bluuebunny/crossref_metadata_2025 huggingface dataset:
Sensitivity to Input Variability of the Adjuvant! Online Breast Cancer Prognostic Model
Authors: Ozanne Elissa M. , Braithwaite Dejana , Sepucha Karen , Moore Dan , Esserman Laura , Belkora Jeffrey
Published: December 2008

Purpose

Adjuvant! Online ( www.adjuvantonline.org ) is a software model that predicts the benefit of adjuvant therapy for women with early-stage breast cancer. The model has been validated, is widely consulted, and has been shown to influence patient choices in the clinical setting. Adjuvant! requires the clinician to input patient age, tumor size, grade, hormone receptor status, number of positive lymph nodes, and comorbidity level. Because comorbidity is strongly and independently associated with survival, this study tested the hypothesis that Adjuvant! predictions would be sensitive to comorbidity inputs.

Methods

Investigators used single-variable deterministic sensitivity analysis to evaluate the effect of varying each input of the model independently for three representative case examples based on National Comprehensive Cancer Network guidelines (NCCN). The main outcome of interest was 10-year mortality prediction.

Results

The analyses show that Adjuvant!'s 10-year mortality predictions are most sensitive to patients’ comorbidity levels and the extent of nodal involvement for the cases, particularly among older women. Comorbidity was the most influential input except in younger women, aged 40 years.

Conclusion

The Adjuvant! model is sensitive to patient comorbidity, and impact on the model outputs are significant enough that they are likely to affect physician recommendations and patients’ treatment choices. For example, incorrect assessments of comorbidities could lead physicians to overtreat or undertreat a patient who is in a gray zone relative to the NCCN guidelines. These results point to the importance of accurately assessing comorbidities in patients with breast cancer when using Adjuvant! and highlight the need for a standardized process of comorbidity ascertainment.
Significance of MYCN Amplification in International Neuroblastoma Staging System Stage 1 and 2 Neuroblastoma: A Report From the International Neuroblastoma Risk Group Database
Authors: Bagatell Rochelle , Beck-Popovic Maja , London Wendy B. , Zhang Yang , Pearson Andrew D.J. , Matthay Katherine K. , Monclair Tom , Ambros Peter F. , Cohn Susan L.
Published: December 2008

Purpose

Treatment of patients with localized neuroblastoma with unfavorable biologic features is controversial. To evaluate the outcome of children with low-stage MYCN-amplified neuroblastoma and develop a rational treatment strategy, data from the International Neuroblastoma Risk Group (INRG) database were analyzed.

Patients and Methods

The database is comprised of 8,800 patients. Of these, 2,660 patients (30%) had low-stage (International Neuroblastoma Staging System stages 1 and 2) neuroblastoma, known MYCN status, and available follow-up data. Eighty-seven of these patients (3%) had MYCN amplified tumors.

Results

Patients with MYCN-amplified, low-stage tumors had less favorable event-free survival (EFS) and overall survival (OS) than did patients with nonamplified tumors (53% ± 8% and 72% ± 7% v 90% ± 1% and 98% ± 1%, respectively). EFS and OS were statistically significantly higher for patients whose tumors were hyperdiploid rather than diploid (EFS, 82% ± 20% v 37% ± 21%; P = .0069; OS, 94% ± 11% v 54% ± 15%; P = .0056, respectively). No other variable had prognostic significance. Initial treatment consisted of surgery alone for 29 (33%) of 87 patients. Details of additional therapy were unknown for 14 patients. Twenty-two patients (25%) underwent surgery and moderate-intensity chemotherapy; another 22 underwent surgery, intensive chemotherapy, and radiation therapy. Nine of the latter 22 underwent stem cell transplantation. Survival in patients who received transplantation did not differ from survival in those who did not receive transplantation.

Conclusion

Among patients with low-stage, MYCN-amplified neuroblastoma, outcomes of patients with hyperdiploid tumors were statistically, significantly better than those with diploid tumors. The data suggest that tumor cell ploidy could potentially be used to identify candidates for reductions in therapy. Further study of MYCN-amplified, low-stage neuroblastoma is warranted.
Modal interactions in a rotating flexible disc
Authors: Pei Yong-Chen , Tan Qing-Chang
Published: December 2008

This article presents a dynamic investigation on the modal interactions in a rotating flexible disc. The governing equation of the rotating flexible disc is modelled by both considering the disc as a von Kármán plate and including the initial transverse runout of the disc. When the equation is discretized by Galerkin's method, non-diagonal elements of the stiffness matrix induced by the centrifugal force of the rotating disc, which represent the modal interactions, remain. Effects of the modal interactions on natural frequency and total deflection of the disc are investigated. The investigation shows that neglecting the modal interactions should cause evident error in the dynamic analysis of rotating flexible discs. The modal interaction results in the initial transverse runout of a given mode not only affects the deflection of the mode itself but also causes the deflection of other modes with different numbers of nodal circles and becomes stronger with an increase in the disc rotating speed and the number of nodal circles.
Enumeration of kinematic chains and mechanisms
Authors: Simoni R , Carboni A P , Martins D
Published: December 2008

A problem still unsolved in kinematics is the enumeration of a complete list of kinematic chains and mechanisms without isomorphisms and without degenerate chains that operate in any screw system. In this paper, a method for the enumeration of kinematic chains without isomorphisms and degenerate chains for all screw systems and a new method of enumeration of kinematic chain inversions (i.e. mechanisms) based on group theory techniques are presented. New concepts of the group theory are introduced and a new method of enumeration of inversions is presented. Kinematic inversions are related to the symmetries of the chain which can be identified analysing the corresponding graph. The symmetry of a graph can be identified for the group of automorphisms of the graph and its orbits provides sets of vertices (links) that are in the same equivalence classes, i.e. they have the same properties of symmetry. The main definitions of group theory and examples of application of the new method of enumeration of inversions are presented. New results are obtained and divided in two classes: original results in non-planar screw systems (λ≠3) and results in agreement with a previously published list for planar kinematic chains and planar mechanisms (inversions). Two tables (1 and 3) are provided, which are up-to-date lists of kinematic chains and mechanisms for several screw systems.
The use of the Taguchi method and principal component analysis for the sensitivity analysis of a dual-purpose six-bar mechanism
Authors: Chen F C , Tzeng Y F , Chen W R , Hsu M H
Published: December 2008

In this paper, the Taguchi method and the principal component analysis were applied to a dual-purpose six-bar mechanism for investigating the influence of manufacturing tolerance and joint clearance on the quality of the mechanism. Experiments were carried out based on the orthogonal array from the Taguchi method, which calculated the S/ N ratios of the positional and angular errors of a dual-purpose six-bar mechanism. Using the principal component analysis, the S/ N ratios were transformed into a multiple performance index to further understand the effect of the control factors on the quality of the six-bar mechanism. Using the analysis of response table and response diagram, the key dimensions of the mechanism could be identified and their tolerance optimized, i.e. decreasing the tolerance of important dimensions and increasing the rest, with the objective of simultaneously improving the quality of the mechanism and reducing the cost.
Engineering at the interface revisited
Authors: Gebeshuber I C
Published: December 2008

Three publications from Part C which strongly influenced the development of the field of lubrication in human joints are revisited and their impact on the field is outlined. Furthermore, the impact of the Journal of Mechanical Engineering Science on the field of lubrication and wear in living and artificial human joints is analysed.

‘Analysis of “boosted lubrication” in human joints’ by Duncan Dowson, Anthony Unsworth, and Verna Wright appeared in 1970, ‘The lubrication of porous elastic solids with reference to the functioning of human joints’ by Gordon R. Higginson and Roger Norman was published in 1974, and ‘Engineering at the interface’ by Duncan Dowson addressed the audience in 1992.
Dynamic reliability-based robust optimization design for a torsion bar
Authors: Wang X-G , Zhang Y-M , Wang B-Y
Published: December 2008

The variation rules of strength, load, and reliability of mechanical components are studied with a change in time, and a model is established for dynamic reliability of mechanical components under the random load acting. According to the model, the design of dynamic reliability sensitivity is discussed, and the approach to calculate it is proposed. By combining the theory of reliability-based optimization design with the method of sensitivity analysis, the computational method of dynamic reliability-based robust optimization design is established, and the problem of dynamic reliability-based robust optimization design of a torsion bar is solved.
Analysis of non-linear vibrations of a microresonator under piezoelectric and electrostatic actuations
Authors: Zamanian M , Khadem S E , Mahmoodi S N
Published: December 2008

In this article, the non-linear vibrations of a piezoelectrically actuated microresonator is studied. The microresonator is assumed as a clamped—clamped Bernouli—Euler microbeam. In contrast to previous researches in which the piezoelectric layer has been deposited on the integral length of the microbeam, here it is assumed that the piezoelectric layer is deposited on a part of microbeam length with equal distance from two ends. The microbeam is actuated by an AC voltage between upper and lower sides of the piezoelectric layer. Also, an electrostatic actuation is applied between the microbeam and an electrode plate, for the first time. The non-linear equation of motion has been derived by using the Hamilton principle by stretching the neutral axis assumption. The obtained equations are solved using the Galerkin, Rayleigh—Ritz, and multiple scale perturbation methods. It is shown that the sensitivity and natural frequency of the piezoelectrically actuated microresonator may be altered and controlled conveniently by applying an electrostatic actuation to the microresonator. Also, it has been shown that the system shows softening or hardening behaviour depending on the value of piezoelectric actuation, electrostatic actuation, axial load, thickness, length, and elasticity module of piezoelectric layer; thickness of microbeam; and its distance from the electrode plate. It is shown that non-linear behaviour of the piezoelectrically actuated microbeam may be changed to a linear behaviour by applying a suitable electrostatic actuation to the microbeam.
Damping in layered and jointed riveted structures with equal thickness
Authors: Mohanty R C , Nanda B K
Published: December 2008

A common problem associated with many engineering structures is the low damping capacity making it unsuitable for use in aerospace and related structures requiring high dynamic stiffness. Attempts have been made by many researchers to design and fabricate structures, which can contribute substantial damping to the structures. One of the techniques used for this purpose is the layered structure jointed with rivets because of its superiority with respect to the requirements of high damping capacity and stiffness compared to a solid one. The presence of joints in such structures allows slip, thereby increasing the inherent damping of the structures due to interface friction. An attempt has been made in the present investigation to study, both numerically and experimentally, the damping mechanism and methodologies adopted in the structures jointed with rivets for enhancing their damping capacity. This is particularly important in applications such as bridges, pressure vessels, building, aircraft and aerospace structures, and frames and machine members, where damping capacity is of primary consideration.
A review of the paper ‘Optimal suppression of parametric vibration in discs under rotating frictional loads’ by H. Ouyang and J. E. Mottershead
Authors: Garvey S D
Published: December 2008

This article addressed a problem that was a source of serious irritation and expense in the automotive industry — brake squeal. It also has application to several other practical situations including data-storage discs and circular saw blades.
Maximizing the lowest eigenvalue of a constrained affine sum with application to the optimal design of structures and vibrating systems
Authors: Ram Y M , Krishna S G
Published: December 2008

This article deals with the problem of maximizing the lowest eigenvalue of an affine sum of symmetric matrices subject to a constraint. It is shown that by the repeated use of eliminants, the problem may be reduced in a systematic manner to that of finding the roots of certain polynomials. However, the process of finding the analytical solution is tedious. Therefore, a Newton iterative method, which solves the problem numerically, is developed.

To demonstrate the results, the Lagrange problem of determining the shape of the strongest column is formulated in the discrete model setting and solved by using the developed method. The design problem of finding the mass distribution in a vibratory system that optimizes its extreme natural frequencies is also given.
Forced convective heat transfer over a non-circular slender cylinder
Authors: Marchesse Y , Changenet C
Published: December 2008

An investigation of heat transfer between a flow and a horizontal non-circular slender cylinder is presented in this article. Both experimental and numerical approaches are considered here. When using identical cylinders and free-stream velocities, a comparison between experimental data and numerical estimation emphasizes the shear stress transport k–ω turbulent model associated with fine mesh near wall to be appropriate for estimating an average value of heat transfer coefficient in the present configuration. From a numerical parametric investigation, which is based on the latter approach, two formulations of heat transfer are to be considered as thickness does not have a real influence in heat transfer for low Reynolds numbers, whereas for higher values, both thickness and width participate in heat transfer.
Design equations for binary shape memory actuators under dissipative forces
Authors: Spinella I , Dragoni E
Published: December 2008

An analytical procedure to design binary shape memory actuators is described. A generic actuator is considered where a cursor is moved against dissipative forces using an elastic system containing a primary shape memory spring and a bias (backup) element. Three typical cases are analysed and differentiated in the way the bias force is applied to the primary shape memory spring, using a constant force, a conventional spring, or a second shape memory spring. Dimensionless, closed-form relationships are developed, which form the basis of a step-by-step procedure for an optimal design of the whole actuator (primary active spring and bias element). Specific formulas regarding the detailed design of the shape memory elements of the actuator in the form of straight wires and wire helical springs are also presented.
Building Bayesian network classifiers through a Bayesian complexity monitoring system
Authors: Ruz G A , Pham D T
Published: December 2008

Nowadays, the need for practical yet efficient machine learning techniques for engineering applications are highly in demand. A new learning method for building Bayesian network classifiers is presented in this article. The proposed method augments the naive Bayesian (NB) classifier by using the Chow and Liu tree construction method, but introducing a Bayesian approach to control the accuracy and complexity of the resulting network, which yields simple structures that are not necessarily a spanning tree. Experiments by using benchmark data sets show that the number of augmenting edges by using the proposed learning method depends on the number of training data used. The classification accuracy was better, or at least equal, to the NB and the tree augmented NB models when tested on 10 benchmark data sets. The evaluation on a real industrial application showed that the simple Bayesian network classifier outperformed the C4.5 and the random forest algorithms and achieved competitive results against C5.0 and a neural network.
Descriptions of reversed yielding of a solid circular bar in torsion
Authors: Rees D W A
Published: December 2008

Two plastic penetrations are possible from applying torque to a solid, circular-section bar: one from applying an elastic—plastic torque and the other from releasing it. The first penetration occurs from the outer radius inwards towards the centre when the deformation becomes increasingly plastic as the flow stress increases beyond the initial yield stress. The second plastic penetration occurs in a similar manner but is a manifestation of the Bauschinger effect, which refers to that reduction in the flow stress required to initiate reversed plasticity. The latter can occur upon the release of the elastic—plastic torque responsible for an initial plastic penetration, usually deeper than the mean radius. A theory of secondary penetration is given for both linear and parabolic hardening materials. By varying the plastic tangent modulus special cases of linear hardening are studied, including ideal materials with perfect (forward) plasticity and those that obey kinematic hardening. Within the chosen hardening law the elastic and plastic strains are developed from the bar's angular twist within its elastic core. Conditions, for which a torque-release is either purely elastic or elastic—plastic, appear to be within the section parameters and the material's flow curve, these providing the depth of a secondary penetration. Two stress distributions, one for the application of torque and the other for torque release, are sufficient to show that residual stress distributions differ from non-hardening theory. Experimental results given suggest that residuals arising from parabolic hardening are more realistic where a second penetration occurs. Experiment also reveals where kinematic and isotropic hardening models apply.
A brief history of the filling simulation of injection moulding
Authors: Cardozo D
Published: December 2008

Injection moulding is one of the most important manufacturing processes for mass production of complex plastic parts. The quality of injection moulded parts depends not only on the material, shape, and function of the part design, but also on how the material is processed during moulding. Traditional design approaches based on intuition, prior experience, and trial-and-error methodology have been becoming less efficient and effective. With advances in numerical modelling and computer simulation techniques, there have been tremendous efforts made to develop computer simulation tools to facilitate injection moulding design and process set-up. This paper reviews the history of research and development in the filling simulation of injection moulding. The existing models are classified into three categories: one-dimensional models, 2.5D models, and three-dimensional models. The basic features and relative key techniques about these models have been discussed. The techniques of tacking the moving flow front have also been presented. It is then followed by conclusions and discussions of these mentioned models.
A review of modular strategies and architecture within manufacturing operations
Authors: Doran D , Hill A
Published: December 2008

This paper reviews existing modularity and modularization literature within manufacturing operations. Its purpose is to examine the tools, techniques, and concepts relating to modular production, to draw together key issues currently dominating the literature, to assess managerial implications associated with the emerging modular paradigm, and to present an agenda for future research directions. The review is based on journal papers included in the ABI/Inform electronic database and other noteworthy research published as part of significant research programmes. The research methodology concerns reviewing existing literature to identify key modular concepts, to determine modular developments, and to present a review of significant contributions to the field. The findings indicate that the modular paradigm is being adopted in a number of manufacturing organizations. As a result a range of conceptual tools, techniques, and frameworks has emerged and the field of modular enquiry is in the process of codifying the modular lexicon and developing appropriate modular strategies commensurate with the needs of manufacturers. Modular strategies and modular architecture were identified as two key issues currently dominating the modular landscape. Based on this review, the present authors suggest that future research areas need to focus on the development and subsequent standardization of interface protocols, cross-brand module use, supply chain power, transparency, and trust. This is the first review of the modular landscape and as such provides insights into, first, the development of modularization and, second, issues relating to designing modular products and modular supply chains.
Weak knock characterization and detection for knock control
Authors: Nilsson Y , Frisk E , Nielsen L
Published: December 2008

Knock is a fundamental phenomenon in combustion engines, and knock control is central in any engine management system. Better understanding of knock, and weak knock in particular, is considered from two main aspects: knock detection and knock characterization. The aim of knock detectors is both to detect knock and to estimate the crank angle at knock onset. Focusing on weaker knock than before, it is shown that knock detectors and algorithms have to take into account other characteristics of knock traces than the standard model. It is shown that the best-performing knock detector of those investigated is one that supervises changes in signal variance, except for low signal-to-noise ratios where it is advantageous to use also the oscillation frequency. Regarding characterization, an important result is that in a wide range of intensities there is an almost linear dependence between the logarithmic normalized knock energy and the rate of cycles with knock. This means for example that a knock controller can use feedback on the rate of cycles with knock instead of knock intensity and vice versa; both can in combination with better detection provide possibilities for smoother and more anticipatory control schemes.
Determining and analysing the stress state under wheeled-vehicle loads
Authors: Pytka J
Published: December 2008

This paper contains experimental data from the soil stress state under wheeled-vehicle loads obtained in several field experiments. Three-wheeled vehicles were used for the tests: a 14t 6×6 and a 6t 4×4 truck as well as a 3.1t agricultural tractor. The vehicles were driven over different types of soils (sandy soil, loess (clay), and turf) and over a snow cover. The measuring method is described. An analysis of principal stresses as well as octahedral stresses was performed taking into account the following factors: vehicle weight and wheel loading, vehicle speed, multiple passes, reduced inflation pressure, and wheel-function modes (rolling and driving). An analysis of octahedral stresses was performed on the basis of correlations between these stresses and the drawbar pull force generated by the vehicle. The most significant finding from this work is that the soil stress under a loaded vehicle depends not only upon the contact pressure but also upon factors that change during operations, such as the speed, wheel slip, load distribution, and multiple passes. This explains why the results of off-road mobility and trafficability models based on flat values of wheel—soil pressure may vary far more than expected. It was also concluded that soil stresses are affected by rolling and driving modes, but the relationships are different for sand and loess soil surfaces.
A thermomechanical analysis based on a contact temperature measurement
Authors: Wagner A , Bajsic I , Fajdiga M
Published: December 2008

Modern headlamps are made from thermoplasts, which are very convenient materials for headlamp design. However, the poor thermomechanical properties of polymers can cause deformations, problems with the photometric properties, and sealing difficulties. In order to predict these deformations, standard methods were used and combined in a new approach for a quick and efficient evaluation of such headlamps. Thin-film resistance temperature detectors were employed at significant points on the headlamp housing to measure the temperature. The results were then used to determine a three-dimensional temperature field for the headlamp housing. This temperature field was subsequently used in a finite element method analysis to determine the deformations in the housing of the headlamp.
A thermodynamic analysis of the use of exhaust gas recirculation in spark ignition engines including the second law of thermodynamics
Authors: Shyani R G , Caton J A
Published: December 2008

This work examines results from a thermodynamic engine cycle simulation of a spark ignition engine with exhaust gas recirculation (EGR). EGR is a common feature of today's engines and is an effective technique to reduce combustion temperatures and nitrogen oxide emissions. Results were obtained for an automotive engine using isooctane. These results are presented as functions of EGR for constant load and speed, and as functions of load and speed for constant EGR level. For both a cooled and an adiabatic EGR configuration, the thermal efficiency first increased, reached a maximum, and then decreased as the EGR levels increased. The thermodynamic gains were largely due to favourable thermodynamic properties, reduced cylinder wall heat losses, and, for part-throttle operation, reduced pumping losses as the EGR level increased. The destruction of availability during the combustion process was highest for the cooled EGR configuration. For the cases examined, the destruction of availability due to combustion ranged from about 18 per cent to 22 per cent of the original fuel availability.
Study of damage in windshield glazing subject to impact by a pedestrian's head
Authors: Xu J , Li Y-B
Published: December 2008

The windshield is one of the major components in a vehicle that determines the injury to a pedestrian's head. Therefore, it is critical to study the damage to windshield glazing so as to promote the protection structure for pedestrians. In this paper, classical plate theory in combination with the Green strain and the von Karman assumption is used to develop constitutive relations to describe the large-deformation behaviour of composite poly(vinyl butyral) (PVB) windshield glazing. Previous test data are used to verify the constitutive relations model. A three-dimensional finite element model describing the impact between the head of a pedestrian and the windshield is constructed to investigate the mechanism underlying the damage to the windshield. Three main crack patterns of composite PVB glazing are proved to exist: a circumferential crack, a spider-web crack, and a plastic crack. Therefore, this paper studies the effect of different impact conditions and windshield structures on the damage to the windshield glazing and on the head injury. The results show that a high speed will cause not only a high initial impact speed but also the equivalent impact weight, which can increase both the probability and extent of head injury. Furthermore, the study proves that the PVB film greatly improves the protection for a pedestrian in a traffic accident and it is advised that more layers of PVB film are introduced into the windshield to protect pedestrians better.
Analysis of the properties of a steering shaft used as a back-up for a steer-by-wire system during system failure
Authors: Hussain K , Baharom M , Day A
Published: December 2008

An analysis is presented to determine the best selection criteria for the properties of a steering shaft to be used as a back-up apparatus for a steer-by-wire (SBW) system during system failure. The properties of interest are the steering-shaft stiffness and its damping coefficient. A mathematical model representing the failed state of an SBW system is derived, and a set of experiments to validate the model is presented. Once the model had been validated, further predictions of the car's handling behaviour for a range of steering-shaft properties and different road speeds were completed by simulations in MATLAB/Simulink. A minimum stiffness which did not cause the car to become unstable owing to overshoot was determined, and the minimum acceptable damping coefficient value was derived. It is concluded that the suggested stiffness and damping coefficient values increased the steering ratio, and the results of further investigations are presented, which confirm that the vehicle is safe to be driven in the event of SBW system failure if the recommended shaft properties are used.
The performance analysis of a solid adsorption solar refrigerator during collector cool-down and refrigerant evaporation/re-adsorption phases
Authors: Ogueke N V , Anyanwu E E
Published: December 2008

Performance analysis of a solid adsorption solar refrigerator during the collector cool-down and refrigerant evaporation/re-adsorption phases is presented. The effects of the condenser pressure, evaporator pressure, and initial adsorbate concentration on the collector cool-down and refrigerant evaporation/re-adsorption were tested. The adsorbate concentration re-adsorbed increased from 55 to 98 per cent when the initial adsorbate concentration was dropped from 0.29 to 0.21 kg/kg, while the mass of ice produced increased from 0 kg of ice/kg of adsorbent to 0.4 kg of ice/kg of adsorbent for the same range of variation of initial adsorbate concentration.
Simulation of traction curving for active yaw — force steered bogies in locomotives
Authors: Simson S A , Cole C
Published: December 2008

Steering bogies and actively steered bogies are subjected to increasing interest. Self-steering bogies have been used in large numbers of hauling locomotives primarily in the USA to reduce flange wear and improve adhesion. However, the steering performance of self-steering bogies is reported to deteriorate under traction. This article compares several bogie types and proposes a new design of steering bogie featuring forced steering combined with control of the bogie yaw movement or actuated yaw forced steered bogie (AY-FS). The bogie stability of a force steered bogie is improved by yaw actuation using a negative derivative control of the bogie yaw misalignment. An additional benefit of the bogie design is that actuators and control sensors for the AY-FS bogie can be mounted on the vehicle body rather than on the bogie frame.

The article presents simulation results for a yaw actuated force steered bogie under traction curving conditions. The AY-FS bogie is compared with rigid and force steered bogies and is shown to give superior performance at high traction adhesion levels during curving. The curving performance improvements achieved depend on the curvature, lateral forces on the vehicle, the traction load, and the rail friction. The greatest curving performance advantages occur in tighter curvatures with high traction loads and low rail friction and with high lateral forces to the inside rail such as would result from coupler loads on pulling locomotives.
Bainitic steel grade for solid wheels: metallurgical, mechanical, and in-service testing
Authors: Gianni A , Ghidini A , Karlsson T , Ekberg A
Published: December 2008

Bainitic steel grades generally have superior rolling contact and thermal fatigue resistances, but poorer wear characteristics when compared with ‘conventional’ pearlitic steel wheels. To improve the wear characteristics, the manufacturing process of bainitic materials needs to be carefully controlled.

In this article, the manufacturing process of the ‘MICRALOS’ bainitic steel grade has been described. The main focus is on metallurgical testing activities performed in order to compare the new steel grade with standard pearlitic steels and to predict the service behaviour of the solid bainitic wheels. Further, on-going field tests on the iron ore line between Luleå and Narvik have been reported, with details about measurement methods and results.

The performance of the wheels is reviewed and compared with the current scientific knowledge of bainitic steel grades and the deterioration of heavy haul wheels. Finally, benefits of and challenges for bainitic wheels in general and for the MICRALOS grade wheels in particular will be discussed.
Running Resistance and Energy Consumption of Ore Trains in Sweden
Authors: Lukaszewicz P
Published: December 2008

Running resistance of ore trains consisting of Uad-type wagons is determined from full-scale measurements on Malmbanan. Tests are also run in curves with the Uad equipped with three piece bogies where the axles are non-steerable and an ore wagon equipped with bogies allowing the axles to better align themselves on straight track and more radially in curves, thus making them steerable. Influence of speed, axle load, curve radii, and train length is studied and quantified. The running resistance is parameterized and expressed in a general way so that it can be calculated for any Swedish ore train consisting of Uad-type wagons. The study shows that the increase in running resistance is linear due to the increasing axle load on tangent track and train length. The increase in resistance due to curves is significant and increases as the curve radius decreases. If the axles align themselves radially, the curve resistance reduces by 40 per cent, compared with the Uad. The results show which parameters in a running resistance formula should be paid extra attention when constructing a train model for simulation purposes. A comparison is made between ore trains and ordinary Swedish loco-hauled freight trains. The energy consumption of an ore train is not much affected if the operational speed increases from 50 to 60 km/h. Also, a reduced aerodynamic drag has a very little effect on the consumption due to the low operational speed. In this article, a review of the study is made with conclusions.
Uncertainty estimation in railway track life-cycle cost: a case study from Swedish National Rail Administration
Authors: Patra A P , Söderholm P , Kumar U
Published: December 2008

Life-cycle cost (LCC) is used as a cost-effective decision support for maintenance of railway track infrastructure. However, a fair degree of uncertainty associated with the estimation of LCC is due to the statistical characteristics of reliability and maintainability parameters. This paper presents a methodology for estimation of uncertainty linked with LCC, by a combination of design of experiment and Monte Carlo simulation. The proposed methodology is illustrated by a case study of Banverket (Swedish National Rail Administration). The paper also includes developed maintenance cost models for track.
Development of a new track geometry assessment technique incorporating rail cant factor
Authors: Sadeghi J , Fathali M , Boloukian N
Published: December 2008

The influence of rail cant on the overall geometry conditions of railway tracks is assessed both theoretically and experimentally in this study. Extensive data obtained from a light railway line are used for experimental investigations. Modelling of rail—wheel contact using the ADAMS/Rail program is undertaken for theoretical investigations. The need to incorporate rail cant into the development of the track geometry indices is identified, and a method of performing this is proposed. Using this approach, a new track index is defined, for which the main geometry parameters, including alignment, profile, track twist, track gauge, and rail cant (rail twist), are considered. For the development of the new track index, these parameters are combined, assigning justified coefficients to each geometry parameter according to its contribution to the overall conditions of the track. The research methodology and the results are discussed. A practical use of the new index is presented to indicate its capability and applicability.
Thrust acceleration estimation using an on-line non-linear recursive least squares algorithm
Authors: Ghahramani N , Naghash A , Towhidkhah F
Published: December 2008

In this article, a robust non-linear recursive algorithm, featuring a highly reduced computational load, is proposed to estimate the thrust acceleration of a typical flight vehicle. The robustness of this new algorithm allows a significant increase of deviations in initial values of the estimated parameters. In the proposed algorithm, at first, a transformation of the non-linear measurement equation to a linear one, without any approximation, is obtained. Then the recursive least squares algorithm is applied to the transformed equation. The maximum achievable accuracy of the estimation for the non-linear problem is obtained analytically by the Cramer—Rao lower bound and is compared with simulation results. Extensive simulations showed that the new method provides an unbiased as well as a more robust thrust acceleration estimate in comparison with the extended Kalman filter. Moreover, the proposed method is beneficial in that it has a lower number of parameters and results in a simple design with less computational effort.
A synthesis of reduced-order gain scheduling controllers for active flutter suppression
Authors: Fujimori A
Published: December 2008

This paper presents a synthesis of reduced-order gain scheduling (GS) controllers based on the balanced truncation (BT) method. A polytopic plant model is first reduced by the modified BT method in which the state transformation matrix is obtained by balancing the weighted average controllability and observability Gramians over the entire range of the varying parameter. Using the reduced-order polytopic models, GS controllers are then designed in the frame of a linear matrix inequality technique. The proposed synthesis is applied to the GS controller design for the active flutter suppression of a high-aspect-ratio aeroelastic wing. The effectiveness of the proposed technique is demonstrated by numerical simulation.
Wind tunnel validation of computational fluid dynamics-based aero-optics model
Authors: Nahrstedt D , Hsia Y-C , Jumper E , Gordeyev S , Ceniceros J , Weaver L , DeSandre L , McLaughlin T
Published: December 2008

A computational fluid dynamics (CFD)-based aero-optics validation study was conducted in wind tunnel tests at the US Air Force Academy. A 12 in diameter hemisphere-on-cylinder laser turret was tested in the 3 ft×3 ft subsonic wind tunnel at flow speeds ranging from mach 0.3 to 0.5. Flow validation was based on mean and rms velocity, mean pressure profile, rms unsteady pressure, and separation point. Optical validation was based on rms phase variance and inflow phase correlation length derived from two-dimensional Hartmann wavefront sensor data, measured over a 5 in beam. The CFD code used a two-equation turbulence model with partially-averaged Navier—Stokes approach. Good agreement was observed between measurements and predictions over line-of-sight angles ranging from 60 to 132° measured with respect to flow heading.
Multi-objective shape control of prestressed structures with genetic algorithms
Authors: Xu X , Luo Y-Z
Published: December 2008

The shape of a prestressed structure is sensitive to external errors/stimuli due to its lightweight and high flexibility. When the shape distortion is deemed unacceptable, adjustment of the nodal positions is required. In this article, the shape control of a prestressed structure is modelled as a multi-objective optimization problem. A novel multi-objective genetic algorithm has been proposed to solve this problem. In the proposed algorithm, a niche technique consisting of a crowding check and a filter process is introduced to ensure the diversity of the population, and simultaneously, to accelerate the revolution process. On the basis of a ranking scheme of the individuals’ degree of constraint violation, a problem-independent penalty method for constraint handling has been proposed. In addition, some well-developed techniques, such as fitness evaluation with a ranking procedure and termination judging with the distance to the idea point, are properly selected and used. The proposed algorithm performs well in seeking Pareto optimal sets for the shape control of prestressed structures, which is verified by two examples.
Feedback control of a circular cylinder wake
Authors: Seidel J , Siegel S , Fagley C , Cohen K , McLaughlin T
Published: December 2008

Feedback flow control of a three-dimensional wake behind a circular cylinder at a Reynolds number of Re=100 was investigated. A combination of numerical simulations, experiments, and control theory was used to understand the flow field and to develop a sensor configuration, a flow state estimator, and a controller. The flow field was analysed by using proper orthogonal decomposition (POD) in two dimensions, and two-dimensional and three-dimensional sensor placements were investigated. The controller input was computed from the POD time coefficients, and actuation was performed by using rigid cylinder motion normal to the free stream. In the two-dimensional computations, feedback was shown to effectively reduce the drag and the fluctuating lift force. When feedback forcing was applied in the three-dimensional wake, both simulations and experiments showed that the vortex shedding could be controlled initially and the amplitude of the fluctuations decreased. However, spanwise phase variations eventually appeared and rendered the controller ineffective.
An alternative mechanical parameter for assessing the viability of articular cartilage
Authors: Brown C P , Crawford R W , Oloyede A
Published: December 2008

This paper is a sequel to previously published findings showing that mechanical indentation alone cannot clearly discriminate between normal and degraded articular cartilage. Consequently, the structural elasticity potential ℜc = ɛr/ σi, which combines indentation stress σi with near-instantaneous rebound ɛr following unloading, is hypothesized as a potential cartilage assessment parameter, which arguably measures the integrity of the collagen fibre—proteoglycan entrapment system. To establish the validity of our hypothesis, samples of normal intact, artificially degraded, and osteoarthritic bovine cartilage were subjected to quasi-static compression at 0.1 s−1 and 0.025 s−1 to 30 per cent strain and then unloaded. A significant reduction in recovery was observed for artificially and naturally degraded samples in the first 5 s following unloading ( p<0.01). The structural elasticity potential provided a considerable improvement over the results obtained using the individual indentation and rebound parameters to distinguish between paired normal and artificially degraded samples and indicated a high statistical significance of p<0.005 when applied to the differentiation of normal and osteoarthritic samples.
Directional fractal signature analysis of trabecular bone: Evaluation of different methods to detect early osteoarthritis in knee radiographs
Authors: Wolski M , Podsiadlo P , Stachowiak G W
Published: December 2008

There is ongoing research directed towards the development of cheap and reliable decision support systems for the detection and prediction of osteoarthritis (OA) in knee joints. Fractal analysis of trabecular bone texture X-ray images is one of the most promising approaches. It is cheap and non-invasive. However, difficulties arise when the fractal signature methods are used to quantify bone roughness and anisotropy on individual scales. This is because the fractal methods are able to quantify bone texture only in the vertical and horizontal directions, and previous studies showed that OA bone changes can occur in any direction. To address these difficulties, three directional fractal signature methods were developed in this study, i.e. a fractal signature Hurst orientation transform (FSHOT) method, a variance orientation transform (VOT) method, and a blanket with rotating-grid (BRG) method. These methods were tested and the best performing method was selected. Unlike other methods, the newly developed techniques are able to calculate fractal dimensions (FDs) on individual scales (i.e. fractal signature) in all possible directions. The accuracy of the methods developed in measuring texture roughness and anisotropy on individual scales was evaluated. The effects of imaging conditions such as image noise, blur, exposure, magnification, and projection angle and the effects of translation of the bone region of interest on texture parameters were also evaluated. Computer-generated fractal surface images with known FDs and X-ray images obtained for a human tibia head were used. Results obtained show that the VOT method performs better than the FSHOT and BRG methods.
The compression—rotation stem: An experimental study on the primary stability of a new revision hip stem
Authors: Kraenzlein J , Mazoochian F , Fottner A , Birkenmaier C , von Schulze Pellengahr C , Jansson V
Published: December 2008

In revision hip arthroplasty with bone defects of the proximal femur, a well-established treatment method is reconstruction with impacted allograft spongiosa chips and cemented implantation of a polished stem. Building on this principle of impacted bone grafting, a femoral implant, which is suited to uncemented hip arthroplasty as well as for uncemented revisions, was designed. This so-called compression—rotation stem (CR stem) is collarless and has flanks which compress the impacted bone chips during implantation and thereby increase the rotational stability. To evaluate the primary stability of this new shaft after impaction grafting, the micromotion was determined using six motion transducers. Under physiological loading conditions with simulation of the muscle activities at the proximal femur the application was dynamically loaded for 15 000 cycles with 1000 ± 500 N and afterwards for 5000 cycles with 1300 ± 1000 N. Uncemented CR stems and the control Exeter stems were implanted in a standardized manner according to the X-Change method. Therefore they were implanted into artificial femora that had been previously resected, hollowed, and filled with impacted human spongeous bone allograft to simulate bone defects. Subsequently, the femora were loaded under identical conditions and the micromotions measured. In the majority of the implantations, no significant differences could be found. In conclusion, similar clinical results for the two stems should be expected.