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Aerospace Engineering

Missouri University of Science and Technology

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Articles 421 - 450 of 473

Full-Text Articles in Mechanical Engineering

Combined Heat And Lass Transfer In Mixed Confection Ower A Horizontal Flat Plate, T. S. Chen, F. A. Strobel Jan 1980

Combined Heat And Lass Transfer In Mixed Confection Ower A Horizontal Flat Plate, T. S. Chen, F. A. Strobel

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The combined effects of buoyancy forces from thermal and species diffusion on the heat and mass transfer characteristics are analyzed for laminar boundary layer flow over a horizontal flat plate. The analysis is restricted to processes with low concentration levels such that the interfacial velocities due to mass diffusion and the diffusion-thermo/thermo-diffusion effects can be neglected. Numerical results for friction factor, Nusselt number, and Sherwood number are presented for gases having a Prandtl number of 0.7, with Schmidt numbers ranging from 0.6 to 2.0. In general, it is found that, for the thermally assisting flow, the surface heat and mass …

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Rubber Covered Rolls-The Nonlinear Elastic Problem, R. C. Batra Jan 1980

Rubber Covered Rolls-The Nonlinear Elastic Problem, R. C. Batra

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The problem of the indentation of a rubberlike layer bonded to a rigid cylinder and indented by another rigid cylinder is analyzed. The rubberlike layer is assumed to be made of a homogeneous Mooncy-Rivlin material. The materially and geometrically nonlinear problem is solved by using the finite-element code developed by the author. Results computed and presented graphically include the pressure profile at the contact surface, stress distribution at the bond surface and the deformed shape of the indented surface. © 1980 by ASME.

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Nucleation Experiments With Monodisperse Nacl Aerosols., Darryl J. Alofs, M. B. Trueblood, D. R. White, V. L. Behr Jan 1979

Nucleation Experiments With Monodisperse Nacl Aerosols., Darryl J. Alofs, M. B. Trueblood, D. R. White, V. L. Behr

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Nucleation Experiments with Monodisperse NaCl Aerosols Showed Good Agreement with the Kohler Theory Relating the Critical Super-Saturation S//c to the Dry Size. Aerosols Produced by Condensing NaCl Showed the Same S//c as Those Produced by Evaporating Aqueous NaCl Solution Droplets. This Indicates that If There is an Energy Barrier in Going from a Dry NaCl Particle to a Solution Droplet, This Energy Barrier is Small. the Fact that the Evaporation Aerosol Particles Are Cubical Crystals and the Condensation Aerosols Are Amorphous Spheres is Shown to Make No Difference in the Nucleation Threshold. the Investigation Also Gives Insights into the Performance …

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Performance Of A Dual-Range Cloud Nucleus Counter., Darryl J. Alofs Jan 1978

Performance Of A Dual-Range Cloud Nucleus Counter., Darryl J. Alofs

Mechanical and Aerospace Engineering Faculty Research & Creative Works

An Instrument for Measuring the Concentrations of Cloud Condensation Nuclei as a Function of Nucleus Critical Supersaturation (S//c) is Described. in the Range 0. 1% Less Than Equivalent to S//c Less Than Equivalent to 0. 1%, the Instrument is Operated as a Vertical Flow Thermal Diffusion Chamber. in the Range of 0. 016% Less Than Equivalent to S//c Less Than Equivalent to 0. 1%, the Chamber is Operated at 100% Humidity, and the Equilibrium Radii of the Nuclei Are Measured with an Optical Counter. This Paper Presents a Large Body of Data Taken in the Laboratory to Evaluate the Performance …

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A Small Horizontal Axis Wind Turbine Feeding Power Into The Utility Grid, G. C. Thomann, M. Jong, M. H. Snyder Oct 1977

A Small Horizontal Axis Wind Turbine Feeding Power Into The Utility Grid, G. C. Thomann, M. Jong, M. H. Snyder

UMR-MEC Conference on Energy / UMR-DNR Conference on Energy

A small horizontal axis wind turbine, with about a 2 kW power output, was constructed to convert wind energy into AC power to be fed into the utility grid. The machine is intended to model operation of the larger wind generators now being built. The variable pitch rotor is 18 ft in diameter and has a GA(W)-1 blade airfoil. The rotor is fabricated from sitka spruce mounted on a commercial propeller/hub system. Rotor speeds of from 75 to 150 rpm are used in operation. A chain drive and helical gear drive system steps up rotor speed to 1800 - 3600 …

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Airfoil Data For Use Of Wind Turbine Designers, Melvin H. Snyder Oct 1977

Airfoil Data For Use Of Wind Turbine Designers, Melvin H. Snyder

UMR-MEC Conference on Energy / UMR-DNR Conference on Energy

This paper reviews design procedures for wind-axis turbine rotors. An "on-design" routine for rotor blade design is presented as well as an "off-design" performance calculation program. Resulting from this review are analyses of desirable characteristics of airfoil sections and of types of data which rotor designers need. Included in the paper are airfoil characteristics for candidate blade sections including 360 degree data for GA(W)-1 and GA(W)-2 airfoils.

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Low Head Power Generation With Bulb Turbines, J. L. Carson, R. S. Samuelson Oct 1977

Low Head Power Generation With Bulb Turbines, J. L. Carson, R. S. Samuelson

UMR-MEC Conference on Energy / UMR-DNR Conference on Energy

Because of uncertainties, delays, and high costs associated with alternative electric energy sources, many agencies responsible for generation of electrical power are investigating means of replacing or supplementing their existing hydroelectric facilities. In the head range between 10 and 60 feet, the bulb-type generating unit, in which the generator is enclosed in a metal capsule within the water passage, has many advantages, including higher efficiency and lower cost, over other types of turbines. Two of the municipalities in the United States which have recently conducted feasibility studies for installing bulb turbines in their systems are the City of Idaho Falls, …

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Studies Of Vibrational Surface Modes In Ionic Crystals. I. Detailed Shell-Model Studies For The Unrelaxed (001) Face Of Seven Crystals Having The Rocksalt Structure, T. S. Chen, F. W. De Wette, G. P. Alldredge Jan 1977

Studies Of Vibrational Surface Modes In Ionic Crystals. I. Detailed Shell-Model Studies For The Unrelaxed (001) Face Of Seven Crystals Having The Rocksalt Structure, T. S. Chen, F. W. De Wette, G. P. Alldredge

Mechanical and Aerospace Engineering Faculty Research & Creative Works

We present a comprehensive, unified account of the lattice dynamics of unrelaxed (001) faces of seven crystals having the rock salt structure, three of which have an absolute gap between the acoustical and optical bulk bands (RbF, RbCl, and NaI) and four of which have overlap between these bulk bands (NaF, NaCl, LiF, and MgO). The results are obtained from calculations of the normal modes of a thin crystal film in which the ionic interactions are described by the rigid-shell model. An outline of the formulation of the shell model for the film is given, and the rapid convergence of …

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Mixed Convection Across A Horizontal Cylinder With Uniform Surface Heat Flux, A. Mucoglu, T. S. Chen Jan 1977

Mixed Convection Across A Horizontal Cylinder With Uniform Surface Heat Flux, A. Mucoglu, T. S. Chen

Mechanical and Aerospace Engineering Faculty Research & Creative Works

No abstract provided.

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Optimal Cantilever Dynamic Vibration Absorbers, R. G. Jacquot, J. Earl Foster Jan 1977

Optimal Cantilever Dynamic Vibration Absorbers, R. G. Jacquot, J. Earl Foster

Mechanical and Aerospace Engineering Faculty Research & Creative Works

This work considers the use of a double-ended cantilever beam as a distributed parameter dynamic vibration absorber applied to a single-degree-of-freedom system in the presence of sinusoidal forces. The problem is analyzed exactly and by an energy approach using a single mode approximation for the cantilever beam. The results for both techniques compare favorably and damping is introduced in the form of a complex beam modulus. Optimal tuning and optimal damping parameters are found for a given ratio of absorber mass to main mass. © 1977 by ASME.

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The Effects Of Main-Flow Radial Velocity On The Stability Of Developing Laminar Pipe Flow, F. C.T. Shen, T. S. Chen, L. M. Huang Jan 1976

The Effects Of Main-Flow Radial Velocity On The Stability Of Developing Laminar Pipe Flow, F. C.T. Shen, T. S. Chen, L. M. Huang

Mechanical and Aerospace Engineering Faculty Research & Creative Works

In studying the stability due to axisymmetric disturbances of the developing flow of an incompressible fluid in the entrance region of a circular tube, a generalized version of the Orr-Sommerfeld equation was derived which takes account of the radial velocity component in the main flow. The new terms in the generalized Orr-Sommerfeld equation are inversely proportional to the Reynolds number. The resulting eigenvalue problem consisting of the disturbance equation and the boundary conditions was solved by a direct numerical integration scheme along with an iteration procedure. Neutral stability curves and critical Reynolds numbers at various axial locations are presented. A …

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Deformation Produced By A Simple Tensile Load In An Isotropic Elastic Body, R. C. Batra Jan 1976

Deformation Produced By A Simple Tensile Load In An Isotropic Elastic Body, R. C. Batra

Mechanical and Aerospace Engineering Faculty Research & Creative Works

It is shown that a simple tensile load produces a simple extension provided the empirical inequalities (Truesdell and Noll [1], eqn. 51.27) hold. © 1976 Noordhoff International Publishing.

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Numerical Simulation Of A Widely Used Cloud Nucleus Counter., Darryl J. Alofs, J. C. Carstens Jan 1976

Numerical Simulation Of A Widely Used Cloud Nucleus Counter., Darryl J. Alofs, J. C. Carstens

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The Performance of the Conventional Horizontal Plate Thermal Diffusion Chamber as a Cloud Nucleus Counter Was Studied. Numerical Calculations Were Performed in Order to Follow the Simultaneous Drop Growth and Sedimentation in the Spatially and Temporally Nonuniform Supersaturation Field. the Effect of Nuclei Distribution and Smallest Detectable Drop Size Were Investigated. the Results Indicate Order of Magnitude Uncertainty in the Count at 0. 1% Supersaturation, and a Factor of 2 Uncertainty at 1. 0% Supersaturation.

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A Closed-Form Solution For The Radiosity At The Edge Of A Rectangular Cavity, Alfred L. Crosbie Jan 1976

A Closed-Form Solution For The Radiosity At The Edge Of A Rectangular Cavity, Alfred L. Crosbie

Mechanical and Aerospace Engineering Faculty Research & Creative Works

No abstract provided.

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Mie Scattering Computations For Moderately Large Spherical Particles, Dwight C. Look Jan 1976

Mie Scattering Computations For Moderately Large Spherical Particles, Dwight C. Look

Mechanical and Aerospace Engineering Faculty Research & Creative Works

No abstract provided.

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Bit Penetration Into Rock-A Finite Element Study, J. K. Wang, T. F. Lehnhoff Jan 1976

Bit Penetration Into Rock-A Finite Element Study, J. K. Wang, T. F. Lehnhoff

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The sequence of rock failure mechanisms and quantitative information on stress, displacement and material failure in the process of bit penetration have been obtained through computer simulation. A finite element approach has been developed to simulate bit penetration from bit-rock interaction to chip formation. A mathematical rock failure model, based on available rock failure experiments, has been proposed to represent post-failure rock behavior and applied in the penetration simulations. The finite element code was developed for two-dimensional plane strain problems to consider non-linear material properties, geometric non-linearity, and fracture propagation. An anistropic element as well as variable stiffness and stress …

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Predicting Natural Frequencies Of A Hydrodynamically Lubricated Journal Bearing With Constant Oil Supply Pressure, D. C. Edwards, N. Khorzad, Charles L. Edwards Jan 1976

Predicting Natural Frequencies Of A Hydrodynamically Lubricated Journal Bearing With Constant Oil Supply Pressure, D. C. Edwards, N. Khorzad, Charles L. Edwards

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The analytical and experimental investigations reported here deal with the natural frequencies and system behavior of a full journal bearing subjected to a small sinusoidal load superimposed on a large unidirectional static load. The analysis, verified by experimentation, shows that the bearing can be regarded as two independent second-order systems acting perpendicular to each other. The variable coefficients of the equations of motion cause the bearing to behave as an underdamped system for low values of static eccentricity ratio to, and as an overdamped system for intermediate values of to. The bearing tends to be unstable above a particular to. …

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Development Of Helicopter Flight Path Models, Alfred Fermelia, Donald A. Gyorog, V. J. Flanigan Jan 1976

Development Of Helicopter Flight Path Models, Alfred Fermelia, Donald A. Gyorog, V. J. Flanigan

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The objective of this paper is to present general techniques for simulating helicopter flight trajectory response. During flight the pilot manipulates the controls either to trim the helicopter for steady flight by balancing the external forces and moments or to produce a desired maneuver by controlling the unbalance of these forces and moments. Discussions of the physical phenomena involved with the aerodynamics of the rotors and fuselage are given in [1] through [3]. The simulated control function will be composed forward-aft cyclic, lateral cyclic, pedal, and collective. This control will be represented by the vector

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Photoionization Of The 6p32,122 Fine-Structure Levels In Cesium, Kaare J. Nygaard, Robert E. Hebner, James A. Jones, Robert J. Corbin Jan 1975

Photoionization Of The 6p32,122 Fine-Structure Levels In Cesium, Kaare J. Nygaard, Robert E. Hebner, James A. Jones, Robert J. Corbin

Physics Faculty Research & Creative Works

The relative photoionization cross sections for cesium atoms selectively excited to the 6P32,122 states have been measured in a triple-crossed-beam experiment. A cesium discharge lamp produced resonant wavelengths of 8521 and 8944 for the excitation process. A Hg-Xe lamp combined with a grating monochromator was used for the actual ionization in the wavelength region from 2500 to 5000. Background counts due to photoionization of ground-state cesium atoms and dimers as well as various surface effects were discriminated against by chopping the excitation light source. The data are compared with results from radiative-recombination measurements in which the fine-structure levels are not …

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Measurement Of Growth Rate To Determine Condensation Coefficients For Water Drops Grown On Natural Cloud Nuclei., A. M. Sinnarwalla, Darryl J. Alofs, J. C. Carstens Jan 1975

Measurement Of Growth Rate To Determine Condensation Coefficients For Water Drops Grown On Natural Cloud Nuclei., A. M. Sinnarwalla, Darryl J. Alofs, J. C. Carstens

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Growth Rate Measurements Were Made for Water Drops Grown on Nuclei in Atmospheric Air Samples Taken in Rolla, Missouri. Rolla, Having a Population of 15,000 and Very Little Industry, is Relatively Free of Urban Pollutants. the Measurements Were Made in a Vertical Flow Thermal Diffusion Chamber at Supersaturations of 0. 5 and 1%. the Time to Grow from Near Dry Radius to the Final Radius (6 to 7. 5 Mu M) Was Measured. If One Assumes the Thermal Accomodation Coefficient is Unity, the Measurements Indicate an Average Value of 0. 026 for the Condensation Coefficient. the Temperature Ranged from 22. …

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Insoluble Condensation Nuclei: The Effect Of Contact Angle, Surface Roughness And Adsorption., P. C. Mahata, Darryl J. Alofs Jan 1975

Insoluble Condensation Nuclei: The Effect Of Contact Angle, Surface Roughness And Adsorption., P. C. Mahata, Darryl J. Alofs

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Condensation of Water Vapor on Various Surfaces Was Studied Experimentally. for Surfaces with an Air-Water Contact Angle Theta Less Than 20 Degree, the Experimentally Determined Values of Critical Supersaturation S//c Agreed with Those Given by the Volmer Theory. at Higher Theta, the Experimental Values of S//c Were Below the Volmer Theory Values. When the Applied Supersaturation Was Less Than S//c, Condensation Was Avoided for Periods as Long as 20 H. It Was Determined Both by Experiment and Theoretical Analysis that the Effect of Surface Roughness is to Decrease S//c Only Slightly. These Results Suggest that Most Insoluble Airborne Particles Are …

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Transport Phenomena In Thermally Stratified Boundary Layers, D. W. Pepper, S. C. Lee Jan 1975

Transport Phenomena In Thermally Stratified Boundary Layers, D. W. Pepper, S. C. Lee

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Studies of heat, mass, and momentum transfer are made to analyze the formation of marine fogs in thermally stratified boundary layers in the atmosphere. The governing partial differential equations of continuity, momentum, temperature, and concentration are used to describe the transport phenomena. An additional equation of turbulence energy is introduced to account for the development of the turbulent motions. Simultaneous solution of this system of equations allows the turbulent exchange coefficients to be treated in the same way as all other dependent parameters. Verification of the theoretical approach is made by comparing the numerical predictions with wind tunnel simulations of …

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Thermal Stresses In A Sphere Due To Local Heating Followed By Complete Cooling, T. S. Chen, K. Thirumalai, J. B. Cheung Jan 1975

Thermal Stresses In A Sphere Due To Local Heating Followed By Complete Cooling, T. S. Chen, K. Thirumalai, J. B. Cheung

Mechanical and Aerospace Engineering Faculty Research & Creative Works

No abstract provided.

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The Application Of Impact Dampers To Continuous Systems, Ranjit K. Roy, Richard D. Rocke, J. Earl Foster Jan 1975

The Application Of Impact Dampers To Continuous Systems, Ranjit K. Roy, Richard D. Rocke, J. Earl Foster

Mechanical and Aerospace Engineering Faculty Research & Creative Works

A study has been made of the application of impact dampers to two types of continuous systems, a simply supported and a clamped beam. Experimental models were tested in the laboratory and computer programs were developed to calculate response by two separate approaches. Results from calculations agreed favorably with experimental tests. Curves presented show the response to be expected for values of significant system parameters and enable the user to apply impact dampers to these types of continuous systems. © 1975 by ASME.

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Transient Thermal Stresses In A Sphere By Local Heating, J. B. Cheung, T. S. Chen, K. Thirumalai Jan 1974

Transient Thermal Stresses In A Sphere By Local Heating, J. B. Cheung, T. S. Chen, K. Thirumalai

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The problem of transient thermal stresses in a solid, elastic, homogeneous, and isotropic sphere is solved for uniform and nonuniform, local surface heating. The temperature solutions are obtained by using separation of variables and integral transformation. The corresponding thermal stresses are derived by superposing a particular displacement potential function on Boussinesq solutions. Numerical solutions for two particular cases of localized heating of a typical brittle spherical solid have been obtained and presented. The results indicate a tensile stress concentration in the interior of the solid below the heated zone. © 1974 by ASME.

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Vibration Characteristics Of Free Thin Cylindrical Shells, Floyd M. Cunningham, D. E. Leanhardt Jan 1974

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 …

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Engineering And Scientific Manpower- A Scarce Resource For The 1970'S, Merl Baker Jan 1973

Engineering And Scientific Manpower- A Scarce Resource For The 1970'S, Merl Baker

Mechanical and Aerospace Engineering Faculty Research & Creative Works

No abstract provided.

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Nonequilibrium Structure Of Argon Shock Waves, Harlan F. Nelson Jan 1973

Nonequilibrium Structure Of Argon Shock Waves, Harlan F. Nelson

Mechanical and Aerospace Engineering Faculty Research & Creative Works

This theoretical study investigates the influence of (1) the nonequilibrium excited state population in the relaxation region and (2) line radiation in the precursor on shock wave structure by considering strong shock waves propagating at Mach 18 and 24 into a theoretical argon-like gas at a pressure of 1 cm Hg and a temperature of 300°K. The argon atom is modeled as having two bound states plus a continuum, and the calculations include finite atom-atom and electron-atom collisional ionization and excitation rates as well as continuum and line radiation. The electron gas is allowed to be at a different temperature …

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Breakdown Of The Laminar Flow Regime In Permeable-Walled Ducts, E. M. Sparrow, G. S. Beavers, T. S. Chen, J. R. Lloyd Jan 1973

Breakdown Of The Laminar Flow Regime In Permeable-Walled Ducts, E. M. Sparrow, G. S. Beavers, T. S. Chen, J. R. Lloyd

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The stability of laminar flow in a parallel-plate channel having one permeable bounding wall is investigated by means of linear theory. The analysis lakes account of the coupling of the disturbance, fields in the channel and in the permeable material and of velocity slip at the surface of the permeable wall. Complementary experiments are performed in which the breakdown of the laminar regime in flat rectangular ducts is identified from pressure-drop measurements and from flow visualization studies. The experiments cover the range of slip velocities from 15-30 percent of the mean velocity and, in addition, the case of zero slip …

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Decision-Directed Detector For Overlapping Pcm/Nrz Signals, Cheng Wang, Thomas L. Noack Jan 1973

Decision-Directed Detector For Overlapping Pcm/Nrz Signals, Cheng Wang, Thomas L. Noack

Mechanical and Aerospace Engineering Faculty Research & Creative Works

A decision-directed (DD) technique for the detection of overlapping PCM/NRZ signals in the presence of white Gaussian noise is investigated. The performance of the DD detector is represented by probability of error PE versus input signal-to-noise ratio (SNR). To examine how much improvement in performance can be achieved with this technique, PE's with and without DD feedback are evaluated in parallel. Further, analytical results are compared with those found by Monte Carlo simulations. The results are shown in good agreement. © 1973, IEEE. All rights reserved.

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