahoma History
Decanting of Neutralized H-Canyon Unirradiated Nuclear Material High Activity Waste Streams
An option to dispose of the High Activity Waste (HAW) stream from the processing of unirradiated materials directly to Saltstone is being evaluated to conserve High Level Waste (HLW) tank farm space and to reduce the future production of HLW glass logs. To meet the Saltstone Waste Acceptance Criteria (WAC), decanting the supernate from precipitated solids was proposed to reduce mercury and radionuclide levels in the waste. Only the caustic supernate will then be sent to Saltstone. Verification that the Saltstone WAC will be met has involved a series of laboratory studies using surrogate and actual HAW solutions from H-Canyon. The initial experiment involved addition of sodium hydroxide (NaOH) to a surrogate HAW test solution and subsequent decanting of the supernate away from the precipitated solids. The chemical composition of the surrogate solution was based on a composition defined from analyses of actual HAW solutions generated during dissolution of unirradiated nuclear materials in H-Canyon [1]. Results from testing the surrogate HAW solution were reported in Reference [2]. Information obtained from the surrogate test solution study was used to define additional experiments on actual HAW solutions obtained from H-Canyon. These experiments were conducted with samples from three different batches of HAW …
Date:
August 5, 2004
Creator:
BRONIKOWSKI, MICHAELG.
Object Type:
Report
System:
The UNT Digital Library
A Model for the Behavior of Magnetic Tunnel Junctions
A magnetic tunnel junction is a device that changes its electrical resistance with a change in an applied magnetic field. A typical junction consists of two magnetic electrodes separated by a nonmagnetic insulating layer. The magnetizations of the two electrodes can have two possible extreme configurations, parallel and antiparallel. The antiparallel configuration is observed to have the higher measured resistance and the parallel configuration has the lower resistance. To switch between these two configurations a magnetic field is applied to the device which is primarily used to change the orientation of the magnetization of one electrode usually called the free layer, although with sufficient high magnetic field the orientation of the magnetizations of both of the electrodes can be changed. The most commonly used models for describing and explaining the electronic behavior of tunnel junctions are the Simmons model and the Brinkman model. However, both of these models were designed for simple, spin independent tunneling. The Simmons model does not address the issue of applied magnetic fields nor does it address the form of the electronic band structure in the metallic electrodes, including the important factor of spin polarization. The Brinkman model is similar, the main difference between the two …
Date:
August 5, 2003
Creator:
Baker, Bryan John
Object Type:
Thesis or Dissertation
System:
The UNT Digital Library
Investigations of the Electronic Properties and Surface Structures of Aluminium-Rich Quasicrystalline Alloys
The work presented in this dissertation has investigated three distinct areas of interest in the field of quasicrystals: bulk structure, transport properties, and electronic structure. First, they have described the results of a study which explored the fundamental interactions between the atomic species of the icosahedral Al-Pd-Mn quasicrystal. The goal of this work was to determine whether the pseudo-MacKay or Bergman type clusters have a special stability or are merely a geometric coincidence. This was carried out by using laser vaporization to produce gas-phase metal clusters, which were analyzed using time-of-flight mass spectrometry. Both the kinetic and thermodynamic stabilities of the clusters were probed. The data indicated no special stability for either pseudo-MacKay or Bergman type clusters as isolated units. This, however, is not proof that these clusters are simply a geometric coincidence. It is possible that such clusters only have stability in the framework of the bulk matrix and do not exist as isolated units. Next, they have reported their investigations of the bulk thermal transport properties of a decagonal Al-Ni-Co two dimensional quasicrystal in the temperature range 373K-873K. The properties of a sample oriented along the periodic axis and another oriented along the aperiodic axis were measured. A …
Date:
August 5, 2003
Creator:
Barrow, Jason A.
Object Type:
Thesis or Dissertation
System:
The UNT Digital Library
The Grandview Tribune (Grandview, Tex.), Vol. 110, No. 47, Ed. 1 Friday, August 5, 2005
Weekly newspaper from Grandview, Texas that includes local, state, and national news along with advertising.
Date:
August 5, 2005
Creator:
Beck-Adams, Candie
Object Type:
Newspaper
System:
The Portal to Texas History
Intelligent Control via Wireless Sensor Networks for Advanced Coal Combustion Systems
Numerical Modeling of Solid Gas Flow, System Identification for purposes of modeling and control, and Wireless Sensor and Actor Network design were pursued as part of this project. Time series input-output data was obtained from NETL's Morgantown CFB facility courtesy of Dr. Lawrence Shadle. It was run through a nonlinear kernel estimator and nonparametric models were obtained for the system. Linear and first-order nonlinear kernels were then utilized to obtain a state-space description of the system. Neural networks were trained that performed better at capturing the plant dynamics. It is possible to use these networks to find a plant model and the inversion of this model can be used to control the system. These models allow one to compare with physics based models whose parameters can then be determined by comparing them against the available data based model. On a parallel track, Dr. Kumar designed an energy-efficient and reliable transport protocol for wireless sensor and actor networks, where the sensors could be different types of wireless sensors used in CFB based coal combustion systems and actors are more powerful wireless nodes to set up a communication network while avoiding the data congestion. Dr. Ahmadi's group studied gas solid flow in …
Date:
August 5, 2007
Creator:
Behal, Aman; Kumar, Sunil & Ahmadi, Goodarz
Object Type:
Report
System:
The UNT Digital Library
Fort Davis, back of enlisted mens barracks
Photograph of the back of the enlisted mens' barracks at Fort Davis. There is a small staircase leading up to the long porch.
Date:
August 5, 2005
Creator:
Belden, Dreanna L.
Object Type:
Photograph
System:
The Portal to Texas History
Fort Davis, Commanding Officer's Quarters
Photograph of the Commanding Officer's Quarters at Fort Davis. The building is made of red brick, and has a large front porch. Identical buildings are visible to the left and right of the officer's quarters.
Date:
August 5, 2005
Creator:
Belden, Dreanna L.
Object Type:
Photograph
System:
The Portal to Texas History
Fort Davis, Commanding Officer's Quarters
Photograph of a plaque outside the Commanding Officer's Quarters. It says: "Commanding Officer's Quarters: This building served as the residence for the commanding officer. Construction of the house began in 1867 under the direction of Lieutenant Colonel Wesley Merritt, who was the first to move in and call it "home". Today it is furnished to the time when Colonel Benjamin H. Grierson, commander of the black Tenth U.S.Cavalry, and his family lived here, 1882-1885."
Date:
August 5, 2005
Creator:
Belden, Dreanna L.
Object Type:
Photograph
System:
The Portal to Texas History
Fort Davis, Commanding Officer's Quarters cistern
Photograph of the Commanding Officer's Quarters cistern at Fort Davis. The cistern is empty and roped off, and there is a sign with the word "cistern" placed in the middle of the roped off area.
Date:
August 5, 2005
Creator:
Belden, Dreanna L.
Object Type:
Photograph
System:
The Portal to Texas History
Fort Davis, Commanding Officer's Quarters, view of back porch and Post Hospital
Photograph of the back porch and Post Hospital at the Commanding Officer's Quarters in Fort Davis. The building is made of red brick, and the windows have green shutters. Another building is visible in the background, in front of a steep, rocky hill.
Date:
August 5, 2005
Creator:
Belden, Dreanna L.
Object Type:
Photograph
System:
The Portal to Texas History
Fort Davis, Commanding Officer's Quarters, view through front door
Photograph of the Commanding Officer's Quarters at Fort Davis, viewed through the front door. The back door is open as well. The inside of the building is dark.
Date:
August 5, 2005
Creator:
Belden, Dreanna L.
Object Type:
Photograph
System:
The Portal to Texas History
Fort Davis, Commissary
Photograph of the front and side of the Commissary at Fort Davis. It is a red adobe building with a front porch, several windows, and a second door on the side of the building. The rocky ridge of a mountain is visible behind the building.
Date:
August 5, 2005
Creator:
Belden, Dreanna L.
Object Type:
Photograph
System:
The Portal to Texas History