Engineering Commons^™

Method And Apparatus For Nondestructive Sample Inspection, R. Zoughi, Sergey Kharkovsky, Mohammad Tayeb Ahmad Ghasr

Electrical and Computer Engineering Faculty Research & Creative Works

An apparatus for inspecting a sample for defects includes a signal generator for generating a signal and a device for splitting the signal into two separate signals which have substantially equal phase and magnitude. A sensor radiates the two signals on the sample and receives the two signals reflected from the sample. A device is provided for determining a difference between the two signals reflected from the sample without unwanted influence of variations of distance between the sensor and sample, and reflections from nearby sample edges and boundaries. A defect is determined to exist when a difference is found between …

Adhesion-Delamination Mechanics Of A Prestressed Rectangular Film Adhered Onto A Rigid Substrate, Ming Fung Wong, Gang Duan, Kai-Tak Wan

Mechanical and Aerospace Engineering Faculty Research & Creative Works

A prestressed rectangular film clamped at both ends delaminates from a rigid punch. based on a thermodynamic energy balance, the delamination mechanics is derived to relate the simultaneous external tensile force applied to the punch, punch displacement, and contact area. Effects of the coupled tensile residual membrane stress and adhesion energy at the punch-film interface are investigated. a "pinch off" (stable shrinking of the contact area to a line) is predicted, contrasting the nonzero "pull-off" radius in a clamped circular film. the model is useful in understanding the behavior of various adhesion-delamination phenomena, especially in one dimensional capacitive microelectromechanical systems …

Additional Shear Wall Values For Light Weight Steel Framing, Reynaud Serrette, Jose Encalada, Georgi Hall, Brandon Matchen, Hoang Nguygen, Alexander Williams

American Iron and Steel Institute (AISI) Specifications, Standards, Manuals and Research Reports (1946 - present)

This report presents the results of 16 monotonic and 28 cyclic tests of flat strap X-braced walls, steel sheathed shear walls, high aspect ratio shear walls and shear walls framed with 54-mil and 43-mil studs. The findings provided a basis for continued research and development efforts, leading to the establishment of provisions for cold-formed steel-framed diagonal strap braced walls and Type I shear walls.

Dielectric Response Of Sr Doped Cacu₃Ti₄O₁₂ Ceramics, Wei Li, Robert W. Schwartz, Aiping Chen, Jinsong Zhu

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Ca1−xSrxCu3Ti4O12 (x=0, 0.1, and 0.2) ceramics were fabricated and their dielectric properties were investigated. It was found that the dielectric constant significantly decreased with the increase of Sr content at low temperature region (<250 K) and remained almost unchanged at high temperature region (>250 K). Three sets of relaxation peaks were observed in electric modulus plots, which were considered to be associated with grains, domain boundaries, and grain boundaries, respectively. Through the analysis of the heights and calculated activation energies of the relaxation peaks, it is strongly believed that the suppressed dielectric constant is related to the change of domain boundaries with Sr doping. ©2007 American Institute of Physics

Damage Detection In Ambient Vibration Using Proportional Flexibility Matrix With Incomplete Measured Dofs, Zhongdong Duan, Guirong Yan, Jinping Ou, Billie F. Spencer

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Structural Damage Detections based on the Changes of Dynamic Properties Are a Major Concern Tor Structural Health Monitoring. in This Paper. Efforts Are Made to Extend the Flexibility-Based Damage Localization Methods, Especially the Damage Locating Vector (DLV) Method, to the Case of Ambient Vibration with Incomplete Measured Degree of Freedom, Where Flexibility Matrices Are Not Available. First, the Method to Assemble a Proportional Flexibility Matrix (PFM) with Arbitrarily Scaled Modal Shapes of Full Measured Degrees of Freedom (DOF) is Introduced. the PFM is within a Scalar Multiplier to the Real Flexibility Matrix, and the Multiplier is Shown to Be the …

Exploring Effective Methods For Simulating Damaged Structures With Geometric Variation: Toward Intelligent Failure Detection, Daniel A. Mcadams, David Comella, Irem Y. Tumer

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Inaccuracies in the modeling assumptions about the distributional characteristics of the monitored signatures have been shown to cause frequent false positives in vehicle monitoring systems for high-risk aerospace applications. to enable the development of robust fault detection methods, this work explores the deterministic as well as variational characteristics of failure signatures. Specifically, we explore the combined impact of crack damage and manufacturing variation on the vibrational characteristics of beams. the transverse vibration and associated eigenfrequencies of the beams are considered. Two different approaches are used to model beam vibrations with and without crack damage. the first approach uses a finite …

Multifrequency Eddy Current Inspection Of Corrosion In Clad Aluminum Riveted Lap Joints And Its Effect On Fatigue Life, Shridhar Natarajan, Anthony Chukwujekwu Okafor

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Aging aircraft are prone to corrosion damage and fatigue cracks in riveted lap joints of fuselage skin panels. This can cause catastrophic failure if not detected and repaired. Hence detection of corrosion damage and monitoring its effect on structural integrity are essential. This paper presents multifrequency eddy current (EC) inspection of corrosion damage and machined material loss defect in clad A1 2024-T3 riveted lap joints and its effect on fatigue life. Results of eddy current inspection, corrosion product removal and fatigue testing are presented.

Ccfss Technical Bulletin Spring 2007, Wei-Wen Yu Center For Cold-Formed Steel Structures

CCFSS Technical Bulletins (1993 - 2020)

No abstract provided.

Percussive Penetration Of Unconsolidated Granular Media In A Laboratory Setting, Leslie S. Gertsch

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

This controlled study examined the feasibility of a simple percussive approach to drilling through unconsolidated regolith deposits on Mars. The experiments showed that the approach is feasible at the low power levels and low confining pressures used, and that the rate of impact is more important to the penetration rate than is the mass of the impactor (hammer). More massive impactors tend to lower energy efficiency, as they do in terrestrial pile-driving. Unexpectedly, penetration plotted against applied energy tends to cluster into parallel linear trends. Within a given cluster, penetration is very sensitive to applied energy, while between clusters, the …

Ccfss News Spring 2007, Wei-Wen Yu Center For Cold-Formed Steel Structures

CCFSS Newsletters (1999 - 2008)

No abstract provided.

Nanofibrous Articles, Gene Kim, Bonnie Bachman, Stephen O. Bozzone

Economics Faculty Research & Creative Works

Nanofibrous articles can be manufactured by a process that includes preparation of a surface of a substrate to provide an adhesion mechanism for securing the nanofibers to the surface. The nanofibers can be dispersed in an area near the substrate for the purpose of being adhered to the surface. If an ordered arrangement of nanofibers is required, an electric field can be provided in the area where the nanofibers are dispersed to selectively control an ordering of the nanofibers as they are adhered to the surface by the adhesion mechanism.

Mechanical Characterization Of Spherical Hydrogels: Contact Diameter Measurement, Joshua Bunch

Opportunities for Undergraduate Research Experience Program (OURE)

In an effort to develop new ophthalmic treatments revolving around the ocular lens, the mechanical characteristics of natural ocular lenses and synthetic models must be determined and compared. One mechanical characteristic that is necessary when making comparisons is the variation of contact circle diameter or contact area with varying strains. A method was used in this experiment to measure the varying contact circle diameter of spherical hydrogels at strains up to 15%. This method could be used to estimate the varying contact diameter of other similar materials such as natural ocular lenses if the precision of the method is improved. …

Parallel Machine Tool Development, Adam Bunton

Opportunities for Undergraduate Research Experience Program (OURE)

The work done during this OURE centered on the parallel machining center that is under development by a research group led by Dr. R. Landers. The specific tasks associated with this research involved the design of several parts, documentation of the processes for assembly and operation, procurement of some materials and stock parts, and involvement with experiments with the machine tool. These various aspects are outlined in the following report, with emphasis on the design of components.

Development Of Single Chamber Solid Oxide Fuel Cells With Porous Samaria Doped Ceria Electrolytes, Nathaniel Goss

Opportunities for Undergraduate Research Experience Program (OURE)

Single chamber solid oxide fuel cells generate electricity using hydrogen and hydrocarbon fuel mixed with oxygen at intermediate temperatures (400-800°C) without using seals to separate the gases. A single-chamber solid oxide fuel cell was fabricated with a porous samaria doped ceria (SOC) electrolyte, nickel oxide anode, and a lanthanum strontium cobalt iron oxide (LSCF) cathode. Instead of separately sintering the different components at different temperatures, the electrolyte and electrodes were co-sintered at 1100°C. The porous SOC electrolyte approached 84% theoretical density when sintered at 1100° C. The fuel cell had a maximum open circuit voltage of .65 V at 550°C. …

Concepts For The Nanosat- 5 Satellite Design Competition, Sunil C. Aggarwal

Opportunities for Undergraduate Research Experience Program (OURE)

This paper presents feasible small space satellite missions which are of interest to the U.S. Air Force and can be used to get selected and win the NANOSAT-5 satellite design competition. Some thought on which of these missions can be used by the University of Missouri-Rolla to successfully take part in the competition have also been presented.

Data Fusion Techniques For Health Monitoring Of Aging Aircraft And Skin Cancer Detection, Kapil Gupta

Doctoral Dissertations

"Data fusion is generally practiced to enhance decision or inference making capability. Sensor and information source data may often be corrupted by noise or other factors. Data fusion can be used to improve sensor and/or information source data quality and reliability and improve detection accuracy. There are several types of data fusion, including raw data level, feature level, and decision level.

This work presents the investigation and development of image and signal processing, computational intelligence, fuzzy logic, and statistical techniques for different types of data fusion for a varied range of applications. Raw data and decision level fusion approaches are …

Mechanical Integrity And Behavior Of Thin Films And Their Applications In Mems, Gang Duan

Doctoral Dissertations

"Electric actuated thin films are widely used in micro-electromechanical systems (MEMS) such as radio frequency switches (RF-switches), micro-pumps and valves, and electrostatic actuators. This dissertation will focus on the operation of a MEMS-RF-switch. In a typical MEMS-RF-switch, a mechanically suspended 1-D rectangular or 2-D axisymmetric thin film is pulled by an electrostatic voltage (V₀) applied to an electrode-pad directly underneath. When V₀ exceeds a certain "pull-in" threshold, V₀*, the thin film makes direct contact with the pad so that either an "on" or "off" signal is induced, and when the voltage is removed, the thin film resumes its original undeformed …

Energy-Aware And Secure Routing With Trust Levels For Wireless Ad Hoc And Sensor Networks, Eyad Taqieddin

Doctoral Dissertations

"This dissertation focuses on the development of routing algorithms for secure and trusted routing in wireless ad hoc and sensor network. The first paper presents the Trust Level Routing (TLR) protocol, an extension of the optimized energy-delay routing (OEDR) protocol, focusing on the integrity, reliability and survivability of the wireless network...The second paper analyzes both OLSR and TLR in terms of survivability and reliability to emphasize the improved performance of the network in terms of lifetime and proper delivery of data...The third paper proposes a statistical reputation model that uses the watchdog mechanism to observe the cooperation of the neighboring …

Mechanical Fastener Pull-Out In Recycled Plastic Lumber, Ryan Dusheke

Opportunities for Undergraduate Research Experience Program (OURE)

The purpose of this paper is to present test results for the examination of mechanical fastener pull-out in plastic lumber. The testing was performed on both 1 Od galvanized steel nails, nominally 3" long and 0.148" in diameter, and No. 10 flathead low-carbon steel screws, nominally I" long. l "x6" Trimax plastic lumber, produced by US Plastic Lumber, was used for all testing. Tests were performed in each of the three sides of the boards. To evaluate the performance of the materials in varying conditions, testing was performed at -20°f, room temperature, and 125°f.

Performance Of Steel Products Coated With Zinc And Zinc Alloys In Pressure Treated Wood, Nahb Research Center, Inc.

American Iron and Steel Institute (AISI) Specifications, Standards, Manuals and Research Reports (1946 - present)

No abstract provided.

Simple Penning Ion Source For Laboratory Research And Development Applications, Joshua L. Rovey, Brandon P. Ruzic, Thomas J. Houlahan

Mechanical and Aerospace Engineering Faculty Research & Creative Works

A simple Penning ion generator (PIG) that can be easily fabricated with simple machining skills and standard laboratory accessories is described. The PIG source uses an iron cathode body, samarium cobalt permanent magnet, stainless steel anode, and iron cathode faceplate to generate a plasma discharge that yields a continuous 1 mA beam of positively charged hydrogen ions at 1 mTorr of pressure. This operating condition requires 5.4 kV and 32.4 W of power. Operation with helium is similar to hydrogen. The ion source is being designed and investigated for use in a sealed-tube neutron generator; however, this ion source is …

Method And System For Far-Field Microscopy To Exceeding Diffraction-Limit Resolution, C. Ya, Hai-Lung Tsai

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The bio-sample (e.g., a live cell) is labeled with a proper number of nanoparticles. Each nanoparticle is pre-co-doped with a controlled ratio of fluorophore donors and acceptors. Two laser pulses are applied to the bio-sample. The first laser pulse has a center wavelength near the peak of absorption spectrum of acceptors. The intensity of first laser pulse is adjusted such that FRET saturation occurs near the center of the focal spot. The focal spot of the first laser pulse is a diffraction-limited Airy disk that has the highest laser intensity in the center of the focal spot. The second laser …

Acoustic Emission Detection And Prediction Of Fatigue Crack Propagation In Composite Patch Repairs Using Neural Networks, Navdeep Singh, Navrag Singh, Anthony Chukwujekwu Okafor

Mechanical and Aerospace Engineering Faculty Research & Creative Works

An aircraft is subjected to severe structural and aerodynamic loads during its service life. These loads can cause damage or weakening of the structure especially for aging military and civilian aircraft, thereby affecting its load carrying capabilities. Hence composite patch repairs are increasingly used to repair damaged aircraft metallic structures to restore its structural efficiency. This paper presents the results of Acoustic Emission (AE) monitoring of crack propagation in 2024-T3 Clad aluminum panels repaired with adhesively bonded octagonal, single sided boron/epoxy composite patch under tension-tension fatigue loading. Crack propagation gages were used to monitor crack initiation. The identified AE sensor …

Wetting Kinetics Of A Thin Film Evaporating In Air, S. Saritha, Partho Neogi

Chemical and Biochemical Engineering Faculty Research & Creative Works

The conservation equation and the equations of motion are solved for a case where a thin liquid film moves out of a slot onto a horizontal surface. The liquid is allowed to evaporate into air. The evaporation process is taken to be isothermal. Lubrication theory approximation is used where only the tangential velocity and its dependence only in the normal direction are considered. The dynamics of thin films includes the use of disjoining pressure for a pure liquid and where there is a dissolved polymer. The results show that evaporation is quicker than film thinning such that a spreading regime …

Heat Transfer Coefficients In A High-Pressure Bubble Column, Chengtian Wu, Muthanna H. Al-Dahhan, Anand Prakash

Chemical and Biochemical Engineering Faculty Research & Creative Works

Time-Averaged Local Heat Transfer Coefficients Were Studied in a 0.16 M Inner Diameter High-Pressure Air-Water Bubble Column. the Effects of the Superficial Gas Velocity (Up to 0.30 M/s), Pressure (Up to 10 Bar), Probe Position, and Probe Orientation Were Investigated. the Heat Transfer Coefficients Increased with Superficial Gas Velocity, and the Values in the Center of the Column Were 9-16% Greater Than Those Near the Wall Region under Atmospheric Pressure (1 Bar). with the Increase in Pressure, the Heat Transfer Coefficients Decreased Due to Combined Effects of Bubble Size Decreasing, Gas Holdup Increasing, and Bubble Number Increasing. the Heat Transfer …

Bridge Damage Detection Using An Intelligent Engineering System, Dionysios N. Danilatos

Masters Theses

"This thesis concerns the design of an algorithm that is capable to detect structural damage in civil infrastructure bridges. The algorithm, which will be dubbed Damage Diagnostics System throughout the thesis, is the software component of a broader Bridge Health Monitoring System. This broader system integrates software and hardware,such as sensors and data acquisition components...The rationale for the Structural Damage Diagnosis is based on the principle of the structural vibration testing. The Health Monitoring System captures the vibration signals, as the bridge responds to excitation from various sources. The purpose of the Diagnostic System is to extract information from the …

Equivalent Circuit For Transient Conduction And Convection Systems, Bassam Sabry Mohammad Abdelnabi

Masters Theses

"Transient response of a natural convection system is investigated by numerical simulation using FLUENT code. An Integrator Circuit analogy was recently proposed for natural convection system. The proposed analogy was further confirmed by these recent simulations. New simulation results also suggest that a natural convection system acts as a "Low Pass" filter for transients. Transient transmission/attenuation factor was found to be a function of both fluid properties and the flow characteristics. Transmission/attenuation factor was also found to be a strong function of fluctuation frequency"--Abstract, page iv.

Design And Implementation Of A Hardened Distributed Network Endpoint Security System For Improving The Security Of Internet Protocol-Based Networks, William Dee Atkins

Masters Theses

"This thesis proposes a distributed approach to securing computer networks by delegating the role of a conventional firewall to a collection of nodes and controllers placed throughout the networks they are intended toprotect from attack. This distributed firewall system is a specific application of a generalized distriubted system framework that is also proposed in this thesis. The design and implementation of both the generalized framework and the application of the framework in creating a distributed firewall system for use on Ethernet-based networks that rely on the Internet Protocol are discussed. Conclusions based upon the preliminary implementation of the proposed systems …

Impact Of Ammonia On The Leaching Characteristics Of Mercury From Coal Fly Ash, Harmanjit Mallhi

Masters Theses

"Approximately half of the electricity produced in the United States is generated by coal-fired power plants. Coal combustion products (CCPs) such as fly ash, bottom ash, flue gas desulphurization (FGD) material, boiler slag are either disposed in landfills or impoundments, or beneficially used...It has been long known that fly ash contains many trace elements (As, Se, Hg Cr, Cd, Ni, Pb, Cu,Co, etc.) that can be of environmental concern. Mercury is of special interest since it is a known carcinogen and has the ability to bio-accumulate. The primary objectives of thesis research were to understand the leaching behavior of mercury …

The Leaching Behavior Of Arsenic, Selenium And Other Trace Elements In Coal Fly Ash, Tian Wang

Doctoral Dissertations

"The goals of this study are four fold, they are: (1) to investigate the leaching behavior of arsenic and selenium from fly ash as well as their affecting factors; (2) to analyze the speciation of arsenic and selenium in fly ash leachate; (3) to develop a modeling approach to quantify the availability and stability of trace cationic elements in fly ash; (4) to apply this model to describe the leaching/adsorption behavior of arsenic and selenium on fly ash, as well as the calcium effect on arsenic (V) adsorption process"--Abstract, page iv.