bluuebunny/crossref_metadata_2025 huggingface dataset:
Double diffusive effects on pressure-driven miscible displacement flows in a channel
Authors: Mishra Manoranjan , De Wit A. , Sahu Kirti Chandra
Published: November 2012

The pressure-driven miscible displacement of a less viscous fluid by a more viscous one in a horizontal channel is studied. This is a classically stable system if the more viscous solution is the displacing one. However, we show by numerical simulations based on the finite-volume approach that, in this system, double diffusive effects can be destabilizing. Such effects can appear if the fluid consists of a solvent containing two solutes both influencing the viscosity of the solution and diffusing at different rates. The continuity and Navier–Stokes equations coupled to two convection–diffusion equations for the evolution of the solute concentrations are solved. The viscosity is assumed to depend on the concentrations of both solutes, while density contrast is neglected. The results demonstrate the development of various instability patterns of the miscible ‘interface’ separating the fluids provided the two solutes diffuse at different rates. The intensity of the instability increases when increasing the diffusivity ratio between the faster-diffusing and the slower-diffusing solutes. This brings about fluid mixing and accelerates the displacement of the fluid originally filling the channel. The effects of varying dimensionless parameters, such as the Reynolds number and Schmidt number, on the development of the ‘interfacial’ instability pattern are also studied. The double diffusive instability appears after the moment when the invading fluid penetrates inside the channel. This is attributed to the presence of inertia in the problem.
Force and power of flapping plates in a fluid
Authors: Li Gao-Jin , Lu Xi-Yun
Published: November 2012

The force and power of flapping plates are studied by vortex dynamic analysis. Based on the dynamic analysis of the numerical results of viscous flow past three-dimensional flapping plates, it is found that the force and power are strongly dominated by the vortical structures close to the body. Further, the dynamics of the flapping plate is investigated in terms of viscous vortex-ring model. It is revealed that the model can reasonably reflect the essential properties of the ring-like vortical structure in the wake, and the energy of the plate transferred to the flow for the formation of each vortical structure possesses a certain relation. Moreover, simplified formulae for the thrust and efficiency are proposed and verified to be reliable by the numerical solutions and experimental measurements of animal locomotion. The results obtained in this study provide physical insight into the understanding of the dynamic mechanisms relevant to flapping locomotion.
Stokes flow singularity at the junction between impermeable and porous walls
Authors: Nitsche Ludwig C. , Parthasarathi Prashanth
Published: November 2012

For two-dimensional, creeping flow in a half-plane, we consider the singularity that arises at an abrupt transition in permeability from zero to a finite value along the wall, where the pressure is coupled to the seepage flux by Darcy’s law. This problem represents the junction between the impermeable wall of the inflow section and the porous membrane further downstream in a spiral-wound desalination module. On a macroscopic, outer length scale the singularity appears like a jump discontinuity in normal velocity, characterized by a non-integrable$1/ r$divergence of the pressure. This far-field solution is imposed as the boundary condition along a semicircular arc of dimensionless radius 30 (referred to the microscopic, inner length scale). A preliminary numerical solution (using a least-squares variant of the method of fundamental solutions) indicates a continuous normal velocity along the wall coupled with a weaker$1/ \sqrt{r} $singularity in the pressure. However, inconsistencies in the numerically imposed outer boundary condition indicate a very slow radial decay. We undertake asymptotic analysis to: (i) understand the radial decay behaviour; and (ii) find a more accurate far-field solution to impose as the outer boundary condition. Similarity solutions (involving a stream function that varies like some power of$r$) are insufficient to satisfy all boundary conditions along the wall, so we generalize these by introducing linear and quadratic terms in$\log r$. By iterating on the wall boundary conditions (analogous to the method of reflections), the outer asymptotic series is developed through second order. We then use a hybrid computational scheme in which the numerics are iteratively patched to the outer asymptotics, thereby determining two free coefficients in the latter. We also derive an inner asymptotic series and fit its free coefficient to the numerics at$r= 0. 01$. This enables evaluation of the singular flow field in the limit as$r\ensuremath{\rightarrow} 0$. Finally, a uniformly valid fit is obtained with analytical formulas. The singular flow field for a solid–porous abutment and the general Stokes flow solutions obtained in the asymptotic analysis are programmed in Fortran for future use as local basis functions in computational schemes. Numerics are required for the intermediate-$r$regime because the inner and outer asymptotic expansions do not extend far enough toward each other to enable rigorous asymptotic matching. The logarithmic correction terms explain why the leading far-field solution (used in the preliminary numerics) was insufficient even at very large distances.
Linear biglobal analysis of Rayleigh–Bénard instabilities in binary fluids with and without throughflow
Authors: Hu Jun , Henry Daniel , Yin Xie-Yuan , BenHadid Hamda
Published: November 2012

Three-dimensional Rayleigh–Bénard instabilities in binary fluids with Soret effect are studied by linear biglobal stability analysis. The fluid is confined transversally in a duct and a longitudinal throughflow may exist or not. A negative separation factor $\psi = \ensuremath{-} 0. 01$, giving rise to oscillatory transitions, has been considered. The numerical dispersion relation associated with this stability problem is obtained with a two-dimensional Chebyshev collocation method. Symmetry considerations are used in the analysis of the results, which allow the classification of the perturbation modes as ${S}_{l} $ modes (those which keep the left–right symmetry) or ${R}_{x} $ modes (those which keep the symmetry of rotation of $\lrm{\pi} $ about the longitudinal mid-axis). Without throughflow, four dominant pairs of travelling transverse modes with finite wavenumbers $k$ have been found. Each pair corresponds to two symmetry degenerate left and right travelling modes which have the same critical Rayleigh number ${\mathit{Ra}}_{c} $. With the increase of the duct aspect ratio $A$, the critical Rayleigh numbers for these four pairs of modes decrease and closely approach the critical value ${\mathit{Ra}}_{c} = 1743. 894$ obtained in a two-dimensional situation, one of the mode (a ${S}_{l} $ mode called mode A) always remaining the dominant mode. Oscillatory longitudinal instabilities ($k\approx 0$) corresponding to either ${S}_{l} $ or ${R}_{x} $ modes have also been found. Their critical curves, globally decreasing, present oscillatory variations when the duct aspect ratio $A$ is increased, associated with an increasing number of longitudinal rolls. When a throughflow is applied, the symmetry degeneracy of the pairs of travelling transverse modes is broken, giving distinct upstream and downstream modes. For small and moderate aspect ratios $A$, the overall critical Rayleigh number in the small Reynolds number range studied is only determined by the upstream transverse mode A. In contrast, for larger aspect ratios as $A= 7$, different modes are successively dominant as the Reynolds number is increased, involving both upstream and downstream transverse modes A and even the longitudinal mode.
Turbulent duct flows in a liquid metal magnetohydrodynamic power generator
Authors: Kobayashi Hiromichi , Shionoya Hiroki , Okuno Yoshihiro
Published: November 2012

We numerically assess the influence of non-uniform magnetic flux density and connected load resistance on turbulent duct flows in a liquid metal magnetohydrodynamic (MHD) electrical power generator. When increasing the magnetic flux density (or Hartmann number), an M-shaped velocity profile develops in the plane perpendicular to the magnetic field; the maximum velocity in the sidewall layer of the M-shaped profile increases to maintain the flow rate. Under the conditions of a relaminarized flow, the turbulence structures align along the magnetic field and flow repeatedly like a von Kármán vortex sheet. At higher Hartmann numbers, the wall-shear stress in the sidewall layer increases and the sidewall jets transit to turbulence. The sidewall jets in the MHD turbulent duct flows have profiles similar to the non-MHD wall jets, i.e. a mean velocity profile with outer scaling, Reynolds shear stress with the opposite sign in a sidewall jet, and two maxima for the turbulent intensities in a sidewall jet. The Lorentz force suppresses the vortices of the secondary mean flow near the Hartmann layer for low Hartmann numbers, whereas the secondary vortices remain near the Hartmann layer for high Hartmann numbers. An optimal load resistance (or load factor) to obtain a maximum electrical efficiency exists, because the strong Lorentz force for a low load factor and unextracted eddy currents for a high load factor reduce efficiency. When the value of the load factor is changed, the profiles of mean velocity and r.m.s. for the optimal load factor produce almost the same profiles as the high load factor near the open-circuit condition.
Computations of fully nonlinear hydroelastic solitary waves on deep water
Authors: Guyenne Philippe , Pǎrǎu Emilian I.
Published: November 2012

This paper is concerned with the two-dimensional problem of nonlinear gravity waves travelling at the interface between a thin ice sheet and an ideal fluid of infinite depth. The ice-sheet model is based on the special Cosserat theory of hyperelastic shells satisfying Kirchhoff’s hypothesis, which yields a conservative and nonlinear expression for the bending force. A Hamiltonian formulation for this hydroelastic problem is proposed in terms of quantities evaluated at the fluid–ice interface. For small-amplitude waves, a nonlinear Schrödinger equation is derived and its analysis shows that no solitary wavepackets exist in this case. For larger amplitudes, both forced and free steady waves are computed by direct numerical simulations using a boundary-integral method. In the unforced case, solitary waves of depression as well as of elevation are found, including overhanging waves with a bubble-shaped profile for wave speeds $c$ much lower than the minimum phase speed ${c}_{\mathit{min}} $. It is also shown that the energy of depression solitary waves has a minimum at a wave speed ${c}_{m} $ slightly less than ${c}_{\mathit{min}} $, which suggests that such waves are stable for $c\lt {c}_{m} $ and unstable for $c\gt {c}_{m} $. This observation is verified by time-dependent computations using a high-order spectral method. These computations also indicate that solitary waves of elevation are likely to be unstable.
Nonlinear self-excited thermoacoustic oscillations: intermittency and flame blowout
Authors: Kabiraj Lipika , Sujith R. I.
Published: November 2012

Nonlinear self-excited thermoacoustic oscillations appear in systems involving confined combustion in the form of coupled acoustic pressure oscillations and unsteady heat release rate. In this paper, we investigate the nonlinear transition undergone by thermoacoustic oscillations to flame blowout via intermittency, in response to variation in the location of the combustion source with respect to the acoustic field of the confinement. A ducted laminar premixed conical flame, stabilized on a circular jet exit with a fully developed exit velocity profile, was investigated. Transition to limit cycle oscillations from a non-oscillatory state was observed to occur via a subcritical Hopf bifurcation. Limit cycle oscillations underwent a further bifurcation to quasi-periodic oscillations characterized by the repeated formation of elongated necks in the flame that pinch off as pockets of unburned fuel–air mixture. The quasi-periodic state loses stability, resulting in an intermittent state identified as type II through recurrence analysis of phase space trajectories reconstructed from the acoustic pressure time trace. In this state, the flame undergoes repeated lift-off and reattachment. Instantaneous flame images suggest that the intermittent flame behaviour is influenced by jet flow dynamics.
Flux correlations in supersonic isothermal turbulence
Authors: Wagner R. , Falkovich G. , Kritsuk A. G. , Norman M. L.
Published: November 2012

Using data from a large-scale three-dimensional simulation of supersonic isothermal turbulence, we have tested the validity of an exact flux relation derived analytically from the Navier–Stokes equation by Falkovich, Fouxon & Oz (J. Fluid Mech., vol. 644, 2010, p. 465). That relation, for compressible barotropic fluids, was derived assuming turbulence generated by a large-scale force. However, compressible turbulence in simulations is usually initialized and maintained by a large-scale acceleration, as in gravity-driven astrophysical flows. We present a new approximate flux relation for isothermal turbulence driven by a large-scale acceleration, and find it in reasonable agreement with the simulation results.
Effect of compressibility on the small-scale structures in isotropic turbulence
Authors: Wang Jianchun , Shi Yipeng , Wang Lian-Ping , Xiao Zuoli , He X. T. , Chen Shiyi
Published: November 2012

Using a simulated highly compressible isotropic turbulence field with turbulent Mach number around 1.0, we studied the effects of local compressibility on the statistical properties and structures of velocity gradients in order to assess salient small-scale features pertaining to highly compressible turbulence against existing theories for incompressible turbulence. A variety of statistics and local flow structures conditioned on the local dilatation – a measure of local flow compressibility – are studied. The overall enstrophy production is found to be enhanced by compression motions and suppressed by expansion motions. It is further revealed that most of the enstrophy production is generated along the directions tangential to the local density isosurface in both compression and expansion regions. The dilatational contribution to enstrophy production is isotropic and dominant in highly compressible regions. The emphasis is then directed to the complicated properties of the enstrophy production by the deviatoric strain rate at various dilatation levels. In the overall flow field, the most probable eigenvalue ratio for the strain rate tensor is found to be −3:1:2.5, quantitatively different from the preferred eigenvalue ratio of −4:1:3 reported in incompressible turbulence. Furthermore, the strain rate eigenvalue ratio tends to be −1:0:0 in high compression regions, implying the dominance of sheet-like structures. The joint probability distribution function of the invariants for the deviatoric velocity gradient tensor is used to characterize local flow structures conditioned on the local dilatation as well as the distribution of enstrophy production within these flow structures. We demonstrate that strong local compression motions enhance the enstrophy production by vortex stretching, while strong local expansion motions suppress enstrophy production by vortex stretching. Despite these complications, most statistical properties associated with the solenoidal component of the velocity field are found to be very similar to those in incompressible turbulence, and are insensitive to the change of local dilatation. Therefore, a good understanding of dynamics of the compressive component of the velocity field is key to an overall accurate description of highly compressible turbulence.
Reflection of Plane Waves in a Rotating Temperature-Dependent Thermoelastic Solid with Diffusion
Authors: Singh B. , Singh L. , Deswal S.
Published: November 2012

The governing equations of a model of rotating generalized thermoelastic diffusion in an isotropic medium with temperature-dependent mechanical properties are formulated in context of Lord-Shulman theory of generalized thermoelasticity. The modulus of elasticity is taken as a linear function of reference temperature. The solution of the governing equations indicates the existence of four coupled plane waves in x-z plane. The reflection of plane waves from the free surface of a rotating temperature-dependent thermoelastic solid half-space with diffusion is considered. The required boundary conditions are satisfied by the appropriate potentials for incident and reflected waves in the half-space to obtain a system of four non-homogeneous equations in the reflection coefficients. The expressions for energy ratios of the reflected waves are also obtained. The reflection coefficients and energy ratios are found to depend upon the angle of incidence, reference temperature, thermodiffusion and rotation parameters. Aluminum material is modeled as the half-space to compute the absolute values of the reflection coefficients and the energy ratios. Effects of temperature dependence and rotation parameters on the reflection coefficients and energy ratios are shown graphically for a certain range of the angle of incidence of the incident plane wave.
An Amplification Factor to Enhance Stability for Structure-Dependent Integration Method
Authors: Chang S.-Y.
Published: November 2012

Chang explicit method (2007) has been shown to be unconditionally stable for a linear elastic system and any instantaneous stiffness softening system while it is only conditionally stable for any instantaneous stiffness hardening system. Its coefficients of the difference equation for displacement increment are functions of initial tangent stiffness. Since Chang explicit method is unconditionally stable for a linear elastic system and any instantaneous stiffness softening system, its stability range can be enlarged if the initial tangent stiffness is enlarged by an amplification factor and then this amplified initial tangent stiffness is used to determine the coefficients. The detailed implementation of this scheme for Chang explicit method is presented and the feasibility of this scheme is verified.
Optimal Design of a Vibration-Based Electromagnetic Energy Harvester Using a Simulated Annealing Algorithm
Authors: Chiu M.-C. , Chang Y.-C. , Yeh L.-J. , Chung C.-H.
Published: November 2012

This paper presents the optimal design of an electromagnetic vibration-based generator using the simulated annealing method (SA). To optimally extract the vibrational energy of a system vibrating at a specific frequency, the selected mass and spring stiffness of a resonant vibration is required. The relationship between induced energy and the generator's structure, its permanent magnet height and diameter, number of turns, and wire diameter in a single air coil are discussed. Also, a prototype of the vibrationbased electrical generator is built and tested via a shaker excited at resonance frequency and input amplitude of 0.06mm. Consequently, results reveal that the design parameters (permanent magnet height and diameter, number of turns, and wire diameter) play essential roles in maximizing electrical power.
Quasi-Steady Flow Dynamics Study of Human Aortic Valve with Numerical Techniques
Authors: Vu H.-H. , Hsu C.-H.
Published: November 2012

Human aortic valve is made of thin collagen type tissue. The three leaflets open and close under fluid forces exerted upon them. To simulate the hemodynamic characteristics of the blood flow, ANSYS CFX10.0 software was utilized to analyze the three-dimensional Reynolds-averaged Navier-Stokes equations. With a quasi-steady analysis model, we predict values of the blood velocity and the wall shear stress both over the valve leaflets and the endothelial lining. In addition, investigation on fluid dynamic of a heart valve supposed suffering prolapsed disease has been also conducted, and compared with normal valve. Analysis results highlight that leaflet opening situation and valve geometry affect the shear stress distribution and vortex flow regime. Maximum shear stress takes place near the center of leaflet trailing edge at the very beginning of systolic phase with value of 7.093N/m2. At peak systole, the maximum wall shear stress distributes near the aortic root where jet impingement takes place. Current study also demonstrated the interactive impact between low and high wall shear stress on relation to heart valve disease.
Modeling and Simulation of Bladder Power Pump Driven by External Electromagnet
Authors: Li X. , Guan T. , Huang W.-J. , Liang C.-H.
Published: November 2012

The clinical urination assist measures are usually taken to overcome the neurogenic bladder difficult to cure, but easily cause patients bladder stones, urinary system infection and other complications. To solve the problem of the urination assist of neurogenic bladder, a bladder power pump (BPP) driven by external electromagnet was proposed in this study according to the structure and micturition mechanism of human urinary bladder. The mathematic models of the BPP were established based on the theories of electromagnetics and fluid dynamics. A simulated experiment system with a bladder physical model for simulating human urinary system was designed according to the similarity criterion of fluid dynamincs. The micturition performance of the BPP was investigated by simulation and experiment. The results showed that the intravesical pressure and urine flow rate of the bladder physical model can be controlled by adjusting electromagnet exciting current. The micturition performance of the BPP is basically accordant with that of human urinary bladder detrusor. The established mathematic models are simple and practicable, which can provide the theoretical guidance for the performance analysis and structural optimization design of the BPP.
Equilibrium Position of a Buoyant Drop in Couette and Poiseuille Flows at Finite Reynolds Numbers
Authors: Bayareh M. , Mortazavi S.
Published: November 2012

The equilibrium position of a deformable drop in Couette and Poiseuille flows is investigated numerically by solving the full Navier-Stokes equations using a finite difference/front tracking method. The objective of this work is to study the motion of a non-neutrally buoyant drop in Couette and Poiseuille flows with different density ratios at finite Reynolds numbers. Couette flow: The equilibrium position of the lighter drops is higher than the heavier drops at each particle Reynolds number. Also, the equilibrium position height increases with increasing the Reynolds number at a fixed density ratio. At this equilibrium distance from the wall, the migration velocity is zero, while the velocity of the drop in the flow direction and rotational velocity of the drop is finite. It is observed that the equilibrium position is independent of the initial position of the drops and depends on the density ratio and the shear Reynolds number. Poiseuille flow: When the drop is slightly buoyant, it moves to an equilibrium position between the wall and the centerline. The equilibrium position is close to the centerline if the drop lags the fluid but close to the wall if the drop leads the fluid. As the Reynolds number increases, the equilibrium position of lighter drops moves slightly closer to the wall and the equilibrium position of heavier drops moves towards the centerline.
Thermoelastic Dynamic Behaviors of a FGM Hollow Cylinder Under Non-Axisymmetric Thermo-Mechanical Loads
Authors: Xie H. , Dai H.-L. , Rao Y.-N.
Published: November 2012

This paper is concerned with two-dimensional (r, θ) thermoelastic dynamic responses of a long functionally graded hollow cylinder subjected to asysmmetrical thermal and mechanical loads. The material properties, except the Poisson's ratio, are assumed to be temperature independent and vary exponentially and continuously in the radial direction. By means of finite difference method and Newmark method, the motion governing equations of the long FGM hollow cylinder are solved. Comparisons between this paper's results and the corresponding analytical results validate the proposed solution. In addition, the effects of the volume fraction, temperature boundary conditions on the hollow cylinder's deformations and stresses distributions are examined, and many other valuable thermoelastic dynamic characteristics are revealed.
Circular Auxetic Plates
Authors: Lim T.-C.
Published: November 2012

This paper investigates the suitability of auxetic materials for load-bearing circular plates. It is herein shown that the optimal Poisson's ratio for minimizing the bending stresses is strongly dependent on the final deformed shape, load distribution, and the type of edge supports. Specifically, the use of auxetic material for circular plates is recommended when (a) the plate is bent into a spherical or spherical-like cap, (b) a point load is applied to the center of the plate regardless of the edge conditions, and (c) a uniform load is applied on a simply-supported plate. However, auxetic materials are disadvantaged when a flat plate is to be bent into a saddle-like shell. The optimal Poisson's ratios concept recommended in this paper is useful for providing an added design consideration. In most cases, the use of auxetic materials for laterally loaded circular plates is more advantageous compared to the use of materials with conventional Poisson's ratio, with other factors fixed. This is achieved through materials-based stress re-distribution in addition to the common practices of dimensioning-based stress redistribution and materials strengthening.
Modified Characteristics-Based Schemes for Compressible Flow Past an Airfoil
Authors: Orang A. A. , Paykani A.
Published: November 2012

In this paper, the numerical study of compressible flow around an airfoil is presented. The flow is analyzed in steady state for subsonic, transonic and even in the supersonic regimes at different angles of attack. In finite-volume method convective fluxes are calculated and compared by two schemes. Modified Jameson flux scheme based on flux averaging with pressure correction is used. Modified Roe scheme which is one of the characteristics-based schemes, with modification in calculation of Jacobian matrix based on Mach number is implemented. Second-order accuracy is used with artificial dissipation to overcome numerical oscillations. The fifth-order Runge–Kutta scheme is used for time discretization. A proper boundary condition based on characteristics is applied. Numerical experiments are performed on the NACA 0012 and also NACA 4412 airfoils. The results confirm the superiority of modified upwind Roe scheme regarding the accuracy, stability and convergence. Results are compared to available results in literature and a good agreement is noticed.
Size and Shape Effects on Strength and Ultimate Strain in FRP Confined Rectangular Concrete Columns
Authors: Yeh F.-Y. , Chang K.-C.
Published: November 2012

This paper is concerned with the effects of column size, carbon fiber-reinforced plastics (CFRP) volumetric ratio, column side to corner radius ratio and column side aspect ratio on the confinement efficiency of rectangular concrete columns confined with CFRP. The confined concrete nonlinear constitutive relationships are adopted which account for concrete under unequal lateral confining stresses under multiaxial stress conditions. A stiffness reduction procedure upon concrete cracking or crushing is also proposed. The finite element model is initially confirmed by comparing its numerical solutions with the experimental results for various parameters. The effects of above parameters on the peak strength and ultimate strain of the confined concrete are then parametrically studied. The test results and results of the parametric study indicate that the column axial compressive strength and ultimate strain increase with CFRP volumetric ratio, but decrease as the column side to corner radius ratio or the column side aspect ratio increases. For columns of a particular corner radius and CFRP volumetric ratio, the column axial compressive strength and ultimate strain decrease as column size and column side to corner radius ratio increases.
The Numerical Method as Applied to Impact Resistance Analysis of Ogival Nose Projectiles on 6061-T651 Aluminum Plates
Authors: Chen Y.-L. , Chen H.-C.
Published: November 2012

This research takes the resistance formula of spherical cavity expansion theory as its foundation. It establishes a predictive model of the residual velocity, ballistic limit velocity, and penetration depth of ogival nose projectiles striking metal target plates at high speed. They are aimed at 6061-T651 aluminum plates of different thicknesses using the iterative algorithm of the numerical method, thereby investigating the theoretical calculation of the residual velocity, penetration depth, ballistic limit velocity, and changes in resistance of ogival nose projectiles when making a normal impact target. In addition to analyzing the resistance undergone by the projectile nose section, this predictive model also considers the effects of friction resistance of the projectile shank section. In this research, we also used the finite element software LS-DYNA to perform a simulated analysis on the penetration depth of the aluminum plate after normal perforation by ogival nose projectiles. Ballistic test experiments were then performed using 0.30” AP (armor piercing) bullets. Finally, a comparative analysis was performed based on the theoretical model, experiments, and numerical simulation results.
Hamiltonian Structure and Stability Analysis for a Partially Filled Container
Authors: Ahmad S. , Yue B. , Shah S. F. , Ahmad S.
Published: November 2012

Hamiltonian system is a special case of dynamical system. Mostly it is used for potential shaping of mechanical systems stabilization. In our present work, we are using Hamiltonian dynamics to study and control the fuel slosh inside spacecraft tank. Sloshing is the phenomenon which is related with the movement of fluid inside a container in micro and macro scale as well. Sloshing of fluid occurs whenever the frequency of container movement matches with the natural frequency of fluid inside the container. Such type of synchronization may cause the structural damage or could be a reason of moving object's attitude disturbance. In spacecraft technology, the equivalent mechanical model for sloshing is common to use for the representation of fuel slosh. This mechanical model may contain a model of pendulum or a mass attached with a spring. In this article, we are using mass-spring mechanical model coupled with rigid body to derive the equations for Hamiltonian system. Casimir functions are used for proposed model. Conditions for the stability and instability of moving mass are derived using Lyapunov function along with Casimir functions. Simulation work is presented to strengthen the derived results and to distribute the stable and unstable regions graphically.
Unsteady Hydromagnetic Flow Due to Concentric Rotation of Eccentric Disks
Authors: Das S. , Jana M. , Jana R. N.
Published: November 2012

The unsteady hydromagnetic flow of a viscous incompressible electrically conducting fluid between two parallel disks rotating with the same angular velocity initially about non-coincident axes, which are suddenly made coincident, has been studied. An analytical solution describing the flow at large and small times after the start is obtained by the use of Laplace transform technique. The physical interpretations for the emerging parameters are discussed with the help of graphs. The shear stresses obtained from the general solution and from the solution for small time are compared.
Students With ASD in Mainstream Primary Education Settings: Teachers' Experiences in Western Australian Classrooms
Authors: Soto-Chodiman Rebecca , Pooley Julie Ann , Cohen Lynne , Taylor Myra Frances
Published: November 2012

The shift to inclusive education within Australia has resulted in increasing numbers of students with autism spectrum disorders (ASD) being placed in mainstream educational settings. This move has created new demands on teachers who are not necessarily trained to meet the challenge. Therefore, the present study aimed to develop an understanding of how 12 Western Australian primary school (K–7) teachers adapted to the challenge of having a student with ASD in their mainstream classroom. Using an interpretivist framework, data from semistructured interviews revealed that teachers perceived a need to first recognise and accept the challenges associated with having a student with ASD in their mainstream classroom before they could move to accessing avenues of support. The implications of this finding are discussed.
Detecting Different Types of Reading Difficulties: A Comparison of Tests
Authors: Moore Danielle M. , Porter Melanie A. , Kohnen Saskia , Castles Anne
Published: November 2012

The focus of this paper is on the assessment of the two main processes that children must acquire at the single word reading level: word recognition (lexical) and decoding (nonlexical) skills. Guided by the framework of the dual route model, this study aimed to (1) investigate the impact of item characteristics on test performance, and (2) determine to what extent widely used reading measures vary in their detection of lexical and nonlexical reading difficulties. Thirty children with reading difficulties were administered selected reading subtests from the Woodcock-Johnson III, the Wechsler Individual Achievement Test – Second Edition, the Castles and Coltheart Reading Test 2 (CC2), as well as a measure of nonverbal IQ. Both within-subjects analyses and descriptive data are presented. Results suggest that in comparison to a pure measure of irregular word reading, children with reading difficulties perform better on word identification subtests containing both regular and irregular word items. Furthermore, certain characteristics (e.g., length, similarity to real words) appear to influence the level of difficulty of nonword items and tests. The CC2 subscales identified the largest proportions of children with reading difficulties. Differences between all test scores were of statistical and clinical significance. Clinical and theoretical implications are discussed.
The Understanding Words Reading Intervention: Evidence From a Case Series Design
Authors: Wright Craig , Conlon Elizabeth G. , Wright Michalle
Published: November 2012

Using a case-series design with double baseline and 10-week maintenance phase, 5 struggling readers from middle- to high-income families (age range 6.4–7.9 years) completed a 5-times-weekly intervention (96 sessions) administered by a parent. All participants completed the intervention with phonological decoding, text-reading accuracy and reading comprehension scores above the 30th percentile. Regular-word reading improved significantly, and 3 out of 5 participants achieved average levels at postintervention testing. Growth of 0.58 standard deviations (SD) was seen in one participant on a test of irregular-word reading. The other 4 participants made growth of > 0.8 SD. However, only 1 participant achieved average levels at postintervention testing on the irregular-word reading measure. Results provide preliminary support for the effectiveness of the intervention in improving word-level decoding and comprehension in struggling readers. Most important, the data provide preliminary evidence that some parents can function as paraprofessionals and provide effective reading intervention for struggling readers. Special education professionals may be able to work around limited funding for struggling readers by recruiting, training, and supervising parents.
Tensions in Home–School Partnerships: The Different Perspectives of Teachers and Parents of Students With Learning Barriers
Authors: Ludicke Penelope , Kortman Wendy
Published: November 2012

This paper presents the findings of a qualitative study of learning partnerships between teachers and parents of students with learning barriers. The aim was to investigate the beliefs and understandings of parents and teacher participants around roles in partnerships, so as to identify operational processes that support effective collaboration. The study was based on the premise that home–school partnerships have been established as a positive influence on the education of students with learning barriers but tensions exist within these partnerships in practice. In the study it was posited that some tensions stemmed from differences in role understandings between parent and teacher. Data revealed key themes emerging from the case studies. Findings indicated that parents and teachers believed that involvement and partnerships are integral to supporting the learning of students with learning barriers. However, differences emerged as to how teachers and parents constructed and interpreted involvement and operational processes supporting partnerships, and the significance each group placed on different aspects of collaboration between parent and teacher.
1H NMR spectroscopy for the in vitro understanding of the glycaemic index
Authors: Dona Anthony C. , Landrey Karola , Atkinson Fiona S. , Brand Miller Jennie C. , Kuchel Philip W.
Published: November 2012

The glycaemic index (GI) characterises foods by using the incremental area under the glycaemic response curve relative to the same amount of oral glucose. Its ability to differentiate between curves of different shapes, the peak response and other aspects of the glycaemic response is contentious. The present pilot study aimed to explore the possibility of using 1H NMR spectroscopy to better understand in vivo digestion characteristics as reflected in the glycaemic response of carbohydrate-rich foods; such an approach might be an adjunct to the in vivo GI test. The glycaemic response of two types of raw wheat flour (2005 from Griffith NSW, Chara, Row 10, Plot 6:181 and store-bought Coles™ Plain Flour) and a cooked store-bought flour was tested and compared with results recorded during the in vitro enzymatic digestion of the wheat flour samples by glucoamylase from Aspergillus niger (EC 3.2.1.3) as monitored by 1H NMR spectroscopy. Comparing the digestion time courses of raw and cooked wheat starch recorded in vitro strongly suggests that the initial rate of glucose release in vitro correlates with the glycaemic spike in vivo. During the in vitro time courses, approximately four times as much glucose was released from cooked starch samples than from raw starch samples in 90 min. Monitoring enzymatic digestion of heterogeneous mixtures (food) by 1H NMR spectroscopy showcases the effectiveness of the technique in measuring glucose release and its potential use as the basis of an in vitro method for a better understanding of the GI.
Changes in regional brain monoaminergic activity and temporary down-regulation in stress response from dietary supplementation withl-tryptophan in Atlantic cod (Gadus morhua)
Authors: Basic Dean , Schjolden Joachim , Krogdahl Åshild , von Krogh Kristine , Hillestad Marie , Winberg Svante , Mayer Ian , Skjerve Eystein , Höglund Erik
Published: November 2012

The brain monoamines serotonin (5-hydroxytryptamine; 5-HT) and dopamine (DA) both play an integrative role in behavioural and neuroendocrine responses to challenges, and comparative models suggest common mechanisms for dietary modulation of transmission by these signal substances in vertebrates. Previous studies in teleosts demonstrate that 7 d of dietary administration withl-tryptophan (Trp), the direct precursor of 5-HT, suppresses the endocrine stress response. The present study investigated how long the suppressive effects of a Trp-enriched feed regimen, at doses corresponding to two, three or four times the Trp levels in commercial feed, last in juvenile Atlantic cod (Gadus morhua) when the fish are reintroduced to a diet with standard amino acid composition. We also wanted to determine whether Trp supplementation induced changes in brain monoaminergic neurochemistry in those forebrain structures innervated by DA- and 5-HTergic neurons, by measuring regional activity of DA and 5-HT in the lateral pallial regions (Dl) of the telencephalon and nucleus lateralis tuberis (NLT) of the hypothalamus. Dietary Trp resulted in a dose-dependent suppression in plasma cortisol among fish exposed to confinement stress on the first day following experimental diet; however, such an effect was not observed at 2 or 6 d after Trp treatment. Feeding the fish with moderate Trp doses also evoked a general increase in DA and 5-HT-ergic activity, suggesting that these neural circuits within the NLT and Dl may be indirectly involved in regulating the acute stress response.
Strategies of Authority in Muslim South Asia in the Nineteenth and Twentieth Centuries
Authors: ROBINSON FRANCIS
Published: November 2012

Starting from the position that authority is constantly a work in progress, this paper examines authority in Muslim South Asia at a time when Muslims felt the challenge of rule by another civilization. It examines the strategies in sustaining their authority: of religious leaders, of Unani hakims and of literary leaders. In all three areas there is a rejection of the Persianate Mughal past and an embracing of Arab models, of the Prophetic model, and in various ways a drawing on British models and British authority. The paper also looks at the strategies of the rulers noting, amongst other things, how the British drew heavily on Mughal models just as Indian Muslims were letting them go, and how, since independence, Muslim rulers have drawn on a mixture of Western, Arab and Prophetic sources. There is also a running discussion throughout the paper of the revolutionary shift towards rooting authority in society at large, and the development of techniques to do so.
Language ideology, fractal recursivity, and discursive agency in the legal construction of linguistic evidence
Authors: Andrus Jennifer
Published: November 2012

This article analyzes the language ideology (Silverstein 1979; Woolard & Schieffelin 1994) circulated in Section 8 of the United States Federal Rules of Evidence (FRE), focusing on the consequences to discursive agency when this language ideology is used to appropriate an utterance for use as evidence. Section 8 of the FRE, or the hearsay rule, bars the testimonial, in-court repetition of second-hand statements. The excited utterance exception to hearsay admits an utterance as long as it was made by an excited speaker, while s/he was under the sway of an exciting event, which the excited utterance must also report. This rule explicitly trusts spontaneous speech, entextualizing it as a trustworthy account of an event, using the reasoning that such an utterance is not made by a speaker capable of self-reflection. I show that this language ideology problematically links discursive agency (Butler 1997; Medina 2006) with an untruthful speaker-role. Using the concept of fractal recursivity (Irvine & Gal 2000), I argue that the presuppositions embedded and circulated metadiscursively in this rule of evidence effectively constitute a speaker without legally “recognizable” discursive agency. This effect is the most noticeable and the most consequential when the excited utterance exception is used to appropriate the speech of women who have been the victims of domestic violence. Ultimately I argue that discursive agency is a feature of language ideology. (Discursive agency, legal discourse, language ideology, evidence, metadiscourse, domestic violence)*
Some structural consequences of diffusion
Authors: Cukor-Avila Patricia
Published: November 2012

This study investigates the diffusion and structural adaptation of quotative be like into a rural African American speech community. The data come from a longitudinal corpus of recordings (1988–2010) with rural African American Vernacular English (AAVE) speakers born between 1894–2002. Previous research suggests other innovative AAVE features have diffused into this community from neighboring urban areas (Cukor-Avila 1995, 2001; Cukor-Avila & Bailey 1995b, 1996) approximately a generation after they appear in urban varieties. The present analysis supports Cukor-Avila (2002) that be like has followed a similar path of diffusion, and adds new recordings of young speakers to provide necessary data to explore the transmission of be like in the community, its continued diffusion, and how these processes reinforce each other as be like becomes the primary means of expressing quoted speech. In addition, the present study explores how quotative be like has been structurally adapted into the AAVE copula system. (AAVE, transmission, diffusion, adaptation, quotative be like)*
Affective stances in teacher-novice student interactions: Language, embodiment, and willingness to learn in a Swedish primary classroom
Authors: Cekaite Asta
Published: November 2012

The present study explores a child, language, and cultural novice's affective and moral socialization during her first year in a Swedish first-grade classroom. Within the language socialization framework, it focuses on the lexicogrammatical and embodied organization of the novice's affectively charged noncompliant responses to (teacher) instructional directives, and the teachers' socializing responsive moves (contextualizing them within local and wider societal values and ideologies). The methods adopted combine a microanalytic approach with ethnographic analyses of socialization within a classroom community.

Longitudinal tracking of the novice's stances demonstrated a trajectory across which socialization into normatively predictable cultural patterns did not occur. As shown, the student's affective stances and the teachers' socializing responses were consequential for the emergence of her “bad subject,” that is, her socioculturally problematic identity (from a “resigned” to an “oppositional” student who was “unwilling” to learn). Such deviant cases, it is argued, provide insights into the contested and dynamic aspects of second language socialization and demonstrate how affective (and moral) stances are mobilized as resources in the indexing of institutional identities. (Language socialization, language novice, affective stance, teacher-student interactions, directive sequences, embodiment, volition)*
The impact of resources on decision making
Authors: Boyle Iain M. , Duffy Alex H.B. , Whitfield R. Ian , Liu Shaofeng
Published: November 2012

Decision making is a significant activity within industry and although much attention has been paid to the manner in which goals impact on how decision making is executed, there has been less focus on the impact decision making resources can have. This article describes an experiment that sought to provide greater insight into the impact that resources can have on how decision making is executed. Investigated variables included the experience levels of decision makers and the quality and availability of information resources. The experiment provided insights into the variety of impacts that resources can have upon decision making, manifested through the evolution of the approaches, methods, and processes used within it. The findings illustrated that there could be an impact on the decision-making process but not on the method or approach, the method and process but not the approach, or the approach, method, and process. In addition, resources were observed to have multiple impacts, which can emerge in different timescales. Given these findings, research is suggested into the development of resource-impact models that would describe the relationships existing between the decision-making activity and resources, together with the development of techniques for reasoning using these models. This would enhance the development of systems that could offer improved levels of decision support through managing the impact of resources on decision making.