Engineering Commons^™

A Mass Spectrometric Study Of Positive Ions Produced In An Experimental Diode, L. A. Addington, Gordon Lewis

Materials Science and Engineering Faculty Research & Creative Works

A simple diode ion source has been developed for direct observation in a mass spectrometer of the positive ions created in an operating diode. The ionic species accelerated toward the cathode were identified. The shape of the peak displayed in the spectrum is related to the region of the diode in which the ions were formed. Variation of experimental parameters, including the composition of the background gases, indicated that the characteristic shapes of the peaks can be related to space charge in the diode. This is complicated by the tendency of some of the species to fragment and further work …

Influence Of Oxygen Activity On The Sintering Of Mgcr2o4, Harlan U. Anderson

Materials Science and Engineering Faculty Research & Creative Works

The sintering behavior of MgCr2O4 powder compacts was investigated as a function of temperature, time, and oxygen activity. The results show that MgCr2O4 cannot be densified to >70% of theoretical density at temperatures up to 1700°C if the oxygen activity exceeds 10−6 atm. The oxygen activity must be decreased to <10−10 atm before densities exceeding 90% of theoretical can be achieved. Weight loss and X‐ray data indicated that maximum density occurred at an oxygen activity just above that where MgCr2O4 becomes unstable. Copyright © 1974, Wiley Blackwell. All rights reserved

X-Ray Powder Data And Unit Cell Parameters Of Mgcl2.6h2o, Charles A. Sorrell, Roy R. Ramey

Materials Science and Engineering Faculty Research & Creative Works

Detailed X-ray powder data for MgCl2·6H2O were obtained by diffractometry by use of CuKα radiation at 22°C. The data were indexed on a bimolecular monoclinic unit cell, space group C2/m, with a = 9.858 ± 0.001 Å; b = 7.107 ± 0.001 Å; c = 6.069 ± 0.001 Å; ß = 93° 47′ ± 10′. Calculated density was 1.591 g/cm3, compared with a measured density of 1.593 ± 0.003 g/cm3. © 1974, American Chemical Society. All rights reserved.

Field Emission Of Boron On Tungsten, P. D. Ownby, Thomas A. Flaim

Materials Science and Engineering Faculty Research & Creative Works

No abstract provided.

Magnetic Properties Of Cadmium Manganese Ferrite, B. W. Jong, P. D. Ownby

Materials Science and Engineering Faculty Research & Creative Works

The room-temperature saturation magnetization of CdxMn1-xFe2O4 decreased with increasing cadmium concentration. When 0 < x < 0.5, the decrease in saturation magnetization was due to the increase in the amount of non-mgnetic distorted cubic Cd(Mn, Fe) 2O4.

Vibration Characteristics Of Free Thin Cylindrical Shells, Floyd M. Cunningham, D. E. Leanhardt

Mechanical and Aerospace Engineering Faculty Research & Creative Works

This paper considers the flexural vibrations of free thin circular cylinders. A frequency equation is derived using free-free characteristic beam functions to represent the variation of mid-surface shell displacement components, u, v and w, with respect to the axial direction. Timoshenko strain-displacement relations for thin cylinders are used to determine elastic vibratory strain energy. Energy methods are applied to obtain the frequency equation and associated amplitude ratios for each of its roots. This energy solution is checked experimentally using a vibration exciter and numerically using the SABOR IV finite element program. With minor modification, the frequency equation conforms to the …

In Vitro Studies Of Lipid Uptake By Medical Grade Silicone Rubbers Used For Heart Valve Balls, Shu Hua Wu

Doctoral Dissertations

"Various chemical and physical aspects of high lipid absorption by medical grade silicone rubber and the dynamic mechanical properties of lipid-rubber systems were studied in order to provide an insight into the problem of 'variance' of these materials when subjected to 'in vitro' and 'in vivo' environments. Wide variations of post cure procedures of the silicone rubber were studied. Different post cures did not appreciably affect the mechanical properties of the silicone rubber. Mass transfer studies demonstrated that the diffusion of linolenic acid into a silicone rubber slab is a purely physical diffusion process (D = 3.2 x 10^{-3 …}

Parameter Identification Of Nonuniform Distributed Rc Networks, Roger Allen Hayes

Doctoral Dissertations

"The problem of the unique parameter identification of nonuniform distributed RC networks is addressed in this dissertation. Previous literature provides for the equivalence of distributed networks with respect to the terminal characteristics. Therefore, the question is whether unique parameter identification is even possible. This work settles that question by presenting the sufficient conditions to insure a unique solution to the parameter identification problem. One theorem requires the knowledge of a driving-point impedance, the knowledge of the physical length, and the constraint that the r(x)c(x) product remains constant to insure uniqueness of the parameters r(x) and c(x). Relaxation of the r(x)c(x) …

Direct And Inverse Heat Conduction In Rock Materials Using The Finite Element Method, Vernon Dale Allen

Doctoral Dissertations

"A finite element method is presented for solution of direct and inverse heat conduction problems in rock materials. Finite element programs for direct and inverse heat conduction problems were developed and demonstrated. Flow charts are given for the finite element programs.

The direct finite element heat conduction program changes material properties with temperature to approximate the temperature dependent properties of rock materials. An example problem was solved by the finite element method and also using Kirchoff's transformation. The finite element solution compared quite well with the Kirchoff transformation solution.

The inverse method utilizes the direct finite element heat conduction program …

Evaluation Of Methods For The Recovery, Chemical And Toxicological Characterization Of Trace Organics, James Robert Matthews

Doctoral Dissertations

"Organic contaminants are generated in substantial quantities by the activities of man and through natural processes, and are present in natural runoff, industrial wastes, and agricultural discharges; synthetic organic chemicals, many of which are refractory and reach surface and subsurface water, are of particular significance. Earlier studies have generally emphasized the organoleptic and esthetic problems caused by trace organics, although their acute and long-term toxic potential has also been recognized.

The overall objective of this investigation was the analytical and toxicological characterization of trace organics recovered concomitantly from Missouri waters of varied character by large-scale solvent extraction (SEM) and carbon …

Hydrodynamic Mixing Model Applied To A Continuous Stirred-Tank Reactor With And Without Second-Order Reaction, Leon L. Otte

Doctoral Dissertations

Paper 1: "A hydrodynamic mixing (HDM) model, used to calculate the steady-state spatial distribution of conversion for a second-order reaction in a continuous stirred-tank reactor (CSTR) for non-premixed reactants was developed and contrasted with other methods. The HDM model is based on a segmental description of the reactor and includes turbulent mixing effects in each segment. As a test of the model, the experimental results obtained from a tubular reactor were found to be very well represented for a range of reactant ratios. Spatial distributions of concentration and segregation intensity (degree of mixing) within the CSTR were determined for a …

Kalman Filter Equalization For Qpsk Communications, Tze-Shen Lee

Doctoral Dissertations

"The discrete complex Kalman filter is considered as an equalizer for quadrature phase shift keyed (QPSK) systems in the presence of additive noise and intersymbol interference (ISI). For a known linear time-invariant channel with finite duration impulse response, the finite n-dimension complex Kalman filter equalizer is able to reduce the degradation caused by ISI. When the channel is unknown, an adaptive Kalman equalizer is used in which the channel complex tap gains are estimated by decision feedback. A two component multipath channel QPSK system is used as an example. Using the Chernoff upper bound to calculate the error probabilities, the …

Surface Elastic Waves In Piezoelectric Semiconductors And Layered Media, Yu-Pin Han

Doctoral Dissertations

"The primary interest of this investigation is to understand the surface elastic wave properties in piezoelectric semiconductors and layered media. Generalized piezoelectric wave equations in piezoelectric semiconductors and layered media are derived. Systems considered are the piezoelectric semiconductor, the two layer piezoelectric insulator-semiconductor, the three layer piezoelectric insulator- gap-semiconductor and the four layer piezoelectric insulator-gap-semiconductor-dielectric substrate. The eigenwave expansion and the iteration methods in the complex domain are used to solve the problems. Mathematically, it represents a solution of the eigenvalue boundary value problem which involves iteration of functions in the complex domain. Solutions obtained are eigenvalues and eigenvectors which …

An Analytical And Experimental Study Of The Dynamic Response Of A Press, Woosoon Bai

Doctoral Dissertations

"This dissertation presents a simplified mathematical model and computer simulation of the vertical motion of a press. The model is verified by comparing simulation results with actual field measurements.

Using this model, the computer simulation is then extended to study the dynamic response of a bolted press, one with loosened anchor bolts, and one which is isolated. Press performance, in terms of acceleration of the press, velocity of its foundation, and forces transmitted to the foundation, is analyzed in relation to the foundation mass and the stiffness of the isolators, where applicable. Comparative performances of the presses secured by the …

Solid Transformations And Premelting Phenomena In Fluorite Structures And The System Srcl₂Bacl₂, Damri Sukhotanang

Doctoral Dissertations

"Thermal expansion and phase transformations in CaF₂, BaF₂, SrCl₂, and BaCl₂ were studied by high temperature x-ray diffractometry, differential thermal analysis, and thermodilatometric analysis. Thermal expansion characteristics of CaF₂, BaF₂ and SrCl₂ are very similar. The structures expand normally at lower temperatures and depart substantially from linearity at higher temperatures, because of formation of defects and disordering of anions. At high temperatures CaF₂ and BaF₂ react with water vapor, even at low humidities, forming oxides and emitting HF, leading to difficulty in observation of phase transformations. SrCl …

Phase Equilibria And Transformations In Potassium Sulfate, Chromate, Molybdate, And Tungstate, Roy Richard Ramey

Doctoral Dissertations

"Thermal expansion and transformations of K₂SO₄, K₂CrO₄, K₂MoO₄, and K₂WO₄ were studied by high temperature diffractometry, differential thermal analysis, and dilatometry. K₂SO₄ and K₂CrO₄ transform from an orthorhombic to a hexagonal structure at 580°C and 670°C respectively, with initiation of the transformation probably related to increased amplitude of S-O tetrahedral vibrations. K₂MoO₄ and K₂WO₄ transform from a monoclinic to an orthorhombic structure at 300° and 370°C respectively. A minor K₂MoO_{4 …}

Removal Of Nutrients By Sorption On Activated Alumina, Checkman Michael Yue

Doctoral Dissertations

"The nutrient enrichment of surface, primarily impounded, water and the associated problems of accelerated eutrophication and prolific algal growth have become a nationwide concern. Phosphorus and nitrogen are considered to be the key elements in abating eutrophication and are contributed from many sources, natural and manmade; prominent among these is the discharge of domestic and industrial wastes.

The purpose of this study was to evaluate the removal of nutrients, primarily phosphorus and nitrogen, with activated alumina using a continuous-flow pilot plant system. Specific objectives were the: development and construction of appropriate bench and field-scale pilot plant units utilizing the rapid …

State-Space Analysis And Synthesis Of Active Rlc Networks, Wen-Pao Lee

Doctoral Dissertations

"This dissertation provides theoretical foundations for the state-space analysis and synthesis of linear active RLC networks containing all four types of controlled sources. The analysis portion is concerned with an explicit representation of the state model and the order of complexity of a general linear active RLC network. The problem considered in the synthesis portion is the realization of a given A-matrix with an active nondegenerate RLC-ladder network or an active RLC network without any particular structure.

The general active RLC network state model representations are explicitly expressed in terms of the fundamental circuit submatrices, the network element submatrices, and …

Transition Boiling Of Normal Pentane From A Horizontal Flat Gold Surface, Ronald M. Canon

Doctoral Dissertations

"The characteristic boiling curve for Normal Pentane was determined at 1 atmosphere pressure with particular attention devoted to the transition boiling region. The heat transfer surface was a horizontal, gold-plated, copper disc.

Stability analysis was employed to demonstrate why previous investigators have had only limited success in collecting data in the transition region and to provide a valid basis for equipment designed to operate in this region.

A method of predicting the transition region boiling curve from the nucleate curve and the Liedenfrost point is presented. The method was found to predict the transition boiling of Normal Pentane, Freon 12, …

Dropwise Condensation As Affected By Vapor Diffusion And Molecular Sticking, Salil K. Banerjee

Doctoral Dissertations

"Experimental values of heat flux in dropwise condensation on a gold plated vertical copper surface were determined in presence and absence of (or minute traces of) noncondensable gas. The noncondensable gas concentration varied from 0.0045% to 7.5% over a range of subcooling from 2.155 to 17.13°F and system pressure of 4.124 to 16.67 psia. The calculated heat transfer coefficient ranged from 1,545 to 11,135 Btu/hr-ft²-°F. In the part of the experiment where precautions were taken to avoid the presence of noncondensable gas in the water vapor, much higher values of heat flux were observed. Values of heat transfer coefficient ranging …

Mathematical Simulation Of Gas And Water Coning In Petroleum Reservoirs By The Dynamic Material Balance Technique, Visheshwar Nath Simlote

Doctoral Dissertations

"The prediction of coning behavior at a producing oil well is one of the most difficult numerical simulation problems. Because of the convergent flow patterns and small sizes of the inner grid blocks, the radial coordinate models used to study the problem have a tendency to become unstable. Since several hundred pore volumes may flow through the inner grid blocks during a rather small time interval, instabilities are likely to occur in the saturation calculations for these grid blocks. The dynamic approach to saturation calculations is a method which first computes the correct material balance and then calculates the saturation …

Nucleate Boiling Of N-Pentane, N-Hexane And Several Mixtures Of The Two From Various Tube Arrays, Kenneth Wayne Wall

Doctoral Dissertations

"An investigation of nucleate boiling heat transfer in saturated pools of Normal Pentane, Normal Hexane and several mixtures of the two was conducted. The fluids were boiled from gold-plated, copper, cylindrical heat transfer surfaces, 4.96 inches long, and 1.048 inch in diameter. The heat transfer elements were boiled in varying vertical tube arrays at a pressure of 14.70 psia.

It was found that the mixtures boiled with a lower heat transfer coefficient than that for either pure component when boiled alone. When boiling in any of the tube bundle arrangements, the heat transfer coefficients for the upper tubes in the …

A Study Of Exothermic Chemical Reaction In A Porous Catalyst Wedge, Joseph Michael Schardl Jr.

Doctoral Dissertations

"Temperature and composition were measured at various locations in a system where ethylene is hydrogenated to ethane on a 1/4 inch porous catalyst wedge made of nickel supported on alumina. 'When the wedge of catalyst was bathed in hydrogen, experimental results indicated a high temperature rise from the feed temperature to the catalyst which is implied by the diffusion controlled regime for solid catalyzed, highly exothermic reactions. This high activity was reversibly reduced by bathing the catalyst wedge in nitrogen for extended time periods (greater than 24 hours). This nitrogen soaking changed the experimental conditions from those of diffusion controlled …

Solid-Fluid Drag Reduction, Ian Radin

Doctoral Dissertations

"Pressure drop measurements were made on a variety of solid-liquid suspension systems in order to study the effects of particle shape and size, concentration, fluid viscosity and tube diameter on drag reduction. Measurements were made over a wide range of Reynolds numbers in two tubes: 1/4 inch and 1 inch in diameter.

Drag reduction could always be obtained with fibrous additives of length-to-diameter ratio greater than 25-35 if the concentration was sufficiently high. The drag reduction behavior of these suspensions is different from that of high polymer and soap solutions. Laminar flow behavior is stabilized giving lower than normal friction …

Numerical Modeling Of The Early Stage Of Cloud Formation In A Simulation Chamber, Adel Nassif Saad

Doctoral Dissertations

"A numerical model has been developed to simulate the growth of cloud droplets by condensation upon a spectrum of hygroscopic nuclei. The model is applicable to cloud simulation chamber conditions as well as to the study of the role of these nuclei on cloud base microstructure.

Equations are given for the growth by condensation of water vapor on a population of hygroscopic nuclei in a volume being cooled by expansion. The equations are integrated simultaneously, using Hamming's modified predictor-corrector method for given initial conditions, to obtain the droplet size distribution, temperature, pressure, supersaturation, and liquid water content. Temperature fluctuations, sedimentation …

Recommended Procedures For Conducting Pull-Over, Pull-Out And Single-Shear Tests Of Mechanical Connections, John Fraczek, George Winter, Teoman Peköz

CCFSS Library (1939 - present)

1. SCOPE 1.1 These methods cover procedures and definitions for the mechanical testing of joints formed by connecting a cold-formed steel member to a cold-formed or hot-rolled steel member with one or more mechanical fasteners. The purpose of these procedures is the determination of the load capacities of the joints so formed. 1.2 The term "mechanical fastener" or "fastener" shall be defined as any mechanical device used in the connection of two or more members, inclusive of such devices as bolts, tapping screws and rivets but exclusive of welds and adhesives. 1.3 The following mechanical tests are described: Sections Pull-Over …

Recommended Procedures For Conducting Pull-Over, Pull-Out And Single-Shear Tests Of Mechanical Connections, John Fraczek, George Winter, Teoman Peköz

CCFSS Library (1939 - present)

SCOPE 1.1 These methods cover procedures and definitions for the mechanical testing of joints formed by connecting a cold-formed steel member to a cold-formed or hot-rolled steel member with one or more mechanical fasteners. The purpose of these procedures is the determination of the load capacities of the joints so formed. 1.2 The term "mechanical fastener" or "fastener" shall be defined as any mechanical device used in the connection of two or more members, inclusive of such devices as bolts, tapping screws and rivets but exclusive of welds and adhesives. 1.3 The following mechanical tests are described: Pull-Over Sections 4-11, …

Local And Overall Buckling Of Cold-Formed Compression Members, John T. Dewolf, George Winter, Teoman Peköz

CCFSS Library (1939 - present)

The objective of this investigation has been to develop information on the interaction between local plate buckling and overall column buckling in cold-formed compression members with a view toward possible improvement of those provisions in the American Iron and Steel Institute Specification for the Design or Cold-Formed Steel Structural Members concerned with column design. Two types of compression members were tested: two channels connected flange-to-flange to form a box section, and two channels connected back-to-back to form an I-section. For both of these shapes, the stress at which local buckling occurs and the postbuckling strength were varied by varying the …

Strain-Aging And The Bauschinger Effect In Steel, S. P. Gupta, A. A. Johnson, Shoukat P. Kodali

CCFSS Proceedings of International Specialty Conference on Cold-Formed Steel Structures (1971 - 2018)

No abstract provided.

Properties Of Cold Compressed Steel Tubes, W. Carl Anderson

CCFSS Proceedings of International Specialty Conference on Cold-Formed Steel Structures (1971 - 2018)

No abstract provided.