bluuebunny/crossref_metadata_2025 huggingface dataset:
Multiple Fan-Heat Sink Cooling System With Enhanced Evaporator Base: Design, Modeling, and Experiment
Authors: Quinones Pablo D. , Mok Lawrence S.
Published: July 2009

A cooling device using stacked centrifugal fans and circular heat sinks was designed for cooling a semiconductor chip with a heat flux near 125 W/cm2. In this device, heat is conducted from the chip to a copper heat distribution block and then distributed to multiple heat sinks via four heat pipes. The copper block with embedded heat pipes or evaporator block was optimized using finite element analysis, and several cases were validated with experimental data. The experiments showed great benefits by having a second fan/heat sink in the device. The copper block by itself was found to contribute more than half of the overall thermal resistance of the cooling device. The thermal spreading resistance of the block can be reduced by about 70% if a piece of high-conductivity material, such as a diamond-copper composite, is inserted into its base. The thermal spreading resistance is generally lower when the thickness of the high-conductivity base piece increases. However, the analysis shows that the benefit of using a high-conductivity base tapers off as the thickness of the base piece nears the diameter of the heat pipes (δ∗=1) and weakly worsens after (δ∗>1). The base will also not have a benefit when the size of the chip approaches that of the copper block (A∗=1).
Peptide- and Aptamer-Functionalized Nanovectors for Targeted Delivery of Therapeutics
Authors: Pangburn Todd O. , Petersen Matthew A. , Waybrant Brett , Adil Maroof M. , Kokkoli Efrosini
Published: July 2009

Targeted delivery of therapeutics is an area of vigorous research, and peptide- and aptamer-functionalized nanovectors are a promising class of targeted delivery vehicles. Both peptide- and aptamer-targeting ligands can be readily designed to bind a target selectively with high affinity, and more importantly are molecules accessible by chemical synthesis and relatively compact compared with antibodies and full proteins. The multitude of peptide ligands that have been used for targeted delivery are covered in this review, with discussion of binding selectivity and targeting performance for these peptide sequences where possible. Aptamers are RNA or DNA strands evolutionarily engineered to specifically bind a chosen target. Although use of aptamers in targeted delivery is a relatively new avenue of research, the current state of the field is covered and promises of future advances in this area are highlighted. Liposomes, the classic drug delivery vector, and polymeric nanovectors functionalized with peptide or aptamer binding ligands will be discussed in this review, with the exclusion of other drug delivery vehicles. Targeted delivery of therapeutics, from DNA to classic small molecule drugs to protein therapeutics, by these targeted nanovectors is reviewed with coverage of both in vitro and in vivo deliveries. This is an exciting and dynamic area of research and this review seeks to discuss its broad scope.
The Machinability of a High Strength Zirconium 8.6 Wt% Aluminum Alloy: Tool-Life Curves
Authors: Schulson E. M. , Norman D. M.
Published: July 2009

Tool-life curves have been obtained for an experimental, high-strength Zr 8.6 wt% Al alloy, in two metallurgical states (two-phase Zr2Al/Zr and single phase Zr3Al). Below a critical cutting speed, the data obey the Taylor expression V τn = C, where V is the cutting speed, τ is tool-life and n and C are constants. This expression is used to determine the cutting conditions which optimize the rate of metal removal during turning operations.
Revised Theory for the Quantitative Analysis of Fabric Hand
Authors: Alley V. L.
Published: July 2009

A revision and extension of theory is presented on the nozzle extraction process for obtaining “Handle Moduli” as a quantitative measure of fabric hand. The original one dimensional theory is replaced with a two dimensional membrane theory and a different internal pressure hypothesis is proposed which gives better agreement between tests from different orifice sizes. Conversion relationships between the original and revised data are given and the interaction of specimen weight on “hand” measurements is formulated.
Torque and Thrust Parameters in Drilling Using Dimensional Analysis
Authors: Roadinger T. J. , Townsend M. A.
Published: July 2009

The application of dimensional analysis to the drilling process has provided relevant dimensionless groups for the prediction of torques and thrust and evaluating the influences of several operating variables. Drill design, operating conditions and various materials properties are considered. The applicable experimental procedures are thereby indicated to identify possible strain rate and/or speed effects. Similarity laws are established for large drills (over 1/2 inch diameter), although the same general forms are found for smaller drills. In conjunction with a mathematical analysis, strain rate and speed effects are found to be equivalent, but do not influence torque and thrust, other things being equal. The effects of pilot holes and point angle parameters are also investigated experimentally. The dimensional analysis-similarity approach allows hypothesizing various independent parameters and establishing their influences, if any. Experimental results here are compared with others’ data in terms of the dimensionless groups and are in general agreement.
High-Frequency Yarn Tension Variations in Spinning
Authors: Dyson E. , Afshari G.
Published: July 2009

A description of an experimental investigation of the variations in yarn tension during both ring and rotor open-end spinning which have frequencies equal to, or greater than, the rotational speed of the system is given. Typical results are illustrated and discussed both in terms of statistical parameters such as the coefficient of variation and in terms of their spectra. Tension variations during rotor spinning are shown to have, in general, a much less pronounced periodic structure then the corresponding variations during ring spinning.
Performance of Photovoltaic Cells in Undersea Environment
Authors: Stachiw J. D.
Published: July 2009

Photovoltaic solar cells can serve as a reliable source of electric power for electronic instrumentation in temporarily or permanently submerged marine systems in the form of bottom installations, buoys, or remotely controlled unmanned vehicles. The power output of submerged solar cells is a function of solar insolation intensity on the water surface, depth of submersion, optical properties of water, temperature, and the orientation of the cell surface with respect to the sun. Experimental data was generated by submerging solar cell panels in different bodies of water with 2.5 to 95 feet (0.75 to 29 meters) visibility range, as defined by the observation of a submerged standard 12-inch Secchi disc, and measuring their performance under load. The power output of horizontally oriented, upward facing, photovoltaic cells submerged to the visual contrast limit/depth was found to be a constant, equal to approximately five to ten percent of the power generated by upward facing horizontally oriented cells in atmospheric environment. At lesser depths, the power output of the cells increased, until in the splash zone the output was essentially the same as in atmospheric environment. Based on these findings it can be concluded that high efficiency silicon solar cells can serve as a practical electrical power supply in electronic devices for marine applications, providing that their depth of submersion is less than the visual contrast limit at the dive location.
A New Method of Studying the Performance of Grinding Wheels
Authors: Kumar K. V. , Cozminca M. , Tanaka Y. , Shaw M. C.
Published: July 2009

A new technique for studying the performance of abrasive tools is described that is not only useful for evaluating the rate of wear of grinding systems but is also capable of yielding difficult to obtain data (such as the effective number of cutting points and local wheel work deflection) essential in fundamental studies of grinding. The new method involves overcut fly cutting with a small (1/8 in × 1/8 in) cluster of abrasive grains that are normally bound together and dressed. The small size of the specimen is particularly important relative to wear studies in that it enables wear data to be obtained with a relatively small amount of grinding and also permits the used abrasive to be studied in the scanning electron microscope.
Control Methods for a Hot Steel Rolling Mill: An Application of Learning Theory and Pattern Recognition
Authors: Desrochers A. A. , Saridis G. N.
Published: July 2009

This paper presents roll force control methods to be used with the predictive force setup model of the finishing stands in a hot steel rolling mill. Current mill practices achieve a desired strip gauge by using a predictive force model to setup the roll gaps on the finishing stands. At any time before the steel enters the first finishing stand a human operator may modify the roll gap settings if it is felt that under the present conditions the force predicted by the setup model is going to be unacceptable. In this paper, the decision process of the operator is modelled by pattern recognition methods to obtain this extra degree of feedforward control. In addition, feedback control is provided from one steel run to the next by an adaptive controller which uses a linear reinforcement learning scheme to adjust its parameters. Results are presented from actual mill data.
Multiphase Bulk Solids Flow Systems
Authors: Emery R. B.
Published: July 2009

Theory and proof are presented here related to fluid pressure control of bulk solids flowability. They are directed toward a quantitative design goal for fluid-solids flow systems. An effort is made to relate multiphase system concept to existing soil mechanics, strength of material and bulk solids flow theory. Gas or liquid interstitial loads often add cumulative effects to the mechanical loads normally considered in bulk solids flow systems. Summation of the mechanical, gas and liquid loads form the basis for multiphase system design. Useful savings in design, construction and maintenance are expected from application of multiphase theory. Quantitative design can, in some cases, provide flow, no-flow, or a controlled combination of flow and no-flow.
On Certain Aspects of Transient Stresses in Cutting Tools
Authors: Chandrasekaran H. , Nagarajan R.
Published: July 2009

The transient aspects of chip formation during the entry of tool into the workpiece and its exit is receiving greater attention of late in the light of the need for correct evaluation of the cutting capabilities of tools during intermittent cutting. The data will also have relevance in understanding the tool performance in operations like milling. The present article is devoted to the specific aspect of transient stresses in the cutting tool-tip during its entry into the work material under different conditions of cutting such as speed, thickness of cut, rake angle and entry mode. From the instantanious force and contact length data, using the single concentrated load approximation the injurious free rake tensile stress transient was studied. This indicates a specific stress peak having its own time history depending upon the cutting conditions used. Useful conclusions on the strength aspects of cutting tools under transient loading conditions have been drawn.
Influences of Friction and Metal Properties on Pure Stretchability of Sheet Metals
Authors: Kobayashi M. , Kurosaki Y. , Kawai N.
Published: July 2009

The influences of the frictional coefficient at the tool-work interface and of the metal properties, such as n-value or r-value, on the stretchability of sheet metals have been examined both theoretically and experimentally. The optimum frictional coefficients for improved stretchability have been found by both numerical analysis and experiment. Their values become smaller as n- and r-values become larger. Stretchability can be markedly improved by reducing the frictional coefficient to less than 0.05, for sheet metals having an n-value of more than 0.2.
Formability Assessment by Bulge Test Employing Grooved Disks (Investigation into the Optimum Geometry of the Groove)
Authors: Kawai N. , Kurosaki Y.
Published: July 2009

The optimum geometry of the groove is investigated in the bulge test employing concentrically grooved disks which was earlier proposed as a press-formability test by the authors. It is recommended that a groove is formed with the circular arc profile to 0.125 t0 in depth at the radial position of 0.4 r2 on the disk surface, where t0 is the initial thickness of a blank and r2 is the radius of the die aperture. It is concluded that both deep-drawability and pure-stretchability of sheet metals can be accurately assessed by a single blank test. The deformation behavior of grooved specimens is examined also by numerical analysis.
Grinding of WC-Co Cemented Carbides
Authors: Zelwer O. , Malkin S.
Published: July 2009

An investigation is reported on the grinding process for WC-Co cemented carbides with diamond wheels. SEM examination of the grinding detritus revealed that material removal occurs mainly by flow-type chip formation. A grinding model is proposed whereby the total grinding energy is partitioned into a chip formation component for material removal, and a plowing component causing plastic deformation of the workpiece by a force along the engaged cutting edges. With many wheel-workpiece combinations, the specific chip formation energy was found to be comparable to the dissociation energy of WC, suggesting chip formation by constrained adiabatic plastic flow to the energy limit. Wheel topography measurements showed an increasing number of cutting points with coarser grit size, which is attributed to coarser grains having more cutting points per grain and less of a tendency to dislodge. Finished surfaces exhibited grooves along the grinding direction with valleys depleted of cobalt and ridges along the sides of the grooves rich in cobalt.
Heat Flow Transducer Responses to Hyperbaric Environments
Authors: Nuckols M. L.
Published: July 2009

The responses of heat flow transducers, used in the evaluation of convective body heat losses, have been investigated at hyperbaric environments. Environmental temperatures, pressures, and gas composition were varied while transducer responses to constant heat fluxes were observed. Ambient temperatures were varied between 3° and 40° C. Ambient pressures were varied between simulated depths of 0 and 1000 feet of seawater (445 psi). Transducer responses to heat fluxes varying between 0 and 250 watts/m2 are reported in the above temperature and pressure ranges within atmospheres of helium, nitrogen, and air. Ambient pressure variations were found to have little effect on the response of the heat flow transudcers to a constant heat source once appropriate temperature corrections were made. However, transducer response variations of up to 14 percent were observed when environmental gas compositions were varied at hyperbaric conditions.
Improved Wheel Tread Profiles for Heavy Freight Vehicles
Authors: Marcotte P. P. , Mathewson K. J. R. , Caldwell W. N.
Published: July 2009

This paper describes recent theoretical and experimental work carried out by CN Rail Research in an effort to improve the performance of conventional 100-ton freight car trucks through the use of nonstandard wheel tread profiles. The steady state curving behavior of a conventional three-piece frame truck has been studied using a nonlinear computer simulation to identify the effects of wheel conicity and track curvature on wheel-rail forces and on wear parameters. Lateral curving forces were compared from a field test using dynamometer tieplates on a 5-degree curve (350 m radius) for four different wheel profiles including the AAR standard for new wheels. Preliminary results of a long term test on cars in revenue service are presented to show the effect of initial wheel profile on the early wear patterns as well as to show the methodology used for comparing the profiles under test. Finally, a brief review is made of the potential benefits resulting from the use of wheel profiles which are better adapted to service-worn rail head contours.
London Transport Trains
Authors: Smith S. F.
Published: July 2009

This Paper describes the process of design and development and procurement of new trains for London Transport, who assume many of the functions of a prime contractor. The Paper gives a number of examples of features which are felt to reduce the maintenance cost or improve the reliability or safety of the rapid transit cars.
Locomotive Friction-Creep Studies
Authors: Logston C. F. , Itami G. S.
Published: July 2009

The utilization of available locomotive wheel-rail adhesion has been and continues to be an area of great concern to locomotive builders and railroads throughout the world. In 1976, EMD completed an extensive four-year research program initiated to investigate the relationship between wheel-rail friction and wheel creep on a locomotive wheel. The purpose of this paper is to present the results of this friction-creep study. Included is a discussion of the various conditions that affect the friction-creep relationship. Test sites, test-procedures, instrumentation, and data analysis methods are also discussed. The conclusions are aimed at providing an understanding of adhesion at the wheel-rail interface and how this pertains to locomotive utilization of that adhesion.
Harmonic Roll Response of a Railroad Freight Car
Authors: Hussain S. M. A. , Garg V. K. , Singh S. P.
Published: July 2009

A mathematical model of a railroad freight car has been developed under the Track-Train Dynamics Program. The model simulates a car equipped with auxiliary suspension devices (e.g., rubber-cushion type or viscous dampers) under various perturbed track conditions. The study compares the model predictions with test data, and demonstrates the application of the model in studies of various auxiliary suspension devices for controlling the harmonic roll response and component loadings of a railroad freight car.
The Influence of Truck Hunting Severity on Freight Car Structures
Authors: Hengel M. F. , Montgomery C. , Billingsley R. H.
Published: July 2009

In recent years much effort has been expended within the industry on investigating the causes of truck lateral instability or hunting. To determine the cause of this phenomenon various research organizations, among them the Association of American Railroads and Arizona State University have performed comprehensive tests to validate mathematical models which can be used to conduct parametric studies. These models allow for investigating various means for alleviating the non-linear instability problem. In addition, much effort has been expended by a number of private companies to develop freight car trucks with superior hunting performance. It is now well understood by the railroad industry that, given the current state-of-the-art in freight car truck design, some truck hunting behavior is unavoidable. Less attention, however, has been directed toward determination of what amount of truck hunting, if any, is acceptable. This paper describes the results of two field investigations in which truck hunting instability led to either excessive wear or structural degradation. Various means readily available to the industry were then investigated as to their effectiveness in controlling hunting. Results are presented showing that the particular problems encountered were avoided by control of the hunting phenomenon rather than its complete elimination.
Development of Multi-Bar Weft-Insert Warp Knit Glass Fabrics for Industrial Applications
Authors: Ko F. , Bruner J. , Pastore A. , Scardino F.
Published: July 2009

The concomitant nature of the translational efficiency of material properties and the toughness of woven fabrics have been a technical problem in many industrial applications involving the use of high modulus materials. Recent advance in warp knitting technology has created new possibilities in the engineering of fabric structures. Work on Multi-Bar Weft-Insert Warp Knit (MB-WIWK) fiberglas fabrics showed that fabric elongation can be engineered without sacrificing yarn properties. The geometry of the structural unit cell in a MB-WIWK fabric is similar to a trellis mechanism which can elongate until jamming, thereby providing a controlled and recoverable amount of fabric extension without exerting a compressive stress on the high modulus yarns. This unique fabric geometry can provide structural integrity plus an energy-absorbing capability which is necessary for satisfactory performance under dynamic loading conditions.
A Model for Drying on Adiabatic Saturation Lines
Authors: Hebrank W. H.
Published: July 2009

A model is developed to simulate continuous steady state evaporation. The process is one that proceeds along adiabatic saturation curves. Aerodynamic effects of dryer air and circulation flow flux are combined with dryer temperature and humidity to compute evaporation rates. The calculation method requires several iteration loops and a computer program to do the work is described. Curves are presented of evaporation rates as affected by temperature, humidity, nozzle heat transfer efficiency and circulation flow quantity. Optimization of process cost and energy are discussed.
The Initial Modulus of Filament Webs
Authors: Dent R. W.
Published: July 2009

A review of the existing theories for the Young’s modulus of continuous filament random webs is given. It is shown that the effect of buckling of the transverse filaments must be included in the theory. This means that filament bending and bond rotation must also be included in the model for the theory to be consistent. Accordingly, we have derived a theory including the effects of buckling, filament bending and bond rotation for the first time and the results are given and compared to those obtained where buckling was neglected.
Adaptive Control Optimization of Grinding
Authors: Amitay G. , Malkin S. , Koren Y.
Published: July 2009

A computerized adaptive control grinding system has been developed. The system is designed to optimize both the grinding and dressing conditions for maximum removal rate subject to constraints on workpiece burn and surface finish. The control strategy of the system is based upon online convergence along a predetermined optimal trajectory derived from grinding theory. A pilot system was developed and illustrative results are presented which demonstrate its performance and the practical feasibility of the optimization concept.
Upper Bound Analysis of Axisymmetric, Closed-Die Forgings
Authors: Dadras P.
Published: July 2009

A kinematically admissible velocity field for axisymmetric closed die forging is proposed. The forging power and load are calculated and compared with experimental values. It is found that the theoretical predictions give estimates that are substantially higher than actual loads and powers. Also, the effect of different parameters on the height and shape of the deformation zone is investigated and it is shown that the height is independent of flash thickness and length. The angle of convergence of flow from the die to the flash decreases as the flash thickness is increased.
Cyclic Behavior of Class U Wheel Steel
Authors: Park Y. J. , Stone D. H.
Published: July 2009

In order to evaluate the material properties of Class U wheel steel under cyclic loading, low-cycle fatigue tests were conducted at room temperature on specimens taken from the rim of the wheel. The test results show that Class U wheel steel experiences significant cyclic softening at lower strains, but cyclically hardens at larger strain levels. Due to the cyclic softening at lower strain levels, the steel will plastically deform, even at stresses of about one-half of the monotonic yield strength. Quantitative fatigue properties, which can then be used to predict accurate fatigue lives of various components of wheels under complex service environments, are also obtained from the low-cycle fatigue tests.
On-Line Hole Quality Evaluation for Drilling Composite Material Using Dynamic Data
Authors: Radhakrishnan T. , Wu S. M.
Published: July 2009

Aircraft manufacturing involves the drilling of a large number of holes for structural joints. The life and proper functioning of the joint can be critically affected by the quality of the hole which generally deteriorates with drill wear. In the use of composite material for the aircraft structure, the “lamination frequency,” associated with the laminated fiber of the material, can be considered to represent the waviness of the hole surface (an aspect of hole quality). The variance associated with this frequency, present in the dynamic nature of the drilling thrust and the hole surface profile, was found to change with the use of the drill. This study presents the possibility of using this change in the lamination frequency content of the drilling thrust for on-line monitoring of the drill condition, through analysis by the Dynamic Data System (DDS) technique.
The Hammer QSD-Quick Stop Device for High Speed Machining and Rubbing
Authors: Black J. T. , James C. R.
Published: July 2009

A quick stop device (QSD) was designed for use in orthogonal machining and rubbing experiments. QSD’s are used to obtain chip root samples that are representative of the deformation taking place during dynamic (actual) cutting conditions. These “frozen” specimens are helpful in examining the plastic deformation that occurs in the regions of compression and shear which form the chip; the secondary shear at the tool-chip interface; and the nose ploughing/flank rubbing action which operates on the newly machined surface. The Hammer QSD employs a shear pin mechanism, broken by a flying hammer, which is traveling at the same velocity as the workpiece. The device has been successfully tested up to 6000 sfpm (30.48 m/sec).
Single Grit Simulation of the Abrasive Machining of Wood
Authors: Dornfeld D. A.
Published: July 2009

The wood-grit interaction between an idealized steel grit and both dry and saturated ponderosa pine (Pinus ponderosa) is investigated for a range of grit rake angles. Regions of rubbing, ploughing and cutting are identified for machining both with the grain and cross grain by scanning electron microscope examination of the machined surfaces. Using data of the tangential force on the simulated grit the coefficient of friction for all test conditions was calculated and the effect of tool rake angle, grain direction and moisture content quantified. A model of the energy of deformation of wood fibers during rubbing and the initial stages of ploughing was postulated based upon the theoretical stress distribution in an elastic material beneath a moving indentor. This model was evaluated using the calculated friction coefficients and wood mechanical properties.
The Role of Wheel-Work Deflection in Grinding Operations
Authors: Kumar K. V. , Shaw M. C.
Published: July 2009

The arc of contact between an individual abrasive particle in a grinding wheel and the workpiece is an important parameter that may be readily calculated if local deflections of wheel and workpiece are neglected. A quick-stop method of determining the difference in contact length due to local wheel-work deflection is presented. Analysis of the results obtained suggest that in fine surface grinding (1) the influence of local wheel-work deflection on contact length is relatively minor (~15%) and (2) the predominant effect is due to wheel deflection and not work deflection. The method presented enables the influence of wheel deflection on contact length to be readily predicted for any grinding situation if the radial component of grinding force and elastic constants of the wheel are known.
Circular Saw Vibration Control by Induction of Thermal Membrane Stresses
Authors: Mote C. D. , Schajer G. S. , Holo̸yen S.
Published: July 2009

Circular saw transverse vibration and product dimensional accuracy were measured during a series of production experiments in which sawblade vibration was controlled by the deliberate introduction of thermal membrane stresses. Induction heating near the saw collar was used to control the temperature difference between two concentric annular zones on the sawblade surface. Optimal temperature conditions were predicted using the critical speed stability theory for symmetrical circular saws and these predictions were verified through production experiments. Feedback control of sawblade temperature was successfully demonstrated in production as a means of reducing blade vibration and improving dimensional accuracy.
Relationships Between Cutting Force Variations and Cutting Factors in Plain Milling Operations. Part 2: Plain Milling With a Multi-Toothed Helical Cutter
Authors: Kato S. , Yamada T. , Hashimoto M. , Yamaguchi K.
Published: July 2009

Cutting force variation in plain milling with a multi-toothed helical cutter can be obtained by calculation on the basis of the measured cutting force variation in plain milling with a single-toothed helical cutter. To comprehend the variation of cutting force quantitatively, a technical term of “variation rate” is defined. The variation rate of cutting force in plain milling with a multi-toothed helical cutter indicates minimum values in a certain number of teeth. To minimize cutting force variation, the relationships between the number of teeth and the cutting factors are discussed from the viewpoint of the variation rate.
Tooling Design for ECM—A Finite Element Approach
Authors: Jain V. K. , Pandey P. C.
Published: July 2009

Over the last few years several models have been suggested for analytical design of tools used in electrochemical machining of complex shaped workpieces. However, little success has been achieved in this direction. This is due to complex nature of interaction between the electrochemical machining parameters and lack of clear understanding of the mechanism of metal removal. This paper reports about the application of Finite Element Technique (FET) to design analysis of ECM tools. The results obtained have been compared with the experimental data and a good correlation has been observed. The paper also discusses in detail the computational aspects.
In-Process Measurement of Surface Roughness in Turning by Laser Beams
Authors: Shiraishi M.
Published: July 2009

A new technique for in-process measurement of surface roughness is introduced which employs an optical method by using double laser beams. This makes it possible to detect the surface roughness not only along the circumferential path but also along the feed direction even during machining. The experimental results show that the presence of chipping and chattering can be detected sensitively along both measurements directions and the maximum roughness value is always obtainable from the reading along the feed direction.
Numerical Techniques in Linear Duct Acoustics—A Status Report
Authors: Baumeister K. J.
Published: July 2009

A review is presented covering both finite difference and finite element analysis of small amplitude (linear) sound propagation in straight and variable area ducts with flow, as might be found in a typical turbojet engine duct, muffler, or industrial ventilation system. Both steady-state and transient theories are discussed. Emphasis is placed on the advantages and limitations associated with the various numerical techniques. Examples of practical problems are given for which the numerical techniques have been applied.
Continuous Miner Noise
Authors: Robertson J. , Kovac J. , Bartholomae R.
Published: July 2009

Noise generated by continuous miners in underground coal production is an important health hazard. Bureau of Mines contract J0387229 charters investigation and control of this noise through laboratory tests of simulated cutting operations and through in-mine noise measurements. The results of these investigations indicate that coal cutting noise and conveyor noise are dominant sources of miner operational noise. Typical noise levels for both cutting and conveying operations are approximately 97 dBA. For full operation of all machine systems, the overall sound pressure level is approximately 101 dBA. In-mine and laboratory test results show excellent agreement in both A-weighted overall levels as well as A-weighted one-third octave band spectra.
Locally and Nonlocally Reacting Flexible Porous Layers; A Comparison of Acoustical Properties
Authors: Ingard K. U.
Published: July 2009

The acoustical properties of a porous layer backed by a rigid wall are studied with particular attention to the difference between locally and nonlocally reacting layers and the role of flexibility of the material. Propagation constant, impedance, reflection, and absorption coefficients are discussed as functions of frequency and the angle of incidence. Characteristics frequencies and scaling laws are considered and the conditions for maximizing the absorption coefficient are determined in terms of the normalized layer thickness D/λ, where λ is the wavelength. The possibility of using the flexibility of the material for the purpose of creating a low frequency resonance with high absorption without significant loss at high frequencies is explored.
Quantitative Relationships for Acoustic Emission from Orthogonal Metal Cutting
Authors: Kannatey-Asibu Elijah , Dornfeld David A.
Published: July 2009

Theoretical relationships have been drawn between acoustic emission (AE) and the metal cutting process parameters by relating the energy content of the AE signal to the plastic work of deformation which generates the emission signals. The RMS value of the emission signal is expressed in terms of the basic cutting parameters. Results are presented for 6061-T6 aluminum and SAE 1018 steel over the range of speeds 25.2 to 372 sfm (0.128 to 1.9 m/s) and rake angles 10 to 40 deg. Good correlation has been found between predicted and experimental signal energy levels. In addition, AE generation from chip contact along the tool face is studied and the AE energy level reflects the existence of chip sticking and sliding on the tool face, and indicates the feasibility of utilizing AE in tool wear sensing.
A Note on the Solution for Continuous Jet Penetration of Solids
Authors: Walters W. P. , Scott B. R.
Published: July 2009

The study extends the simplified solution of Hashish and duPlessis by obtaining an exact solution to their governing equation. This exact solution does not invoke many of the assumptions specified by Hashish and duPlessis. The solution expresses the penetration depth as an implicit function of time and may be used to provide further insight into the penetration of solid materials by water jets.
On Circular Pipe Wall Vibratory Response Excited by Internal Acoustic Fields
Authors: Loh H.-T. , Reethof G.
Published: July 2009

Internal acoustic fields in pipes as generated by control valves, for example, interact with the pipe walls such that very large drops in transmission loss are experienced at a series of discrete frequencies, the coincidence frequencies. This paper develops the analysis for the calculation of the pipe vibration amplitude at the coincidence frequencies so that the radiation external to the pipe can be estimated. External acoustic loading and material damping are considered. The analysis was applied to experiments which were performed on a somewhat idealized test fixture. Combining the results of the analysis with the test results permitted the estimation of the material damping for the particular material used. Results show that structural damping for the low carbon steel varies from 0.04 at high frequency to a high of 0.20 at the lowest frequency which agrees fairly well with the results from other research on flat steel plates. The rather large values of the estimated damping coefficients may well be caused by the visco-elastic damping materials used at the ends of the pipe’s tee section.
On the Acoustical Implications of Vortex Shedding from an Exhaust Pipe
Authors: Rienstra S. W.
Published: July 2009

Asymptotic approximations for small Strouhal number are derived for the solution of the problem of the interaction between an acoustic wave and a subsonic jet flow issuing from a semi-infinite pipe. Density and sound speed differences between the jet flow and the (slowly moving) ambient medium, and a general edge condition are included. The approximations relate to the field inside the jet flow, to the far field, to the reflection coefficient, end-impedance and end correction for the reflected wave inside the pipe, and to the transmitted and radiated sound power. Within the range of parameters considered, the effect of the density and sound speed differences and ambient flow is found to be appreciable, although the character of the solution is not changed. However, the choice of the edge condition does have important implications; specifically, the phase of the reflected wave is most sensitive to only slight deviations from the Kutta condition.
Variational Formulations for the Finite Element Analysis of Noise Radiation from High-Speed Machinery
Authors: Thompson B. S.
Published: July 2009

Variational theorems are presented for analyzing the vibrational response of flexible linkage mechanisms and the surrounding acoustic medium in which they are immersed. These theorems are established by generalizing Hamilton’s principle through using Lagrange multipliers to incorporate field equations and boundary conditions within the functional. The same philosophy is adopted to handle the conditions at the fluid-structural interface. When independent arbitrary variations of the system parameters are permitted, these acousto-elastodynamic theorems yield as characteristic equations the equation of motion for each member of the linkage, the acoustical wave equation, the compatibility conditions at the interface between the fluid and solid continua, and also the boundary conditions. These variational statements provide the foundations for several different classes of finite element analysis.
Drop-Size Distributions of Newtonian and Bingham Liquid Sprays Produced by Fan-Jet Pressure Nozzles With and Without the Preorifice
Authors: Janna William S. , John James E. A.
Published: July 2009

Measurements were made of the drop-size distributions of water and of paint sprays produced by fan-jet pressure nozzles, operating in the pressure range 900 to nearly 3000 psi (6200–20,680 kPa). A collection device was constructed and droplets were captured on soot-coated and on plain microscope slides. Subsequent sizing of the impacted particles with a microscope yielded drop-size distribution data of accumulated volume percent versus diameter. Data were gathered of water and of paint sprays produced by a fan-jet pressure nozzle-preorifice combination. The effect of the preorifice on drop-size distribution was evaluated.
Some Problems in Winding Geometry
Authors: Schoppee M. M.
Published: July 2009

The efficiency of wound, hollow-fiber separation modules used to remove dissolved salts from water by the process of reverse osmosis may be improved by alterations in module geometry. Normally, the hollow-fiber membranes composing the module are helically wound about a cylindrical core. Flow rate through the module may be increased, however, if the cross-sectional density of wound fibers varies uniformly along the module axis. This paper explores the analytical requirements for the helical winding of a conical mandrel with filamentary material in a manner that eventually produces a cylindrically shaped package. The effect of specifying either a constant yarn feed rate or a constant spindle speed during winding is considered in relation to restrictions on the length of material added per circuit.
Determination of Balloon Surface in Textile Machines—A Finite Segment Approach
Authors: Lisini G. G. , Nerli G. , Rissone P.
Published: July 2009

This paper describes an application of the finite-segment technique to the study of balloon in textile machines. The method is applicable to many textile processes and is very useful for correct designing of the related machines. Experimental results, which in general agree with the theoretical ones, are also reported.
Table Sliding Taper Hobbing of Conical Gear Using Cylindrical Hob. Part 1: Theoretical Analysis of Table Sliding Taper Hobbing
Authors: Mitome K.
Published: July 2009

First this paper deals with a kinematic analysis of hobbing. As a result, all the tooth surfaces of a gear cut by this hobbing are proved to be slightly different respectively. Next an ideal gear by this hobbing is defined, and an imaginary generating rack which generates the ideal gear is obtained. Finally how to determine cutting dimensions is presented.
Optimization of Multipass Turning With Constraints
Authors: Ermer D. S. , Kromodihardjo S.
Published: July 2009

Single pass operation is not always the most economical or the most productive, for under such practical constraints as available horsepower, desired surface finish, minimum tool life and maximum permissible feed and speed, it can be shown that two passes, or sometimes even three passes, can be cheaper or take less production time. The objective of this paper is to illustrate when multipass turning is optimum and what ratios of rough to finishing depths of cut will give the optimum. The optimizing is determined by geometrical programming combined with linear programming. This mathematical approach can handle as many constraints as required, and any combination of them can be tight or loose at the optimum solution. Several examples are given to demonstrate the application of the method and the advantage of the process optimizing technique.
Compensatory Control of Roundness Error in Cylindrical Chuck Grinding
Authors: Rao S. B. , Wu S. M.
Published: July 2009

Traditional methods of improving the roundness generating capability of cylindrical grinding machine calls for the manufacture of an ultra-high precision spindle and bearings and careful and painstaking assembly. This approach, where the effort is directed to the reduction or even elimination of the causes of errors, and which is used for all precision machines, has enabled the achievement of high accuracies but only at exorbitant costs. This paper presents a completely different approach to the problem which is based on contemporary technology and holds the promise of bringing high precision into the realm of economical manufacturing. This new approach is based on the precise measurement, on the analysis of the cause of error, on the capability of on-line mathematical modeling, and, finally, on forecasting and compensation. The system, which was implemented on a cylindrical grinding machine, showed a considerable degree of success, enabling the reduction of roundness error by up to 50 percent. The degree of success of this work indicates the feasibility of employing this approach to other types of form inaccuracies on other conventional machine tools.
Drawing Force in Deep Drawing of Cylindrical Cup With Flat-Nosed Punch
Authors: Korhonen A. S.
Published: July 2009

A method for estimating the maximum drawing force in the deep drawing of cylindrical cups with flat-nosed punch is developed. The criterion is obtained using the load maximum principle for localization of the plastic flow. The criterion is then applied in an attempt to develop a simple and practically applicable method for deep drawing force evaluation. Simple charts are presented to obtain the maximum drawing force as a function of the tooling geometry and anisotropy for steel, brass and stainless steel.
Acceleration Detection and Inertia Compensation of Pantograph Head Using a Constant Flow Hydraulic Servo
Authors: Vinayagalingam T.
Published: July 2009

The paper presents a novel form of acceleration detection which is suitable for use in hydraulic amplification stages for relatively low frequency, high power output servo systems. The acceleration detector was developed as part of a research program concerned with the development of a servo assisted pantograph to provide improved current collection on high speed electrified railways.
Review of Noise Reduction Methods for Centrifugal Fans
Authors: Neise W.
Published: July 2009

Several methods of reducing the noise of centrifugal fans are discussed, most of which were aimed at a lower blade passage frequency level because tonal noise components are of particular annoyance. The various methods are (1) increasing the cutoff clearance, (2) increasing the radius of curvature of the cutoff edge, (3) angle of inclination between impeller blades and cutoff edge, (4) staggering the blades of double inlet or double row impellers, (5) wire meshes mounted along the inner and outer circumference of the radial blade row, (6) irregular blade spacing, (7) mismatch between the acoustic impedances of fan and duct system, (8) triangular guide belt around the impeller, (9) rectangular fan casing, (10) circular fan casing, (11) acoustically optimized fan casing, (12) optimum annular clearance between impeller eye and intake nozzle, (13) acoustical lining of the interior of the fan casing, (14) using minima of the fan acoustic radiation efficiency, and (15) resonators at the cutoff.
Acoustic Similarity Laws for Fans
Authors: Neise W. , Barsikow B.
Published: July 2009

In order to verify experimentally acoustic similarity laws for fans, experiments were made with three, dimensionally similar centrifugal fans of 140, 280, and 560 mm impeller diameter. The fans were connected to anechoically terminated discharge ducts. It is shown that the influence of the Reynolds number on the radiated sound pressure is negligible within 1.4•105 ≦ Re ≦ 2.2•106, which is the range covered by the measurements. This is in agreement with earlier studies in which the Reynolds number was varied from 1.4•104 to 4.5•105. From the experimental results it is concluded that fan noise data that are taken on model fans can be extrapolated to other dimensionally similar fans of different size for arbitrary fan speeds and working fluids, provided that the operating condition and the measurement position are the same.
Effect of Crystallinity and Orientation on Oscillation During Drawing of Polyethylene Terephthalate
Authors: Behery H. M. , Porcher B. K.
Published: July 2009

Stress oscillations have been observed in cold-drawn synthetic monofilaments and films. The effects of these oscillations on cross-section and lengthwise filament properties have been under investigation. Mathematical models based on heat transfer and theory of elasticity have been proposed by some investigators. But, quantification of these micro-stress-oscillations has not been completed. Alteration of filament structure by drawn oscillations may change optical, thermodynamic, chemical, and tensile properties. Micro-stress-oscillations during cold-drawing were investigated in polyethylene terephthalate monofilaments with various crystallinities and orientations. Micro-stress-oscillations observed were quantified on the basis of average oscillation period, and maximum, minimum, and average oscillation amplitude. Results showed that drawing rate and orientation had the greatest effect on the occurrence of micro-stress oscillation. The frequency of the oscillations increased as the drawing rate decreased and also with the decrease of filament orientation. Crystallinity and yield load did not show any appreciable effect on the occurrence of micro-stress-oscillation. Oscillations altered the filament optical properties, light transmission, and reflection.
Development of a Cross-Braced Truck
Authors: Mulcahy H. W. , Weeks R. J.
Published: July 2009

This paper describes the analytical, design, and test processes utilized in development of a cross-braced freight car truck intended for service on American railroads. Analytical techniques predict the stability boundaries and curving characteristics, and suggest ranges of suspension parameters to satisfy various service conditions. Within the constraints normally placed on truck suspension systems, a viable design is evolved and the system is further qualified by extensive dynamic testing.