bluuebunny/crossref_metadata_2025 huggingface dataset:
The GDP-dependent Rab27a effector coronin 3 controls endocytosis of secretory membrane in insulin-secreting cell lines
Authors: Kimura Toshihide , Kaneko Yukiko , Yamada Shogo , Ishihara Hisamitsu , Senda Takao , Iwamatsu Akihiro , Niki Ichiro
Published: September 2008

Rab27a is involved in the control of membrane traffic, a crucial step in the regulated secretion. Typically, the guanosine triphosphate (GTP)-bound form has been considered to be active and, therefore, searching for proteins binding to the GTP-form has been attempted to look for their effectors. Here, we have identified the actin-bundling protein coronin 3 as a novel Rab27a effector that paradoxically bound guanosine diphosphate (GDP)-Rab27a in the pancreatic β-cell line MIN6. Coronin 3 directly bound GDP-Rab27a through its β-propeller structure. The most important insulin secretagogue glucose promptly shifted Rab27a from the GTP- to GDP-bound form. Knockdown of coronin 3 by RNAi resulted in the inhibition of phogrin (an insulin-granule-associated protein) internalization and the uptake of FM4-64 (a marker of endocytosis). Similar results were reproduced by disruption of the coronin-3–GDP-Rab27a interaction with the dominant-negative coronin 3, and coexpression of the GDP-Rab27a mutant rescued these changes. Taken together, our results indicate that interaction of GDP-Rab27a and coronin 3 is important in stimulus-endocytosis coupling, and that GTP- and GDP-Rab27a regulates insulin membrane recycling at the distinct stages.
Centrin4 coordinates cell and nuclear division inT. brucei
Authors: Shi Jie , Franklin Joseph B. , Yelinek Jordan T. , Ebersberger Ingo , Warren Graham , He Cynthia Y.
Published: September 2008

Centrins are Ca2+-binding proteins that have been implicated in a number of biological processes, including organelle duplication, mRNA export, DNA repair and signal transduction. In the protozoan parasite Trypanosoma brucei we have previously described TbCentrin2, which is present on a bi-lobed structure, and involved in the duplication and segregation of the Golgi complex. Recently, another centrin, TbCentrin4, was also found at the bi-lobe and has been implicated in organelle segregation and cytokinesis. We now show that cytokinesis is not inhibited, but that a dysregulation of nuclear and cell division leads to the production of zoids – daughter siblings that contain all organelles except the nucleus. Our results, therefore, suggest that TbCentrin4 is involved in processes that coordinate karyokinesis and cytokinesis.
Chondroitin-4-sulfation negatively regulates axonal guidance and growth
Authors: Wang Hang , Katagiri Yasuhiro , McCann Thomas E. , Unsworth Edward , Goldsmith Paul , Yu Zu-Xi , Tan Fei , Santiago Lizzie , Mills Edward M. , Wang Yu , Symes Aviva J. , Geller Herbert M.
Published: September 2008

Glycosaminoglycan (GAG) side chains endow extracellular matrix proteoglycans with diversity and complexity based upon the length, composition and charge distribution of the polysaccharide chain. Using cultured primary neurons, we show that specific sulfation in the GAG chains of chondroitin sulfate mediates neuronal guidance cues and axonal growth inhibition. Chondroitin-4-sulfate (CS-A), but not chondroitin-6-sulfate (CS-C), exhibits a strong negative guidance cue to mouse cerebellar granule neurons. Enzymatic and gene-based manipulations of 4-sulfation in the GAG side chains alter their ability to direct growing axons. Furthermore, 4-sulfated chondroitin sulfate GAG chains are rapidly and significantly increased in regions that do not support axonal regeneration proximal to spinal cord lesions in mice. Thus, our findings show that specific sulfation along the carbohydrate backbone carries instructions to regulate neuronal function.
Cytosolic Ca2+ prevents the subplasmalemmal clustering of STIM1: an intrinsic mechanism to avoid Ca2+ overload
Authors: Malli Roland , Naghdi Shamim , Romanin Christoph , Graier Wolfgang F.
Published: September 2008

The stromal interacting molecule (STIM1) is pivotal for store-operated Ca2+ entry (SOC). STIM1 proteins sense the Ca2+ concentration within the lumen of the endoplasmic reticulum (ER) via an EF-hand domain. Dissociation of Ca2+ from this domain allows fast oligomerization of STIM1 and the formation of spatially discrete clusters close to the plasma membrane. By lifetime-imaging of STIM1 interaction, the rearrangement of STIM1, ER Ca2+ concentration ([Ca2+]ER) and cytosolic Ca2+ signals ([Ca2+]cyto) we show that [Ca2+]cyto affects the subcellular distribution of STIM1 oligomers and prevents subplasmalemmal STIM clustering, even if the ER is depleted. These data indicate that [Ca2+]cyto, independently of the ER Ca2+ filling state, crucially tunes the formation and disassembly of subplasmalemmal STIM1 clusters, and, thus, protects cells against Ca2+ overload resulting from excessive SOC activity.
Hairless induces cell death by downregulation of EGFR signalling activity
Authors: Protzer Cornelia E. , Wech Irmgard , Nagel Anja C.
Published: September 2008

Overexpression of the Notch antagonist Hairless (H) during imaginal development in Drosophila is correlated with tissue loss and cell death. Together with the co-repressors Groucho (Gro) and C-terminal binding protein (CtBP), H assembles a repression complex on Notch target genes, thereby downregulating Notch signalling activity. Here we investigated the mechanisms underlying H-mediated cell death in S2 cell culture and in vivo during imaginal development in Drosophila. First, we mapped the domains within the H protein that are required for apoptosis induction in cell culture. These include the binding sites for the co-repressors, both of which are essential for H-mediated cell death during fly development. Hence, the underlying cause of H-mediated apoptosis seems to be a transcriptional downregulation of Notch target genes involved in cell survival. In a search for potential targets, we observed transcriptional downregulation of rho-lacZ and EGFR signalling output. Moreover, the EGFR antagonists lozenge, klumpfuss and argos were all activated upon H overexpression. This result conforms to the proapoptotic activity of H, as these factors are known to be involved in apoptosis induction. Together, the results indicate that H induces apoptosis by downregulation of EGFR signalling activity. This highlights the importance of a coordinated interplay of Notch and EGFR signalling pathways for cell survival during Drosophila development.
Diphthamide modification of eEF2 requires a J-domain protein and is essential for normal development
Authors: Webb Tom R. , Cross Sally H. , McKie Lisa , Edgar Ruth , Vizor Lucie , Harrison Jackie , Peters Jo , Jackson Ian J.
Published: September 2008

The intracellular target of diphtheria toxin is a modified histidine residue, diphthamide, in the translation elongation factor, eEF2 (also known as EFT1). This enigmatic modification occurs in all eukaryotes and is produced in yeast by the action of five gene products, DPH1 to DPH5. Sequence homologues of these genes are present in all sequenced eukaryotic genomes and, in higher eukaryotes, there is functional evidence for DPH1, DPH2, DPH3 and DPH5 acting in diphthamide biosynthesis. We identified a mouse that was mutant for the remaining gene, Dph4. Cells derived from homozygous mutant embryos lacked the diphthamide modification of eEF2 and were resistant to killing by diphtheria toxin. Reporter-tagged DPH4 protein localized to the cytoskeleton, in contrast to the localization of DPH1 and consistent with evidence that DPH4 is not part of a proposed complex containing DPH1, DPH2 and DPH3. Mice that were homozygous for the mutation were retarded in growth and development, and almost always die before birth. Those that survive long enough had preaxial polydactyly, a duplication of digit 1 of the hind foot. This same defect has been seen in embryos that were homozygous for mutation of DPH1, suggesting that lack of diphthamide on eEF2 could result in translational failure of specific proteins, rather than a generalized translation downregulation.
Optimizing PCBN cutting tool performance in hard turning
Authors: Kountanya R K
Published: September 2008

Surface finish, in addition to tool wear, is an important aspect of PCBN tool performance in hard turning. A set of experiments that focused on the effects of corner radius, chamfer angle/width, and edge radius in addition to severity of interruption and speed/feed at constant depth of cut were performed. The severity of interruption was critical to both tool wear and surface finish performance. The edge radius was also shown to be a key factor in determining the rate of increase in Ra with maximum flank wear length lW. Experiments in continuous hard turning were then performed to determine the evolution of Ra with lW at different V and f. Ra showed a linearly increasing trend with lW at all V and f. At constant V, Ra increased with f independent of lW, but at a constant f, Ra decreased with V as an interaction with lW. A model that relates Ra and lW, V and f was formulated and validated using more experimental data and data available in the literature. An optimization algorithm is proposed which maximizes the material removal rate holding Ra at a constant prescribed value, operating at V within a prescribed limit. The algorithm essentially takes advantage of the lower Ra at a higher V and lower lW. An internally consistent baseline is used to evaluate the significance and benefit of adopting the algorithm. Finally, guidelines for implementation in real-world situations are presented.
An investigation of through-hole impact testing of weld root imperfections in friction stir welded 12 per cent chromium alloy steel
Authors: Thomas W M , Pisarski H G , Norris I M , Marks D J , Godden J C
Published: September 2008

In welded components the toughness of the joint is of great concern. Imperfections, especially surface-breaking imperfections, can exist in the root region and these can lead to serious consequences. Results of impact testing root imperfections in friction stir welded 12 per cent Cr steel using a through-hole impact test are presented. Compared to tests taken from the parent material, the impact energy measured from certain welds, with a surface-breaking imperfection at the weld root was reduced significantly.
Using the orthogonal array with grey relational analysis to optimize the laser hybrid welding of a 6061-T6 Al alloy sheet
Authors: Kim H R , Lee K Y
Published: September 2008

A methodology for determining the optimum process conditions associated with Nd: YAG laser — gas metal arc hybrid welding of 6061-T6 Al alloy sheet is presented. The weldability is dependent on various process parameters which include the welding wire type, shielding gas, laser power, laser focus, travelling speed, welding wire feed rate, root opening tolerance, and voltage. Experiments are performed with designated welding conditions obtained using an L18 orthogonal array. For the evaluation of weldability, comparing the result of the ultimate tensile strength on the weld zone is essential. In order to determine the optimum welding conditions, a grey relational analysis is carried out through the result of the ultimate tensile strength for each welding experiment. Based on the results of the grey relational analysis, a set of optimum welding parameters is obtained. Using the analysis of variance approach the significant welding parameters are found. The results show that the optimum welding conditions determined using grey relational analysis are much better than the original preliminary set of experimental conditions.
Technology insertion in the defence industry: A primer
Authors: Kerr C I V , Phaal R , Probert D R
Published: September 2008

A key challenge for the defence industry is how to take full advantage of the latest research and technology developments for current in-service products. The route to managing the flow of technology for platform modernization and achieving the rapid fielding of new technologies for phased capability delivery can be obtained through technology insertion. However, there lacks a common understanding of the technology insertion activity. This paper provides a concise overview of the topic in order to provide a standard frame of reference. A generic definition of the term is proposed together with a taxonomy that places technology insertion into context with other technology management processes. In addition, the components and dimensions of technology insertion are presented. The fundamental principles and enablers associated with technology insertion are elicited. These concepts are illustrated by real-world examples from the defence industry.
Applying design of experiments to improve a laser welding process
Authors: Tanco M , Ilzarbe L , Viles E , Alvarez M J
Published: September 2008

A case study on laser welding processing at a one-model car production line at a recognized automotive plant is presented. The process under study is used to weld together the roof and sides of a car by means of two lasers. This process has quality issues related to the frequent appearance of pores in both cords. As this problem had been occurring for the last two years, it was evident that it was necessary to tackle it from a different angle, so experimentation was identified as the tool needed. A design of experiments approach was chosen as an efficient technique to maximise the information gained from the experimentation. An average reduction in the number of pores of 97 per cent is obtained.
Multi-objective optimization of electrochemical machining process parameters using a particle swarm optimization algorithm
Authors: Rao R V , Pawar P J , Shankar R
Published: September 2008

The selection of optimum values of important process parameters of electrochemical machining processes such as the tool feed rate, electrolyte flow velocity, and applied voltage play a significant role in optimizing the measures of process performance. These performance measures generally include dimensional accuracy, tool life, material removal rate, and machining cost. In this paper, a particle swarm optimization algorithm is presented to find the optimal combination of process parameters for an electrochemical machining process. The objectives considered are dimensional accuracy, tool life, and the material removal rate subjected to the constraints of temperature, choking, and passivity. Both single- and multi-objective optimization aspects are considered. The results of the proposed algorithm are compared with the previously published results obtained by using other optimization techniques.
Flexible dot-matrix display manufacture by offset lithography
Authors: Southee D J , Hay G I , Evans P S , Harrison D J
Published: September 2008

Novel thermochromic graphic displays manufactured by printing thermochromic ink films in conjunction with conductive lithographic films (CLFs) are presented. Work in formulating lithographic printing inks is described. The properties of the deposited ink films and demonstration display structures employing these materials are discussed. These low-cost printed structures could be incorporated in the manufacture of electronic systems with integrated printed power sources affording environmental benefits when compared with conventional manufacturing techniques.
A parametric study of part distortions in fused deposition modelling using three-dimensional finite element analysis
Authors: Zhang Y , Chou K
Published: September 2008

A finite element analysis (FEA) model was previously developed by the current authors to simulate the fused deposition modelling (FDM) process. The model considered coupled thermal and mechanical phenomena and incorporated an element activation function to mimic the additive nature of FDM. Due to repetitive heating and cooling in the FDM process, residual stresses accumulate in a part during deposition. In this study, an FEA model is used to evaluate the distortions of a part. A parametric study, with three factors and three levels, is performed to evaluate the effects of the deposition parameters on residual stresses and part distortions. Prototype models with larger sizes are fabricated, measured, and compared with the simulations.

The simulation results are summarized as follows. First, the scan speed is the most significant factor affecting part distortions, followed by the layer thickness. Second, the road width alone is insignificant. However, the interaction between the road width and the layer thickness is significant as well. Third, there are other two-way and three-way interactions that are of secondary significance. In general, residual stresses in FDM parts increase with the layer thickness. Residual stresses also increase with the road width, but to a lesser extent, although largely affected by the layer thickness. The FDM part distortions from the experiment show a similar trend as concluded in the simulations, but without quantitative correlation.
Heat-transfer analysis of flat steel ribbon-wound cryogenic high-pressure vessel
Authors: Chen Z P , Yu C L , Zheng J Y , Zhu G H
Published: September 2008

In the past 40 years, more than 7000 layered vessels using flat ribbon-wound cylindrical shells have been manufactured in China. Theoretical as well as experimental investigations show that there are distinct economical and engineering advantages in using such vessels. In this paper, based on the analysis of the heat transfer process in a flat steel ribbon-wound liquid hydrogen high-pressure vessel, a heat transfer model of the walls of the shell and head has been set up. The temperature difference among the interfaces, the heat transfer through the shell and head, and the evaporation rate of the vessel under a steady heat-flow condition has been calculated. The numerical calculations show that such a structure meets the design requirements.
Magnetic flux distribution modelling of magnetically-impelled arc butt-welding of steel tubes using finite-element analysis
Authors: Vendan S Arungalai , Manoharan S , Buvanashekaran G , Nagamani C
Published: September 2008

Magnetically-impelled arc butt-welding (MIAB) is a pressure-welding process. In this process, heat is generated prior to forging by an arc created between two clamped and aligned tubes. This arc rapidly rotates along the peripheral edges of the tubes to be welded due to the electromagnetic force resulting from the interaction of the arc current and the magnetic field in the gap. To be precise, the magnetic flux density is the significant parameter that governs the arc rotation and the weld quality. This paper presents a three-dimensional finite-element model to determine the magnetic flux density distribution in the MIAB welding process. The objective of this study is to perform a non-linear electromagnetic analysis using the finite-element package ANSYS, and to explore the interdependence of MIAB welding parameters such as gap size, exciting current in the coil, and coil position from the weld centre, which influence the electromagnetic force generated in the welding process and weld quality. The results of this analysis are verified with the available experimental data for steel tubes (outer diameter 50 mm and thickness 2 mm). The results obtained using finite-element analysis establish that the magnetic flux density distribution in the gap increases with increasing exciting current and decreasing gap size and coil position from the weld centre.
Solving reachable workspace of some parallel manipulators by computer-aided design variation geometry
Authors: Lu Y , Shi Y , Hu B
Published: September 2008

To shape the workspace of some novel parallel manipulators (PMs) is significant. A novel computer-aided design (CAD) variation geometry approach is proposed to shape and solve the reachable workspace of some PMs with three to six degrees of freedom (DOFs). Some basic techniques are described for designing the simulation mechanism and solving the reachable workspace. The simulation mechanisms of some PMs with three to six DOFs are created. When varying the driving dimensions of the active legs in the given extent, the simulation mechanisms vary correspondingly, and the position components of the moving platform are solved automatically. By transferring the position solutions into spatial spline curves in the simulation mechanism, all the boundary surfaces of the workspace can be created and visualized dynamically. Comparing with analytic approaches for solving workspace, the CAD variation geometry approach is simple, straightforward, accurate, and repeatable.
A kinematic representation of Bennett's tetrahedron of reference
Authors: Baker J E
Published: September 2008

The geometrical device of a tetrahedron used by Bennett to elucidate the surprising mobility of his four-bar kinematic chain is here interpreted as harbouring a very compact multi-loop linkage, including a pair of six-bar chains of unusual constitution. Their embodied non-linear helical joints are of particular relevance to workers in the area of finite displacements. The intermingled loops call for an intricate set of relationships, and investigation of mobilities is executed with dual screw-vectors, a most effectual tool for the task.
Hydrodynamically detailed performance analysis of a mixed-flow waterjet pump using computational fluid dynamics
Authors: Oh H W , Yoon E S
Published: September 2008

The hydrodynamic design optimization and performance analysis of a mixed-flow waterjet pump have been achieved using the validated commercial computational fluid dynamics (CFD) code. The detailed flow field in the waterjet pump is investigated by the CFD code adopted in the present study. Predicted characteristic curves, including the cavitation performance, agree very well with the test data for a designed mixed-flow waterjet pump over the entire operating conditions. A hydraulically detailed performance analysis with a net positive suction head can be used efficiently as a tool for the practical design optimization and assist in the understanding of the operational characteristics of general purpose mixed-flow pumps.
Mathematical model for predicting the blade behaviour of horizontal axis wind turbine
Authors: Wang J , Qin D , Zhang Q
Published: September 2008

A mathematical model using both beam finite element and thin-walled structure theory is developed to predict the natural frequency and blade behaviour of a horizontal axis wind turbine under constant wind speed and turbulence condition. First of all, the deformation pattern of the blade is defined on the basis of thin-walled structure theory and Timoshenko beam theory, and by considering the blade as a rotation cantilever beam, the governing equation is obtained using the principle of virtual work. Then, it is discreted by a beam element. Constraints are applied to define boundary conditions and coupling of flapwise, edgewise, and elongation deformations on the governing equation using the penalty method. Finally, natural frequencies of the blade are analysed. Detailed expressions for centrifugal and Coriolis forces are obtained. The stress on the root and displacement at the tip are also analysed in detail. The blade's deflection in turbulent conditions is simulated and shown to mostly influence flapwise blade deformation.
A beam-bending eigenstrain analysis of residual elastic strains in multi-scan laser-formed steel samples
Authors: Korsunsky A M , Vorster W J J , Zhang S Y , Topić M , Venter A M
Published: September 2008

Laser-induced forming and microstructural modification of materials and components is a technique that offers interesting possibilities for improved control over the final state of the workpiece, and the possibility of generating carefully tailored residual stress states and spatially varying microstructures best suited to specific industrial applications. A key challenge in the development of this technique is the characterization of the relationship between process parameters and the resulting state of the workpiece; and the optimization of processing conditions in order to deliver a desired result. The results of an experimental study of microstructure and residual elastic strains (RES) in multi-scan laser-bent steel plates by the combination of microscopy and strain mapping using energy-dispersive synchrotron X-ray diffraction have been recently reported. This paper is devoted to the presentation of simplified eigenstrain analysis of the RES fields arising due to laser processing that allows approximate plastic strain profiles to be extracted for the purpose of improved process characterization and optimization.
Feasible design region and sealing property of hypotrochoidal gerotor geometry
Authors: Hsieh C-F , Yan H-S
Published: September 2008

This paper proposes a method on how to correctly determine the feasible design region without any undercutting on the outer and inner rotor profiles. The non-undercutting equations are derived by the theory of gearing and the feasible design region is determined by considering the non-undercutting curves of the inner and the outer rotors. Numerical examples show that the non-undercutting curves of the inner rotors are above the non-undercutting curves of the outer rotors. So, there is no undercutting on the outer and inner rotors when the parameter is given under the region of the non-undercutting curve of the outer rotor. Besides, the curvature equations of the outer and inner rotors are derived for assessing the sealing property and forecasting the variation of Hertz stress. The sealing property will be an inferior quality in the larger curvature difference region, and the larger variation of Hertz stress would also be predicted.
Influence of selectable parameters in element-free Galerkin method: One-dimensional bar axially loaded problem
Authors: Valencia O F , Gómez-Escalonilla F J , Díez J López
Published: September 2008

Meshless methods (MMs) have become interesting and promising methods in solving partial differential equations, because of their flexibility in practical applications when compared with the standard finite-element method (e.g. crack propagation, large deformations, and so on). Implementation of these methods requires a good understanding of the influence of some specific selectable parameters. In this article, those parameters are analysed for one of the most popular MMs, the element-free Galerkin method, considering both accuracy and computational cost. Thus, the dependence of the solutions on grid irregularity, order of the polynomial basis, type of weight function, and the support size is investigated, and conclusions are drawn with respect to recommended or ‘optimal’ values for one-dimensional bar problems with applied axial loads.
Lattice Boltzmann BGK model for gas flow in a microchannel
Authors: Aminfar H , Mohammadpourfard M
Published: September 2008

As microdevices have to be operated in a fluid medium, the understanding of flow at a microlevel is fundamental for the development of microelectromechanical systems. In the present work, the velocity distribution in a rectangular cross-section and the pressure drop along the length of the microchannel are studied using different expressions for the complete momentum accommodation coefficient and relaxation time in the lattice Boltzmann method, BGK model (LBGK), with the transition region 0.1< Kn<0.5 and low Reynolds number Re<1. By taking into account the correction for the Knudsen number, complete accommodation coefficient and relaxation time, the number of iterations will reduce considerably in simulation. Also, results obtained in the two-dimensional microchannel with an aspect ratio of 50 are in good agreement with the analytical and numerical predictions.
Effects of channel width on film condensation in a top-closed vertical channel
Authors: Chang T B , Wang F J
Published: September 2008

This article conducts a theoretical investigation into the condensation of a saturated vapour within a top-closed, vertical isothermal channel. The theoretical model takes account of the inertia and convection effects in a condensate layer and the shear stress at the liquid—vapour interface. Using a dimensionless transformation method, the complex partial differential governing equations are transformed into a corresponding system of ordinary differential equations, which are then solved using the forward Runge—Kutta shooting scheme. Numerical results indicate that the condensate flowrate decreases and the negative shear stress at the liquid—vapour interface increases as the channel width is reduced. Conversely, a larger channel width increases the shear stress at the channel wall, but has no apparent effect on the temperature profile within the condensate layer.
Dynamic behaviour of V-belt drive system in the presence of sheaves’ lateral misalignment
Authors: Fenina S , Fakhfakh T , Haddar M
Published: September 2008

This paper presents the effects of lateral misalignment of sheaves, on the transverse span displacements of a serpentine belt drive system that contains a driving sheave, a driven sheave, a belt, and a dynamic tensioner. This defect gives rise to dangerous operating conditions for the system. A hybrid discrete—continuous model is adopted, in which the coupling between the discrete variables describing the rotational motion of the three sheaves and the tensioner arm and the continuous variables describing the transverse motion of the belt spans is taken into account. An analytical method based on the perturbation method is used to determine the explicit expressions of the transverse span displacements and permits the study of the effects of design variables on the dynamic behaviour of the system in the presence of the defect described earlier.
A method for finding repeated roots in transcendental eigenvalue problems
Authors: Ram Y M
Published: September 2008

The eigenvalues of a gyroscopic system depend on a parameter, and the system may become unstable when eigenvalues collide. For continuous systems, the eigenvalue problem is represented by a matrix with transcendental elements. A method is developed to determine the value of the parameter that causes eigenvalues to collide. The method is implemented using a certain formula for the determination of the derivative of a matrix determinant without the use of symbolic expansion of the determinant. This formula simplifies the computational task considerably. Applications of the method are demonstrated by problems involving buckling by circulatory forces and oscillations of a gyroscopic system.
Thermo-hydrodynamic study of the journal bearing under static load
Authors: Ighil N Tala , Bounif A , Maspeyrot P
Published: September 2008

A number of studies have been carried out on the hydrodynamic lubrication of journal bearings. This article seeks to summarize this work, presenting it in the form of a flow chart. The treatment of rupture and reformation of the film fluid in the contact region, for a steady loaded circular journal bearing, are accomplished using the Reynolds and the Jakobsson—Floberg and Olsson (JFO) boundary conditions.

A flow chart taking into account the resolution of some of the hydrodynamic lubrication problems is elaborated. A computer code is carried out for solving the Reynolds equation and for calculating the most important parameters relating to a hydrodynamic contact. The obtained results for a finite-length bearing are compared with those obtained from the short-bearing hypothesis. In addition, a global thermal study is carried out in order to evaluate the effect of temperature.
A regenerative flow compressor as a secondary air pump for engine emission control
Authors: Engeda A , Elkacimi Y
Published: September 2008

A secondary air pump (SAP) is an air compressor that supplies air to the exhaust system of an automotive engine for the emission control of the engine. The SAP system has been offered as an emission control device in later versions of cars, starting in the mid-1990s. Various types of rotary and positive displacement air pumps have been tested and used for SAP application. The regenerative flow compressor/pump (RFC or RFP) and the centrifugal compressor have been found to be best suited for SAP application. This paper discusses the performance of an RFC for SAP application and shows the RFC to be the best choice for satisfying the required specifications of the SAP.

Computational fluid dynamics analysis of the RFC for an SAP application was carried out to study its performance in detail.
Cavity generation by accelerated relative motions between solid walls contacting in liquid
Authors: Washio S , Takahashi S , Murakami K , Tada T , Deguchi S
Published: September 2008

A contact motion between two solids in a liquid can give rise to a cavity. To investigate this phenomenon, processes of cavity generation in a liquid between two walls making accelerated relative motions in their normal and tangential directions have been observed in detail, using microscopes and high-speed video cameras. The results are as follows: generation and subsequent expansion of a cavity are influenced by factors such as the initial clearance between the walls, the acceleration of motion, the initial pressure, the liquid viscosity, and the contact area. In contrast, air solubility in oil does not affect generation, but the size of a bubble remaining in the liquid. The pressure in a liquid film between two parallel walls normally moving away with a constant acceleration has also been theoretically analysed, providing the basis for the generation of tensile stresses in liquid films. Finally, the following idea of mechanism has been proposed: a tensile stress occurring in a liquid film breaks the liquid—solid interface, producing a rift, which develops into a visible cavity. Considering that liquid machines have many parts of contacting solids making relative motions, it is presumed that cavitation in them can start from this phenomenon.
Analysis of the variability in collapse time of a process storage vessel due to internal steam condensation
Authors: Cronin K , Davis M
Published: September 2008

An expression to predict the time taken for a storage vessel to collapse because of the development of a net external pressure was obtained in a previous paper. Steam condensation inside the vessel was the mechanism chosen to produce this mode of failure. There is considerable natural dispersion in the causes of this phenomenon, meaning that collapse times are unpredictable in practice. An experimental arrangement to obtain data on dispersion in this phenomenon was devised. A large series of replicate tests were conducted to quantify the statistics describing the dispersion. Two probabilistic modelling techniques, the perturbation method and the Monte-Carlo simulation, were employed to analyse this variation. Good agreement was found between the predictions of the modelling techniques and the experimentally obtained results.
Parameter design of water jet nozzle utilizing independence axiom
Authors: Lee J , Shin H
Published: September 2008

This paper explores the design of a water jet nozzle for cleaning the glass surface of a thin film transistor liquid crystal display. The theoretical background in this study is based on cavitation theory, main factors of cavitation, and bubble theory in determining the dominant design parameters (DPs) associated with nozzle design. From the bubble dynamics theory, three functional requirements (FRs) are extracted to maximize the cleaning effects in the context of axiomatic design. Based on the independence design axiom, the decoupled design matrix between FRs and DPs is developed. In this study, the sensitivity of the design matrix is evaluated via both design of experiments (DOEs) based analysis of means and back-propagation neural network-based causality analysis. Axiomatic design solutions are further compared with those obtained from a formal optimization method. This study shows that the axiomatic design with DOE is efficient since it does not require any mathematical formulation of design problem and its solution is easily obtained when the decoupled design matrix is quantitatively described.
Stamina of a non-gasketed flange joint under combined internal pressure and axial loading
Authors: Abid M , Awan A W , Nash D H
Published: September 2008

The performance of a bolted flange joint is characterized mainly by its ‘strength’ and ‘sealing capability’. A number of numerical and experimental studies have been conducted to study these characteristics under internal pressure loading conditions alone. However, limited work is found in the literature under conditions of combined internal pressure and axial loading. The effect of external, axial loading pressure being unknown, the optimal performance of the bolted flange joint cannot be achieved. Current design codes do not address the effects of axial loading on structural integrity and sealing ability. To study joint strength and sealing capability under combined loading conditions, an extensive experimental and numerical study of a non-gasketed flange joint was carried out. Actual joint load capacity was determined at both design and test stages with the maximum external axial loading that can be applied for safe joint performance. Experimental and numerical results have been compared and overall joint performance and behaviour is discussed in detail.
Single-blade impeller development using the design of experiments method in combination with numerical simulation
Authors: De Souza B , Niven A , Daly J
Published: September 2008

This paper concerns the optimization of single-blade impellers as used in the waste-water industry. When considering wastewater pump hydraulics, both the ability to handle solids and hydraulic efficiency become essential criteria for optimization. An innovative approach was taken to this optimization problem through the combination of two separate tools: design of experiments (DOE) and computational fluid dynamics (CFD).

Through the use of DOE, it was possible to investigate the effect on hydraulic performance of five key parameters identified as being critical to solids handling. The designed experiment required 32 runs only, as compared with 243 runs (35), which would have been necessary using the traditional ‘trial-and-error’ approach.

For each DOE run, unique impeller geometry was created. A transient numerical methodology was adopted for the performance evaluation of each impeller. The methodology was validated and verified on several single-blade impellers covering a range of design specific speed ( Ns=32 to 77). In all benchmark models, excellent agreement with experimental data was observed.

The models, resulting from the designed experiment, have advanced the state of the art in terms of single-blade impeller design, quantified relationships between solids handling parameters and led to the development of new higher efficiency single-blade impellers with improved solids handling ability over conventional designs.
A musculoskeletal full-body simulation of cross-country skiing
Authors: Holmberg L J , Lund A M
Published: September 2008

This paper presents a measurement-driven, musculoskeletal, full-body simulation model for biomechanical analysis of the double-poling (DP) technique in cross-country skiing. DP is a fast and powerful full-body movement; therefore, it is interesting to examine whether inverse dynamics using static optimization is working for a musculoskeletal full-body model with high accelerations, a large range of motion, and realistic loads. An experiment was carried out to measure motion and pole force of a skier on a double-poling ergometer. Using the measurement data, a simulation model was implemented in the AnyBody Modeling System (AnyBody Technology A/S, Denmark). Experimental results of motion and pole force from the DP ergometer, and also simulation results of relative muscle force profiles, are presented. These results agree with results found in literature when the kinematics and external kinetics are similar. Consequently, it should be possible to use computer simulations of this type for cross-country skiing simulations. With a simulation model, it is possible to perform optimization studies and to ask and answer ‘what if’ questions. Solutions to such problems are not easy to obtain by traditional testing alone.
Influence of footwear and soil density on loading within the shoe and soil surface during running
Authors: Dixon S J , James I T , Blackburn K , Pettican N , Low D
Published: September 2008

Using pressure transducers in soil surfaces prepared in controlled conditions, the vertical stress was recorded at 100 mm, 200 mm, and 350 mm depth within two soil surfaces of 1460 kg/m3 and 1590 kg/m3 for five subjects of 747–843 N body weight running at 4 m/s (5 per cent). Simultaneous in-shoe pressure data were collected to investigate the influence of soil density on loading experienced by the player and to provide information on the load applied to the surface. For each soil density, the subjects wore three different footwear types: soccer boots with traditional studs, boots with moulded studs, and boots designed for synthetic turf. For the mean of all subjects, there was no significant difference in the maximum vertical soil stress or loading rate between surfaces at any depth but within each surface there was a significant reduction of 32 kPa between –100 mm and the other depths. The peak loading rate was two orders of magnitude greater at –100 mm than at –200 mm or –350 mm. The variation in maximum vertical stress at –100 mm for different subjects was significant ( p<0.001) and increased with increasing subject weight ( R2 = 0.87); at –200 mm and –350 mm there was no significant subject or density effect; a similar pattern was observed with the peak loading rate, with a linear relationship between the loading rate and the subject weight. In-shoe pressure data revealed no significant differences in the peak force or loading rate between surfaces, but a significantly lower heel pressure for the soft (1460 kg/m3) surface compared with the hard (1590 kg/m3) surface ( p<0.05). Wearing of different footwear had no influence on the peak force or pressure but revealed a lower rate of loading of force for the moulded boot than for the studded boot when performing on the hard surface. There was a low and non-significant relationship between the peak input force and the peak force experienced within the surface ( R2 = 0.01; p > 0.05), however, peak resultant pressure data were used successfully to model the vertical stress distribution during running using a linear elastic model of soil behaviour. This novel approach to understanding the behaviour of the soil surface and the player has revealed a complex relationship between the input load and the load experienced by the surface. Future models will seek to understand this relationship further.
Optimization of accelerometers for measuring walking
Authors: Foster R , Lanningham-Foster L , Levine J
Published: September 2008

The devastating impact of obesity on global health is without question and it is generally agreed that low levels of physical activity, particularly sitting (i.e., sedentariness), are important in its pathogenesis. Therefore, the measure of physical activity such as walking is vital to its use in the research and clinical milieu.

This study investigated three accelerometry parameters (sampling rate, range, and data depth) on ten healthy subjects (BMI 18–31 kg/m2) walking on a calibrated treadmill at eight speeds (0, 0.95, 1.74, 2.48, 3.22, 4.04, 4.83, and 5.70 km/h) while wearing a three-axis accelerometer on the thigh (Crossbow Technology, San Jose, CA) in order to find an optimal system for the determination of walking speed, as well as a new data analysis strategy using a differentiation of the acceleration values (jerk). Twenty-four sampling rates (2–25 Hz in 1-Hz intervals) and seven acceleration ranges (± 1  g – ± 2.5  g at 0.25- g intervals) were used to create a 24 × 7 factorial design. Data was also truncated from two to seven digits in the mantissa.

This study found that although there is an improvement in walking speed prediction when sampling rate was set above 4 Hz ( P<0.0002), there was no further improvement when the sampling rate is set higher. This study found that there is an increase in walking speed prediction accuracy when the range of acceleration is limited to ± 1  g ( P<0.0024 for ± 2  g versus ± 1  g). This study found that increasing or decreasing data depth has no impact on walking speed prediction accuracy. Further, this study found that a model based on jerk was accurate at predicting walking speeds ( r2 0.9 for all comparisons).

For measuring walking using a sensor on the thigh, there is no significant improvement gained by large sampling rates, data ranges, or data precision. A model based on the time rate of change of acceleration is a valid analysis tool for measuring walking.
Characteristics of head impacts sustained by youth ice hockey players
Authors: Mihalik J P , Guskiewicz K M , Jeffries J A , Greenwald R M , Marshall S W
Published: September 2008

This study aimed to measure the magnitude of head impacts sustained by 14 male, youth (13 years old) ice hockey players wearing instrumented helmets, and to compare impacts across event type (practice, game), player position, and location. Head impact magnitudes were captured during 58 games and 51 practices. Mixed linear models were utilized to analyze differences by event type, player position, and location of impact. Game impact magnitudes were significantly greater than practice impacts. Impacts sustained by forwards were similar in magnitude to those sustained by defensemen. Significant differences between head impact locations across all player positions were observed. Impacts to the top of the head were significantly greater than impacts to the back, front, left, and right sides. Youth ice hockey players sustain helmet impacts nearing 20  g on average, similar to measured values in collegiate American football players, and of potential concern because this sample involves younger athletes. Future biomechanical studies are needed to better interpret the finding that there is an increased likelihood of higher magnitude head impacts to the top of the head. The authors' long-term goal is to improve the understanding of impacts that may lead to concussions in young athletes.
Evaluation of the risk of batted-ball injury for slow-pitch softball pitchers
Authors: Ciocco M , McDowell M
Published: September 2008

Over the past few years, there has been a significant change in the material used to construct softball bats. Since 2000, there has been a significant increase in the number of slow-pitch softball bats sold that are constructed entirely of composite-based materials. It is theorized that the introduction of these composite bats has resulted in an increase in batted-ball speed, which directly corresponds to a decrease in available pitcher reaction time and can lead to an increase in the risk of injury. To test this theory, a controlled field-test study was conducted using five different certified softball bat models and four experienced testers to quantify the performance of composite-based softball bats compared to a wooden softball bat. For the composite bats, the available pitcher reaction times varied from 0.390 to 0.365 s for a pitcher standing 15.24 m (50 ft) from the batter, while, for the wooden bat, the available pitcher reaction times varied from 0.452 to 0.419 s. This study demonstrates that composite-based slow-pitch softball bats perform at an unsafe level when the results are compared to published safety studies in the sports of softball and baseball, which advocate available pitcher reaction times of 0.409 to 0.420 s. In addition, possible mitigation methods are discussed that could make the sport of slow-pitch softball safer.