472 research outputs found
Participation Motivation in Martial Artists in the West Midlands Region of England
The objectives were to identify the participation motivations and the perceived importance of certain
participation factors in martial artists in the West Midlands, England, UK. A 28-item adapted version of the Participation Motivation Questionnaire with additional demographic questions was distributed to 30 martial arts clubs in the West Midlands region. Eight questions that assessed the perceived importance
for participation of progression through grades, learning self defence skills, technical ability of
instructors, cost of participating, development of confidence, underpinning philosophy and instructional
style were included. Seventy-five questionnaires were returned from a total of 11 clubs from across
representing practitioners in Tai Chi, Karate, Kung fu, Aikido, Jeet Kune Do, British Free Fighting,
Taekwon-Do and Jujitsu. Results indicated that the rank order in terms of participation motives was: 1-
Affiliation; 2-Friendship; 3-Fitness; 4-Reward/status; 5-Competition; 6-Situational and 7-Skill
development. Participants who trained for more than 4 hours per week placed greater importance on the
underpinning philosophy of the martial art. Findings suggest that whilst there is a gender discrepancy in
participation level, once engaged, females were equally committed to weekly training. The âstyleâ of the
instructor is of paramount importance for enhancing student motivation to participate. High volume
practitioners would appear to be fully immersed in the holistic appreciation of the martial art through
increased value placed on its underpinning philosophy
On the Modelling of Immiscible Viscous Fingering in Two Phase Flow in Porous Media
Viscous fingering in porous media is an instability which occurs when a low-viscosity injected fluid displaces a much more viscous resident fluid, under miscible or immiscible conditions. Immiscible viscous fingering is more complex and has been found to be difficult to simulate numerically and is the main focus of this paper. Many researchers have identified the source of the problem of simulating realistic immiscible fingering as being in the numerics of the process, and a large number of studies have appeared applying high-order numerical schemes to the problem with some limited success. We believe that this view is incorrect and that the solution to the problem of modelling immiscible viscous fingering lies in the physics and related mathematical formulation of the problem. At the heart of our approach is what we describe as the resolution of the âM-paradoxâ, where M is the mobility ratio, as explained below. In this paper, we present a new 4-stage approach to the modelling of realistic two-phase immiscible viscous fingering by (1) formulating the problem based on the experimentally observed fractional flows in the fingers, which we denote as fâw, and which is the chosen simulation input; (2) from the infinite choice of relative permeability (RP) functions, kârw and kâro, which yield the same fâw, we choose the set which maximises the total mobility function, λT (where λT=λo+λw), i.e. minimises the pressure drop across the fingering system; (3) the permeability structure of the heterogeneous domain (the porous medium) is then chosen based on a random correlated field (RCF) in this case; and finally, (4) using a sufficiently fine numerical grid, but with simple transport numerics. Using our approach, realistic immiscible fingering can be simulated using elementary numerical methods (e.g. single-point upstreaming) for the solution of the two-phase fluid transport equations. The method is illustrated by simulating the type of immiscible viscous fingering observed in many experiments in 2D slabs of rock where water displaces very viscous oil where the oil/water viscosity ratio is (ÎŒo/ÎŒw)=1600. Simulations are presented for two example cases, for different levels of water saturation in the main viscous finger (i.e. for 2 different underlying fâw functions) produce very realistic fingering patterns which are qualitatively similar to observations in several respects, as discussed. Additional simulations of tertiary polymer flooding are also presented for which good experimental data are available for displacements in 2D rock slabs (Skauge et al., in: Presented at SPE Improved Oil Recovery Symposium, 14â18 April, Tulsa, Oklahoma, USA, SPE-154292-MS, 2012. https://doi.org/10.2118/154292-MS, EAGE 17th European Symposium on Improved Oil Recovery, St. Petersburg, Russia, 2013; Vik et al., in: Presented at SPE Europec featured at 80th EAGE Conference and Exhibition, Copenhagen, Denmark, SPE-190866-MS, 2018. https://doi.org/10.2118/190866-MS). The finger patterns for the polymer displacements and the magnitude and timing of the oil displacement response show excellent qualitative agreement with experiment, and indeed, they fully explain the observations in terms of an enhanced viscous crossflow mechanism (Sorbie and Skauge, in: Proceedings of the EAGE 20th Symposium on IOR, Pau, France, 2019). As a sensitivity, we also present some example results where the adjusted fractional flow (fâw) can give a chosen frontal shock saturation, Sâwf, but at different frontal mobility ratios, M(Sâwf). Finally, two tests on the robustness of the method are presented on the effect of both rescaling the permeability field and on grid coarsening. It is demonstrated that our approach is very robust to both permeability field rescaling, i.e. where the (kmax/kmin) ratio in the RCF goes from 100 to 3, and also under numerical grid coarsening.publishedVersio
Simulation, modelling and development of the metris RCA
In partnership with Metris UK we discuss the utilisation of modelling and simulation methods in the development of a revolutionary 7-axis Robot CMM Arm (RCA). An offline virtual model is described, facilitating pre-emptive collision avoidance and assessment of optimal placement of the RCA relative to scan specimens. Workspace accessibility of the RCA is examined under a range of geometrical assumptions and we discuss the effects of arbitrary offsets resulting from manufacturing tolerances. Degeneracy is identified in the number of ways a given pose may be attained and it is demonstrated how a simplified model may be exploited to solve the inverse kinematics problem of finding the âcorrectâ set of joint angles. We demonstrate how the seventh axis may be utilised to avoid obstacles or otherwise awkward poses, giving the unit greater dexterity than traditional CMMs. The results of finite element analysis and static force modelling on the RCA are presented which provide an estimate of the forces exerted on the internal measurement arm in a range of poses
Characteristics, accuracy and reverification of robotised articulated arm CMMs
VDI article 2617 specifies characteristics to describe the accuracy of articulated arm coordinate measuring machines (AACMMs) and outlines procedures for checking them. However the VDI prescription was written with a former generation of machines in mind: manual arms exploiting traditional touch probe technologies. Recent advances in metrology have given rise to noncontact laser scanning tools and robotic automation of articulated arms â technologies which are not adequately characterised using the VDI specification. In this paper we examine the âguidelinesâ presented in VDI 2617, finding many of them to be ambiguous and open to interpretation, with some tests appearing even to be optional. The engineer is left significant flexibility in the execution of the test procedures and the manufacturer is free to specify many of the test parameters. Such flexibility renders the VDI tests of limited value and the results can be misleading. We illustrate, with examples using the Nikon RCA, how a liberal interpretation of the VDI guidelines can significantly improve accuracy characterisation and suggest ways in which to mitigate this problem.
We propose a series of stringent tests and revised definitions, in the same vein as VDI 2617 and similar US standards, to clarify the accuracy characterisation process. The revised methodology includes modified acceptance and reverification tests which aim to accommodate emerging technologies, laser scanning devices in particular, while maintaining the spirit of the existing and established standards. We seek to supply robust re-definitions for the accepted terms âzero pointâ and âuseful arm lengthâ, pre-supposing nothing about the geometry of the measuring device.
We also identify a source of error unique to robotised AACMMs employing laser scanners â the forward-reverse pass error. We show how eliminating this error significantly improves the repeatability of a device and propose a novel approach to the testing of probing error based on statistical uncertainty
Reliability and Cell-to-Cell Variability of TAS-MRAM arrays under cycling conditions
The impact of 500k write cycles on 1kbits TASMRAM arrays has been evaluated by extracting a set of characteristic parameters describing the technology in terms of cell-to cell variability and switching reliability. The relationship between switching voltages and cell resistances has been investigated in order to define the most reliable working conditions
Automated characterization of TAS-MRAM test arrays
In this work the characterization results of 1kbit TAS-MRAM arrays obtained through RIFLE Automated Test Equipment of 1Kbit array are reported. Such ATE, ensuring flexibility in terms of signals and timing, allowed evaluating hysteresis and to perform 50k write cycles in a very limited time, getting a first insight on TAS-MRAM arrays performance and reliability
Exact Localized Solutions of Quintic Discrete Nonlinear Schr\"odinger Equation
We study a new quintic discrete nonlinear Schr\"odinger (QDNLS) equation
which reduces naturally to an interesting symmetric difference equation of the
form . Integrability of the symmetric mapping
is checked by singularity confinement criteria and growth properties. Some new
exact localized solutions for integrable cases are presented for certain sets
of parameters. Although these exact localized solutions represent only a small
subset of the large variety of possible solutions admitted by the QDNLS
equation, those solutions presented here are the first example of exact
localized solutions of the QDNLS equation. We also find chaotic behavior for
certain parameters of nonintegrable case.Comment: 12 pages,4 figures(eps files),revised,Physics Letters A, In pres
Addiction to Runx1 is partially attenuated by loss of p53 in the EΌ-Myc lymphoma model
The Runx genes function as dominant oncogenes that collaborate potently with
Myc or loss of p53 to induce lymphoma when over-expressed. Here we examined the
requirement for basal Runx1 activity for tumor maintenance in the E”-Myc model
of Burkittâs lymphoma. While normal Runx1fl/fl lymphoid cells permit mono-allelic
deletion, primary E”-Myc lymphomas showed selection for retention of both alleles
and attempts to enforce deletion in vivo led to compensatory expansion of p53null blasts
retaining Runx1. Surprisingly, Runx1 could be excised completely from established E”-
Myc lymphoma cell lines in vitro without obvious effects on cell phenotype. Established
lines lacked functional p53, and were sensitive to death induced by introduction of a
temperature-sensitive p53 (Val135) allele. Transcriptome analysis of Runx1-deleted
cells revealed a gene signature associated with lymphoid proliferation, survival
and differentiation, and included strong de-repression of recombination-activating
(Rag) genes, an observation that was mirrored in a panel of human acute leukemias
where RUNX1 and RAG1,2 mRNA expression were negatively correlated. Notably,
despite their continued growth and tumorigenic potential, Runx1null lymphoma cells
displayed impaired proliferation and markedly increased sensitivity to DNA damage
and dexamethasone-induced apoptosis, validating Runx1 function as a potential
therapeutic target in Myc-driven lymphomas regardless of their p53 status
Osteopontin and disease activity in patients with recent-onset systemic lupus erythematosus:results from the SLICC Inception Cohort
Objective. In cross-sectional studies, elevated osteopontin (OPN) levels have been proposed to reflect, and/or precede, progressive organ damage and disease severity in systemic lupus erythematosus (SLE). We aimed, in a cohort of patients with recent-onset SLE, to determine whether raised serum OPN levels precede damage and/or are associated with disease activity or certain disease phenotypes. Methods. We included 344 patients from the Systemic Lupus International Collaborating Clinics (SLICC) Inception Cohort who had 5 years of followup data available. All patients fulfilled the 1997 American College of Rheumatology (ACR) criteria. Baseline sera from patients and from age- and sex-matched population-based controls were analyzed for OPN using ELISA. Disease activity and damage were assessed at each annual followup visit using the SLE Disease Activity Index 2000 (SLEDAI-2K) and the SLICC/ACR damage index (SDI), respectively. Results. Compared to controls, baseline OPN was raised 4-fold in SLE cases (p < 0.0001). After relevant adjustments in a binary logistic regression model, OPN levels failed to significantly predict global damage accrual defined as SDI â„ 1 at 5 years. However, baseline OPN correlated with SLEDAI-2K at enrollment into the cohort (r = 0.27, p < 0.0001), and patients with high disease activity (SLEDAI-2K â„ 5) had raised serum OPN (p < 0.0001). In addition, higher OPN levels were found in patients with persistent disease activity (p = 0.0006), in cases with renal involvement (p < 0.0001) and impaired estimated glomerular filtration rate (p = 0.01). Conclusion. The performance of OPN to predict development of organ damage was not impressive. However, OPN associated significantly with lupus nephritis and with raised disease activity at enrollment, as well as over time
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