424 Matching Results

Search Results

Advanced search parameters have been applied.

Automatic Dilution Gaging of Rapidly Varying Flow

Description: From introduction: The purpose of this report is to develop and evaluate a method to automate the constant-rate-injection technique, described by Cobb and Bailey, with sufficient accuracy and reliability to determine discharge in storm sewers under rapidly varying flow conditions.
Date: October 1983
Creator: Duerk, Marvin D.
Partner: UNT Libraries Government Documents Department

Small-orifice tubes for minimizing dilution in exhaust-gas samples

Description: Report presenting an investigation to find a means of obtaining undiluted exhaust-gas samples from a Wright R-2600-B aircraft engine equipped with short individual stacks. Preliminary tests to aid in determining the best design, location, and orientation of orifices ranging in size. Results regarding the Briggs & Stratton engine tests and Wright aircraft engine tests are provided.
Date: February 1943
Creator: Cook, Harvey A. & Olson, Walter T.
Partner: UNT Libraries Government Documents Department

Derivation of Equivalent Continuous Dilution for Cyclic, Unsteady Driving Forces

Description: This article uses an analytical approach to determine the dilution of an unsteadily-generated solute in an unsteady solvent stream, under cyclic temporal boundary conditions. The goal is to find a simplified way of showing equivalence of such a process to a reference case where equivalent dilution is defined as a weighted average concentration. This derivation has direct applications to the ventilation of indoor spaces where indoor air quality and energy consumption cannot in general be simultaneously optimized. By solving the equation we can specify how much air we need to use in one ventilation pattern compared to another to obtain same indoor air quality. Because energy consumption is related to the amount of air exchanged by a ventilation system, the equation can be used as a first step to evaluate different ventilation patterns effect on the energy consumption. The use of the derived equation is demonstrated by representative cases of interest in both residential and non-residential buildings.
Date: December 15, 2010
Creator: Laboratory, Lawrence Berkeley National; Technical University of Denmark, Department of Civil Engineering; Mortensen, Dorthe K.; Walker, Iain S. & Sherman, Max H.
Partner: UNT Libraries Government Documents Department

HB-Line Dissolver Dilution Flows and Dissolution Capability with Dissolver Charge Chute Cover Off

Description: A flow test was performed in Scrap Recovery of HB-Line to document the flow available for hydrogen dilution in the dissolvers when the charge chute covers are removed. Air flow through the dissolver charge chutes, with the covers off, was measured. A conservative estimate of experimental uncertainty was subtracted from the results. After subtraction, the test showed that there is 20 cubic feet per minute (cfm) air flow through the dissolvers during dissolution with a glovebox exhaust fan operating, even with the scrubber not operating. This test also showed there is 6.6 cfm air flow through the dissolvers, after subtraction of experimental uncertainty if the scrubber and the glovebox exhaust fans are not operating. Three H-Canyon exhaust fans provide sufficient motive force to give this 6.6 cfm flow. Material charged to the dissolver will be limited to chemical hydrogen generation rates that will be greater than or equal to 25 percent of the Lower Flammability Limit (LFL) during normal operations. The H-Canyon fans will maintain hydrogen below LFL if electrical power is lost. No modifications are needed in HB-Line Scrap Recovery to ensure hydrogen is maintained less that LFL if the scrubber and glovebox exhaust fans are not operating.
Date: January 15, 2003
Creator: Hallman, D.F.
Partner: UNT Libraries Government Documents Department

Complexation of Plutonium (IV) with Fluoride at Variable Tempeartures

Description: Complexation of Pu(IV) with fluoride was studied by solvent extraction at 25, 40 and 55 C in 2.2 mol {center_dot} kg{sup -1} HClO{sub 4}. The distribution ratio of Pu(IV) between the organic and aqueous phases decreased as the concentration of fluoride was increased due to the formation of Pu(IV)-F complexes in the aqueous phase. Two complexes, PuF{sup 3+} and PuF{sub 2}{sup 2+}, were identified under the conditions in this work and their stability constants at 25, 40 and 55 C and I = 2.2 mol {center_dot} kg{sup -1} HClO{sub 4} were determined from the distribution data. The Specific Ion Interaction approach (SIT) was used to extrapolate the constants to the state of infinite dilution. Data from this work indicate that the complexation of Pu(IV) with fluoride is endothermic and entropy-driven. The complexation becomes stronger at higher temperatures.
Date: June 10, 2009
Creator: Xia, Yuanxian; Rao, Linfeng; Friese, Judah I.; Moore, Dean A. & Bachelor, P. P.
Partner: UNT Libraries Government Documents Department

A Re-examination of the Dilution of Auditor Misstatement Risk Assessments: An Experimental Study of the Impact of Client Information Type, Workload, and PCAOB Guidance on Dilution

Description: Many external parties such as investors, creditors, and regulatory agencies, use a company’s financial statements in their decision-making. In doing so, they rely on audit opinions on whether financial statements are fairly stated. However, evidence suggests that there are factors in the audit environment that influence auditor judgments. For example, nondiagnostic client information dilutes auditor judgments when compared to judgments based on diagnostic information alone, especially for less experienced auditors (Hackenbrack 1992; Hoffman and Patton 1997; Glover 1994; Shelton 1999). High time pressure conditions mitigate this effect by refocusing auditor attention toward relevant client information, therefore reducing the impact of nondiagnostic information (Glover 1994, 1997). This research study examines other common audit environment factors to determine if they too influence audit judgment results. An online questionnaire of 149 auditors, CPAs and other accounting professionals indicate that the inclusion of nondiagnostic client information results in a significant change in auditor judgments. The direction of this change follows a theorized pattern; risk assessments that were initially high are reduced, while those that were initially low are increased. Significance was not consistently found for a workload and PCAOB effect on auditor judgment. However, a comparison of the absolute value of dilution effect means across conditions reveals some trending for the proposed unwanted effect of high workload, and the beneficial effect of PCAOB guidance. These results have important implications for auditing research and practice. It extends previous archival research on workload effects and uses a unique questionnaire design to reexamine workload pressures in a behavioral setting. The results of hypothesis testing on workload pressure and PCAOB guidance, although lacking consistent statistical significance; exhibit trends that agree with proposed theoretical relationships. Tests on the effects of nondiagnostic information show strong statistical support for previous studies in the area of psychology and audit. This study’s greatest ...
Date: December 2015
Creator: Perry, Suzanne M.
Partner: UNT Libraries

Use of an Eductor to Reliably Dilute a Plutonium Solution

Description: Savannah River Site (SRS) in South Carolina is dissolving Pu239 scrap, which is a legacy from the production of nuclear weapons materials, and will later convert it into oxide form to stabilize it. An eductor has been used to both dilute and transfer a plutonium containing solution between tanks. Eductors have the advantages of simplicity and no moving parts. Reliable control of dilution is important because the geometry of the receiving tank could potentially allow a nuclear criticality. Dilution factor was to have been controlled by the appropriate choice of flow restrictor in the line between the plutonium solution tank and the eductor. However, dilution factors measured for liquid transfers with different flow restrictors showed unexpected trends, causing concern that the process was not well understood. As a result, the performance of the eductor and associated piping were analyzed using a mathematical model. The one dimensional, two phase model accounted for eductor performance and for air and vapor coming out of solution at low pressures. The unexpected trends were shown to be the result of variations in viscosities and densities of both the plutonium solution and the nitric acid solution used as both the motive fluid and diluent. The model agreed well with existing data and was then used to make pre-test predictions of flows for four solution transfers with good agreement. This provided confidence that the eductor system was a reliable method for obtaining specified dilution factors. Based on model results, recommendations were made and implemented for the operation of the eductor transfer system. One unexpected result of the analysis was the observation that slow corrosion inside the eductor is increasing the dilution factor, which is a conservative trend.
Date: March 23, 1999
Creator: Steimke, J.L.
Partner: UNT Libraries Government Documents Department

E-Area Performance Assessment Interim Measures Assessment FY2003

Description: Projected impacts on disposal limits of various studies have been estimated. Interim measures to compensate for the impacts are needed for the Engineered Trench and the Intermediate Level Vault. Interim measures are due to projected decreases in the radionuclide disposal limits derived from the groundwater pathway as a result of the Aquifer Source Node study and consideration of potential artificial dilution caused by the large size of the grid elements in the Intermediate Level Vault groundwater model. Recently, it became evident that, in the development of the groundwater model for the Slit Trenches, the selection of aquifer source nodes (i.e., the spatial elements of the saturated zone model into which the flux of radionuclides from the unsaturated zone model is introduced) was not optimum6. Optimizing the source nodes would likely result in increases in the resulting groundwater concentrations, which would suggest that the radionuclide disposal limits should be reduced. However, other studies may result in increases in disposal limits 7. Therefore, a decision was made to develop and implement an annual summary of the potential impact of technical studies and other information on radionuclide disposal limits and whether mitigating measures should be imposed pending completion and implementation of the studies. This report is the first such summary.
Date: October 15, 2003
Creator: Wilhite, E.L.
Partner: UNT Libraries Government Documents Department

Application of a General Computer Algorithm Based on the Group-Additivity Method for the Calculation of Two Molecular Descriptors at Both Ends of Dilution: Liquid Viscosity and Activity Coefficient in Water at Infinite Dilution

Description: This paper presents the application of a commonly used computer algorithm based on the group-additivity method for the calculation of the liquid viscosity coefficient at 293.15 K and the activity coefficient at infinite dilution in water at 298.15 K or organic molecules.
Date: December 10, 2017
Creator: Naef, Rudolf & Acree, William E. (William Eugene)
Partner: UNT College of Arts and Sciences

The Effect of Compression Ratio, Cooled Exhaust Gas Mixed With Inlet Air, and Inlet-Air Temperature on the Knock-Limited Performance of a Full-Scale Single-Cylinder Engine

Description: Report presenting a study to determine the effect on the knock-limited permissible power output on the indicated specific fuel consumption and on the cylinder temperatures of exhaust-gas dilution of the inlet-air charge, inlet-air temperature without exhaust-gas dilation, and of compressible ratio.
Date: March 1944
Creator: Bolz, Ray E. & Breitwieser, Roland
Partner: UNT Libraries Government Documents Department

Dry Blending to Achieve Isotopic Dilution of Highly Enriched Uranium Oxide Materials

Description: The end of the cold war produced large amounts of excess fissile materials in the United States and Russia. The Department of Energy has initiated numerous activities to focus on identifying material management strategies for disposition of these excess materials. To date, many of these planning strategies have included isotopic dilution of highly enriched uranium as a means of reducing the proliferation and safety risks. Isotopic dilution by dry blending highly enriched uranium with natural and/or depleted uranium has been identified as one non-aqueous method to achieve these risk (proliferation and criticality safety) reductions. This paper reviews the technology of dry blending as applied to free flowing oxide materials.
Date: April 1, 2001
Creator: Henry, Roger Neil; Chipman, Nathan Alan & Rajamani, R. K.
Partner: UNT Libraries Government Documents Department

Measurements with a recuperative superfluid Stirling refrigerator

Description: A superfluid Stirling refrigerator cooled to 168 mK using a 4.9% {sup 3}He- {sup 4}He mixture and exhausting its waste heat at 383 mK. Cooling power versus temperature and speed is presented for 4.9%, 17%, and 36% mixtures. At the highest concentration, a dissipation mechanism of unknown origin is observed.
Date: August 1, 1995
Creator: Watanabe, A.; Swift, G.W. & Brisson, J.G.
Partner: UNT Libraries Government Documents Department

Factors Affecting Indoor Air Concentrations of Volatile Organic Compounds at a Site of Subsurface Gasoline Contamination

Description: We report a field study of soil gas transport of volatile organic compounds (VOCs) into a slab-on-grade building found at a site contaminated with gasoline. Although the high VOC concentrations (30-60 g m{sup -3}) measured in the soil gas at depths of 0.7 m below the building suggest a potential for high levels of indoor VOC, the measured indoor air concentrations were lower than those in the soil gas by approximately six orders of magnitude ({approx} 0.03 mg m{sup -3}). This large ratio is explained by (1) the expected dilution of soil gas entering the building via ambient building ventilation (a factor of {approx}1000), and (2) an unexpectedly sharp gradient in soil gas VOC concentration between the depths of 0.1 and 0.7 m (a factor of {approx}1000). Measurements of the soil physical and biological characteristics indicate that a partial physical barrier to vertical transport in combination with microbial degradation provides a likely explanation for this gradient. These factors are likely to be important to varying degrees at other sites.
Date: November 1, 1995
Creator: Fischer, M. L.; Bentley, A. J.; Dunkin, K. A.; Hodgson, A. T.; Nazaroff, W. W.; Sextro, R. G. et al.
Partner: UNT Libraries Government Documents Department

Does Mixing Make Residential Ventilation More Effective?

Description: Ventilation dilutes or removes indoor contaminants to reduce occupant exposure. In a multi-zone environment such as a house, there will be different dilution rates and different source strengths in every zone. The total ventilation rate is the most important factor in determining the exposure of occupants to given sources, but the zone- specific distribution of exhaust and supply air, and the mixing of ventilation air can have significant roles. Different types of ventilation systems will provide different amounts of mixing depending on several factors such as air leakage through the building envelope, air distribution systems and the location of sources and occupants. This paper reports recent results of investigations to determine the impact that air mixing has on exposures of residential occupants to prototypical contaminants of concern. Evaluations of existing field measurements and simulations reported in the literature are combined with new analyses to provide an integrated overview of the topic. The results show that for extreme cases additional mixing can be a significant factor but for typical homes looking at average exposures mixing is not helpful and can even make exposures worse.
Date: August 16, 2010
Creator: Sherman, Max & Walker, Iain
Partner: UNT Libraries Government Documents Department

Muon Acceleration - RLA and FFAG

Description: Various acceleration schemes for muons are presented. The overall goal of the acceleration systems: large acceptance acceleration to 25 GeV and 'beam shaping' can be accomplished by various fixed field accelerators at different stages. They involve three superconducting linacs: a single pass linear Pre-accelerator followed by a pair of multi-pass Recirculating Linear Accelerators (RLA) and finally a non-scaling FFAG ring. The present baseline acceleration scenario has been optimized to take maximum advantage of appropriate acceleration scheme at a given stage. The solenoid based Pre-accelerator offers very large acceptance and facilitates correction of energy gain across the bunch and significant longitudinal compression trough induced synchrotron motion. However, far off-crest acceleration reduces the effective acceleration gradient and adds complexity through the requirement of individual RF phase control for each cavity. The RLAs offer very efficient usage of high gradient superconducting RF and ability to adjust path-length after each linac pass through individual return arcs with uniformly periodic FODO optics suitable for chromatic compensation of emittance dilution with sextupoles. However, they require spreaders/recombiners switchyards at both linac ends and significant total length of the arcs. The non-scaling Fixed Field Alternating Gradient (FFAG) ring combines compactness with very large chromatic acceptance (twice the injection energy) and it allows for large number of passes through the RF (at least eight, possibly as high as 15).
Date: October 1, 2011
Creator: Bogacz, Alex
Partner: UNT Libraries Government Documents Department

THERMODYNAMICS OF ELECTROLYTES. X. ENTHALPY AND THE EFFECT OF TEMPERATURE ON THE ACTIVITY COEFFICIENTS.

Description: Heat of dilution and of solution data are fitted to the form of equation corresponding to that used successfully for activity and osmotic coefficients over a wide range of concentration. The resulting parameters give the change with temperature of the activity and osmotic coefficients. Results are reported for 84 electrolytes of 1-1, 2-1, 3-1, and 2-2 valence types.
Date: November 1, 1977
Creator: Silvester, Leonard F. & Pitzer, Kenneth S.
Partner: UNT Libraries Government Documents Department

Air Distribution Effectiveness for Different MechanicalVentilation Systems

Description: The purpose of ventilation is to dilute indoor contaminants that an occupant is exposed to. In a multi-zone environment such as a house, there will be different dilution rates and different source strengths in every zone. Most US homes have central HVAC systems, which tend to mix conditions between zones. Different types of ventilation systems will provide different amounts of dilution depending on the effectiveness of their air distribution systems and the location of sources and occupants. This paper will report on work being done to both model the impact of different systems and measurements using a new multi-tracer measurement system that has the capacity to measure not only the flow of outdoor air to each zone, but zone-to-zone transport. The ultimate objective of this project is to determine the effectiveness of different systems so that appropriate adjustments can be made in residential ventilation standards such as ASHRAE Standard 62.2.
Date: August 1, 2007
Creator: Sherman, Max H. & Walker, Iain S.
Partner: UNT Libraries Government Documents Department

An Inverted Co-Flow Diffusion Flame for Producing Soot

Description: We developed an inverted, co-flow, methane/air/nitrogen burner that generates a wide range of soot particles sizes and concentrations. By adjusting the flow rates of air, methane, and nitrogen in the fuel, the mean electric mobility diameter and number concentration are varied. Additional dilution downstream of the flame allows us to generate particle concentrations spanning those produced by spark-ignited and diesel engines: particles with mean diameters between 50 and 250 nm and number concentrations from 4.7 {center_dot} 10{sup 4} to 10{sup 7} cm{sup -3}. The range of achievable number concentrations, and therefore volume concentrations, can be increased by a factor of 30 by reducing the dilution ratio. These operating conditions make this burner valuable for developing and calibrating diagnostics as well as for other studies involving soot particles.
Date: June 21, 2005
Creator: Stipe, Christopher B.; Higgins, Brian S.; Lucas, Donald; Koshland, Catherine P. & Sawyer, Robert F.
Partner: UNT Libraries Government Documents Department