bluuebunny/crossref_metadata_2025_split huggingface dataset:
Investigation of sub-Kolmogorov inertial particle pair dynamics in turbulence using novel satellite particle simulations
Authors: Ray Baidurja , Collins Lance R. 
Published: March 2013

AbstractClustering (or preferential concentration) of weakly inertial particles suspended in a homogeneous isotropic turbulent flow is driven primarily by the smallest eddies at the so-called Kolmogorov scale. In particle-laden large-eddy simulations (LES), these small scales are not resolved by the grid and hence their effect on both the resolved flow scales and the particle motion have to be modelled. In order to predict clustering in a particle-laden LES, it is crucial that the subgrid model for the particles captures the mechanism by which the subgrid scales affect the particle motion (Ray & Collins, J. Fluid Mech., vol. 680, 2011, pp. 488–510). In this paper, we describe novel satellite particle simulations (SPS), in which we study the clustering and relative velocity statistics of inertial particles at separation distances well below the Kolmogorov length scale. SPS is designed to isolate pairwise interactions of particles, and is therefore well suited for developing two-particle models. We show that the power-law dependence of the radial distribution function (RDF), a statistical measure of clustering, is predicted by the SPS in excellent agreement with direct numerical simulations (DNS) for Stokes numbers up to 3, implying that no explicit information from the inertial range is required to accurately describe particle clustering. This result further explains our successful prediction of the RDF power using the drift-diffusion model of Chun et al. (J. Fluid Mech., vol. 536, 2005, pp. 219–251) for $\mathit{St}\leq 0. 4$. We also consider the second-order longitudinal relative velocity structure function for the particles; we show that the SPS is able to capture its power-law exponent for $\mathit{St}\leq 0. 5$ and attribute the disagreement at larger $\mathit{St}$ to the effect of the larger scales of motion not captured by the SPS. Further, the SPS is able to capture the ‘caustic activation’ of the structure function at zero separation and predict the critical $\mathit{St}$ and rate of activation in agreement with the DNS (Salazar & Collins, J. Fluid. Mech., vol. 696, 2012, pp. 45–66). We show comparisons between filtered DNS and equivalently filtered SPS, and the findings are similar to the unfiltered case. Overall, SPS is an efficient and accurate computational tool for investigating particle pair dynamics at small separations, as well as an interesting platform for developing LES subgrid models designed to accurately reproduce particle clustering.
The non-resonant response of fluid in a rapidly rotating sphere undergoing longitudinal libration
Authors: Zhang Keke , Chan Kit H. , Liao Xinhao , Aurnou Jonathan M. 
Published: March 2013

AbstractWe investigate the problem of oscillatory flow of a homogeneous fluid with viscosity $\nu $ in a fluid-filled sphere of radius $a$ that rotates rapidly about a fixed axis with angular velocity ${\Omega }_{0} $ and that undergoes weak longitudinal libration with amplitude $\epsilon {\Omega }_{0} $ and frequency $\hat {\omega } {\Omega }_{0} $, where $\epsilon $ is the Poincaré number with $\epsilon \ll 1$ and $\hat {\omega } $ is dimensionless frequency with $0\lt \hat {\omega } \lt 2$. Three different methods are employed in this investigation: (i) asymptotic analysis at small Ekman numbers $E$ defined as $E= \nu / ({a}^{2} {\Omega }_{0} )$; (ii) linear numerical analysis using a spectral method; and (iii) nonlinear direct numerical simulation using a finite-element method. A satisfactory agreement among the three different sets of solutions is achieved when $E\leq 1{0}^{- 4} $. It is shown that the flow amplitude $\vert \boldsymbol{u}\vert $ is nearly independent of both the Ekman number $E$ and the libration frequency $\hat {\omega } $, always obeying the asymptotic scaling $\vert \boldsymbol{u}\vert = O(\epsilon )$ even though various spherical inertial modes are excited by longitudinal libration at different libration frequencies $\hat {\omega } $. Consequently, resonances do not occur in this system even when $\hat {\omega } $ is at the characteristic value of an inertial mode. It is also shown that the pressure difference along the axis of rotation is anomalous: this quantity reaches a sharp peak when $\hat {\omega } $ approaches a characteristic value. In contrast, the pressure difference measured at other places in the sphere, such as in the equatorial plane, and the volume-integrated kinetic energy are nearly independent of both the Ekman number $E$ and the libration frequency $\hat {\omega } $. Absence of resonances in a fluid-filled sphere forced by longitudinal libration is explained through the special properties of the analytical solution that satisfies the no-slip boundary condition and is valid for $E\ll 1$ and $\epsilon \ll 1$.
Gravity-driven granular free-surface flow around a circular cylinder
Authors: Cui X. , Gray J. M. N. T. 
Published: March 2013

AbstractSnow avalanches and other hazardous geophysical granular flows, such as debris flows, lahars and pyroclastic flows, often impact on obstacles as they flow down a slope, generating rapid changes in the flow height and velocity in their vicinity. It is important to understand how a granular material flows around such obstacles to improve the design of deflecting and catching dams, and to correctly interpret field observations. In this paper small-scale experiments and numerical simulations are used to investigate the supercritical gravity-driven free-surface flow of a granular avalanche around a circular cylinder. Our experiments show that a very sharp bow shock wave and a stagnation point are generated in front of the cylinder. The shock standoff distance is accurately reproduced by shock-capturing numerical simulations and is approximately equal to the reciprocal of the Froude number, consistent with previous approximate results for shallow-water flows. As the grains move around the cylinder the flow expands and the pressure gradients rapidly accelerate the particles up to supercritical speeds again. The internal pressure is not strong enough to immediately push the grains into the space behind the cylinder and instead a grain-free region, or granular vacuum, forms on the lee side. For moderate upstream Froude numbers and slope inclinations, the granular vacuum closes up rapidly to form a triangular region, but on steeper slopes both experiments and numerical simulations show that the pinch-off distance moves far downstream.
Exact solutions for cylindrical ‘slip–stick’ Janus swimmers in Stokes flow
Authors: Crowdy Darren G. 
Published: March 2013

AbstractA Janus swimmer is any force-free, torque-free organism, particle or micro-robot operating at low Reynolds numbers and having contiguous regions of its boundary on which different boundary conditions are in play. In this paper we study a ‘slip–stick’ Janus swimmer theoretically within a two-dimensional model. The boundary of the swimmer is split into two zones: its motion is driven by an imposed tangential stress on a portion of the boundary with the complement taken to be a no-slip surface. The Stokes flow generated by the swimmer, and its swimming speed, are determined in closed analytical form as a function of the angle over which the stress actuation is active.
ELUSIVE CODES IN HAMMING GRAPHS
Authors: HAWTIN DANIEL R. , GILLESPIE NEIL I. , PRAEGER CHERYL E. 
Published: March 2013

AbstractWe consider a code to be a subset of the vertex set of a Hamming graph. We examine elusive pairs, code-group pairs where the code is not determined by knowledge of its set of neighbours. We construct a new infinite family of elusive pairs, where the group in question acts transitively on the set of neighbours of the code. In these examples, the alphabet size always divides the length of the code. We show that there is no elusive pair for the smallest set of parameters that does not satisfy this condition. We also pose several questions regarding elusive pairs.
Local Bondage in Global Economies: Servants, wage earners, and indentured migrants in nineteenth-century France, Great Britain, and the Mascarene Islands
Authors: STANZIANI ALESSANDRO 
Published: March 2013

AbstractThis paper compares the definitions, practices, and legal constraints on labour in Britain, France, Mauritius, and Reunion Island in the eighteenth and nineteenth centuries. It argues that the way in which indentured labour was defined and practised in the colonies was linked to the definition and practice of wage labour in Europe and that their development was interconnected. The types of bondage that existed in the colonies were extreme forms of the notion, practices, and rules of labour in Europe. It would have been impossible to develop the indenture contract in the British and French empires if wage earners in Britain and France had not been servants. The conceptions and practices of labour in Europe and its main colonies influenced each other and were part of a global dynamic.
Cognitive biases and auditory verbal hallucinations in healthy and clinical individuals
Authors: Daalman K. , Sommer I. E. C. , Derks E. M. , Peters E. R. 
Published: March 2013

BackgroundSeveral cognitive biases are related to psychotic symptoms, including auditory verbal hallucinations (AVH). It remains unclear whether these biases differ in voice-hearers with and without a ‘need-for-care’.MethodA total of 72 healthy controls, 72 healthy voice-hearers and 72 clinical voice-hearers were compared on the Cognitive Biases Questionnaire for psychosis (CBQp), which assesses ‘intentionalizing’, ‘jumping to conclusions’, ‘catastrophizing’, ‘dichotomous thinking’ and ‘emotional reasoning’ in vignettes characterized by two themes, ‘threatening events’ and ‘anomalous perceptions’.ResultsHealthy voice-hearers scored intermediately on total CBQp between the control and clinical groups, differing significantly from both. However, on four out of five biases the scores of the healthy voice-hearers were comparable with those of the healthy controls. The only exception was ‘emotional reasoning’, on which their scores were comparable with the clinical group. Healthy voice-hearers demonstrated fewer biases than the psychotic patients on the ‘threatening events’, but not the ‘anomalous perceptions’, vignettes. CBQp scores were related to both cognitive and emotional, but not physical, characteristics of voices.ConclusionsMost cognitive biases prevalent in clinical voice-hearers, particularly with threatening events themes, are absent in healthy voice-hearers, apart from emotional reasoning which may be specifically related to the vulnerability to develop AVH. The association between biases and both beliefs about voices and distress/emotional valence is consistent with the close links between emotions and psychotic phenomena identified by cognitive models of psychosis. The absence of reasoning biases might prevent the formation of threatening appraisals about anomalous experiences, thereby reducing the likelihood of distress and ‘need for care’.
The innovation game: lessons in strategy and managing operations
Authors: Yalabik Baris , Howard Mickey , Roden Sinéad 
Published: March 2013

PurposeThis paper seeks to present a teaching tool (the Innovation Game) which aims to demonstrate the challenges of developing an effective innovation strategy in the context of new product development. The goal of the game is to enable participants to experience how strategic and operational choices made in relation to innovation strategy are interrelated and how these choices can impact on new product development success. Specifically the paper aims to explore the impact of choices made in relation to capability accumulation, capacity management and product‐portfolio management.Design/methodology/approachAfter presenting the learning objectives for the game with the support of relevant literature, the paper describes the design of the game and the context in which it was played. The paper reviews feedback (learning outcomes) from formal reflective post‐game sessions with participants. This feedback indicates that the learning objectives have been satisfied.FindingsThrough experiential learning and reflective practice participants learn, for example, that: capabilities need to match the intended strategy; investing in production capacity can be leveraged to aid negotiations with competitors, or it can be used as a bully tactic; and, it sometimes is better to be an R&D “follower” rather than a “leader”. The participants also learn that the alignment of operational and strategic choices is necessary in order to leverage success in developing new products but that the actions and strategies of competitors have a direct impact also and need to be considered carefully.Research limitations/implicationsThe teaching tool adopts a participative game playing and reflective learning approach to introduce into class some of the real‐life competitive dynamics of managing new product development and decision making normally confined to the boardroom. While it is argued that the game demonstrates the challenges of developing successful strategy, the game is set in a static context in which certain external contingencies are not accounted for.Originality/valueDemonstration of the importance of strategy to new product development is particularly difficult because of the longitudinal nature of product development and the tacit nature of the decision making process which often transpires long after projects are completed. The paper posits that the value of the Innovation Game is in reflecting on it as a practical, interactive tool that helps participants appreciate the challenges inherent in strategic and operational decision making related to innovation strategy and new product development success.
Workload control
Authors: Hendry Linda , Huang Yuan , Stevenson Mark 
Published: March 2013

PurposeThe purpose of this paper is to present a successful implementation of a comprehensive workload control (WLC) concept; and to describe the associated implementation process.Design/methodology/approachLongitudinal action research using a contingency‐based approach to ensure alignment between the case company and the characteristics of the WLC approach; and the resulting expected improvements in performance. A set of 17 issues and responses from the literature is used as a checklist for implementing WLC.FindingsPerformance improvements include: reduced lead times; significant improvement in lateness and tardiness; reduced costs; improved internal and external co‐ordination; and higher quality. The relevance of 15 of the 17 implementation issues is confirmed along with the same response as in previous research for ten issues and an improved response for five issues. In addition, three new issues are identified and addressed.Research limitations/implicationsDependability was a more important competitive priority in this company than speed; and, therefore, the ability of WLC to reduce lead times was not fully assessed.Practical implicationsThe importance of a contingency‐based approach to production planning and control is confirmed. Comprehensive WLC approaches are closely aligned with the high‐variety/low‐volume context of make‐to‐order (MTO) companies.Originality/valueThis is the first paper that empirically demonstrates performance improvements resulting from WLC alongside a detailed discussion of the implementation process. Few examples of successful implementations have been published previously, and these tend to treat the implementation process as a “black box”. Where more detail on the implementation process has been given in previous studies, evidence of effectiveness in practice was not provided.
Interlending and document supply: a review of the recent literature: 80
Authors: McGrath Mike 
Published: March 2013

PurposeThe paper's aim is to provide a review of the literature concerning interlending and document supply and related matters.Design/methodology/approachThe paper is based on the reading of over 150 journals, as well as monographs, reports and web sites.FindingsThe Finch report in the UK recommends the Gold route to open access and with this a tipping point would appear to have been reached for open access – at least where authors are funded. More papers from the 12th ILDS conference are reviewed.Originality/valueThe paper represents a useful source for librarians and others concerned with interlending and document supply as well as such related matters as resource sharing and open access.
ANRT Lille: the French national centre for the reproduction of PhD theses
Authors: Schöpfel Joachim 
Published: March 2013

PurposeThe purpose of this paper is to describe the ANRT, its purpose and activity in the French national network for the dissemination and preservation of PhD theses.Design/methodology/approachThe paper includes a historical study and an evaluation of current activities and future perspectives.FindingsThe ANRT has played a significant role in the back‐office of the French network for the dissemination and preservation of PhD theses for over 40 years. Its online catalogue contains more than 200,000 PhD theses that academic or other research institutions can order in print format or on microfiche. Complementary to this national mandate, the ANRT runs a print‐on‐demand service for more than 7,200 PhD theses called “Thèses à la carte”. Today, the development of electronic theses and dissertations (ETD) and open access is challenging the future of the ANRT.Originality/valueThe ANRT Lille is one of those institutions that are more or less unknown to the wider public and even to LIS professionals. This paper presents it for the first time to a larger and international readership.
Using reliability indicators to explore human factors issues in maintenance databases
Authors: Karanikas Nektarios 
Published: March 2013

PurposeThe aim of this paper is to explore the usefulness of repairable parts simple historical databases in assisting the human factors experts to identify candidate areas for applying human factors methods. Therefore, also contributing to the search for maintenance quality improvement.Design/methodology/approachThe study was based on the failure history of part fleets installed on the same type of jet engines, and used mean time between failures (MTBF) and failure rates plots, the Laplace trend test, the AMSAA‐Crow‐Duane model and serial correlations.FindingsIncreasing and decreasing trends in failure rates indicated factors that cause deflection from the literature assumptions of constant failure mode and “as good as new” maintenance philosophy. Further statistical calculations revealed patterns between MTBF and frequency of maintenance, specific serial numbers (SN) vulnerability to replacement and depot maintenance tasks, correlations between MTBF and number of both installations and maintenances, and influence of the maintenance month on the maintenance‐failure hours' interval.Practical implicationsThe literature refers to the relation between the parts reliability and the human factors in the maintenance domain. The research confirmed the literature references in data collection problems coming from human factors interferences; the patterns found were attributed to system deficiencies related to workload management, parts configuration management, supervision and manufacturing problems.Originality/valueThe application of this research in combination with methods such as field observations and interviews of personnel involved in the maintenance domain can uncover specific maintenance working environment weaknesses and lead to suitable remedies.
Gage R2&E2: an effective tool to improve the visual control of products
Authors: Maire Jean‐Luc , Pillet Maurice , Baudet Nathalie 
Published: March 2013

PurposeThe variability of the results of a visual control is often high. This paper aims to propose a new tool to give information about what improvement actions can be carried out to reduce this variability.Design/methodology/approachThe variability of a visual control can be measured by Kappa's Fleiss which measures the level of agreement between appraisers and experts. The R&R Gage is then classically used to give information about corrective actions which can be carried out in order to improve this level of agreement. The paper demonstrated that this information is not always sufficient.FindingsBy considering the two essential steps of a visual control (exploration and evaluation), the R2&E2 Gage proposed gives more precise information about the improvement actions to carry out to reduce the variability of a visual control. Repeatability and reproducibility, for detection and evaluation purposes, are considered separately.Research limitations/implicationsThis R2&E2 gage is one result of a European research program called INTERREG. The aim of this program, which brings together two laboratories from the University of Savoy and EPFL, two institutional partners (CTDEC and CETEHOR) and some Swiss and French industrial companies, is to create methodological support and the tools needed to improve the visual control of high added‐value products.Practical implicationsThis R2&E2 gage has been used in six industrial companies involved in the European program INTERREG. Significant improvement of the visual control has been observed over a short time.Originality/valueThe paper fulfils an identified need of industrial firms to have efficient tools improving the visual control of their products.
Improving trade promotions through virtual forward buying
Authors: Poddar Amit , Donthu Naveen 
Published: March 2013

Purpose
– The purpose of this paper is to propose a virtual forward-buying model that allows for forward buying but reduces the channel cost with no major behavioral change on the part of manufacturers and retailers.

Design/methodology/approach
– Using simulations, the authors compare the proposed virtual forward-buying model with the traditional forward-buying and everyday-low-price approaches.

Findings
– The authors find that the proposed model leads to lower overall channel costs that are shared equitably between both the manufacturer and the retailer.

Research limitations/implications
– No primary or secondary is used, a situation that is usually very difficult to find in this area.

Practical implications
– The paper presents a new method to improve trade promotion efficiencies that does not require a drastic change of habits for either the manufacturer or the retailer; allows the practice of forward buying to continue; and leads to channel cost reductions for both parties.

Originality/value
– The paper presents research in an area that is under-researched due to lack of data.