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Articles 1201 - 1230 of 1287
Full-Text Articles in Engineering
Generic Singularities Of Robot Manipulators, Ming-Chuan Leu, D. K. Pai
Generic Singularities Of Robot Manipulators, Ming-Chuan Leu, D. K. Pai
Mechanical and Aerospace Engineering Faculty Research & Creative Works
The singularities of the differential kinematic map, i.e. of the manipulator Jacobian, are considered. The authors first examine the notion of a generic kinematic map, whose singularities form smooth manifolds of prescribed dimension in the joint space of the manipulator. For three-joint robots, an equivalent condition for genericity using determinants is derived. The condition lends itself to symbolic computation and is sufficient for the study of decoupled manipulators, i.e. manipulators that an be separated into a three-joint translating part and a three-joint orienting part. The results are illustrated by analyzing the singularities of two classes of three-joint positioning robots.
Optimal Design Rules Applied To The Design Of High-Speed Mechanisms Under Deflection And Stress Constraints, Frank W. Liou, Jenny Liu
Optimal Design Rules Applied To The Design Of High-Speed Mechanisms Under Deflection And Stress Constraints, Frank W. Liou, Jenny Liu
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Presented in this paper are two approaches for the design of flexible mechanisms under stress and deflection constraints. Based on the optimality conditions derived in this paper, two procedures are developed to design the minimum weight of mechanisms subject to stress and deflection limitations. The first procedure is the improvement of Thornton's design process r 17), and the second procedure is based on the interpolation technique. Several design examples are also presented to demonstrate these methods.
Axisymmetric Vibrations Of Reinforced Orthotropic Shallow Spherical Caps, Victor Birman, George J. Simitses
Axisymmetric Vibrations Of Reinforced Orthotropic Shallow Spherical Caps, Victor Birman, George J. Simitses
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Axisymmetric vibrations of reinforced shallow, spherical caps manufactured from orthotropic materials are considered. The closed form solution is obtained for the natural frequency of the cap with a clamped and immovable circular edge by assuming that the motion component parallel to the cap boundary plane (in plane) is negligible. Parametric studies are performed to assess the effect of various geometric and structural parameters on the natural frequency of the cap and, most importantly, to identify the most influencing parameters of the problem. From the generated data, it is concluded that the national frequency increases with increasing extensional stiffness and eccentricity …
Adiabatic Shear Banding In Plane Strain Problems, R. C. Batra, De Shin Liu
Adiabatic Shear Banding In Plane Strain Problems, R. C. Batra, De Shin Liu
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Plane strain thermomechanical deformations of a viscoplastic body are studied with the objective of analyzing the localization of deformation into narrow bands of intense straining. Two different loadings, namely, the top and bottom surfaces subjected to a prescribed tangential velocity, and these two surfaces subjected to a preassigned normal velocity, are considered. In each case a material defect, flaw, or inhomogeneity is modeled by introducing a temperature bump at the center of the specimen. The solution of the initial boundary value problem by the Galerkin-Adams method reveals that the deformation eventually localizes into a narrow band aligned along the direction …
Measured Spectra Of The Hygroscopic Fraction Of Atmospheric Aerosol Particles, Darryl J. Alofs, Donald E. Hagen, Max B. Trueblood
Measured Spectra Of The Hygroscopic Fraction Of Atmospheric Aerosol Particles, Darryl J. Alofs, Donald E. Hagen, Max B. Trueblood
Mechanical and Aerospace Engineering Faculty Research & Creative Works
The Relation between Dry Diameter (Xo) and Critical Supersaturation (Sc) for Atmospheric Submicron Aerosol Particles is Investigated. the Particles Are Passed through an Electrostatic Aerosol Size Classifier, and Then through an Isothermal Haze Chamber. Results Are Reported in Terms of an Apparent Volume Fraction of Soluble Material, Εv, Defined Such that for Particles Composed Only of Ammonium Sulfate and Water Insoluble Compounds, Εv is the Actual Volume Fraction of Soluble Material. the Probability Distribution of Εv is Found to Be Approximately Gaussian in the Εv Range 0.2 to 1.3. the Mean Εv is 0.5, for Electrostatic Aerosol Classifier Settings of …
A Comment On ‘Failure Modes Of Hybrid Composites …’, Serge Abrate
A Comment On ‘Failure Modes Of Hybrid Composites …’, Serge Abrate
Mechanical and Aerospace Engineering Faculty Research & Creative Works
This paper comments on an earlier paper on the failure modes of hybrid composites by Pitkethly and Bader, which appeared in the Carbon Fiber Conference issue. © 1988 IOP Publishing Ltd.
Characteristics And Optimal Design Of Variable Airgap Linear Force Motors, Ming-Chuan Leu, E. V. Scorza, D. L. Bartel
Characteristics And Optimal Design Of Variable Airgap Linear Force Motors, Ming-Chuan Leu, E. V. Scorza, D. L. Bartel
Mechanical and Aerospace Engineering Faculty Research & Creative Works
An analytical model for predicting the characteristics of variable airgap linear force motors is developed. the model takes into account magnetic losses including the leakage and fringing effects and the reluctance existing at the contacts between permanent magnets and pole pieces. the model is validated by comparing its predicted characteristics with the results obtained from experiments and a finite element program. with the use of the modelled characteristics, computer programs based on the method of constrained steepest descent with state equations are developed for automating and optimising the design of linear force motors. Numerical studies are made for both minimisation …
Condensation Method For Humidity Measurement In The Umr Cloud Simulation Chamber., Donald E. Hagen, Daniel R. White, Darryl J. Alofs
Condensation Method For Humidity Measurement In The Umr Cloud Simulation Chamber., Donald E. Hagen, Daniel R. White, Darryl J. Alofs
Mechanical and Aerospace Engineering Faculty Research & Creative Works
A Cloud Simulation Facility Has Been Developed for the Study of Various Atmospheric Cloud Processes. the Initial Relative Humidity of the Air Sample Put into the Cloud Chamber is a Key Parameter in Virtually Any Experiment and Needs to Be Known Accurately. This Report Describes How the Cloud Simulation Chamber itself Has Been Used as a Condensation Type Hygrometer to Calibrate the System's Humidifier. Two Distinct and Physically Different Methods for Inferring Mixing Ratio Are Used, One Exploiting the Sensitivity of Aerosol Activation to Humidity, and the Other Exploiting the Sensitivity of the Rate of Growth of Cloud Droplets to …
Effect Of Nominal Strain-Rates On The Initiation And Growth Of Adiabatic Shear Bands In Steels, R. C. Batra
Effect Of Nominal Strain-Rates On The Initiation And Growth Of Adiabatic Shear Bands In Steels, R. C. Batra
Mechanical and Aerospace Engineering Faculty Research & Creative Works
No abstract provided.
Power Filter Resonant Frequency Modulation Network, Don Cronin
Power Filter Resonant Frequency Modulation Network, Don Cronin
Mechanical and Aerospace Engineering Faculty Research & Creative Works
A power filter resonant frequency modulation network for coupling between a load and a variable voltage direct current power source which is subjected to superposition of alternating current thereon at various frequencies and at various voltage levels, the filter including first and second series inductor arrangements in the positive and negative buses between the power supply and the load, with capacitive elements in parallel between the two buses. Each series inductor arrangement includes a first inductor in series with a frequency and voltage responsive inductive load device, which is a second inductor having a tertiary winding loaded with a coil …
University Of Missouri-Rolla Cloud Simulation Facility: Proto Ii Chamber, Daniel R. White, James L. Kassner, John C. Carstens, Donald E. Hagen, John L. Schmitt, Darryl J. Alofs, Alfred R. Hopkins, Max B. Trueblood, Max W. Alcorn, William L. Walker
University Of Missouri-Rolla Cloud Simulation Facility: Proto Ii Chamber, Daniel R. White, James L. Kassner, John C. Carstens, Donald E. Hagen, John L. Schmitt, Darryl J. Alofs, Alfred R. Hopkins, Max B. Trueblood, Max W. Alcorn, William L. Walker
Mechanical and Aerospace Engineering Faculty Research & Creative Works
The Graduate Center for Cloud Physics Research at UMR Has Developed a Cloud Simulation Facility to Study Phenomena Occurring in Terrestrial Clouds and Fogs. the Facility Consists of a Pair of Precision Cooled-Wall Expansion Chambers Along with Extensive Supporting Equipment. the Smaller of These Chambers, Described in This Article, is Fully Operational, and is Capable of Simulating a Broad Range of In-Cloud Thermodynamic Conditions. It is Currently Being Used to Study Water Drop Growth and Evaporation for Drops Nucleated (Activated) on Well-Characterized Aerosol Particles. Measurements Have Been Made Not Only for Continuous Expansions (Simulated Updraft) But Also for Cyclic Conditions, …
The Force On A Lattice Defect In An Elastic Body, R. C. Batra
The Force On A Lattice Defect In An Elastic Body, R. C. Batra
Mechanical and Aerospace Engineering Faculty Research & Creative Works
It is shown that the force on a lattice defect in an elastic body is, like the force on a disclination in a nematic liquid crystal, a real force which, for equilibrium, must be balanced by an external force applied to the closed surface enclosing the defect. © 1987 Martinus Nijhoff Publishers.
Effect Of Material Parameters On The Initiation And Growth Of Adiabatic Shear Bands, R. C. Batra
Effect Of Material Parameters On The Initiation And Growth Of Adiabatic Shear Bands, R. C. Batra
Mechanical and Aerospace Engineering Faculty Research & Creative Works
The thermomechanical problem involving simple shearing of a finite slab made of an isotropic and viscoplastic material is studied with the objective of finding the effect of the strain hardening parameter, strain-rate hardening parameters, thermal softening coefficient and thermal conductivity on the initiation and growth of adiabatic shear bands. The body is placed in a hard loading device, i.e., the velocity is prescribed at its top and bottom surfaces. A shear band is presumed to have formed if the addition of a perturbation in the temperature at the onset of plastic flow results in a localization of the shear strain. …
Elasto-Composition Waves In Inhomogeneous Solids, R. C. Batra, Manfred Wuttig
Elasto-Composition Waves In Inhomogeneous Solids, R. C. Batra, Manfred Wuttig
Mechanical and Aerospace Engineering Faculty Research & Creative Works
No abstract provided.
Closed-Loop Dynamic Response Of A Static Scherbius Drive., Aaron J. Miles, B. Lequesne
Closed-Loop Dynamic Response Of A Static Scherbius Drive., Aaron J. Miles, B. Lequesne
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Generalized root-loci techniques, for squirrel-cage motors have been extended to wound-rotor, slip-energy-recovery systems (static Scherbius drive). The influence of a feedback control loop on these root loci is considered. General conclusions on Scherbius drive dynamics, as well as supporting experimental results, are presented.
Generalized Root-Loci Theory For The Static Scherbius Drive, B. Lequesne, Aaron J. Miles
Generalized Root-Loci Theory For The Static Scherbius Drive, B. Lequesne, Aaron J. Miles
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Generalized root-loci techniques, developed in the mid 70's for squirrel cage motors, have been extended in the static Scherbius configuration to wound rotor, slip energy, recovery systems. This arrangement is now applied to large power drives in the 0.5 to 50 MW range. In this paper, general results applicable to all machines are presented for the open-loop control scheme, but only the sub synchronous mode of operation in which a voltage source type inverter is used is addressed. Copyright © 1984 by The Institute of Electrical and Electronics Engineers, Inc.
Generalized Root-Loci Theory For The Static Scherbius Drive, B. Lequesne, Aaron J. Miles
Generalized Root-Loci Theory For The Static Scherbius Drive, B. Lequesne, Aaron J. Miles
Mechanical and Aerospace Engineering Faculty Research & Creative Works
No abstract provided.
Electronic Ballast Having Emitter Coupled Transistors And Bias Circuit Between Secondary Winding And The Emitters, Don Cronin
Mechanical and Aerospace Engineering Faculty Research & Creative Works
An electronic ballast for energizing fluorescent lamps comprising a converter including a rectifier and a filter for converting an alternating source voltage into a direct current voltage, a network including first and second switching transistors, a tank circuit having a primary winding of a transformer, a secondary winding of the transformer for providing feedback of a portion of the voltage developed across the tank circuits and a bias circuit coupled between the opposite ends of the secondary winding and the emitters of the transistor for alternatively applying bias to the transistors, the network serving to convert a direct current voltage …
Saint-Venant's Principle In Linear Elasticity With Microstructure, R. C. Batra
Saint-Venant's Principle In Linear Elasticity With Microstructure, R. C. Batra
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Toupin's version of the Saint-Venant principle in linear elasticity is generalized to the case of linear elasticity with microstructure. That is, it is shown that, for a straight prismatic bar made of an isotropic linear elastic material with microstructure and loaded by a self-equilibrated force system at one end only, the strain energy stored in the portion of the bar which is beyond a distance s from the loaded end decreases exponentially with the distance s. © 1983 Martinus Nijhoff Publishers.
Linear Inversion Method To Obtain Aerosol Size Distributions From Measurements With A Differential Mobility Analyzer, Donald E. Hagen, Darryl J. Alofs
Linear Inversion Method To Obtain Aerosol Size Distributions From Measurements With A Differential Mobility Analyzer, Donald E. Hagen, Darryl J. Alofs
Mechanical and Aerospace Engineering Faculty Research & Creative Works
The Use of a Differential Mobility Analyzer to Perform Aerosol Size Spectrum Measurements Requires an Inversion Method to Go from the Measured Sensor Responses to the Desired Size Spectrum Information. Here We Present a Linear Inversion Method that Can Be Run on a Microcomputer or a Small Minicomputer. It Does Not Use Some of the Approximations Made in the Techniques Currently Available and Hence Gives Better Inversion Accuracy. the Method Shows Good Immunity to Both Random and Systematic Experimental Error. It is Applied to Numerous Test Case Aerosols. © 1983 Elsevier Science Publishing Co., Inc.
Inversion To Obtain Aerosol Size Distributions From Measurements With A Differential Mobility Analyzer, Darryl J. Alofs, P. Balakumar
Inversion To Obtain Aerosol Size Distributions From Measurements With A Differential Mobility Analyzer, Darryl J. Alofs, P. Balakumar
Mechanical and Aerospace Engineering Faculty Research & Creative Works
To Measure Size Distributions of Sub micrometer Aerosols with an Electrical Differential Mobility Analyzer (DMA) Requires an Inversion Procedure. the Knutson (1976) and the Hoppel (1978) Inversion Procedures Were Numerically Investigated for the Case of Log-Normal Aerosol Size Distributions. It Was Found that the Hoppel Procedure Converges to the Same Result as that Given by the Knutson Procedure. the Computational Range for Geometric Mean Diameter (Χg) Was 0.025-0.25 Μm, and for Geometric Standard Deviation (Σg) Was 1.1-2.4. the Inversion Error Was Found to Be Greater Than 10% in Certain "Forbidden Zones" of Χg and Σ …
Development Of A Friction Element For Metal Forming Analysis, W. D. Webster, Robert L. Davis
Development Of A Friction Element For Metal Forming Analysis, W. D. Webster, Robert L. Davis
Mechanical and Aerospace Engineering Faculty Research & Creative Works
A three-dimensional finite element friction element has been developed. The friction element has been used in the analysis of round-to-square forward extrusion.Comparison with some limited experimental data is presented. © 1982 by ASME.
A Mathematical Model Used In Conjunction With A Finite Element Analysis To Aid In The Design And Analysis Of Bourdon Tubes, R. C. Weber, Robert L. Davis
A Mathematical Model Used In Conjunction With A Finite Element Analysis To Aid In The Design And Analysis Of Bourdon Tubes, R. C. Weber, Robert L. Davis
Mechanical and Aerospace Engineering Faculty Research & Creative Works
A mathematical model that describes a variety of Bourdon tube geometries has been used for the three-dimensional analysis of Bourdon tubes. The variation of the stresses and tip deflections with respect to the variables used in the mathematical model are then presented as an aid in the design and analysis of the Bourdon tube. The finite element program represents a user-orientated package for calculation of tip deflections and stresses. Stresses and deflections are compared to both strain gage data and instrumented tip deflections as well as published data to establish the credibility of both the model and computer program. © …
High Pressure Liquid Jet Nozzle System For Enhanced Mining And Drilling, B. P. Selberg
High Pressure Liquid Jet Nozzle System For Enhanced Mining And Drilling, B. P. Selberg
Mechanical and Aerospace Engineering Faculty Research & Creative Works
This invention is directed to a nozzle configuration capable of enhancing the cutting and drilling effects of high pressure liquid fluid jets. The jet system is particularly adapted to configurations of two or more liquid jets which are oriented to converge at a common point. The internal nozzle configuration produces controlled instability in the jet stream causing a more rapid breakup into droplets which can be combined to produce very fast moving jets and slow moving jets when collision between droplets occur. The velocity of the fast jets so formed may be several times greater than the original velocity of …
A Potential Problem With The Tsi Electrostatic Aerosol Classifier, Darryl J. Alofs, Max B. Trueblood
A Potential Problem With The Tsi Electrostatic Aerosol Classifier, Darryl J. Alofs, Max B. Trueblood
Mechanical and Aerospace Engineering Faculty Research & Creative Works
No abstract provided.
Novel Demonstration Of Total Internal Reflection, Dwight C. Look
Novel Demonstration Of Total Internal Reflection, Dwight C. Look
Mechanical and Aerospace Engineering Faculty Research & Creative Works
No abstract provided.
Atmospheric Measurements Of Ccn In The Supersaturation Range 0.013-0.681%., Darryl J. Alofs, T. H. Liu
Atmospheric Measurements Of Ccn In The Supersaturation Range 0.013-0.681%., Darryl J. Alofs, T. H. Liu
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Concentrations of Cloud Condensation Nuclei in the Atmosphere Were Measured at Rolla, Missouri, Near Ground Level. a Total of 432 Spectra Were Measured over a 10-Month Period. No Consistent Seasonal or Diurnal Pattern Was Observed. Possible Implications for Fogs and Stratus Clouds and for Nuclei Chemical Composition Are Discussed.-From Authorscloud Condensation Nuclei Rolla Missouri Fogs
Combined Heat And Lass Transfer In Mixed Confection Ower A Horizontal Flat Plate, T. S. Chen, F. A. Strobel
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 …
Rubber Covered Rolls-The Nonlinear Elastic Problem, R. C. Batra
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.
Nucleation Experiments With Monodisperse Nacl Aerosols., Darryl J. Alofs, M. B. Trueblood, D. R. White, V. L. Behr
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 …