Engineering Commons^™

A Finite Element Formulation For Aft Fan Duct Acoustic Radiation, Walter Eversman

Mechanical and Aerospace Engineering Faculty Research & Creative Works

A finite element code has been developed for the prediction of the radiated acoustic field in and around the aft fan duct of a turbofan engine. The acoustic field is modeled based on the assumption that the steady flow in and around the nacelle is irrotational as is the acoustic perturbation. The geometry of the nacelle is axisymmetric, and the acoustic source is harmonic and decomposed into its angular harmonics. The steady flow is computed on the acoustic mesh and provides data for the acoustic calculations. The jet is included in the steady flow potential flow model by separating the …

Integrating Design Into The Sophomore And Junior Level Mechanics Courses, Douglas R. Carroll

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Engineering schools across the country are developing ways of integrating design into their curriculum, and a question that often arises is how to best integrate design into the sophomore and junior level courses. Freshman design projects or mechanical dissection courses are designed to give the students hands-on experience in conceptual design and construction, with little if any of the mathematical modeling normally used in engineering design. The capstone senior design project is a true engineering design experience, where students draw from their background to conceptualize, analyze, model, refine, and optimize a product to meet design, manufacturing, and life cycle cost …

Adaptive Critic Based Neurocontroller For Autolanding Of Aircraft With Varying Glideslopes, Gaurav Saini, S. N. Balakrishnan

Mechanical and Aerospace Engineering Faculty Research & Creative Works

In this paper, adaptive critic based neural networks have been used to design a controller for a benchmark problem in aircraft autolanding. The adaptive critic control methodology comprises successive adaptations of two neural networks, namely `action' and `critic' networks until closed loop optimal control is achieved. The autolanding problem deals with longitudinal dynamics of an aircraft which is to be landed in a specified touchdown region in the presence of wind disturbances and gusts using elevator deflection as the control for glideslope and flare modes. The performance of the neurocontroller is compared to that of a conventional PID controller. Neurocontroller's …

Adaptive Critic Based Neurocontroller For Autolanding Of Aircrafts, S. N. Balakrishnan, Gaurav Saini

Mechanical and Aerospace Engineering Faculty Research & Creative Works

In this paper, adaptive critic based neural networks have been used to design a controller for a benchmark problem in aircraft autolanding. The adaptive critic control methodology comprises successive adaptations of two neural networks, namely action and critic network (which approximate the Hamiltonian equations associated with optimal control theory) until closed loop optimal control is achieved. The autolanding problem deals with longitudinal dynamics of an aircraft which is to be landed in a specified touchdown region (within acceptable ranges of speed, pitch angle and sink rate) in the presence of wind disturbances and gusts using elevator deflection as the control …

Stability Of Discrete-Time Matrix Polynomials, Khanh Tu Ngo, Kelvin T. Erickson

Electrical and Computer Engineering Faculty Research & Creative Works

This paper derives conditions for the stability of discrete-time systems that can be modeled by a vector difference equation, where the variables are m x 1 vectors and the coefficients are m x m matrices. Stability of the system is related to the locations of the roots of the determinant of a real m x m matrix polynomial of nth order. In this case, sufficient conditions for the system to be stable are derived. The conditions are imposed on the infinity norm of two matrices constructed from the coefficient matrices and do not require the computation of the determinant polynomial. …

The New--But Is It Improved?--Power System, Mariesa Crow

Electrical and Computer Engineering Faculty Research & Creative Works

In this paper, the author examines the effect that deregulation will have on the US power system. The paper details how the electric power industry in the USA is undergoing major changes, both politically and technically, as a result of the Federal Energy Regulatory Commission's Orders 888 and 889 issued in 1996. These orders essentially deregulate the transmission network, allowing producers and customers access to the network for electricity transactions.

Evaluation Of Unified Interaction Parameter Model Parameters For Calculating Activities Of Ferromanganese Alloys: Mn-Fe-C, Mn-Fe-Si, Mn-C-Si, And Mn-Fe-C-Si Systems, L. I. Hongjie, Arthur E. Morris

Materials Science and Engineering Faculty Research & Creative Works

Interaction parameters for Mn-based alloys were evaluated using both carbon solubility and activity data for species in binary and ternary manganese alloys. The parameters at 1400 °C are the following εcc = -4.5; εccc = 58.8; εFeCC = 1.5; εFeCC = 2.5; In γC0 = -1.15 . εsisi = 15.5; εsisisi = 2.69; εFeSi = 2.5; εcsi = 12.4; εccsi = 27.5; In γSi0 = -7.46 The unified interaction parameter model (UIPM) was used to calculate the activity coefficients of species and the solubility of carbon in ferromanganese alloys (up to quaternary Mn-Fe-C-Si). The results were in good agreement with …

Short-Term Resource Scheduling With Ramp Constraints [Power Generation Scheduling], Chung-Li Tseng, Chao-An Li, A. J. Svoboda, R. B. Johnson

Engineering Management and Systems Engineering Faculty Research & Creative Works

This paper describes a Lagrangian relaxation-based method to solve the short-term resource scheduling (STRS) problem with ramp constraints. Instead of discretizing the generation levels, the ramp rate constraints are relaxed with the system demand constraints using Lagrange multipliers. Three kinds of ramp constraints, startup, operating and shutdown ramp constraints are considered. The proposed method has been applied to solve the hydro-thermal generation scheduling problem at PG&E. An example alone with numerical results is also presented

Stemming Technique For Loading Angled Holes Charged With Anfo, Michael David Wilkins

Masters Theses

"Little research has been published on stemming blast holes, particularly what happens during the process. Previous work has concentrated on the performance of the inert material to find the best way to seal the hole and retain the explosive energy, at the exclusion of determining what happens during the loading and stemming process. Such studies were carried out by Konya and Worsey.

The major problem with stemming studies is that rock is an opaque material, and the actual mechanisms involved during the stemming process cannot be viewed. For this reason, tests were performed using clear tubes to simulate a blast …

Damage Detection Of Bridge-Like Structures Using State Space Models, Javier Valentin Sivico

Masters Theses

"A global damage detection algorithm for bridge-like structures is proposed. This method provides the capability of determining the reduction in both stiffness and damping parameters of the structural elements. It is assumed the mass of the structural elements is not affected by the damages, which is a reasonable assumption for bridge-like structures. The proposed method uses the state space representation of the structural dynamics to make the diagnosis of the structural integrity. Given that the state space representation of any system is not unique, the damage detection procedure is developed for the physical coordinates of the state space representation. A …

Prediction Of Yarn Strength From Fiber Properties Using Fuzzy Artmap, Raonak Zaman, Donald C. Wunsch

Electrical and Computer Engineering Faculty Research & Creative Works

The count-strength-product (CSP) of cotton yarn is a complex function of fiber properties and spinning performance. The traditional way of predicting yarn CSP is using linear multiple regression. The correlation coefficient between actual CSP and predicted CSP obtained from linear regression is almost always less than 0.9. In this paper, we used a Fuzzy ARTMAP network to predict yarn CSP from fiber properties and spinning performance. Fiber properties and spinning data were used as inputs to ART_a, and yarn CSP was used as ART_b input. Our objectives are: better prediction of the quality of the end product, …

Safety Analysis Of Redundant Systems Using Fuzzy Probability Theory, James P. Dunyak, Ihab W. Ssad, Donald C. Wunsch

Electrical and Computer Engineering Faculty Research & Creative Works

No abstract provided.

A Biologically Inspired Connectionist Architecture For Directing Attention To Salient Visual Field Objects, David Lee Enke

Engineering Management and Systems Engineering Faculty Research & Creative Works

In an attempt to incorporate basic visual attention abilities into existing artificial vision systems, a neural model of the bidirectional interactions within and between the brain regions believed to be involved in human visual attention has been developed. This model currently gives an artificial vision system the ability to attend to salient, or pop-out features and objects within the vision system''s field of view. After a review of the physiology of human visual attention, a network model of the aforementioned neural interactions is presented, followed by a demonstration of its performance.

Derivation Of Fuzzy Membership Functions Using One-Dimensional Self-Organizing Maps, Thomas E. Sandidge, Cihan H. Dagli

Engineering Management and Systems Engineering Faculty Research & Creative Works

This paper discusses a system of self-organizing maps that approximate the fuzzy membership function for an arbitrary number of fuzzy classes. This is done through the ordering and clustering properties of one-dimensional self-organizing maps and iterative approximation of conditional probabilities of nodes in one map being the winner given that a node in the other map is the winner. Application of this system reduces fuzzy membership design time to that required to train the system of self-organizing maps.

Technology Acquisition And Utilization In Metal Goods, N. Alp, B. Alp, Yildirim Omurtag

Engineering Management and Systems Engineering Faculty Research & Creative Works

This paper analyzes the technology acquisition and utilization process in metal goods manufacturing organizations through a survey instrument which is conducted in the Mid-West region of the US. The goal of this study is to identify the channels, types, reasons, impacts, difficulties, and limitations of technology acquisition and utilization process in metal goods sector.

Innovative Applications Of Groupware For Solving Engineering Design Problems, Leslie F. Monplaisir, Colin Othniel Benjamin, Choayuan Lu

Engineering Management and Systems Engineering Faculty Research & Creative Works

In these case studies, groupware was used as a group decision-making environment to assist teams evaluating a quality function deployment framework for risk management and agile manufacturing system designs. In the first case, teams identified customers' requirements and risk categories for a research and development project. They then mapped the relationship between these customer requirements and the risk categories. In the second case, cross-functional teams collaborated in selecting the best layout for a cellular manufacturing facility. These experimental findings support the use of group decision systems by design and project teams required to manage R&D projects or to design agile …

The Effect Of Casting Shape And Size On Solidification Time: A New Approach, Murat Tiryakioǧlu, Ergin Tiryakioǧlu, Donald R. Askeland

Materials Science and Engineering Faculty Research & Creative Works

The limitations of Chvorinov's Rule for predicting the solidification time of a casting are discussed and previous studies intended to modify Chvorinov's Rule in order to express the effect of the size and shape of castings on solidification time are reviewed. A new model that introduces a shape factor is presented that predicts the solidification times of castings as well as or better than Chvorinov's Rule, particularly for more complex shapes. The validity of the new model is compared with the conventional Chvorinov's Rule by a statistical analysis of twelve sets of data obtained from the literature.

Ferroelectric Films As A Fashion Object For Polycrystalline Film Investigation, V. Petrovsky, Harlan U. Anderson, M. Shumsky

Materials Science and Engineering Faculty Research & Creative Works

BaxSr1-xTiO3 (BST), PbZrxTi1-xO3 (PZT) and two-layer PZT-BST films were prepared on Pt, Si(100) and Si(111) substrates by a sol-gel method. XRD analysis shows that the PZT films on the Si(111) substrates tended to be preferentially oriented in the (110) direction. The nondestructive readout of the state of ferroelectric polarization was investigated by three methods: the pyroelectric effect, the non-linearity of the capacitance and the field effect in MOS structures. It is shown that all three methods provide nondestructive readout, and the choice between them depends on the intended use.

Hydro Unit Commitment In Hydro-Thermal Optimization, Chao-An Li, E. Hsu, Chung-Li Tseng, A. J. Svoboda, R. B. Johnson

Engineering Management and Systems Engineering Faculty Research & Creative Works

In this paper, the authors develop a model and technique for solving the combined hydro and thermal unit commitment problem, taking into full account the hydro unit dynamic constraints in achieving overall economy of power system operation. The combined hydrothermal unit commitment problem is solved by a decomposition and coordination approach. Thermal unit commitment is solved using a conventional Lagrangian relaxation technique. The hydro system is divided into watersheds, which are further broken down into reservoirs. The watersheds are optimized by network flow programming (NFP). Priority-list-based dynamic programming is used to solve the hydro unit commitment (HUC) problem at the …

Managing Cultural Differences For Engineers, Halvard E. Nystrom

Engineering Management and Systems Engineering Faculty Research & Creative Works

Understanding cultural issues, developing cross-cultural communication skills and recognizing the need to effectively apply these skills in the global arena are becoming critical success factors for an increasing number of engineers. To address these needs, an engineering management class has been developed at the University of Missouri-Rolla, USA, that uses a team project approach as the major method to achieve the learning objectives. The student teams develop training manuals for dealing with engineers from specific international cultures, based on the material learned in class as well as personal interactions with individuals of the specific ethnic background. An application of this …

Numerical Simulations Of Full- Scale Corroded Pipe Tests With Combined Loading, Samit Roy, S. Grigory, M. Smith, M. F. Kanninen, M. Anderson

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The ANSI/ASME B31G guideline has been useful to pipeline operators in assessing the integrity of corroded line pipe. Because large safety margins have had to be incorporated, the guidelines can be excessively conservative, which in turn can force costly repairs and replacements that may not actually be necessary. On the other hand, because the current guidelines consider only pressure loading and neglect bending and axial compression, they could give nonconservative failure predictions when combined loading exists. Therefore, a study was initiated to develop a theoretically sound methodology for assessing the integrity of corroded line pipe subjected to combined loading. A …

Analysis Of Rockbolt Reinforcement Using Beam-Column Theory, Samit Roy, Anand B. Rajagopalan

Mechanical and Aerospace Engineering Faculty Research & Creative Works

A simple analytical procedure that applies classical beam-column theory for evaluating passive rock bolt roof reinforcement is presented in this paper. The analytical model is derived from first principles and is capable modelling any number of reinforcing bolts. Each rock bolt is modelled as a linear spring and the model allows for non-uniform bolt spacing. In this study the rock beam is assumed to be isotropic and linearly elastic for the sake of simplicity. However, the analytical model can be extended to include anisotropic rock mass as well as inelastic material behavior. The solution to the couped set of governing …

Radiative Heating In Scramjet Combustors, Harlan F. Nelson

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Currently, there is considerable interest in scramjet engines for hypersonic aircraft and missiles. This paper presents preliminary calculations of the radiative heating of the walls of scramjet combustion chambers. The analysis assumes isothermal, constant property flow fields that are representative of actual combustor flow fields. The fuel is H2, and N2 is taken as inert. Temperature in the combustor is on the order of 2000-3000 K and the pressure is of the order of 5 atm. The combustion products consist mainly of H2O and OH. These gases are strong radiators in the infrared. Radiation heating can be significant because of …

A System For Collecting Milligram Quantities Of Cloud Condensation Nuclei, Darryl J. Alofs, Donald E. Hagen, Steven D. Medley, Daniel R. White, John L. Schmitt, Allen L. Williams

Mechanical and Aerospace Engineering Faculty Research & Creative Works

An Experimental System to Collect Cloud Condensation Nuclei (CCN) Onto Filters in Amounts Sufficient for Chemical Analysis is Described. This Experimental Apparatus is Designed to Process Ambient Air at a Rate of More Than 1 M3/min. Two Identical Systems Have Been Built. One is Installed in a Laboratory at Rolla, MO. the Other is Installed on an 11 M Long Trailer. the System Isolates Three Size Classes of CCN, Having Mass Median Diameters of 0.27, 0.12, and 0.075 Μm, Respectively, and Mass Collection Rates of 11.5, 1.28, and 0.13 Mg/day, Respectively. the above Sizes and Collection Rates Are Obtained from …

Vehicle Performance Optimization Utilizing The Air Turbo-Ramjet Propulsion System; Methodology Development And Applications, Kirk Christensen

Doctoral Dissertations

"The ATR (Air TurboRocket) is an air breathing propulsion system in which the turbocompressor turbine is powered by a hot drive gas which is generated independently of the air flow through the compressor. The ATR has a lower specific impulse (Isp) and higher thrust compared to a similar size turbojet but a lower thrust and higher Isp compared to similar size solid rocket motor (SRM). This work defines the benefits of ATR propulsion for tactical vehicles.

ATR simulation codes were developed to support analysis of hypothetical ATR powered vehicles. Both turbojet powered and SRM powered vehicles were also evaluated against …

Service Quality Using The Deviation-Score Approach To Fit In Contingency Theory In A U.S. Army Corps Of Engineers Setting, Donald Robert Groh

Doctoral Dissertations

"The purpose of this study is to learn how organizational work unit context, structure, and processes relate to service quality. The theoretical basis for the research is that organizational work units should be structured based on the work that they perform. If the work that a unit performs is highly variable, then the work unit should be structured in such a way as to provide flexibility, that is, few rules and procedures and highly decentralized decision making. If the work that a unit performs is not variable, then the work unit should be structured to provide a non-varying product or …

Multiobjective Optimum Design Of Static And Seismic-Resistant Structures With Genetic Algorithm, Fuzzy Logic And Game Theory, Dan Li

Doctoral Dissertations

"The goal of this research is to develop a constrained multiobjective optimization method in the form of a robust, practical, problem-independent algorithm, and to investigate the effect of multiobjective optimization on structural design.

This research studies the properties and characteristics of multiobjective optimization and solutions. Design objectives, constraints and design variables as well as their effect on structural design and behaviors are investigated. Dynamic input energy for a multidegree-of-freedom structure is formulated. A multiobjective optimization algorithm based on game theory is developed. Fuzzy set theory is introduced to construct a fuzzy constrained environment. A Pareto genetic algorithm is developed based …

Immobilization Of Radioactive Materials In Iron Phosphate Glass, Melissa G. Mesko

Doctoral Dissertations

"The current study investigates the feasibility of using iron phosphate glass for the immobilization of radioactive wastes considered incompatible with borosilicate glass. Wastes may be incompatible with borosilicate glass due to high phosphorus content (Hanford tank sludges), the presence of halides (CsCl and SrF₂ capsules), or large amounts of uranium (SNF).

Between 20 and 60 wt% Hanford tank sludge was vitrified with an iron phosphate glass at ≤ 1200°C in 1 hour. The chemical durability of iron phosphate glassy wasteforms was as good as, or better than a reference borosilicate glass (10^-9 g/cm²/min) in distilled water …

Magnetic Dynamics In Underdoped Yba2⁢Cu3⁢O7−X: Direct Observation Of A Superconducting Gap, Pengcheng Dai, Mohana Yethiraj, Herbert A. Mook, Terrence B. Lindemer, Fatih Dogan

Materials Science and Engineering Faculty Research & Creative Works

Polarized and unpolarized triple-axis neutron measurements were performed on an underdoped crystal of YBa₂⁢Cu_3⁢O_7−x (x = 0.4 ±0.02, T_c = 62.7⁢K). Our results indicate, contrary to earlier evidence, that the spin excitations in the superconducting state are essentially the same as those in the fully doped material except that the unusual 41 meV resonance is observed at 34.8 meV. The normal state spin excitations are characterized by a weakly energy-dependent continuum whose temperature dependence shows the clear signature of a superconducting gap at T_c. The enhancement at the resonance is accompanied by …

The Transport Properties Of Nanocrystalline Srce0.95yb0.05o3 Thin Films, Igor Kosacki, Harlan U. Anderson

Materials Science and Engineering Faculty Research & Creative Works

The results of electrical transport measurements on nanocrystalline SrCe0.95Yb0.05O3 thin films are presented. Dense SrCe0.95Yb0.05O3 thin films with 30-70 nm grain size have been obtained using a spin-coating technique. These films exhibit about 103 higher electrical conductivity when compared with the bulk polycrystalline material. The grain size of thin films is stable to temperatures as high as 1000 °C since no grain-coarsening was observed. These unique electrical properties of nanocrystalline SrCe0.09Yb0.05O3 thin films are attributed to a dominant role of grain boundaries and/or interfaces. © 1996 American Institute of Physics.