3,790 Matching Results

Search Results

Advanced search parameters have been applied.

Testing New Measures of Age Independent Body Size in White-Tailed Deer (Odocoileus virginianus)

Description: The four elements of the lower hind foot (calcaneus, metatarsal, naviculo-cuboid, and tibia) were tested for use as age-independent proxies of body size in white-tailed deer using known aged specimens from Ft. Hood Texas. Statistical analysis indicates that the calcaneum and the tibia are good proxies of age-independent body size in white-tailed deer. In addition to expanding the list of elements that can be used for studies of age-independent body size, these elements can also be used to age faunal remains to an ordinal scale of juveniles and adults. This is useful for research regarding prehistoric prey populations; as a single element can be used to determine prey body size and age simultaneously, which are the two variables used to assess changes in human subsistence practices via the archaeological remains of their prey.
Date: August 2009
Creator: Densmore, Julie A.
Partner: UNT Libraries

Size Effect in the Electrical Conductivity of Bismuth

Description: If a physical dimension of a metallic specimen is comparable with, or smaller than, the mean free path of the conduction electrons, then the observed electrical conductivity will be less than that of a conventional bulk sample. This phenomenon is called a size effect, and is the result of electron scattering from the specimen surfaces. In the present investigation, measurements were made on electropolished monocrystalline specimens ranging from matchbox geometry to thick-film geometry in order to obtain further information on the size effect in bismuth at liquid helium temperatures.
Date: August 1967
Creator: Vaughn, Bobby J.
Partner: UNT Libraries

Drop-size distributions for impinging-jet breakup in airstreams simulating the velocity conditions in rocket combustors

Description: Report presenting drop-size-distribution data obtained for heptane sprays produced by pairs of impinging jets in airstreams over ranges of orifice diameter, liquid-jet velocity, and velocity difference between the airstream and the liquid jet.
Date: March 1958
Creator: Ingebo, Robert D.
Partner: UNT Libraries Government Documents Department

Improved Grindability of Taconite Ores by Microwave Heating

Description: The 11.S. Bureau of Mines has conducted studies to utilize rapid microwave heating to stress fracture ore samples. Iron ores containing hematite, magnetite, and goethite were subjected to microwave energy in batch operations at 3 kW and heated to average maximum temperatures between 840 and 940 *C. Standard Bond grindability tests showed that microwave heating reduced the work index of iron ores by 10 to 24 pct. In a microwave chamber designed to simulate a continuous throughput operation at 3 kW, the grindability of a tacon-te ore was improved by 13 pct at a bulk temperature of 197 *C. Because stress cracking occurred at a lower temperature, less energy was consumed. To further improve the economics of microwave fracturing, higher powers up to 16 kW were used to rapidly heat samples to relatively low temperatures in a continuous, belt-fed applicator. A significant improvement of grindability was obtained with a larger rod mill feed size in comparison to a minus 6-mesh Bond feed.
Date: 1995
Creator: Walkiewicz, John W.; Lindroth, David P. & Clark, Andrea E.
Partner: UNT Libraries Government Documents Department

Effect Size Reporting and Interpreting Practices in Published Higher Education Journal Articles

Description: Data-driven decision making is an integral part of higher education and it needs to be rooted in strong methodological and statistical practices. Key practices include the use and interpretation of effect sizes as well as a correct understanding of null hypothesis significance testing (NHST). Therefore, effect size reporting and interpreting practices in higher education journal articles represent an important area of inquiry. This study examined effect size reporting and interpretation practices of published quantitative studies in three core higher education journals: Journal of Higher Education, Review of Higher Education, and Research in Higher Education. The review covered a three-year publication period between 2013 and 2015. Over the three-year span, a total of 249 articles were published by the three journals. The number of articles published across the three years did not vary appreciably. The majority of studies employed quantitative methods (71.1%), about a quarter of them used qualitative methods (25.7%), and the remaining 3.2% used mixed methods. Seventy-three studies were removed from further analysis because they did not feature any quantitative analyses. The remaining 176 quantitative articles represented the sample pool. Overall, 52.8% of the 176 studies in the final analysis reported effect size measures as part of their major findings. Of the 93 articles reporting effect sizes, 91.4% of them interpreted effect sizes for their major findings. The majority of studies that interpreted effect sizes also provided a minimal level of interpretation (60.2% of the 91.4%). Additionally, 26.9% of articles provided average effect size interpretation, and the remaining 4.3% of studies provided strong interpretation and discussed their findings in light of previous studies in their field.
Access: This item is restricted to UNT Community Members. Login required if off-campus.
Date: August 2016
Creator: Stafford, Mehary T.
Partner: UNT Libraries


Description: This collection of mathematical data consists of two tables of decimal constants arranged according to size rather than function, a third table of integers from 1 to 1000, giving some of their properties, and a fourth table listing some infinite series arranged according to increasing size of the coefficients of the terms. The decimal values of Tables I and II are given to 20 D.
Date: March 1, 1971
Creator: Robinson, H.P. & Potter, Elinor
Partner: UNT Libraries Government Documents Department

Semiconductor Bridge Cable Test

Description: The semiconductor bridge (SCB) is an electroexplosive device used to initiate detonators. A C cable is commonly used to connect the SCB to a firing set. A series of tests were performed to identify smaller, lighter cables for firing single and multiple SCBs. This report provides a description of these tests and their results. It was demonstrated that lower threshold voltages and faster firing times can be achieved by increasing the wire size, which reduces ohmic losses. The RF 100 appears to be a reasonable substitute for C cable when firing single SCBs. This would reduce the cable volume by 68% and the weight by 67% while increasing the threshold voltage by only 22%. In general, RG 58 outperforms twisted pair when firing multiple SCBs in parallel. The RG 58's superior performance is attributed to its larger conductor size.
Date: January 1, 2002
Creator: KING, TONY L.
Partner: UNT Libraries Government Documents Department

Evaluation of process for sludge particle size reduction

Description: This document evaluates the available technology for K Basin sludge particle size. The results can be used to demonstrate the sensitivity or lack thereof, of K Basin sludge to available reduction processes and TWRS proposed particle acceptance criteria.
Date: March 18, 1997
Creator: Precechtel, D.R. & Packer, M.J., Fluor Daniel Hanford
Partner: UNT Libraries Government Documents Department

Electrical Conductivity in Thin Films

Description: This thesis deals with electrical conductivity in thin films. Classical and quantum size effects in conductivity are discussed including some experimental evidence of quantum size effects. The component conductivity along the applied electric field of a thin film in a transverse magnetic field is developed in a density matrix method.
Date: May 1973
Creator: Meyer, Frederick Otto
Partner: UNT Libraries

The effects of birth order and family size on children's locus of control

Description: The present study was concerned with investigating children's generalized locus of control of reinforcement and its possible relationship to the demographic variables of birth order and family size. The sample consisted of 93 school children in Grades 6, 7, and 8. The analysis of data was by a 2 x 3 factorial design.
Date: August 1975
Creator: Schniederjan, Patrick
Partner: UNT Libraries

Passive legged, multi-segmented, robotic vehicle.

Description: The Passive-legged, Multi-segmented, Robotic Vehicle concept is a simple legged vehicle that is modular and scaleable, and can be sized to fit through confined areas that are slightly larger than the size of the vehicle. A specific goal of this project was to be able to fit through the opening in the fabric of a chain link fence. This terrain agile robotic platform will be composed of multiple segments that are each equipped with appendages (legs) that resemble oars extending from a boat. Motion is achieved by pushing with these legs that can also flex to fold next to the body when passing through a constricted area. Each segment is attached to another segment using an actuated joint. This joint represents the only actuation required for mobility. The major feature of this type of mobility is that the terrain agility advantage of legs can be attained without the complexity of the multiple-actuation normally required for the many joints of an active leg. The minimum number of segments is two, but some concepts require three or more segments. This report discusses several concepts for achieving this type of mobility, their design, and the results obtained for each.
Date: November 1, 2003
Creator: Hayward, David R.
Partner: UNT Libraries Government Documents Department

Experimental Investigation of a 7-Inch-Tip-Diameter Transonic Turbine

Description: Report presenting performance results for a 7-inch transonic turbine and a comparison of said turbine with a 14-inch turbine of geometrically similar design. The size effect on performance was found to generally be due to the inability to fabricate the smaller blades to the same percentage of dimensional deviation as that of larger blades. Results regarding overall performance and performance under specific inlet conditions are provided.
Date: January 16, 1958
Creator: Whitney, Warren J. & Wintucky, William T.
Partner: UNT Libraries Government Documents Department

Microstructural dynamic study of grain growth

Description: A simulation procedure for grain growth has been developed which accounts for local structure and topology. The simulated microstructures show excellent agreement with those found in isotropic polycrystalline metals and ceramics. The grain size distribution, topological distribution, and the topology-grain relations are all in excellent agreement with experiment. Similarly, the kinetics found also reproduce the experimental results. It is suggested that the growth exponent, n < 1/2, is inherent to the grain growth process and is not due to impurities, preferred orientation, etc. as had been previously thought.
Date: January 1, 1986
Creator: Anderson, M. P.; Grest, G. S. & Srolovitz, D. J.
Partner: UNT Libraries Government Documents Department

Survey of procedures for estimating the distribution of spherical particles from plane sections

Description: Estimating the size distribution of particles in a sample volume from area analysis of a planar slice is one of the difficult fundamental problems of applied stereology. The original formulation of an integral equation by Wicksell (1925) as an approach to this problem led to the development of several procedures for solution, including a simple model of successive differences by Saltikov (1967), a generalized method of successive differences by Lewis et al (1973), a method of moments by Watson (1971), polynominal fits by Minerbo and Levy (1969), spectral differentiation and product integration by Anderssen and Jakemann (1975), and ridge regression and cross validation by Wahba (1979). This discussion presents yet another method (Histogram Method) for solution of the problem, and introduces a constrained minimum variance estimator procedure which eliminates the negative probability anomaly. Several examples of the use of the above methods in analysis of real data are given. The utility of the constrained minimum variance procedure used with the Saltikov and Histogram methods is demonstrated.
Date: January 1, 1979
Creator: Goldman, A.; Lewis, H.D. & Visscher, W.M.
Partner: UNT Libraries Government Documents Department

Comparison of Millipore Particle Measurement Computer System (. pi. MC), wet sieve analysis and microscopy analysis (modified Zeiss analyzer) for particle characterization. Period covered: July--September 1975

Description: A comparative study of powder characteristics measured by the Millipore Particle Measurement Computer System (..pi..MC) versus wet sieve analysis and microscopy analysis was prompted by a need to replace the latter methods with a more automated system. With the present procedures followed in instrument operation and computation of the data, the results indicate the following problem areas with the ..pi..MC: (1) inconsistency in its measurements; (2) automatic chord measurements do not relate to applicable particle dimensions unless spherical; (3) assumption of a general particle shape to describe individual particles is not valid; (4) distributions generated by this system are generally incomplete and instrument dependent; and (5) it does not correlate with sieve analysis or with microscopy (Zeiss) analysis. (auth)
Date: January 1, 1975
Creator: Duncan, A. A.
Partner: UNT Libraries Government Documents Department

Processing Variables of Alumina Slips and Their Effects on the Density and Grain Size of the Sintered Sample

Description: High densities and small grain size of alumina ceramic bodies provide high strength and better mechanical properties than lower density and larger grain size bodies. The final sintered density and grain size of slip-cast, alumina samples depends greatly on the processing of the slip and the alumina powder, as well as the sintering schedule. There were many different variables explored that include initial powder particle size, slurry solids percent, amount and type of dispersant used, amount and type of binder used, and sintering schedule. Although the experimentation is not complete, to this point the sample with the highest density and smallest grain size has been a SM8/Nano mixture with Darvan C as the dispersant and Polyvinyl Alcohol (PVA) as the binder, with a solids loading of 70 wt% and a 1500 C for 2 hours sintering schedule. The resultant density was 98.81% of theoretical and the average grain size was approximately 2.5 {micro}m.
Date: January 1, 2002
Creator: Rowley, R. & Chu, H.
Partner: UNT Libraries Government Documents Department

Influence of Iron Oxide Particles on the Strength of Ball-Milled Iron

Description: Detailed microstructural and mechanical property studies of ball-milled iron, in the powder and consolidated states, are reviewed and assessed. The analyses cover three and one-half orders of magnitude of grain size (from 6 nm to 20 mm) and focus on the influence of oxide particles on the strength. The study includes the early work of Koch and Yang, Kimura and Takaki and continues with the more recent work of Umemoto et al and Belyakov, Sakai et al. It is shown that the major contributors to strength are the nanooxide particles. These particles are created by adiabatic shear banding during ball-milling leading to a bimodal distribution of particles. The predicted strength from particles, {sigma}{sub p}, is given by {sigma}{sub p} = B {center_dot} (D*{sub S}){sup -1/2} where D*{sub S} is the surface-to-surface interparticle spacing, and B = 395 MPa {center_dot} {micro}m{sup -1/2}. A model is proposed that accounts for the influence of the bimodal particle size distribution on strength.
Date: December 7, 2005
Creator: Lesuer, D R; Syn, C K & Sherby, O D
Partner: UNT Libraries Government Documents Department

Method for determining aerosol particle size, device for determining aerosol particle size

Description: A method for determining the mass median diameter D of particles contained in a fluid is provided wherein the data of the mass of a pre-exposed and then a post-exposed filter is mathematically combined with data concerning the pressure differential across the same filter before and then after exposure to a particle-laden stream. A device for measuring particle size is also provided wherein the device utilizes the above-method for mathematically combining the easily quantifiable data.
Date: December 1, 1997
Creator: Novick, Vincent J.
Partner: UNT Libraries Government Documents Department