Development of Continuous, Direct Feedback Control Systems for Sintering of Metallic Components (open access)

Development of Continuous, Direct Feedback Control Systems for Sintering of Metallic Components

N,N.-Ethylenebisstearimide (EBS) is one of the most commonlyused lubricants in the powder metallurgy (PM) industry in the sintering process. During sintering, the lubricated powder compacts are heat-treated to temperatures in excess of 1,200 °C thus fusing adjacent particles and yielding a part with improved mechanical strength. Delubrication commonly is achieved in the first zone of a sintering furnace by heating the part to temperatures in the 500-600 °C temperature range at a fixed rate and under controlled atmospheric conditions; this strategy minimizes defects, carbon contamination, and compact deformation. The de-lubricated part then enters the second zone (commonly in the 1200-1300 °C temperature range) for sintering. The third zone cools the sintered part at a desired rate to obtain the requisite micro-structural properties. Controlled delubrication is imperative towards achieving high quality parts for the following reasons: the elevated thermal gradient at the transition between the first and second zones can cause parts to expand rapidly and develop microscopic fissures (.blistering.); improper gas flows and belt speeds can lead to carbon deposition on the part and at the grain boundaries (sooting); delubrication products deposit throughout the furnace, even in the coolers, which are far removed from the preheating chamber, leading to significant …
Date: September 18, 2006
Creator: Apelian, Diran & Baum, Marc M.
Object Type: Report
System: The UNT Digital Library
SEY and Surface Analysis Measurements on FNAL Main Injector Ring S/S Beam Chamber Material (open access)

SEY and Surface Analysis Measurements on FNAL Main Injector Ring S/S Beam Chamber Material

Material was provided by Dr. Weiren Chou, FNAL. Both mildly-activated used, and new sections of stainless steel (type 316L) beam chamber were measured. Centimeter-sized coupons were cleanly dry-cut from the large flat surface (called ''flat side'' in the plots) and from the ID end (inside diameter of the ring, in the case of the used material) and narrow end (in the case of the new material). The unused material was ultra-soniced in acetone (to remove storage residue), then rinsed with ethanol and blown dry with filtered N{sub 2}-gas, to simulate new chamber installation final rinse. Used material was installed, as cut. Surface chemistry was measured using x-ray photoelectron spectroscopy (sometimes called ''ESCA''). With this technique, soft x-rays (1486 eV) illuminate the sample, penetrating into the surface ten microns. Photoelectrons are generated from energy levels of the constituent compounds/elements present. Those electrons, within 5 nm or so of the surface, escape without energy loss and preserve valence information about the atomic levels from which they were generated. An electron energy analyzer, of good energy resolution, measures the photoelectron energy, thereby yielding both valence (chemical) information and relative atomic abundances in the top 5 nm of surface. Using appropriate sensitivity factors, these …
Date: September 18, 2006
Creator: Kirby, Robert E.
Object Type: Report
System: The UNT Digital Library
Data Analysis for Infiltration Modeling: Techical Evaluation of Previous Soil Depth Estimation Methods and Develoment of Aternate Parameter Values (open access)

Data Analysis for Infiltration Modeling: Techical Evaluation of Previous Soil Depth Estimation Methods and Develoment of Aternate Parameter Values

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Date: September 18, 2006
Creator: Rehfeldt, K.
Object Type: Report
System: The UNT Digital Library
PSA-Based Screening Outcomes, Dietary Heterocyclic Amine Exposure, and Prostate Cancer Risk in African Americans: Annual Report (Year 1 of 3) (open access)

PSA-Based Screening Outcomes, Dietary Heterocyclic Amine Exposure, and Prostate Cancer Risk in African Americans: Annual Report (Year 1 of 3)

Prostate cancer (PC) is the second leading cause of male U.S. cancer deaths, with African-Americans having the highest rate of PC mortality worldwide, as well as more abnormal results from screening tests that correlate with current or eventual PC. A 3-year prospective clinic-based study is studying the performance of current (PSA and DRE) vs. (% free PSA) clinical biomarkers of PC risk in 400 African-American men 50 to 70 years of age who undergo PC screening in Oakland, CA (East Bay San Francisco area), as well as possible association of PC screening results for these men with their dietary exposures to the cancer-causing heterocyclic amine, 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) that forms when meat is cooked. This study expands an ongoing NIH-funded study (by the same research team) to add a new %-free-PSA test, results of which will be compared with PSA/DRE results and PhIP exposures estimated by dietary interviews. For 392 men studied under the NIH protocol, an odds ratio (95% CL) of 32 (3.2, 720) for highly elevated PSA ({ge}20 ng/mL) was observed in the highest 15% vs. the lower 50% of estimated daily PhIP intakes. Approximately 100 additional men have completed participation in the expanded NIH/DOD-supported study. This study will …
Date: January 18, 2006
Creator: Bogen, K T
Object Type: Report
System: The UNT Digital Library
A Computational Approach to Understanding Aerosol Formation and Oxidant Chemistry in the Troposphere (open access)

A Computational Approach to Understanding Aerosol Formation and Oxidant Chemistry in the Troposphere

An understanding of the mechanisms and kinetics of aerosol formation and ozone production in the troposphere is currently a high priority because these phenomena are recognized as two major effects of energy-related air pollution. Atmospheric aerosols are of concern because of their effect on visibility, climate, and human health. Equally important, aerosols can change the chemistry of the atmosphere, in dramatic fashion, by providing new chemical pathways (in the condensed phase) unavailable in the gas phase. The oxidation of volatile organic compounds (VOCs) and inorganic compounds (e.g., sulfuric acid, ammonia, nitric acid, ions, and mineral) can produce precursor molecules that act as nucleation seeds. The U.S. Department of Energy (DOE) Atmospheric Chemistry Program (ACP) has identified the need to evaluate the causes of variations in tropospheric aerosol chemical composition and concentrations, including determining the sources of aerosol particles and the fraction of such that are of primary and secondary origin. In particular, the ACP has called for a deeper understanding into aerosol formation because nucleation creates substantial concentrations of fresh particles that, via growth and coagulation, influence the Earth's radiation budget. Tropospheric ozone is also of concern primarily because of its impact on human health. Ozone levels are controlled by …
Date: April 18, 2006
Creator: Francisco, Joseph S.; Kathmann, Shawn M.; Schenter, Gregory K.; Dang, Liem X.; Xantheas, Sotiris S.; Garrett, Bruce C. et al.
Object Type: Report
System: The UNT Digital Library
A Study of Xi_c(2980)^+ and Xi_c(3077)^+ (open access)

A Study of Xi_c(2980)^+ and Xi_c(3077)^+

We present a study of two states decaying to {Lambda}{sub c}{sup +} K{sup -} {pi}{sup +} using the BABAR detector at the SLAC PEP-II asymmetric-energy e{sup +}e{sup -} storage rings. We use an integrated luminosity of 288.5 fb{sup -1} collected at the center-of-mass energy {radical}s = 10.58 GeV, near the peak of the {Upsilon}(4S) resonance, plus 27.2 fb{sup -1} collected approximately 40MeV below this energy. We search for the particles {Xi}{sub c}(2980){sup +} and {Xi}{sub c}(3077){sup +}, recently discovered by the Belle Collaboration, in their decays to {Lambda}{sub c}{sup +}K{sup -}{pi}{sup +}, where {Lambda}{sub c}{sup +} {yields} pK{sup -}{pi}{sup +}. We find a signal with 7.0{sigma} significance for the {Xi}{sub c}(2980){sup +} state with a mass difference with respect to the {Lambda}{sub c}{sup +} of (680.6 {+-} 1.9 {+-} 1.0)MeV/c{sup 2} (first error is statistical and second error is systematic). The measured width for this state is (23.6 {+-} 2.8 {+-} 1.3)MeV, and the yield is 284 {+-} 45 {+-} 46 events. We find a signal with 8.6{sigma} significance for the {Xi}{sub c}(3077){sup +} state with a mass difference with respect to the {Lambda}{sub c}{sup +} of (790.0 {+-} 0.7 {+-} 0.2) MeV/c{sup 2}, a width of (6.2 {+-} 1.6 …
Date: August 18, 2006
Creator: Aubert, B.
Object Type: Article
System: The UNT Digital Library
HANFORD SITE RIVER PROTECTION PROJECT (RPP) TRANSURANIC (TRU) TANK WASTE IDENTIFICATION & PLANNING FOR REVRIEVAL TREATMENT & EVENTUAL DISPOSAL AT WIPP (open access)

HANFORD SITE RIVER PROTECTION PROJECT (RPP) TRANSURANIC (TRU) TANK WASTE IDENTIFICATION & PLANNING FOR REVRIEVAL TREATMENT & EVENTUAL DISPOSAL AT WIPP

The CH2M HILL Manford Group, Inc. (CHG) conducts business to achieve the goals of the Office of River Protection (ORP) at Hanford. As an employee owned company, CHG employees have a strong motivation to develop innovative solutions to enhance project and company performance while ensuring protection of human health and the environment. CHG is responsible to manage and perform work required to safely store, enhance readiness for waste feed delivery, and prepare for treated waste receipts for the approximately 53 million gallons of legacy mixed radioactive waste currently at the Hanford Site tank farms. Safety and environmental awareness is integrated into all activities and work is accomplished in a manner that achieves high levels of quality while protecting the environment and the safety and health of workers and the public. This paper focuses on the innovative strategy to identify, retrieve, treat, and dispose of Hanford Transuranic (TRU) tank waste at the Waste Isolation Pilot Plant (WIPP).
Date: January 18, 2006
Creator: Kristofzski, John G.; Tedeschi, A. R.; Johnson, M. E.; Jennings, M. J. & Clark, D. L.
Object Type: Article
System: The UNT Digital Library