bluuebunny/crossref_metadata_2025 huggingface dataset:
ANTI–DOMESTIC VIOLENCE COALITION PRACTICE: THEORIZING COLLABORATION AND PARTICIPATION
Authors: Wies Jennifer R.
Published: December 2011

The persistence of domestic violence continues to be a significant social problem throughout the world. In the United States, approximately one in four women will experience at least one form of violence during the course of her lifetime. In response to this epidemic, community‐based coalitions have emerged to provide emergency shelter and advocacy services to victims and their families. This article focuses on one anti–domestic violence coalition to examine two areas of coalition practice. First, coalition collaboration occurs as a means for responding to the scarcity of resources within a community, thereby linking coalition practice to larger political‐economic structures. Secondly, coalition members are motivated to participate in coalitions as a way of expressing their commitment to and identification with a larger feminist social movement. With a deeper appreciation of the political‐economic constraints that necessitate collaboration and a greater understanding of coalition members’ motivations for participation in an underfunded coalition, this article considers the theoretical expansion of coalition research and offers considerations for coalition practice.
FOOD FOR THOUGHT: COALITION PROCESS AND A COMMUNITY‐BASED RESEARCH AND SERVICE‐LEARNING PROJECT
Authors: Behrman Carolyn
Published: December 2011

Community‐based research and service‐learning (CBRSL) represents an important and expanding approach to academic inquiry and pedagogy employed by several fields, including cultural anthropology. Much of the theoretical work on this approach, while providing an essential foundation for research, fails to account fully for the complexities encountered in the actual practice of community‐based collaborative work. Drawing on nearly a decade of my own field experience, both teaching about and participating in community‐based research, I examine the concepts of “community” and “neighborhood” as they are constructed by collaborating partners to frame a discussion of the overall objectives of community‐based projects. In particular, I outline and explore the lifecycle of an ongoing CBRSL project, its role in the systematic generation of local transformative knowledge, and I examine how, at each stage in its evolution, the process is shaped by the interaction of individual agents within the constraints of the cultural structure in which such research takes place. This approach is valuable because it allows us to both better understand the degree to which theoretical constructs are shared by coalition members and to explicate the ramifications that variation in understanding between members holds for project success. Success, in the case of CBRSL, is multidimensional and fluid, as expectations and goals vary between partners and shift across the lifecycle of the project. I conclude that what is of lasting value to all participants is the shared appreciation of the challenges and long‐term benefits of coalition building between academic and nonacademic communities to address real world problems.
A SOCIAL NETWORK ANALYSIS APPROACH TO UNDERSTAND CHANGES IN A CANCER DISPARITIES COMMUNITY PARTNERSHIP NETWORK
Authors: Luque John S. , Tyson Dinorah Martinez , Bynum Shalanda A. , Noel‐Thomas Shalewa , Wells Kristen J. , Vadaparampil Susan T. , Gwede Clement K. , Meade Cathy D.
Published: December 2011

The Tampa Bay Community Cancer Network (TBCCN) is one of the Community Network Program sites funded (2005–10) by the National Cancer Institute's Center to Reduce Cancer Health Disparities. TBCCN was tasked to form a sustainable, community‐based partnership network focused on the goal of reducing cancer health disparities among racial–ethnic minority and medically underserved populations. This article reports evaluation outcome results from a social network analysis and discusses the varying TBCCN partner roles—in education, training, and research—over a span of three years (2007–09). The network analysis included 20 local community partner organizations covering a tricounty area in Southwest Florida. In addition, multiple externally funded, community‐based participatory research pilot projects with community–academic partners have either been completed or are currently in progress, covering research topics including culturally targeted colorectal and prostate cancer screening education, patient navigation focused on preventing cervical cancer in rural Latinas, and community perceptions of biobanking. The social network analysis identified a trend toward increased network decentralization based on betweenness centrality and overall increase in number of linkages, suggesting network sustainability. Degree centrality, trust, and multiplexity exhibited stability over the three‐year time period. These results suggest increased interaction and interdependence among partner organizations and less dependence on the cancer center. Social network analysis enabled us to quantitatively evaluate partnership network functioning of TBCCN in terms of network structure and information and resources flows, which are integral to understanding effective coalition practice based on Community Coalition Action Theory (

Butterfoss and Kegler 2009

). Sharing the results of the social network analysis with the partnership network is an important component of our coalition building efforts. A comprehensive baseline needs assessment for the next five‐year funding phase (2010–15) of TBCCN Community Networks Program Centers (CNP Center) is under way to further evaluate the growth and sustainability of the partnership network, with an emphasis on community‐based intervention research that takes into account culture and literacy.
On the Duality in the Existence of R-R Links for Three Positions
Authors: Suh Chung Ha
Published: December 2011

The present paper intends to report a discovery of geometric invariant in finite synthesis of space mechanism called “the duality of R-R link.” The duality itself is first proven here by using the screw geometry to give it a simple and intuitive form. Second, proving the 4-bar mechanism made by the dual R-R links is a Bennett mechanism it is made possible to synthesize the Bennett mechanisms for rigid-body guidance and function generation. Synthesizing the Bennett mechanisms the first time, for these practical uses, is important in itself. However, from the point of view of “the duality” it is only one special application.
Noise of Involute Helical Gears
Authors: Attia A. Y.
Published: December 2011

The problem of involute helical gear noise is studied by running a pair of 6 DP gears in a power circulating rig inside an anechoic room. More than 3500 magnetic tape recordings were taken and analyzed, for gears running at different speeds and transmitting different loads. A pair of 14 DP nickel steel gears of finished, ground, and shaved teeth was also tested to study the effect of surface finish on gear noise. Experimental results revealed that the main sources of gear noise are impact between gear teeth and friction. A sudden rise in noise level has been noticed when a whole number of teeth are in contact. This paper presents experimental results and study of noise of involute helical gears of different facewidths and pitches, running at different speeds, and transmitting different loads. The source of gear noise and noise generating mechanisms are also discussed.
Rolamite-Geometry and Force Analysis
Authors: Cadman R. V.
Published: December 2011

The rolamite is a precision roller-band mechanism which was recently developed. The looseness of the rolamite geometry is a function of the band tension. The tight geometry and the slightly loose (small-deflection) geometry may be described by simple equations. Typical digital computer results are presented for the interroller clearance in the very loose (large-deflection) geometry. The rolamite may be made to generate forces if the band flexural rigidity is varied, or if it is precurved. An energy method is used to derive a general form of the force equation.
Problems of High-Speed Hydrodynamics
Authors: van Driest E. R.
Published: December 2011

A hard look at the problems provoked by the quest for higher speeds of underwater craft shows that they can indeed be solved in a practical manner using the knowledge and principles derived in the evolution of the science of high-speed aerodynamics. Hydrodynamic heating, turbulent heat transfer and friction, boiling and cavitation, friction reduction by additives, normal and oblique shock waves, and rocket propulsion are topics brought under discussion. Propulsion remains the prime area of future endeavor in order to achieve the speeds demanded by modern times.
Dynamic Characteristics of Spatial Mechanisms
Authors: Givens E. J. , Wolford J. C.
Published: December 2011

An energy method given by Quinnfor determining the dynamic characteristics of planar mechanisms under the action of displacement-related forces is extended to spatial linkages. These linkages may, in addition, be subjected to time-related forces or to velocity-related damping forces. Recently developed matrix methods are used in the linkage analysis resulting in a method well suited to digital computation.
Complex Harmonic Analysis of Plane Mechanisms. Programming on Digital Computers and Experimental Examples
Authors: Bogdan R. C. , Larionescu D. , Ca˘rut¸as¸u I.
Published: December 2011

This article examines the plane hinged mechanisms with the aid of two original methods, i.e., a theoretical method and an experimental one. Each of these methods is based on the fact that the functions characterizing the motion of a large class of mechanisms are periodic functions. This fact determines the mathematical tools for the theoretical method; namely, complex Fourier series and the approximation exponential polynomial. For the experimental method this fact is of importance in the suitable choice of a system of successive derivatives of the electrical signal furnished by a polar mechanical transducer which represents the path of any point of the mechanism. The theoretical method of complex harmonic analysis represents the examination of binary structural groups with the aid of Fourier series expressed in complex form. The manner of applying this method to the investigation of plane hinged mechanisms is shown. In the case of the five-link mechanism of aspect I the method is brought to the level of a calculation algorithm which may be used on a digital computer. A numerical example is given with the aid of a CET-501 digital computer.
An Analytical Method for Synthesizing the Four-Bar Crank-Rocker Mechanism
Authors: Chen F. Y.
Published: December 2011

An algebraic method is presented for synthesizing the four-bar crank-rocker mechanisms in general, with the offset slider-crank mechanism as a special case, for coordinating the prescribed input and output link extreme positions. Solutions to the equations of constraint are derived for different cases. Among a large number of the available solutions, an optimal design is governed by a given parameter which is determined based on a design criterion. Numerous examples are provided.
Calculation and Construction of the Burmester Points for Five Positions of a Moving Plane
Authors: Dijksman E. A.
Published: December 2011

A new method has been developed to derive the 10 Hackmu¨ller conics going through the four Burmester points of five positions of a moving plane, and each going through another virtual center of rotation. The calculation and graphical construction of the Burmester points in this paper are based upon this development. The calculation itself has been translated into the ALGOL computer-language and is available at the University of Eindhoven.
Gross Motion Attributes of Certain Spatial Mechanisms
Authors: Jenkins E. M. , Crossley F. R. E. , Hunt K. H.
Published: December 2011

A new method is presented by which positions of peculiar kinematic interest, such as ends of travel, locking positions and points of “uncertainty,” in certain types of spatial mechanisms can be readily ascertained. This method is based upon an analysis of the curves of intersection of the surfaces generated by points in the mechanisms, and is there related in such a manner as to render it useful both in determining the positiona interrelationships of components of the mechanisms, and in classifying the mechanism according to its motion.
Entrainment Patterns of Screw Hopper Dischargers
Authors: Bates L.
Published: December 2011

Helical Screws are commonly used to extract bulk solids from the outlet slots of hoppers. The manner in which material flows into the screw affects the flow characteristics of the hopper, residence periods of the contents in various locations, segregation, attrition and torque requirements of the screw. Regimes of motion of the solids in various sections of the equipment are outlined and a simple qualitative analysis enables predictions to be made based on material factors and screw dimensions. Consequential factors are discussed relevant to design and applications.
A Study of Factors Affecting the Performance of Screw Conveyers and Feeders
Authors: Carleton A. J. , Miles J. E. P. , Valentin F. H. H.
Published: December 2011

A study of the literature on screw conveyers and feeders has been made. Most of the work is concerned with conveying material and in these cases the degree of fill in the trough is kept low to protect intermediate bearings and minimize power requirements. An equally important application for the screw, but one which has received less attention, is its use as a constant rate feeder and in this case the screw is run full. The object of the present work has been to find the effect of various parameters on screw performance at all degrees of fill. Experiments are described in which the effects of screw geometry, speed, filling, and the use of materials with different properties have been investigated.
Stresses in Wedges of Cohesionless Materials Formed by Free Discharge at the Apex
Authors: Marais G. van R.
Published: December 2011

Cohesionless wedges formed by free discharge at the apex exist completely in the active critical state. With active failure movement, sections only of the wedge may be in the active state. Base settlement induces intermediate stress states between the active and passive.
On the Design of Oscillating Conveyers
Authors: Morcos W. A. , Massoud M. F.
Published: December 2011

The paper studies the conditions of conveying material on an oscillating trough. Two criteria for estimating the efficiency of different designs of such conveyers are proposed. The analysis of the problem put in evidence the conditions required to obtain displacement of the conveyed material up or down on an inclined oscillating plane conveyer and those to be avoided as design points.
Limit Plasticity Approach to Some Cases of Flow of Bulk Solids
Authors: Mro´z Z. , Drescher A.
Published: December 2011

Depending on the stress state, a bulk solid, regarded as the elastic-plastic material, can exhibit workhardening, worksoftening or perfectly plastic properties. During continuing motion, the solid flow can be assumed as incompressible, and the stress field satisfies a condition of critical state which can be identified with the Coulomb yield condition. The model of Coulomb material is introduced; such material satisfies the Coulomb yield condition and the flow law associated with this condition by the plastic potential rule. In general, the Coulomb material is stronger than the considered bulk solid in the critical state. The kinematic approach and the familiar upper bound theorem are applied in order to determine lower bounds on pressure exerted by the flowing material on bin walls and to determine flowability criterion. In the latter section, the flow induced by a horizontally moving rough plate is analyzed and two flow patterns are considered.
Experience With Nonmechanical Solids Flow Control Device in the Waste Calcining Facility
Authors: Bendixsen C. L. , Lohse G. E.
Published: December 2011

Large volumes of radioactive granular solids are being safely and efficiently handled, pneumatically, on a production scale in the Waste Calcining Facility at the Idaho Chemical Processing Plant. The low-pressure system uses no mechanically operated equipment, and hence has required minimal maintenance. Several unique devices in nonaccessible areas control and direct the flow of the solids from a cyclone and a fluidized bed to underground storage bins. A flow control valve is used to divert solids from a common supply header to any selected terminal by using an airstream to disturb the solids angle of repose. A pneumatic ejector is used for the dual purpose of removing solid fines from a low pressure cyclone and of preventing a backflow of air into the cyclone which would reduce its air-solids separation efficiency. An air purging system is used in the solids removal line from the fluidized bed to control solids flow, and thereby regulate the bed level in the vessel. The absence of moving parts in these devices makes them particularly attractive for use where reliable operation and minimum maintenance is of utmost importance.
Investigations on the Movement of Fuel Elements in the Core of a Pebble Bed Reactor
Authors: Bedenig D. , v. d. Decken C. B. , Rausch W.
Published: December 2011

For several years gas-cooled high temperature reactors have been developed in Germany, the main feature of which are their pebble-type fuel elements. The pebble bed is in the state of a continuous circulation process which is the reason for a series of nuclear and technical advantages. To make use of these advantages, comprehensive experimental studies on the flow behavior of a pebble bed were carried out. First, experimental equipment and the most successful method of measurement are described. Then typical results of parameter studies are reported as well as a theoretical model to calculate the pebble bed flow behavior. At last typical functions describing the flow behavior in the core of the THTR 300 MWe Prototype Reactor are reported.
Flow Patterns of Granular Materials in Flat-Bottom Bins
Authors: Giunta J. S.
Published: December 2011

Bins with flat bottoms and multiple openings are commonly used in industry to store granular solids because of their lower cost and because they occupy smaller vertical space than bins with a singular hopper outlet. However, in many flat-bottom bins the live capacity is much smaller than the bin volume because the spacing of openings does not permit the flow patterns above the openings to intersect. A theory has been developed to predict the boundary of the flow patterns that occur in these bins when circular openings are used, and experimental results in a small-scale bin have been found to agree closely with the theory. Boundaries of flow patterns are a function of the effective angle of friction of the material, the diameter of the opening, and the head of material in the bin. In general, the flow patterns expand outward from the edge of the opening, and become almost vertical near the top of the bin. Results of this study make it possible to determine which materials can be satisfactorily stored and which opening designs must be used to achieve adequate live-storage capacity in flat-bottom bins.
The Critical Porosity of Free Flowing Solids
Authors: Scarlett B. , Todd A. C.
Published: December 2011

The behavior of samples of free flowing sand under applied shear stress have been investigated in an annular shear cell of novel design. Measurements of critical porosity, dilation and shear stress are reported and discussed. A random chord size distribution is proposed to characterize a bed of particles and a relationship between this parameter and the critical porosity is derived. Experimental and theoretical values are compared.
Incipient and Nucleate Boiling of Liquid Hydrogen
Authors: Coeling K. J. , Merte H.
Published: December 2011

Experimental data are presented for natural convection heat transfer and for the point of inception of vapor formation for liquid hydrogen and liquid nitrogen. Nucleate boiling results with liquid hydrogen are also presented, indicating the so-called hysteresis effect with increasing and decreasing heat flux. The variables covered include heater surface material, roughness, and orientation.
A Theoretical Study of the Elastic Behavior of Two Normally Intersecting Cylindrical Shells
Authors: Hansberry J. W. , Jones N.
Published: December 2011

A theoretical study has been made into the elastic behavior of a joint formed by the normal intersection of a right circular cylindrical shell with another of larger diameter. The wall of the larger cylinder is assumed to remain open inside the joint in order to give an arrangement which is encountered frequently in pressure vessels or pipeline intersections. An external bending moment which acts in the plane of the joint is applied to the nozzle cylinder and is equilibriated by moments of half this magnitude applied to either end of the parent cylinder. A solution for this loading has been obtained by assuming antisymmetric distributions of certain stresses across a plane transverse to the joint. The analysis presented is believed to be valid for nozzle to cylinder diameter ratios of less than 1:3. Numerical results are given for a number of cases having radius ratios of 1:10 and 1:4.
Local Flexibility Coefficients for the Built-In Ends of Beams and Plates
Authors: Matusz J. M. , O’Donnell W. J. , Erdlac R. J.
Published: December 2011

The usual methods of structural analysis (including most modern computer methods) are based on the assumption that cross sections remain plane. Consequently local flexibilities at structural discontinuities are not included in these analyses. The present paper considers the effects of local deformations at the built in end of a beam or plate. Influence coefficients are given for the “mean” rotation and deflection due to bending M and shear V acting on the support. The plane strain coefficients also represent limiting solutions for shells with very large diameter to thickness ratios. These “mean” values are defined so that the work done by M and V acting through them is equal to the work done by the corresponding local stresses and deformations acting on the support. Theoretical solutions are obtained for a quarter plane support using DUZ, a finite difference clasticity computer program. The suitability of this method for evaluating local flexibilities at reentrant corners, and the usefulness of the “mean” rotation and deflection values is verified experimentally.
On the Plastic Tensile Instability Criteria
Authors: Negroni F. , Thomsen E. G.
Published: December 2011

The Dorn maximum load criterion and the Swift criterion for plastic tensile instability of a flat sheet stretched by in-plane forces are discussed. Both hypotheses are applicable when an initial nonuniformity of a sheet material is considered but that one is valid which is satisfied first. Experimental results in biaxial stretching of aluminum sheet specimens showed general agreement with both criteria; however, the Dorn maximum load criterion more accurately described the condition for necking when both principal strain rates on the plane of the sheet were positive. The significance and the calculation of the strain hardening parameter n = (ε/σ)(dσ/dε) are discussed, and the effect of prior deformation of the material on instability is analyzed.
Optimum Die Angles and Maximum Attainable Reductions in Rod-Drawing
Authors: Caddell R. M. , Atkins A. G.
Published: December 2011

Die friction and redundant deformation cause working stresses in drawing to be greater than simple homogeneous deformation would demand. At small die angles, frictional effects are large but the influence of redundant deformation is negligible; as die angles increase, the relative effects of these two factors reverse. Because of this interaction, an optimum angle exists for each combination of reduction and coefficient of friction where the drawing stress becomes a minimum. By modifying the normal Sachs equation to include redundant deformation, minima in the curves of drawing stress versus die angle are demonstrated. Additionally, some theoretical considerations of the maximum possible reduction per pass are presented.
Experimental Investigation of the Plastic Limit Pressures of Reinforced Openings in Cylindrical Shells
Authors: Chukwujekwu S. E. , Ruiz C.
Published: December 2011

The experimental results obtained from 10 cylindrical vessels of diameters ranging between 6 and 12 in. with a radial branch of equal strength to the vessel and various degrees of reinforcement are described and compared with theoretical predictions. Design curves, valid for nozzle reinforced openings in both cylindrical and spherical vessels, are proposed.
Some Considerations on Prevention of Chatter Vibration in Boring Operations
Authors: Kato S. , Marui E. , Kurita H.
Published: December 2011

In this paper, the chatter vibration occurring in a boring bar is treated theoretically and experimentally, and the concrete means for the prevention of chatter are examined from two points of view. First, the effectiveness of the Lanchester damper is investigated and a way of designing the optimum damper is suggested. It may be inevitable that the boring bar has directional characteristics in vibrational properties. It is shown, secondly, that the chatter behaviour can be improved through the good use of the directional characteristics of the boring bars.
Steering a Flexible Railway Truck on Curved Track
Authors: Newland D. E.
Published: December 2011

This paper gives a linear analysis for the steady motion of a flexible two-axle railway truck on curved track. Most existing truck designs are too rigid to be self-steering, but provided that the primary suspension is sufficiently flexible, it is shown that a truck can negotiate main line curves without slipping or flange contact. Results are obtained for the maximum rolling displacement of the wheelsets (the tracking error), Fig. 8, and the minimum radius of curvature for no slipping, Fig. 10, expressed as a function of the suspension stiffness. It is shown that lateral loads due to superelevation deficiency have only a small effect on the motion of the truck, which is mainly determined by creep forces arising from the geometric inability of the four wheels to roll freely on curved track.
Vehicle Vibration Analysis Using Frequency Domain Techniques
Authors: Lins W. F.
Published: December 2011

This paper describes a method of determining and evaluating vehicle vibration through frequency-response functions. Human transfer functions and absorbed power are used to investigate the effects of vibration on the human being. The advantages and limitations of frequency domain analysis in contrast to vehicle simulation in the time domain are discussed. A test case showing a series of computer simulations using both techniques is presented, and a comparison of the results is made.
Minimum Weight Design of Disks Using a Frequency Constraint
Authors: de Silva B. M. E.
Published: December 2011

The problem considered is that of minimizing the weight of a circular disk subject to specified behavioral and side constraints. The behavioral constraints have been restricted to a consideration that the lowest natural frequency of vibration should exceed a specified resonance frequency while the side constraints impose restrictions on the dimensions and tolerances of the disk. The problem has been formulated as a nonlinear programming problem characterized by a “black box” type representation for the frequency calculations. This paper includes a description of the synthesis procedures used together with a discussion of results.
Experimental Studies of Vibration of Axially Excited Circular Cylindrical Shells Containing Fluid
Authors: Pih H. , Wu C. G.
Published: December 2011

This paper reports a series of experimental studies on the vibration characteristics of circular cylindrical shells containing water under axial excitation. The conditions for the formation of bubble clusters in the fluid during the vibration and the interaction between the shell and the fluid are investigated. The pressure distributions and strains in the tank are correlated. Dynamic responses of the pressure and strains after bubble formation are observed. The wave velocity of the liquid-container system is also determined. It was found that the pressure equation derived, based on one-dimensional strain, could be made to agree with the experimental result when the wave velocity was corrected by an experimentally determined factor. The deformation of the tank was not axisymmetrical in most cases during the vibration. The inertia effect of the tank was not quite negligible. Drastic changes in the pressure and strain were observed after bubble formation.
Flow-Induced Vibrations of Metal Bellows
Authors: Gerlach C. R.
Published: December 2011

Results are given of an experimental and analytical study of longitudinal vibrations resulting from internal flow in metal bellows. It is shown that vortex shedding from the convolutions is the fluid excitation mechanism responsible for the vibrations. An N-degree-of-freedom spring-mass mechanical model is presented which is useful for predicting the bellows frequencies, and methods for estimating the fluid added mass for use in the model are discussed. Results of experiments designed to determine the vortex shedding forces are presented. An argument is given advocating the use of an effective vortex shedding force coefficient for vortex shedding excitation problems because of inaccuracies in experimentally obtained vortex amplitude and phase angle data.
Methods of Reducing the Response of Integrally Stiffened Structures to Random Pressures
Authors: Clarkson B. L. , Cicci F.
Published: December 2011

Experimental and theoretical studies of the response of integrally stiffened skin structures to random acoustic pressures are described. Typical structures are lightly damped and show significant response in the frequency range 100 to 2000 Hz. Some methods of increasing the damping are described and experimental results quoted. In the most efficient system investigated a damping treatment adding only 2 percent by weight to the structure reduced the rms stress by a factor of approximately three for the case of broad band excitation having a constant spectral density in the range 100 to 1000 Hz.
Expected Equivalent Damping Under Random Excitation
Authors: Torres M. R. , Mote C. D.
Published: December 2011

An analytical technique for obtaining an expected equivalent damping coefficient for a single-degree-of-freedom structure under random loading is discussed and illustrated. The expected energy dissipation is determined by integration of the product of the inelastic deformation energy and the amplitude probability density throughout the range of displacements. The technique is applied in detail to an elastic-perfectly plastic model subjected to excitation simulating the El Centro and Golden Gate earthquakes. A maximum expected equivalent damping ratio of only 0.117625 occurs when the mean displacement equals 2.765 times the yielding displacement under the following conditions: (a) the response peak amplitudes are Rayleigh distributed, (b) the excitation is a wide band random process, and (c) the material is elastic-perfectly plastic.
Stress Analysis of Unnotched C-Rings Used for Stress Cracking Studies
Authors: Fernandez S. O. , Tisinai G. F.
Published: December 2011

A technique for measuring elastic strains and the location between the plastically and elastically deformed portions of an unnotched C-ring sample is presented. Such C-rings when used to study sulfide stress cracking may incur cracks caused by both hydrogen embrittlement and stress corrosion cracking, whereas the presence of notches in the C-rings conceivably may force failure by only hydrogen embrittlement. Current studies by the authors on sulfide stress cracking include the use of both notched and unnotched C-rings.
Self-Cleaning Oil Bath Engine Intake Filter for Locomotive Applications
Authors: Sexton R. W. , Sparrow J. K.
Published: December 2011

The self-cleaning oil bath air filter has been used for over 30 years for filtering intake air for large, stationary diesel engines. It has proven successful under all types of operating conditions, from the hot, sandy climate of the Southwest to the subfreezing temperatures in the North. Only recently has it been adapted successfully to locomotive applications. Previous performance standards required of locomotive engine air filters did not require the high filtering performance of this type of filter. Only since the introduction of the high horsepower diesel locomotives, where air filter standards have been considerably increased beyond the abilities of conventional locomotive filters, has the self-cleaning principle of good oil bath filtration become feasible. The purpose of this paper is to show how, through design, testing, and applications, this type of oil bath principle can be adapted to meet the critical air-cleaning needs of today’s modern locomotive engines.
Analysis of Central Bursting Defects in Extrusion and Wire Drawing
Authors: Avitzur B.
Published: December 2011

The central burst defect, also called chevroning, in the extruded or drawn product is analyzed. A criterion for the unique conditions that promote this defect has been derived. Measures to prevent the occurrence of central burst are indicated. A major conclusion of the study is that, for a range of combinations of cone angle, reduction, and friction, central bursting is expected in any metal that can be called “Mises’ material.”1 Under such a combination (reduction, cone angle, and friction), even the most ductile material can burst centrally. The flow characteristics, described by Mises’ stress deviator-strain rate relations associated with Mises’ yield criterion, are the only metal properties needed to predict central bursting. No additional fracture criterion is associated with this failure.
Analysis of Downhole Measurements of Drill String Forces and Motions
Authors: Cunningham R. A.
Published: December 2011

The records studied from tests made by Esso Production Research Company confirm and give quantitative values to many phenomena which have been observed qualitatively or which have been indicated by existing evidence. Phenomena that were distinctly shown to exist in some cases are irregular bit rotation, torque fluctuations, bit bouncing, bit weight fluctuations, and large losses of rotary horsepower along the drill stem. In many cases, weight fluctuations appear to be excited by either the rotation of the drill stem or the mud-pump pressure fluctuations, or both. In at least one case, these fluctuations resulted in the bit bouncing clear of the hole bottom.
Downhole Measurements of Drill String Forces and Motions
Authors: Deily F. H. , Dareing D. W. , Paff G. H. , Ortloff J. E. , Lynn R. D.
Published: December 2011

A self-contained downhole recording instrument was developed and used to measure and record drilling string forces and motions. The eight signals recorded by pulse-width modulation on magnetic tape were: axial, torsional, and bending loads; axial, angular, and lateral accelerations; and internal (pipe) and external (annular) pressure. The device was used over a two-year period to collect data in fifteen wells under a wide range of drilling conditions. After about nine minutes of cumulative recording time, the tool was retrieved and brought to the surface. Data were converted from the magnetic tape to analog type oscillograph display and, in some cases, were digitized for analysis purposes. Normal variations in measured downhole bit load usually ranged between 25 and 50 percent of the mean value. Maximum bit loads reached over 3.5 times mean loads in some instances. Frequencies of weight, torque and bending traces showed evidences of rock bit tooth action, of cone action, of rotation, and also of pump pulsations. Large annular pressure variations accompanied large load variations.
Effect of a Time-Dependent Stenosis on Flow Through a Tube
Authors: Young D. F.
Published: December 2011

A common occurrence in the arterial system is the narrowing of arteries due to the development of atherosclerotic plaques or other types of abnormal tissue development. As these growths project into the lumen of the artery, the flow is disturbed and there develops a potential coupling between the growth and the blood flow through the artery. A discussion of the various possible consequences of this interaction is given. It is noted that very small growths leading to mild stenotic obstructions, although not altering the gross flow characteristics significantly, may be important in triggering biological mechanisms such as intimal cell proliferation or changes in vessel caliber. An analysis of the effect of an axially symmetric, time-dependent growth into the lumen of a tube of constant cross section through which a Newtonian fluid is steadily flowing is presented. This analysis is based on a simplified model in which the convective acceleration terms in the Navier-Stokes equations are neglected. Effect of growth on pressure distribution and wall shearing stress is given and possible biological implications are discussed.
Underwater Power From Aluminum
Authors: Bobb F. H.
Published: December 2011

A thermochemical power system having the highest theoretical performance (hp-hr/cu ft propellants) and particularly suited for underwater applications (power, heat, and propulsion) is described. In this system aluminum is reacted exothermally with sea-water to produce gaseous exhaust products, hydrogen-and steam. The exhaust products are expanded through a prime mover to produce shaft horsepower, or a combustion process can be added before the prime mover to convert the hydrogen to steam for applications that require condensable exhaust products. Open cycle (shallow depth operation) and closed cycle (deep depth operation) systems are described. The technique for reacting aluminum and water at low temperatures is discussed and aluminum-water reaction test data are presented. Design concepts of practical systems are shown, and typical power systems are compared relative to total energy, volume, and weight.
Stress Concentration Factors in Shouldered Shafts Subjected to Combinations of Flexure and Torsion
Authors: Rylander H. G. , daRocha P. M. A. , Kreisle L. F. , Vaughn G. J.
Published: December 2011

Geometric stress concentration factors were determined experimentally for shouldered aluminum shafts subjected to combinations of flexural and torsional loads. Diameter ratios were varied from 0.42 to 0.83, and fillet radius to small diameter ratios were varied from 0.1 to 0.7 with bending moment to torque ratios varying over a range from 1:4 to 4:1. Experimental values for the stress concentration factors were obtained by using birefringent coatings and a reflection polariscope. Strain gage measurements and torsional relaxation solutions were used to verify some of the polariscope data. For the cases considered, the static geometric stress concentration factor was between 1.11 and 1:50 for pure torsion, between 1.08 and 1.46 for pure bending, and between 1.09 and 1.50 for combined torsion and bending. The directions of the principal stresses on the surface of the shouldered shafts do not change due to the presence of the discontinuity for a particular specimen and type of loading. Also, the location of the maximum stress in the fillet of a particular specimen under a certain type of loading does not change as the magnitude of the load is varied, but it does vary with the type of loading.
Temperature Responses and Experimental Errors for Multitooth Milling Cutters
Authors: Wang K. K. , Wu S. M. , Iwata K.
Published: December 2011

A milling cutter temperature measuring technique was devised using garter spring pickups and standard thermocouples positioned at the back of inserts. Temperature signals as many as eight teeth were recorded simultaneously. It was found that the average cutting temperature of a multitooth cutter was higher than a flycutter at the same cutting conditions. The difference between one and two-tooth cutters was the largest and it tended to decrease when the number of teeth increased. The experimental error was thoroughly analyzed. The standard error for a flycutter was found to be about one half of that for multitooth cutters. Analysis of the temperature responses and the experimental errors indicated that a two-tooth cutter rather than a flycutter should be used to evaluate the performance of a multitooth cutter.
Thermal Aspects of the Abrasive Cutoff Operation. Part 2—Partition Functions and Optimum Cutoff
Authors: Eshghy S.
Published: December 2011

The theoretical results of Part 1 are extended to the study of partition functions which determine the various fractions of the total heat generation. Four major fractions are those of wheel transient, work transient, chip flux, and ambient losses. Thermal penetration of the wheel is studied in detail. Thermally optimum conditions are defined and sought. A procedure for selecting optimum downfeed rates is given.
The Wheel Wear and Metal Removal Mechanisms in Vertical Spindle Abrasive Machining of Mild Steel
Authors: Pollock C.
Published: December 2011

The primary metal removal mechanisms in vertical spindle abrasive machining are chip removal by firmly bonded abrasive grains in the wheel matrix, and secondary removal by the reuse of loose abrasive between the wheel-work interface. As you increase the strength (go to harder grades) of segments, the secondary metal removal rate tends to remain constant. However, the metal removed by firmly bonded abrasive increases rapidly. Changing from an E to an F grade approximately doubles the primary metal removal rate. Segmental wheels sharpen themselves by two major mechanisms—primary and secondary wear. Primary wear is caused by the common mechanisms of attrition, grain fracture, and bond failure. The secondary mechanism is caused by loose abrasive and metal chips in the wheel-work interface.
Analysis of Rod Shaving and Orthogonal Cutting
Authors: Feilbach W. H. , Avitzur B.
Published: December 2011

The relationship between shaving and drawing or extension is discussed. For small reduction ratios, this relationship is evidenced by a transition from converging flow of the metal to shaving as the tool angle is increased. This transition is defined as the critical rake angle for shaving. An expression for the relative pressure required for orthogonal cutting is derived through the upper-bound approach. With this as a basis, an approximate upper-bound solution for shaving is obtained. This equation gives the relative stress or pressure required for shaving as a function of the process variables, both dependent and independent. The independent variables are rake angle (α), reduction ratio (R0/Rf), relative back stress (σzb/σ0), and friction factor (m). The dependent variables are defined as relative chip radius (r0/t0), relative chip velocity (ωr0/v0), and built-up edge angle (α1). Results of a computer minimization procedure for this equation are presented. In this technique, the required relative stress for shaving is determined through trial-and-error variation of the dependent variables for selected combinations of the independent variables. These results are used to predict the critical rake angle for shaving and the critical rake angle for disappearance of the built-up edge. Comparison with experimental results indicates that the prediction of the critical angle for shaving is useful.
The Geometry of the Shear Zone in Metal Cutting
Authors: Scrutton R. F.
Published: December 2011

The choice of a suitable trajectory shape and slip-line field for the shear zone must be influenced by the degree of work hardening and thermal softening, and is necessarily difficult. Although probably incorrect, the geometry of a polar slip-line field is described in terms of the properties of circular and logarithmic spiral trajectories, as this affords a suitable starting point. It is then assumed that the fundamental quantity is the trajectory shape, and it is shown that a slip-line field may be determined which corresponds to any given set of spiral trajectories. The choice of spirals is limited by the condition of volume continuity. The results of Kececioglu (1960) [4] are reexamined in the light of more recent theories of the shear zone and the experimentally determined strain-rate values are shown to be incorrectly derived. A suitable trajectory shape must first be adopted before calculating the value of the strain rate in terms of the width of the zone.
Toothed Couplings—Analysis and Optimization
Authors: Moked I.
Published: December 2011

The paper is a theoretical analysis of a toothed coupling. It shows the inherent necessity of backlash and its optimal value; it presents a critical comparison of all the existing designs and those proposed by the author, based upon: (a) Maximum and total lag angle between the shafts as a function of misalignment; (b) maximum backlash that may appear between the teeth; (c) angles at which the teeth are in contact; (d) power losses; and (e) type of contact stresses. Finally, it presents the coupling with conical teeth against conical teeth as an optimal toothed coupling.
Optimal Synthesis of Randomly Generated Linkages
Authors: Garrett R. E. , Hall A. S.
Published: December 2011

Departing somewhat from the classical techniques of mechanism synthesis, a design process is developed whereby the speed of the digital computer is a primary design criterion. By efficient use of basic input-output kinematic relationships and the computer’s random number generator, it is possible to obtain four or six-link mechanisms in a few minutes of computer time without any knowledge of synthesis techniques. Although the random approach is applied in this paper to the design of four-link and six-link function generators, it is an approach applicable to coupler-curve, multi-degree of freedom, and three-dimensional synthesis problems.
Strain-Frequency-Temperature Relationships in Polymers
Authors: Warnaka G. E. , Miller H. T.
Published: December 2011

The strain dependence of polymers has been observed to be related to the time-temperature dependence. The paper shows the analytical and empirical relationships.
Design of Space Mechanisms for Rigid Body Guidance
Authors: Suh C. H.
Published: December 2011

A generalized description of three-dimensional finite displacement of rigid body in matrix form is developed with constraint equations representing the physical constraint of basic space linkage elements. RRSS four-bar and RSSR-SS five-bar space mechanisms are investigated to give equations of synthesis for rigid body guiding through finitely separated multipositions in space and also equations of analysis to analyze the performance of rigid body guidance of the synthesized mechanisms.