bluuebunny/crossref_metadata_2025_split huggingface dataset:
Non-linear finite-element analyis on microcomputers for metal forging
Authors: Hussin A A M , Hartley P , Sturgess C E N , Rowe G W 
Published: July 2007

In recent years microcomputers have become more powerful and for some purposes are now able to compete with minis and mainframe computers. It is now possible to implement a wide variety of CAD packages and linear finite-element stress analysis programmes on microcomputers, but the solution of non-linear problems - for example, forging - is more complex. This paper shows that a microcomputer can, nevertheless, be used for the analysis of a bulk metal forming process where there are both geometric and material non-linearities. The programs give reliable estimates of metal flow, grid distortions, stress, and strain distributions in the workpiece, as well as the forming force. An elastic-plastic finite-element method is used, with SSS-Fortran as the computing language. The results of such simulations can be used in-house to form the basis of improved forging die design, and, hence, a better final product, without the need for much of the expensive and time-consuming experimental trials currently practiced in industry.
C∗ correlations for creep crack growth in weld metals
Authors: Gooch D J , Kimmins S T 
Published: July 2007

Creep crack growth tests have been performed on compact tension specimens of 2 1/4CrlMo, C—Mn, and AISI 316 weld metals at 565°C, at 360 and 390°C, and at 600°C, respectively. The data have been analysed in terms of the C∗ creep parameter obtained directly from experimental measurements and by use of estimation formulae which depend on uniaxial creep data and evaluation of a reference stress. When expressed in the form d a/d t = D C∗ q the two approaches result in correlations which differ both in the constant, D, and in the exponent, q. The differences in the constant may be largely rationalized in terms of the constraint on deformation appropriate to the test conditions and the effects of this on the reference stress. The exponent, q, was generally lower when the estimation formulae were used than when C∗ was calculated from measured displacement rates. This was attributed to the lower stress dependence of the load-line displacement rates of the compact tension specimens compared with that of the uniaxial minimum creep rate at similar stress levels. This arises because primary creep strains may dominate the overall deformation behaviour of a compact tension specimen for many practical circumstances.
A micropolariscope for automatic stress analysis
Authors: Fessler H , Marston R E , Ollerton E 
Published: July 2007

A micropolariscope has been developed for the automatic analysis of photoelastic data. It will position frozen stress slices mounted on its stage to within ±0.002 mm, and takes readings of isoclinic angles and fractional fringe orders, repeatable to within ±0.08 degrees and ±0.001 fringes. A rectangular grid of up to 3 × 50 points can be read automatically, taking about 1¼ minutes per point; the readings are stored on a floppy disc and printed out. The original slice is itself sliced, and the subslice is viewed again in the orthogonal direction to produce a second set of readings. Software has been devised to analyse the two sets of readings. It makes use of Tesar's modification of Frocht's Shear Difference method to calculate five cartesian stresses, which may be plotted and printed in tabular form. Flexible facilities are provided for editing, correcting, plotting, and printing intermediate stages in the analysis, and for storing results in data files
The analysis of elastic stress distribution in threaded tether connections
Authors: Newport A , Topp D A , Glinka G 
Published: July 2007

A technique is presented for predicting the load distribution and local stress distribution in threaded tether connections. The load distribution is derived by modelling the connection as a system of springs and beams. This distribution is then used in conjunction with the appropriate stress concentration factors derived by the finite element method to obtain the local stress distribution. A comparison is made between the theoretical predictions of local stress and published experimental results obtained from a photoelastic model.
On the numerical solution of line contact problems involving bonded and unbonded strips
Authors: Jaffar M J , Savage M D 
Published: July 2007

This paper investigates the contact problem in which an elastic strip is indented by a rigid body (punch) of arbitrary shape. Both bonded and unbonded strips are considered. A numerical method due to Gladwell (1)† is shown to be a direct and effective technique for analysing the effect of any punch whose profile is a polynomial of degree n, over a range of a/t (semi-contact width to a depth ratio) which is of practical interest 0 ≤ a/t ≤ 10 for Poisson's ratio 0 ≤ v ≤ 0.5. For the cylindrical punch results are presented and compared with Meijers' asymptotic analytic solutions (2). For small a/t agreement is very good as expected. For a/t large, however, there are some large discrepancies which can be traced to an error in Meijers— expression for pressure distribution when v ≠ 0.5. Results are also presented for both the flat and the linear punch.
Axial–Torsional interactions and wire deformation in 19-wire spiral strand
Authors: Utting W S , Jones N 
Published: July 2007

Tensile tests were performed on a straight steel strand of three layer (12/6/1) construction, having a core wire diameter of 3.66 mm and 3.33 mm diameter helical wires, under conditions of full end-fixity, partial restraint, and ends free from torsional restraint. The torque generated under tensile load was recorded as well as the strand extension and rotation over a 600 mm gauge length. Wire tensions and bending moments in the outer layer of helical wires were determined at the mid-strand position from the outputs of strain gauges in groups of three with parallel grids and mounted parallel to the wire axis on the crown of each wire. The rate of strand extension under tensile load was found to be greater in tests with reduced torsional restraint, the greatest rate occurring in the free-end test. The strand rotation rate was also found to be greatest in the free-end test. The greatest difference from the theoretically predicted rates occurred in a free-end test with increasing load; predicted values of extension and rotation underestimated the test results by 12 and 23 per cent, respectively. Displacement of the load-torque plots occurred in the direction of reducing torque as testing proceeded. This appears to indicate the redistribution of the strand load between the layers of wires. Wire tensions showed a more even sharing of load in the fixed-end condition than in the free-end condition. The increase in rate of tension with strand load was less for most wires in tests with reduced torsional restraint, with the lowest tension rates developing in the free-end condition. For most wires, the rate of bending moment change with strand load was greater (in the sense tending to decrease tensile stress on wire crowns) in tests with reduced torsional restraint. However, the bending moment rates varied greatly between wires, the variation being greater in tests with reduced torsional restraint than in fixed-end tests.
Contributions of rider-induced loads to bicycle frame stress
Authors: Hull M L , Bolourchi F 
Published: July 2007

Presented in this paper is a new method for design analysis of bicycle frames. The new method relies on measurements of rider induced loading to perform a stress analysis of a bicycle frame. The vehicle for the stress analysis is ANSYS, a commercially available finite element code. Through application of individual measured loads, the method examines the corresponding nodes of maximum stress. Polar plots are developed to illustrate the variation of stress as a function of crank arm angle. Polar plots are also developed for the nodes experiencing the maximum total stress. Such a procedure enables the contribution of individual measured loads to the maximum stress to be ascertained. With this information, not only are the important loads for design analysis identified, but also the structural members of relative high and low stress are determined. Accordingly, these results have application to the detailed design of individual structural members. To illustrate the new method, stress analysis of an aluminum frame is undertaken. The loading data are derived from an earlier study by the authors where significant seat, handlebar, and pedal loads were measured together with absolute pedal position. The loading data simulate that of steady-state cycling over flat terrain at about 9 m/s (20 mile/hr). The node of maximum total stress under steady-state loading is found to be the intersection of the top and seat tubes. Inasmuch as frames typically fail in the area of the bottom bracket (i.e., intersection of down and seat tubes), this result contradicts experience. This contradiction is explained by observing that the alternating stress/mean stress ratio is significantly greater for the bottom bracket area.
On the effect of key edge shape on keyway edge stresses in shafts in torsion
Authors: Fessler H , Appavoo T 
Published: July 2007

Two-dimensional, photoelastic tests of cross-sections of two keyed shafts with 13 different shapes of keys showed that rounded edges of keys give lower stress concentrations in the shaft than chamfered edges. Stress concentrations are reduced by making both rounding radii and chamfers larger than the key way fillet radius. Making the key a sliding fit in the keyway allows significant relative movement and produces lower stress concentrations than the usual interference fits. Boussinesq's theoretical solution for stresses near a concentrated edge load has been successfully used for direct calibration of small photoelastic models.
Damage development in composites: Mechanisms and modelling
Authors: Talreja R 
Published: July 2007

This paper presents first a review of the mechanisms of damage and its development in composite materials subjected to mechanical loads. The materials considered are thermosetting polymers reinforced with short or long fibres of glass or carbon. Laminates with woven fabric are also considered. A discussion regarding how the essential features of the damage mechanisms may be incorporated in a modelling approach is then given. Two basically different but complementary approaches, namely, micromechanics modelling and continuum damage modelling, are described. The present author's own approach using the internal variables concept is discussed at some length, and the predictions of elastic property degradation given by it are illustrated by experimental data. This paper is an updated and expanded version of a previous paper written by the author (32).
Optimal proportional-integral-derivative control of shape memory alloy actuators using genetic algorithm and the Preisach model
Authors: Ahn K. K. , Nguyen B. K. 
Published: July 2007

Shape memory alloy (SMA) actuators, which have the ability to return to a predetermined shape when heated, have many potential applications in aeronautics, surgical tools, robotics, and so on. Although the number of applications is increasing, there has been limited success in precise motion control owing to the hysteresis effect of these smart actuators. The present paper proposes an optimization of the proportional-integral-derivative (PID) control method for SMA actuators by using genetic algorithm and the Preisach hysteresis model. In this work, the numerical Preisach model with geometrical interpretation is used for hysteresis modelling of SMA actuators. This model is then incorporated in a closed-loop PID control strategy. The optimal values of PID parameters are determined by using genetic algorithm to minimize the mean squared error between desired output displacement and simulated output. This is used to reduce hysteresis effects and improve accuracy for the displacement of SMA actuators.
A new adaptive learning algorithm for robot manipulator control
Authors: Hasan A. T. , Hamouda A. M. S. , Ismail N , Al-Assadi H M A A 
Published: July 2007

This paper is devoted to the development and implementation of neural network technology to solve the inverse kinematics problems for serial robot manipulators, given the desired Cartesian path of the end effector of the manipulator in a free-of-obstacles workspace. Offline smooth geometric paths in the joint space of the manipulator are obtained. The proposed technique does not require any prior knowledge of the kinematics model of the system being controlled; the main idea of this approach is the use of an artificial neural network to learn the robot system characteristics rather than having to specify an explicit robot system model. Since one of the most important problems in using artificial neural networks is the choice of the appropriate network configuration, two different configurations were compared; they were trained to learn the desired set of joint angles positions from a given set of end effector positions. The generality and efficiency of the proposed algorithm are demonstrated through simulations of a general six-degrees-of-freedom serial robot manipulator.
Experimental Study on Gas-phase Ionization Process for Ion Attachment Mass Spectrometry
Authors: Chen Lei , Suzuki Yaeko , Hara Kenji , Korenaga Takashi 
Published: July 2007

Abstract
In this study, in order to investigate the mechanism of Li+ attachment process, dimethylarsinic acid (DMAA) was detected by selective-ion monitoring mode of ion attachment mass spectrometry (IAMS) and the Li+ binding energy of N2 and DMAA was also calculated. The results indicated the possibility of the transfer of Li+ from N2Li+ to DMAA in IAMS analysis. This study could contribute to the development and application of IAMS technique.
Expression of Plasmid DNA Released from DNA Conjugates of Gold Nanorods
Authors: Horiguchi Yukichi , Niidome Takuro , Yamada Sunao , Nakashima Naotoshi , Niidome Yasuro 
Published: July 2007

Abstract
Pulsed-laser irradiation induced the release of plasmid DNA from conjugates of DNA and gold nanorods (GNRs). Gel electrophoresis indicated that 1% of the plasmid DNA conjugated with GNRs was released from the conjugates. In vitro assay indicated that 0.5% of plasmid DNA was active.
The continuous ranked probability score for circular variables and its application to mesoscale forecast ensemble verification
Authors: Grimit E. P. , Gneiting T. , Berrocal V. J. , Johnson N. A. 
Published: July 2007

AbstractAn analogue of the linear continuous ranked probability score is introduced that applies to probabilistic forecasts of circular quantities, such as wind direction. This scoring rule is proper and thereby discourages hedging. The circular continuous ranked probability score reduces to angular distance when the forecast is deterministic, just as the linear continuous ranked probability score generalizes the absolute error. Furthermore, the circular continuous ranked probability score provides a direct way of comparing deterministic forecasts, discrete forecast ensembles, and post‐processed forecast ensembles that can take the form of circular probability density functions.The circular continuous ranked probability score is used in this study to compare predictions of 10 m wind direction for 361 cases of mesoscale, short‐range ensemble forecasts over the North American Pacific Northwest. Simple, calibrated probability forecasts based on the ensemble mean and its forecast error history over the period outperform probability forecasts constructed directly from the ensemble sample statistics. These results suggest that short‐term forecast uncertainty is not yet well predicted at mesoscale resolutions near the surface, despite the inclusion of multi‐scheme physics diversity and surface boundary parameter perturbations in the mesoscale ensemble design. Copyright © 2006 Royal Meteorological Society
A baroclinic instability test case for atmospheric model dynamical cores
Authors: Jablonowski Christiane , Williamson David L. 
Published: July 2007

AbstractA deterministic initial‐value test case for dry dynamical cores of atmospheric general‐circulation models is presented that assesses the evolution of an idealized baroclinic wave in the northern hemisphere. The initial zonal state is quasi‐realistic and completely defined by analytic expressions which are a steady‐state solution of the adiabatic inviscid primitive equations with pressure‐based vertical coordinates. A two‐component test strategy first evaluates the ability of the discrete approximations to maintain the steady‐state solution. Then an overlaid perturbation is introduced which triggers the growth of a baroclinic disturbance over the course of several days.The test is applied to four very different dynamical cores at varying horizontal and vertical resolutions. In particular, the NASA/NCAR Finite Volume dynamics package, the National Center for Atmospheric Research spectral transform Eulerian and the semi‐Lagrangian dynamical cores of the Community Atmosphere Model CAM3 are evaluated. In addition, the icosahedral finite‐difference model GME of the German Weather Service is tested. These hydrostatic dynamical cores represent a broad range of numerical approaches and, at very high resolutions, provide independent reference solutions. The paper discusses the convergence‐with‐resolution characteristics of the schemes and evaluates the uncertainty of the high‐resolution reference solutions. Copyright © 2006 Royal Meteorological Society
The validity of serum levels as a surrogate measure of systemic exposure to metal ions in hip replacement
Authors: Daniel J. , Ziaee H. , Pynsent P. B. , McMinn D. J. W. 
Published: July 2007

Metal ions generated from joint replacements are a cause for concern. There is no consensus on the best surrogate measure of metal ion exposure. This study investigates whether serum and whole blood concentrations can be used interchangeably to report results of cobalt and chromium ion concentrations. Concentrations of serum and whole blood were analysed in 262 concurrent specimens using high resolution inductively-coupled plasma mass-spectrometry. The agreement was assessed with normalised scatterplots, mean difference and the Bland and Altman limits of agreement. The wide variability seen in the normalised scatterplots, in the Bland and Altman plots and the statistically significant mean differences between serum and whole blood concentrations suggest that they cannot be used interchangeably. A bias was demonstrated for both ions in the Bland-Altman plots. Regression analysis provided a possible conversion factor of 0.71 for cobalt and 0.48 for chromium. However, even when the correction factors were applied, the limits of agreement were greater than ±67% for cobalt and greater than ±85% for chromium, suggesting that serum and whole blood cannot be used interconvertibly. This suggests that serum metal concentrations are not useful as a surrogate measure of systemic metal ion exposure.
In vivo movement analysis of the patella using a three-dimensional computer model
Authors: Yamada Y. , Toritsuka Y. , Horibe S. , Sugamoto K. , Yoshikawa H. , Shino K. 
Published: July 2007

We used three-dimensional movement analysis by computer modelling of knee flexion from 0° to 50° in 14 knees in 12 patients with recurrent patellar dislocation and in 15 knees in ten normal control subjects to compare the in vivo three-dimensional movement of the patella. Flexion, tilt and spin of the patella were described in terms of rotation angles from 0°. The location of the patella and the tibial tubercle were evaluated using parameters expressed as percentage patellar shift and percentage tubercle shift. Patellar inclination to the femur was also measured and patellofemoral contact was qualitatively and quantitatively analysed. The patients had greater values of spin from 20° to 50°, while there were no statistically significant differences in flexion and tilt. The patients also had greater percentage patellar shift from 0° to 50°, percentage tubercle shift at 0° and 10° and patellar inclination from 0° to 50° with a smaller oval-shaped contact area from 20° to 50° moving downwards on the lateral facet. Patellar movement analysis using a three-dimensional computer model is useful to clearly demonstrate differences between patients with recurrent dislocation of the patella and normal control subjects.
Medium-term results of the Bernese periacetabular osteotomy in the treatment of symptomatic developmental dysplasia of the hip
Authors: Garras D. N. , Crowder T. T. , Olson S. A. 
Published: July 2007

We studied the medium-term outcome of the Bernese periacetabular osteotomy in 52 patients (58 hips) with symptomatic developmental dysplasia of the hip and a mean age of 37.6 years (13 to 48). The operations were performed between 1993 and 2005 by the senior author with a mean follow-up of 66.7 months (13 to 153). There were 42 women (47 hips) and ten men (11 hips). Of these patients, 24 (30 hips) had an osteotomy on the right side and 22 (28 hips) on the left. Six patients had bilateral operations. The clinical outcome was assessed using the modified Merle d’Aubigne scale, and pre- and post-operative radiological evaluation using the modified Tonnis osteoarthritis score, the centre-edge angle, the acetabular index, the status of Shenton’s line, and the cross-over sign. The mean centre-edge angle and the acetabular index were 14° (2° to 34°) and 23.6° (0° to 40°) before operation, and 36.6° (16° to 72°) and 7.9° (0° to 28°) after, respectively (p < 0.001, analysis of variance (ANOVA)). Shenton’s line was intact in 23 hips (39.6%) before operation and in 48 hips (82.8%) after. The cross-over sign was present in 31 hips (53.4%) before and in three hips (5.2%) after operation (p < 0.001, ANOVA). The total Merle d’Aubigne clinical score improved from a mean of 12.6 (9 to 15) to 16.0 (12 to 18) points (p < 0.001, ANOVA). Only four hips required subsequent total hip replacement. Our results indicate that the Bernese periacetabular osteotomy provides good symptomatic relief for patients with little to no arthritis (Tonnis type 0 or 1) with an underlying deformity that can be corrected to a position of a stable, congruent hip joint.
Insufficient duration of venous thromboembolism prophylaxis after total hip or knee replacement when compared with the time course of thromboembolic events
Authors: Warwick D. , Friedman R. J. , Agnelli G. , Gil-Garay E. , Johnson K. , FitzGerald G. , Turibio F. M. 
Published: July 2007

Patients who have undergone total hip or knee replacement (THR and TKR, respectively) are at high risk of venous thromboembolism. We aimed to determine the time courses of both the incidence of venous thromboembolism and effective prophylaxis. Patients with elective primary THR and TKR were enrolled in the multi-national Global Orthopaedic Registry. Data on the incidence of venous thromboembolism and prophylaxis were collected from 6639 THR and 8326 TKR patients. The cumulative incidence of venous thromboembolism within three months of surgery was 1.7% in the THR and 2.3% in the TKR patients. The mean times to venous thromboembolism were 21.5 days (sd 22.5) for THR, and 9.7 days (sd 14.1) for TKR. It occurred after the median time to discharge in 75% of the THR and 57% of the TKA patients who developed venous thromboembolism. Of those who received recommended forms of prophylaxis, approximately one-quarter (26% of THR and 27% of TKR patients) were not receiving it seven days after surgery, the minimum duration recommended at the time of the study. The risk of venous thromboembolism extends beyond the usual period of hospitalisation, while the duration of prophylaxis is often shorter than this. Practices should be re-assessed to ensure that patients receive appropriate durations of prophylaxis.