bluuebunny/crossref_metadata_2025 huggingface dataset:
The Upper Bound Approach to Plane Strain Problems Using Linear and Rotational Velocity Fields—Part I: Basic Concepts
Authors: Avitzur Betzalel , Pachla Waclaw
Published: July 2009

This paper investigates an upper bound approach to plane strain deformation of a rigid, perfectly plastic material. In this approach the deformation region is divided into a finite number of rigid triangular bodies that slide with respect to one another. Neighboring rigid body zones are analyzed in specific cases where the zones are (1) both in rotational motion, (2) one in linear, the other in rotational motion and (3) both in linear motion. Specific equations are presented that describe surfaces of velocity discontinuity (shear boundaries) between the moving bodies, and the velocity discontinuities and shear power losses for each of the three cases. The shape of the surface of velocity discontinuity is uniquely determined by the velocity ratios of neighboring bodies, their relative directions of motion and, where applicable, the positions of their centers of rotation. Where one or both neighboring bodies exhibit rotational motion, the surface of velocity discontinuity is found to be a cylindrical surface. In the case of two neighboring bodies, each with linear motion, the surface of velocity discontinuity is found to be planar. The velocity discontinuity is found to be constant along the entire surface of velocity discontinuity. The characteristics of the surfaces of velocity discontinuity in plane strain deformation are investigated. The upper-bound approach to plane strain problems can be successfully adapted to real metal forming processes, including sheet and strip drawing, extrusion, forging, rolling, leveling, ironing, and machining.
Uncertain Eigenvalue Analysis of Composite Laminated Plates by the Stochastic Finite Element Method
Authors: Nakagiri S. , Takabatake H. , Tani S.
Published: July 2009

Uncertain eigenvalue problem of linear vibration is analyzed by means of the stochastic finite element method, the basis of which utilizes mean-centered second order perturbation technique. Attention is paid to the fluctuation of the stacking sequence, that is, fiber orientation and layer thickness of FRP laminated plates. The stacking sequence is expressed in terms of probabilistic variables. The eigenvalue problem is formulated based on the Kirchhoff-Love’s theory of thin plate, the stretching, coupled and bending stiffnesses of which are uncertain due to the stacking sequence. The numerical analyses deal with the vibration of simply-supported graphite/epoxy plates. The sensitivity of the input stacking sequence and the correlation coefficients of the probabilistic variables are evaluated quantitatively.
Verification of On-Line Computer Control of EDM by Data Dependent Systems
Authors: Pandit S. M. , Mueller T. M.
Published: July 2009

A new method of computer control of electro-discharge machining based on Data Dependent Systems (DDS) methodology has been recently proposed. The control is based on a parameter which effectively represents the resistance of arc and is isolated by the DDS model from the random current and voltage signals in spite of the large noise. This paper presents an experimental verification to show that this parameter indeed represents the arc resistance which cannot be measured by any other means and that the parameter is quite sensitive to the change from beneficial sparking condition to the harmful arcing condition. Off-line analysis of the EDM process under different conditions is presented with this parameter as the response variable. Development of the control strategy using the results of this analysis is illustrated. Implementation of the strategy by means of a Motorola microcomputer is described. A comparison of metal removal rate (MRR), surface roughness, and tool wear for the computer control and the optimal manual adjustment recommended by the EDM machine manufacturer is presented. It shows that the computer control yields an increase in the MRR of 47 percent and 19 percent, while the ratio of tool wear to MRR reduces by 26 percent and 16 percent, respectively, in finishing and roughing conditions.
Torque Sensor For Direct-Drive Manipulators
Authors: deSilva C. W. , Price T. E. , Kanade T.
Published: July 2009

This paper describes the development of a joint torque sensor for the second direct-drive manipulator at Carnegie-Mellon University (CMU DD Arm II). The approach taken is to develop the sensor using static design considerations and then test it to verify its dynamic performance. Several design considerations applicable to semiconductor strain-gage torque sensors are presented. These are strain capacity limit, nonlinearity, sensitivity, and stiffness specifications. Associated design equations have been developed in the present work. A numerical example is given to illustrate the use of these design considerations. The development of a circular-shaft torque sensor for the CMU DD Arm II, that employs semiconductor strain gages, is described. Typical results from a static calibration test and from step and impulse tests are presented. Test show that the torque sensor performs well under dynamic conditions in a bandwidth of 100 Hz.
An Integrated CAD/CAPP System with “Know-hows” on Machining Accuracies of Parts
Authors: Iwata K. , Sugimura N.
Published: July 2009

An prototype of an integrated CAD/CAPP system named CIMS has been developed. The sequence of machine tools and the machining sequence are determined by the CIMS based on the models of the parts designed by the CAD system. A modeling system was developed to construct the models of the parts which include both the geometrical information and the technological information of the accuracy, the surface roughness and the material. Since the machining sequence is influenced by the accuracy of the part, a systematic method was proposed to describe the know-hows which give the relations between the machining accuracies and the machining sequences. A procedure was proposed to determine the sequence of machine tools and the machining sequence by applying the know-hows. The system developed is able to generate suitable process plan which is almost the same as ones designed by the experienced process planners.
A New Approach to Development of a Grinding Force Model
Authors: Younis M. , Sadek M. M. , El-Wardani T.
Published: July 2009

A theoretical model has been developed for representing the grinding forces. This is based on the fact that the chip formation during grinding consists of three states: ploughing, cutting, and rubbing. Expressions for the total normal and tangential force components during these three stages were established. These components were expressed in terms of the chip thickness coefficient, the friction coefficient between the grit tip area and the workpiece, the stress coefficient arising during ploughing and, finally, the loading coefficient. The latter is expressed as an exponential in time. All these coefficients were determined experimentally by performing normal grinding tests at specified configurations. During these tests the forces were measured simultaneously with the loaded area on the grinding wheel during the process of grinding. The loaded area on the wheel surface was measured by a new technique using fiber-optics. This is based on the measurement of the reflectivity of the loaded particles. This system was calibrated by high magnification photographs taken of the surface texture. The predicted normal and tangential forces during the grinding process were compared with those experimentally obtained during the grinding tests mentioned earlier, showing reasonable agreement, both quantitatively and qualitatively.
Measurement of the Interfacial Stresses in Rolling Using the Elastic Deformation of the Roll
Authors: Meierhofer D. J. , Stelson K. A.
Published: July 2009

A new method to measure the frictional stresses and normal pressure in the roll gap during cold rolling, and experimental verification of this new method, are presented. The method overcomes many of the shortcomings of pin-type sensors. The elastic deformation of the roll itself is measured with strain gages, and is used to calculate the stresses between the sheet and the roll. Since no modification of the roll is necessary, the deformation process is undisturbed by the measurement. Mechanical isolation of the sensor is unnecessary. The mathematical procedure used to calculate the normal pressure and frictional stresses from the measured strains explicitly acknowledges that these strains are the result of the entire distribution of pressures and shears in the roll gap. An experimental rolling mill was constructed to verify the proposed method. Lead was rolled, and the resulting pressure and frictional stress distributions in the roll gap were measured. Several features of these distributions are in agreement with measurements made by various investigators using other techniques, thereby confirming the usefulness of the new method. Future work is proposed to increase the accuracy with which the roll gap stresses may be measured.
Development of a Forecasting Compensatory Control System for Cylindrical Grinding
Authors: Kim K. H. , Eman K. F. , Wu S. M.
Published: July 2009

A forecasting compensatory control (FCC) system was developed to improve workpiece roundness in cylindrical grinding operations. The spindle radial error motion (SREM) at the grinding position, identified as the dominant error source was modeled by an autoregressive model and compensated for by a forecasting algorithm. A digital method for measuring SREM at the grinding position which incorporates master roundness compensation was proposed and a piezo-electric drive system for the generation of the compensatory mechanical motion was developed. The implementation of the proposed method resulted in a substantial improvement of workpiece roundness.
Grinding Titanium With Coated Abrasives Under an Aqueous Solution of Inorganic Phosphate Salts
Authors: Duwell E. J. , Cosmano R. J. , Abrahamson G. R. , Gagliardi J. J.
Published: July 2009

Aqueous solutions of inorganic salts are known to be effective grinding lubricants for titanium. Early work by Professor Shaw at MIT drew particular attention to the use of phosphate salts, and although not commercially available as grinding fluids, some metal fabricators have compounded phosphate-containing fluids for their own use from the raw chemicals. In this paper, the dynamics of grinding Ti(6Al-4V) alloy are described using phosphate salt solutions. The results show that both aluminum oxide and silicon carbide coated abrasive belts have unique advantages in this application, with aluminum oxide exhibiting easy penetration and fast cutting behavior early on, while silicon carbide appears to have longer range durability.
A Simple Model for Convective Cooling During the Grinding Process
Authors: Lavine Adrienne S.
Published: July 2009

Heat generated during grinding may cause thermal damage to the workpiece and wheel. To avoid this, grinding fluids are often used, but their effects are not well understood. A simple analytical model of the convective heat transfer between the wheel and workpiece surfaces and the grinding fluid is described. The model predicts the convective heat transfer coefficient at the workpiece surface, the fraction of energy entering the workpiece, and the workpiece surface temperature. Despite its simplicity, the model shows remarkable agreement with published data for conventional and creep feed grinding conditions.
Grinding Forces and Energy
Authors: Brach K. , Pai D. M. , Ratterman E. , Shaw M. C.
Published: July 2009

Grinding forces and energy play an important role in all abrasive machining operations. While specific grinding energy may be obtained from workpiece dynamometer values or by measuring spindle power, care must be exercised in converting dynamometer reading into power consumed. This is particularly true for operations involving a large ratio of wheel depth of cut to wheel diameter or when the radial force on the wheel is large relative to the tangential component. Interpretation of workpiece dynamometer results are discussed and several specific examples are considered including the diamond sawing of granite and the creep feed grinding of metal.
In-Process Detection of Chatter Threshold
Authors: Rahman M.
Published: July 2009

This investigation is an attempt to propose a method to determine the chatter threshold precisely so that a flexible manufacturing system can be materialized or a dynamic performance test criteria for a machine tool can be established. It has been found that the chatter threshold can be easily detected through the in-process measurement of the horizontal deflection of the workpiece. Comparison with other available methods shows that the proposed method is simple and more accurate.
Decouplers in Integrated Cellular Manufacturing Systems
Authors: Black J. T. , Schroer B. J.
Published: July 2009

This paper describes the use of decouplers within an integrated manufacturing cell operating in a Just-In-Time (JIT) environment. The operation of a cell and the function of decouplers are described. A simulation model was developed using GPSS/PC to study cell behavior and the effects of decouplers on the manufacturing cell. The influence of machine time and quality levels on the production rate of the cell is examined.
Distortion in Thermal Field Around Inserted Thermocouples in Experimental Interfacial Studies—Part II: Effect of the Heat Flow Through the Thermocouple
Authors: Attia M. H. , Kops L.
Published: July 2009

The effect of heat flow along thermocouple wires on the disturbance in a two-dimensional steady temperature field around the thermocouple hole is investigated. The hole is located at a finite distance from an isothermal heat input boundary in a direction perpendicular to the heat flow lines. Using the electrical analog technique, a method was devised to simulate the partial heat flow through the thermocouple leads. The developed computer-aided scanning and measurement system allowed detailed examination of the disturbed temperature field. The error in the temperature sensed by the thermocouple is evaluated and presented in a dimension less form for a wide range of partial heat flow rates.
Tool Design for ECM: Correction Factor Method
Authors: Reddy M. S. , Jain V. K. , Lal G. K.
Published: July 2009

A simple model for tool (cathode) design for plane parallel electrochemical machining and electrochemical drilling has been proposed. Assuming the initial tool shape to be complementary to required work shape, the desirable and predicted anode profiles have been compared and the error between them has been evaluated. Using this error, the correction factor has been calculated to modify the tool shape. This procedure is repeated till the designed tool can produce an anode profile within the prescribed tolerance limits. Using this technique, tools for tapered, flat, exponential, parabolic, and nonstandard work shapes have been designed. Bare tools have been designed for straight and tapered sided holes. Comparison between analytical and experimental results shows a good agreement between them.
Pressbrake Bending in the Punch-Sheet Contact Region—Part 2: Gap Formation and the Direction of Sheet Motion
Authors: Pourboghrat F. , Stelson K. A.
Published: July 2009

In Part 1 of this paper, simple models of nonuniformities in pressbrake bending in the punch-sheet contact region were presented. An extreme manifestation of these nonuniformities is the appearance of a gap between the punch and the sheet. The models from Part 1 are used in Part 2 to predict the possible formation of this gap as a function of the geometry and the frictional conditions. To determine the direction of the frictional force at the die, methods to determine the direction of sheet motion on the die are presented. Elastic and rigid-plastic material models of the sheet are considered, and are shown to produce remarkably similar results.
Criteria for the Prevention of Split Ends
Authors: Zhu Y. D. , Avitzur B.
Published: July 2009

A criterion for the prevention of split ends (alligatoring) is expressed mathematically. This criteria, t0/R0>1.81×(t0/tf−1) is derived through the extension of an earlier upper bound solution for strip rolling of a perfectly plastic mises material. The treatment is based on the division of the deformation region to a series of triangles, undergoing rigid body rotational motions.
The Prevention of Central Bursts During Rolling
Authors: Avitzur B. , Van Tyne C. J. , Turczyn S.
Published: July 2009

An upper bound analysis has been developed to model the flat rolling of a perfectly plastic material. A rigid body rotational velocity field was assumed for the deformation region. This field permits the possible formation of an internal void. The process conditions under which it is energetically favorable for a void to develop have been determined. It has been found that internal void formation (central burst) is more likely to occur in thick strips and sheets when small reductions are taken. Both front and back tension tend to promote the development of a central burst with the back tension reducing the safe, noncentral burst domain to a greater degree. Criteria curves for the central burst domain and the safe domain are presented for a wide range of process variables.
Analysis of Contact Stress and Deformation in a Trilobe Polygonal Connection
Authors: Czyzewski T. , Odman M. T.
Published: July 2009

A numerical method for determination of contact stress and deformation in a multilobe connection of shafts and hubs is presented. It relies upon NASTRAN for computation of surface deflections of both members which are then matched by means of relative rotation. Several examples of stress distribution in a trilobe connection and the effects of torque and internal clearance upon maximum pressure, extent of contact, its location and torsional compliance are given. Results discredit the application of well-known Hertzian formulas to this closely conformal non-Hertzian contact and suggest a surprisingly simple approximation. This is the first published solution to the problem of contact in a trilobe connection.
Finite Element Method for the Analysis of a Material Property Identification Algorithm for Pressbrake Bending
Authors: Kim S. , Stelson K. A.
Published: July 2009

Finite element analysis is used to evaluate an algorithm to identify the material characteristics of a sheet being bent in a pressbrake from force and displacement measurements. In this way, calculations are used as a numerical experiment so that the accuracy of the simplified model assumed for the identification algorithm can be assessed. The results also suggest ways to improve the algorithm. The identification algorithm is used as part of a real time control system for bending. The finite element analysis shows that the stress estimates are accurate, but that the strain estimates need improvement either by the use of an empirical calibration factor or by the development of a more exact theory.
Worst Case Tolerance Analysis with Nonlinear Problems
Authors: Greenwood W. H. , Chase K. W.
Published: July 2009

When designers assign tolerances on engineering drawings, they have a significant influence on the resulting cost and producibility of manufactured products. A rational basis for assigning tolerances involves constructing mathematical models of tolerance accumulation in assemblies of parts. However, tolerance stacks in two or three-dimensional problems or other nonlinear assembly functions may distort the resultant assembly tolerances, altering the range and symmetry. An iterative method is described for adjusting the nominal dimensions of the component parts such that the specified assembly limits are not violated.
The Mechanism of Chatter Vibration in a Spindle-Workpiece System: Part 1—Properties of Self-Excited Chatter Vibration in Spindle-Workpiece System
Authors: Marui E. , Kato S. , Hashimoto M. , Yamada T.
Published: July 2009

The elimination of chatter vibration is important to improve cutting accuracy and to improve productivity of the cutting operation. In this study, the characteristics of the primary and regenerative chatter vibration occurring in the spindle-workpiece system are investigated experimentally using six spindle-workpiece systems having different vibratory properties. The vibratory locus of the spindle-workpiece system is found. The phase lag between the cutting force and chatter displacement and the phase lag between the successive chatter marks are obtained quantitatively. These phase lags are closely related to the energy supply. The chatter vibration hardly grows up in the spindle-workpiece system having large dynamic rigidity.
The Mechanism of Chatter Vibration in a Spindle-Workpiece System: Part 2—Characteristics of Dynamic Cutting Force and Vibration Energy
Authors: Marui E. , Kato S. , Hashimoto M. , Yamada T.
Published: July 2009

The cutting force acting in the dynamic state of a lathe spindle-workpiece system is affected by the dynamic variations of cutting depth, cutting velocity, and rake angle. In this study, the influences of these parameters on the dynamic cutting force are measured by unique experiments. The phase lag between the dynamic cutting force and vibration displacement is clarified under various cutting conditions. The dynamic cutting force when the cutting velocity and the rake angle are dynamically changed is measured, and the results are represented as the cutting velocity coefficients and the rake angle coefficients. Based on these results, the energy supplied by the dynamic cutting force is obtained and the mechanism by which the chatter vibration occurs is discussed.
The Detection of Tool Breakage in Milling Operations
Authors: Altintas Y. , Yellowley I. , Tlusty J.
Published: July 2009

The paper describes a rather simple and efficient algorithm for processing the milling force signal to detect cutter breakage. Using sampling synchronized with cutter teeth the basic variation per tooth is removed by calculating average forces per tooth. The first difference of these forces detects both breakage and some sudden changes in cutting conditions (cornering, milling over a slot). The second difference distinguishes between the two. The algorithm is illustrated by computational simulations as well as by measurements in milling tests.
Whirling Vibration in Drilling. Part 3: Vibration Analysis in Drilling Workpiece with a Pilot Hole
Authors: Ema S. , Fujii H. , Marui E.
Published: July 2009

The whirling vibration of the drill when beginning the drilling of a workpiece with a pilot hole, is theoretically examined. It becomes clear that the whirling is a regenerative chatter vibration which is caused by the regenerative effect at the major cutting edge and the frictional force occurring due to the interference between the flank surface of the major cutting edge and the workpiece surface. As the amplitude and the vibration speed of the drill are restricted by the characteristic of the frictional force, distinctive vibration wave forms are observed. It is also found that the frequency of the whirling vibration which is decreased by the frictional force, is considerably lower than the natural frequency of the system, and that the odd number polygon is produced by the regenerative effect.
Analysis of the Cutting Process of a Cylindrical Workpiece Clamped by a Three-Jaw Chuck
Authors: Matin M. A. , Rahman M.
Published: July 2009

A theoretical analysis has been carried out on the cutting dynamics of a solid cylindrical rotating workpiece clamped by a three-jaw chuck with balanced pressure at the jaws and subjected to a cutting operation. The net reaction balancing the cutting force is found to consist of infinite number of force components oscillating at frequencies 3ω, 6ω, 9ω ... etc., where ω is the angular speed of rotation of the workpiece, and a stationary force term 3F0/2 where F0 is the static balancing force impressed on each jaw-line. The stationary force term tends to give a uniform depth of cut. However the harmonic force terms tend to spoil the uniformity in the depth of cut. Under resonant condition of the third harmonic force maximum depth of cut occurs in the mid positions between two jaws and minimum along the jaw-positions. Resonant vibration of the system takes place at angular spindle speeds ωr = ω0/3P where P is an integer and ω0 = (K/M)1/2 is the angular natural frequency of vibration of the system.
Chatter Growth—Tests to Evaluate the Theory
Authors: Thompson R. A.
Published: July 2009

Tests were run on a 30-hp Mazak slant turn lathe machining Inconel 718 with a 883 grade tungsten carbide button insert. The purpose of the tests was to evaluate the regenerative chatter theory of reference 1 and the chatter sensor and adaptive control strategies it predicts. The cutting system’s mechanical response was measured by shaking it at constant force through the swept frequency range of 30 to 1000 Hz. From these tests and static stiffness tests, the system’s effective mass, damping, and stiffness were measured. Cutting force tests were run to measure the machining system’s cutting compliance. The results of the shake and cutting tests were substituted into the regenerative stability model to predict the machine’s chatter behavior. The theory was consistent with test observations.
Computer-Aided Manufacture of High Precision Cams
Authors: Papaioannou S. G. , Kiritsis D.
Published: July 2009

Current methods for generating curves in numerically controlled systems rely on a Boolean formulation of the step selection problem. This paper takes a different approach, in which the next step is selected by solving an integer programming problem. The structure of this problem is such that a step maximizing the advance along the curve can be obtained by inspection. This criterion reduces the number of steps required to traverse the curve and results in a high degree of smoothness and accuracy. Based on this formulation, step selection rules are derived for both implicitly and parametrically defined curves. Parametric curve representation arises most naturally in the design of cams. The proposed method can be used to generate a cam profile with an accuracy equal to the resolution of the machine tool. Examples and appropriate formulas are given for drum cams and for plate cams with a roller, flat-faced or oscillating follower.
Vibration of Orthotropic Rectangular Plates With Variable Thickness
Authors: Liu Wei-Cheun , Chen Stanley S. H.
Published: July 2009

The problem vibration of rectangular orthotropic plates with variable thickness and mixed boundary conditions are solved by a modified energy method. A general expression is written for the deflection of the plate without aiming at any particular combination of boundary conditions. Boundary conditions are satisfied approximately by adjusting a set of so-called fixity factors. A computer program has been developed to solve for natural frequencies of plates with variable thicknesses and having different orthotropic properties.
Ball-Mills Versus End-Mills for Curved Surface Machining
Authors: Vickers G. W. , Quan K. W.
Published: July 2009

The use of end-mills for machining low curvature surfaces is examined in relation to the more popular ball-mills. End-mills are shown to give a better match to the required surface geometry and hence reduce the number of surface passes required. They also have a much better efficiency of material removal and longer tool life. It is shown that the use of end-mills for curved surface work can typically reduce the overall cutting time by a factor of twenty-four.
A New Approach of Formulating the Transfer Function for Dynamic Cutting Processes
Authors: Wu D. W.
Published: July 2009

The dynamics of a cutting process are very complex in nature. It involves not only the changes of plastic state in the intensive deformation zone but also the elastic behavior of work material surrounding the deformation zone, especially in the vicinity of the tool nose region. These changes are induced by the inner and outer modulations of the uncut chip thickness during the process and at the same time govern the variation of the cutting force. Based on these causal relationships, the transfer function between the vibration variables and the dynamic force components for a single degree-of-freedom machining system has been developed. The characterization of the mechanics of the cutting process by the new model provides more insight into the physics of the cutting dynamics. The model has been tested through computer simulation for both orthogonal wave-generating and wave-removing processes. By reference to existing experimental evidence, the theoretical predictions show a very good agreement with the test results.
In-Process Detection of Tool Failure in Milling Using Cutting Force Models
Authors: Altintas Y. , Yellowley I.
Published: July 2009

The authors show that first and second differencing of a time averaged resultant force is extremely effective in the recognition of tool breakage in milling. In order to be useful in production, however, such a system needs to have a knowledge of allowable levels of the first difference. It is shown that these levels, (thresholds), are extremely dependent on the ratio of cutter radius to width of cut, (immersion ratio). A method of on-line identification of the immersion ratio and threshold tuning is presented with experimental verification.
Grinding Mechanisms and Strength Degradation for Ceramics
Authors: Malkin S. , Ritter J. E.
Published: July 2009

This paper presents a critical review and evaluation of our fundamental knowledge of the grinding mechanisms for ceramic materials and their influence on the finished surface and mechanical properties. Two main research approaches are identified: a “machining” approach and an “indentation fracture mechanics” approach. The machining approach has typically involved measurement of the grinding forces and specific energy coupled with microscopic observations of the surface morphology and grinding detritus. Any proposed mechanisms of abrasive-workpiece interaction must be consistent with the magnitude of the specific energy and its dependence on the grinding conditions. The “indentation fracture mechanics” approach assumes that the damage produced by grinding can be modeled by the idealized flaw system produced by a sharp indentor. Indentation of a ceramic body is considered to involve elastic/plastic deformation with two principal crack systems propagating from the indentation site: lateral cracks which lead to material removal and radial/median cracks which cause strength degradation. Each of these approaches provides important insight into grinding behavior and strength degradation, but each has its shortcomings. Further efforts to develop a fundamental model for grinding of ceramics would benefit from the integration of both of these approaches.
Laboratory Measurement of Bit Bearing Temperatures in Rotary Drilling With the Garter Spring Pick-up System
Authors: Karfakis M. G. , Heins R. W.
Published: July 2009

In order to determine the factors affecting bearing temperatures—factors such as formation temperatures, rotary speed, bit thrust, airflow rate, and temperature—a pilot-scale laboratory micro-bit drill rig was instrumented. The paper describes the successful control of variables and measurements of bearing temperature of a thermocouple instrumented micro-bit using the garter spring pick-up system. The first step in tapping the energy of a geothermal reservoir, once it is located, is drilling the necessary wells to allow the heat energy to be transported to the surface. Currently, drilling for geothermal wells in elevated temperature formations is done using unsealed bits with air as the drilling fluid. Reduced bit life, due to bearing failure, with the consequent reduced overall penetration rates, can be attributed to the high temperature encountered. Limited knowledge and understanding of how temperature affects drilling operations is a deterrent to the improvement of the existing drilling system.
Investigations on Laser Dressing of Grinding Wheels—Part II: Grinding Performance of a Laser Dressed Aluminum Oxide Wheel
Authors: Ramesh Babu N. , Radhakrishnan V.
Published: July 2009

Based on the results of the preliminary study on the influence of high intensity Nd: YAG laser radiation on grinding wheel constituents, an experimental set-up for dressing a grinding wheel was made. Studies were carried out to evaluate the performance of a laser dressed Al2O3 wheel in surface grinding under dry cutting conditions. Results confirmed the viability of this approach and indicated the existence of an optimal dressing condition for good results.
Abrasive-Waterjet Deep Kerfing and Waterjet Surface Cleaning for Nuclear Facilities
Authors: Hashish M. , Echert D. C.
Published: July 2009

A deep kerf tool was designed to cut through the thick, reinforced concrete structures of nuclear facilities to help make the decommissioning process more efficient. Abrasive-waterjet (AWJ) cutting technology is used as the basis of the system. The cutting tool has a rotary nozzle that directs a high-pressure AWJ in a circular pattern. The circular pattern and the angle of jet impact create a slot wider in diameter than the tool itself as the tool moves across the face of the concrete. This makes it possible to insert the tool into the slot and create a deep cut for each pass along it until the desired depth is reached. In this testing program, concrete as thick as 1.5 meters was cut through from one side. The cutting rate of the tool ranges from 0.2 to 0.6 m2/hr. The tool employs a computer-controlled traverse mechanism with a simple device that can detect obstacles, such as uncut reinforcing bars (rebar) or hard aggregate. An electronic sensor system to identify, in real-time, when rebar is being cut was developed and tested with good results. A cleaner/scarifier tool for removing the surface layers of contaminated concrete and decontaminating metal surface was also designed and tested. It uses ultrahigh-pressure waterjets mounted on a rotating arm to remove or clean the target surface. Concrete can be scarified to a depth of 7 mm at a rate of 11 m2/hr. Concrete and metal surfaces can be cleaned of paint and corrosion at a rate of 33 m2/hr. Spoils recovery using a shroud/vacuum system is more than 99 percent for each tool.
Design Parameters of Continuous Centrifugals
Authors: Ramamurti V. , Ramaprasad K. S. , Ramakrishna Y.
Published: July 2009

Continuous sugar centrifugal is used to separate sugar and molasses from massecuite. The centrifugal basket is pierced with numerous holes to allow the molasses to escape and is lined with metal gauze, which serves to retain the sugar while allowing the molasses to pass through. The centrifugal basket is conical in shape (Fig. 1), runs at a constant speed in the range 1200 to 2200 rpm., and is fed by a continuous stream of material. The semicone angle α varies from 25 deg to 35 deg. What prompted this investigation is a fairly high level of working stress experienced in commerically available centrifugals, often close to yield stress. This technical brief presents the steady state stress distribution patterns in these centrifugals using a fairly accurate model. Since the problem under consideration is cyclic, a symmetric model using the finite element method with triangular shell elements is employed to determine the stresses and displacements. Besides, the critical speeds of the baskets have also been computed using Rayleigh’s method.
A Mathematical Approach to Automatic Configuration of Machining Fixtures: Analysis and Synthesis
Authors: Chou Y-C. , Chandru V. , Barash M. M.
Published: July 2009

Drawing on screw theory and engineering mechanics, a mathematical theory for automatic configuration of machining fixtures for prismatic parts is developed. There are two parts in the theory: analysis and synthesis. The following functions of fixtures are analyzed: deterministic workpiece location, clamping stability, and total restraint. The synthesis of fixtures includes the determination of locating and clamping points on workpiece surface and the determination of clamping forces. The theory deals with the general case of 3-dimensional parts, polygon support (as opposed to three-point support), and multiple machining operations.
Heavy Axle Load Wheel-Rail Contact Stresses and Their Tread-Crown Curvature Relationships
Authors: Kumar S. , Singh S. P.
Published: July 2009

This paper presents a theoretical/design analysis of wheel-rail contact stresses and geometries for U.S. freight cars of 70, 95, 100, and 125 ton freight capacities operating on various crown rails. After discussing various types of rail stresses, it is pointed out that the contact stresses are the major factor and the only parameter that enables a designer to improve or optimize the rail life and performance. In order to determine the most suitable diameters for the heavier cars, an engineering lower bound analysis of the contact has been completed. It uses in a two-dimensional Hertzian analysis, the field information of well worn-out wheel and rail contacts which are almost rectangular and of 1 in. width. The lower engineering bound values of maximum normal contact stresses for the 100 and 125 ton cars using wheels of diameters from 33 to 42 in. are given. This stress for the current 100 ton car with 36 in. diameter wheels is 98.35 ksi. To approach this value for the 125 ton car it is necessary to use 42 in. diameter wheels which is strongly recommended for the U.S. railroads. A Hertz theory based analysis of the contact stresses with varying wheel diameter, tread profile radius and rail crown radius for the 70, 95, 100, and 125 ton cars has been presented. Using the field information that the difference in radii of curvature of worn wheel and rail is approximately 5 in., choice of radii of rail and wheel profile curvatures is made so that the design radii difference is always 5 in. or more. Wheel diameter and wheel profile radius ranges used for this analysis were 33 to 44 in. and 15 to 35 in., respectively. The rail crown radius range was 10 to 30 in. It was concluded that a rail crown radius of 15 to 20 in. and wheel tread profile radius of 22 to 30 in. are good initial ranges for further analysis of design.
Loop formation in graphitic nanoribbon edges using furnace heating or Joule heating
Authors: Jia Xiaoting , Campos-Delgado Jessica , Gracia-Espino Edgar Eduardo , Hofmann Mario , Muramatsu Hiroyuki , Kim Yoong Ahm , Hayashi Takuya , Endo Morinobu , Kong Jing , Terrones Mauricio , Dresselhaus Mildred S.
Published: July 2009

Here the authors report the use of either furnace heating or Joule heating to pacify the exposed graphene edges by loop formation in a novel graphitic nanoribbon material, grown by chemical vapor deposition. The edge energy minimization process involves the formation of loops between adjacent graphene layers within the nanoribbons. A comparison is made of the similarities and differences between the loop structures formed using these two methods. An estimation of the temperature of these graphitic nanoribbons during Joule heating is also reported based on the melting and evaporation of Pt nanoparticles.
Transition between kinetic and mass transfer regimes in the initiated chemical vapor deposition from ethylene glycol diacrylate
Authors: Ozaydin-Ince Gozde , Gleason Karen K.
Published: July 2009

In this work, initiated chemical vapor deposition (iCVD) of the poly(ethylene glycol diacrylate) is reported and the effects of process parameters on the deposition rates are investigated. The systematic studies of depositions performed at different filament temperatures showed that the deposition rates increased with the temperature due to the increase in the radical concentration which was monitored with a gas-phase Fourier transform infrared spectroscopy. For temperatures below 242±3 and 224±2°C for 2 and 1SCCM (SCCM denotes cubic centimeter per minute at STP) of monomer flowrates, respectively, a reaction-kinetics limited regime was observed, where the deposition kinetics was limited by the decomposition of the radicals. In this regime, the deposition rates were highly dependent on the filament temperature and the apparent activation energy was found to be 166±5kJ∕mol, consistent with the cleavage of the O–O bond in the tert-butyl peroxide initiator as the rate limiting reaction in the deposition mechanism. Above these temperatures, transition to a mass transfer limited regime was observed where the deposition rates were less dependent on the filament temperature. In the studies performed at different substrate temperatures, on the other hand, an inverse relation between the deposition rate and the substrate temperature was observed which indicated an adsorption limited regime. The studies presented in this work demonstrate the dependence of the deposition kinetics on the process temperatures, which can also be applied to other iCVD systems to achieve higher deposition rates and better conformality.
Measurement of electron temperatures and electron energy distribution functions in dual frequency capacitively coupled CF4/O2 plasmas using trace rare gases optical emission spectroscopy
Authors: Chen Zhiying , Donnelly Vincent M. , Economou Demetre J. , Chen Lee , Funk Merritt , Sundararajan Radha
Published: July 2009

Measurements of electron temperatures (Te) and electron energy distribution functions (EEDFs) in a dual frequency capacitively coupled etcher were performed by using trace rare gas optical emission spectroscopy (TRG-OES). The parallel plate etcher was powered by a high frequency (60 MHz) “source” top electrode and a low frequency (13.56 MHz) “substrate” bottom electrode. Te first increased with pressure up to ∼20 mTorr and then decreased at higher pressures. Increasing the bottom rf power resulted in higher electron temperatures. Electron temperatures in 90% CF4+10% O2 plasmas were similar to those in 80% CF4+20% O2 plasmas. EEDF exhibited bi-Maxwellian characteristics with enhanced high energy tail, especially at pressures >20 mTorr.
Interface-mediated ultrafast carrier conduction in oxide thin films and superlattices for energy
Authors: Ramanathan Shriram
Published: July 2009

Some recent observations on carrier (electronic and ionic) transport in thin film and nanostructured metal oxides and superlattices, where interfaces play a dominant role in overall conductivity response, are reviewed. Conduction in nominally pure oxides is compared to heavily aliovalently doped oxides (that correspond to changes in the Debye length over few orders of magnitude). The role of dopant segregation and their spatial variation in affecting transport is pointed out. The ability to utilize interfaces in enabling ultrafast-ion conduction as well as the creation of novel interfacial materials and implications in energy technologies as well as some scientific questions that may warrant further attention are highlighted.
Comment on “Remeasuring the Double Helix”
Authors: Becker Nils B. , Everaers Ralf
Published: July 2009

Mathew-Fenn
et al
. (Reports, 17 October 2008, p. 446) reported unexpected distance fluctuations in short end-labeled DNA constructs and interpreted them as evidence for cooperative DNA stretching modes. We show that when accounting for a subtle linker leverage effect, their data can be understood within standard noncooperative DNA elasticity.
Chronic Stress Causes Frontostriatal Reorganization and Affects Decision-Making
Authors: Dias-Ferreira Eduardo , Sousa João C. , Melo Irene , Morgado Pedro , Mesquita Ana R. , Cerqueira João J. , Costa Rui M. , Sousa Nuno
Published: July 2009

Brain Rewiring After Stress

Chronic stress, mainly through the release of corticosteroids, affects executive behavior through sequential structural modulation of brain networks. Stress-induced deficits in spatial reference, working memory, and behavioral flexibility are associated with synaptic and dendritic reorganization in both the hippocampus and the medial prefrontal cortex. However, the effects of chronic stress on action selection strategies are unclear.

Dias-Ferreira
et al.

(p.
621
) examined whether chronic stress affects the ability of animals to select the appropriate actions based on the consequences of their choice, and found that rats exposed to chronic unpredictable stress rapidly shift toward using habitual strategies. The shift in behavioral strategies observed in chronically stressed animals corresponded to dramatic and divergent changes in connectivity in the associative and sensorimotor corticostriatal circuits underlying these behaviors.
Computing Has Changed Biology—Biology Education Must Catch Up
Authors: Pevzner Pavel , Shamir Ron
Published: July 2009

Biologists need better computational education so that researchers can benefit from the bioinformatics revolution.
The Map of Altinum, Ancestor of Venice
Authors: Ninfo Andrea , Fontana Alessandro , Mozzi Paolo , Ferrarese Francesco
Published: July 2009

Arial mapping during an extreme drought has revealed the detailed plan of a major Roman city in the Venice lagoon.
A Second Opinion for Our Planet
He Knew He Was Right
The Irrepressible Life of James Lovelock and Gaia /
James Lovelock
In Search of Gaia

by John Gribbin and Mary Gribbin

Allen Lane, London, 2009. 262 pp. £20, C$42. ISBN 9781846140167. Princeton University Press, Princeton, NJ, 2009. 286 pp. $24.95, £16.95. ISBN 9780691137506.
The Vanishing Face of Gaia
A Final Warning

by James Lovelock

Allen Lane, London, 2009. 199 pp. £20, C$34. ISBN 9781846141850. Basic Books, New York, 2009. 288 pp. $25. ISBN 9780465015498.
Authors: Kump Lee R.
Published: July 2009

The prolific Gribbins provide a short, authorized biography of Lovelock. In his own latest book, Lovelock argues that climatic change is likely to lead to a hotter Earth that is able to sustain only a small fraction of the world's current population.
Barcoding of Plants and Fungi
Authors: Chase Mark W. , Fay Michael F.
Published: July 2009

DNA barcoding enables rapid and accurate identification of species in many groups of organisms, but cannot always distinguish between closely related species of land plants or fungi.
Civic Collaboration
Wiki Government
How Technology Can Make Government Better, Democracy Stronger, and Citizens More Powerful

by Beth Simone Noveck

Brookings Institution Press, Washington, DC, 2009. 246 pp. $28.95, £20.99. ISBN 9780815702757.
Authors: Shneiderman Ben
Published: July 2009

Drawing on her work developing the Peer-to-Patent network, Noveck describes how Web 2.0 technologies could be used to promote participatory democracy and more efficient government.
Saving a Venomous Ghost
Authors: Thomas Claire
Published: July 2009

Despite periodic predictions that it will go extinct, the Hispaniolan solenodon endures, and scientists now want to ensure the rare mammal's survival.
Nursing China's Ailing Forests Back to Health
Authors: Stone Richard
Published: July 2009

A lauded effort to create mixed forest stands is giving villagers and loggers a chance to make a living while restoring ecosystem vitality.
Identification of Novel
Mycobacterium bovis
Antigens by Dissection of Crude Protein Fractions
Authors: Meikle V. , Alito A. , Llera A. S. , Gioffré A. , Peralta A. , Buddle B. M. , Cataldi A.
Published: July 2009

Culture filtrate and cell extracts from
Mycobacterium bovis
cultures contain molecules which could promote protective immunity to tuberculosis in animals. Different protein fractions of
M. bovis
cultures were obtained by elution electrophoresis and were tested in experimentally infected cattle. The fractions that elicited gamma interferon (IFN-γ) responses were resolved by two-dimensional gel electrophoresis, and individual proteins were identified by matrix-assisted laser desorption ionization-time of flight mass spectrometry. The open reading frames were cloned, expressed as their recombinant forms, and retested with naturally and experimentally infected animals. Eleven protein fractions were highly reactive, from which the Rv1636, HspX, Rv0138, Rv2524, EsxI, and Rv3740 recombinant proteins were obtained. EsxI and HspX were the antigens most recognized by the IFN-γ release assay. In summary, a proteomic approach allowed the identification of novel antigens useful for the diagnosis of bovine tuberculosis.