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Physical Domain (physical + domain)
Selected AbstractsAdaptive and Feature-Preserving Subdivision for High-Quality Tetrahedral MeshesCOMPUTER GRAPHICS FORUM, Issue 1 2010D. Burkhart I.3.5 [Computer Graphics]: Curve, surface, solid, and object representations Abstract We present an adaptive subdivision scheme for unstructured tetrahedral meshes inspired by the, -subdivision scheme for triangular meshes. Existing tetrahedral subdivision schemes do not support adaptive refinement and have traditionally been driven by the need to generate smooth three-dimensional deformations of solids. These schemes use edge bisections to subdivide tetrahedra, which generates octahedra in addition to tetrahedra. To split octahedra into tetrahedra one routinely chooses a direction for the diagonals for the subdivision step. We propose a new topology-based refinement operator that generates only tetrahedra and supports adaptive refinement. Our tetrahedral subdivision algorithm is motivated by the need to have one representation for the modeling, the simulation and the visualization and so to bridge the gap between CAD and CAE. Our subdivision algorithm design emphasizes on geometric quality of the tetrahedral meshes, local and adaptive refinement operations, and preservation of sharp geometric features on the boundary and in the interior of the physical domain. [source] Quality of life in chronic hemodialysis patients in RussiaHEMODIALYSIS INTERNATIONAL, Issue 3 2006Irina A. VASILIEVA Abstract The aim of this cross-sectional study was to compare health-related quality of life (HRQOL) of Russian hemodialysis (HD) patients with the general population and international data, and to determine factors influencing HRQOL. One thousand forty-seven HD patients from 6 dialysis centers were studied (576 male, age 43.5±12.5 years, HD duration 55.0±47.2 months). Health-related quality of life was evaluated by SF-36. Self-appraisal Depression Scale (W. Zung), State-Trait Anxiety Inventory, and Level of Neurotic Asthenia Scale were used. Hemodialysis patients scored significantly lower than the general Russian population in the majority of SF-36 scales. The only exception was the Mental Health score, which was even better than the general population. The Mean physical component score (PCS) of HD patients was 36.9±9.7, and the mental component score was (MCS) 44.2±10.5. In multiple linear regression analysis, increasing age, HD duration, depression level and number of days of hospitalization in the past 6 months were significant independent predictors of low PCS along with a low level of serum albumin. Advancing age was also a predictive factor for low MCS along with increase of HD duration, depression level, trait anxiety, and level of asthenia. As far as we know, this is the first study to report on HRQOL of a large sample of Russian HD patients performed using SF-36. Compared with the general population, Russian HD patients had significantly lower scores on the majority of SF-36 scales, especially in the physical domain. The mean PCS and MCS were comparable with European data for HD patients. A number of demographic, clinical, and psychological variables affect HRQOL. [source] Discrete singular convolution methodology for free vibration and stability analyses of arbitrary straight-sided quadrilateral platesINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING, Issue 11 2008Ömer Civalek Abstract A new discrete singular convolution (DSC) method is developed for vibration, buckling and static analyses of arbitrary straight-sided quadrilateral plates. The straight-sided quadrilateral domain is mapped into a square domain in the computational space using a four-node element. By using the geometric transformation, the governing equations and boundary conditions of the plate are transformed from the physical domain into a square computational domain. Numerical examples illustrating the accuracy and convergence of the DSC method for straight-sided quadrilateral thin plates such as rectangular, skew, trapezoidal and rhombic plates are presented. The results obtained by the DSC method were compared with those obtained by the other numerical and analytical methods. Copyright © 2007 John Wiley & Sons, Ltd. [source] An interpolation-based local differential quadrature method to solve partial differential equations using irregularly distributed nodesINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING, Issue 7 2008Hang Ma Abstract To circumvent the constraint in application of the conventional differential quadrature (DQ) method that the solution domain has to be a regular region, an interpolation-based local differential quadrature (LDQ) method is proposed in this paper. Instead of using regular nodes placed on mesh lines in the DQ method (DQM), irregularly distributed nodes are employed in the LDQ method. That is, any spatial derivative at a nodal point is approximated by a linear weighted sum of the functional values of irregularly distributed nodes in the local physical domain. The feature of the new approach lies in the fact that the weighting coefficients are determined by the quadrature rule over the irregularly distributed local supporting nodes with the aid of nodal interpolation techniques developed in the paper. Because of this distinctive feature, the LDQ method can be consistently applied to linear and nonlinear problems and is really a mesh-free method without the limitation in the solution domain of the conventional DQM. The effectiveness and efficiency of the method are validated by two simple numerical examples by solving boundary-value problems of a linear and a nonlinear partial differential equation. Copyright © 2007 John Wiley & Sons, Ltd. [source] A parallel implicit/explicit hybrid time domain method for computational electromagneticsINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 8 2009Z. Q. Xie Abstract The numerical solution of Maxwell's curl equations in the time domain is achieved by combining an unstructured mesh finite element algorithm with a cartesian finite difference method. The practical problem area selected to illustrate the application of the approach is the simulation of three-dimensional electromagnetic wave scattering. The scattering obstacle and the free space region immediately adjacent to it are discretized using an unstructured mesh of linear tetrahedral elements. The remainder of the computational domain is filled with a regular cartesian mesh. These two meshes are overlapped to create a hybrid mesh for the numerical solution. On the cartesian mesh, an explicit finite difference method is adopted and an implicit/explicit finite element formulation is employed on the unstructured mesh. This approach ensures that computational efficiency is maintained if, for any reason, the generated unstructured mesh contains elements of a size much smaller than that required for accurate wave propagation. A perfectly matched layer is added at the artificial far field boundary, created by the truncation of the physical domain prior to the numerical solution. The complete solution approach is parallelized, to enable large-scale simulations to be effectively performed. Examples are included to demonstrate the numerical performance that can be achieved. Copyright © 2009 John Wiley & Sons, Ltd. [source] Numerical method for calculation of the incompressible flow in general curvilinear co-ordinates with double staggered gridINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Issue 12 2003A. Shklyar Abstract A solution methodology has been developed for incompressible flow in general curvilinear co-ordinates. Two staggered grids are used to discretize the physical domain. The first grid is a MAC quadrilateral mesh with pressure arranged at the centre and the Cartesian velocity components located at the middle of the sides of the mesh. The second grid is so displaced that its corners correspond to the centre of the first grid. In the second grid the pressure is placed at the corner of the first grid. The discretized mass and momentum conservation equations are derived on a control volume. The two pressure grid functions are coupled explicitly through the boundary conditions and implicitly through the velocity of the field. The introduction of these two grid functions avoids an averaging of pressure and velocity components when calculating terms that are generated in general curvilinear co-ordinates. The SIMPLE calculation procedure is extended to the present curvilinear co-ordinates with double grids. Application of the methodology is illustrated by calculation of well-known external and internal problems: viscous flow over a circular cylinder, with Reynolds numbers ranging from 10 to 40, and lid-driven flow in a cavity with inclined walls are examined. The numerical results are in close agreement with experimental results and other numerical data. Copyright © 2003 John Wiley & Sons, Ltd. [source] Numerical simulation of vortical ideal fluid flow through curved channelINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Issue 11 2003N. P. Moshkin Abstract A numerical algorithm to study the boundary-value problem in which the governing equations are the steady Euler equations and the vorticity is given on the inflow parts of the domain boundary is developed. The Euler equations are implemented in terms of the stream function and vorticity. An irregular physical domain is transformed into a rectangle in the computational domain and the Euler equations are rewritten with respect to a curvilinear co-ordinate system. The convergence of the finite-difference equations to the exact solution is shown experimentally for the test problems by comparing the computational results with the exact solutions on the sequence of grids. To find the pressure from the known vorticity and stream function, the Euler equations are utilized in the Gromeka,Lamb form. The numerical algorithm is illustrated with several examples of steady flow through a two-dimensional channel with curved walls. The analysis of calculations shows strong dependence of the pressure field on the vorticity given at the inflow parts of the boundary. Plots of the flow structure and isobars, for different geometries of channel and for different values of vorticity on entrance, are also presented. Copyright © 2003 John Wiley & Sons, Ltd. [source] A ,-coordinate three-dimensional numerical model for surface wave propagationINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Issue 11 2002Pengzhi Lin Abstract A three-dimensional numerical model based on the full Navier,Stokes equations (NSE) in , -coordinate is developed in this study. The , -coordinate transformation is first introduced to map the irregular physical domain with the wavy free surface and uneven bottom to the regular computational domain with the shape of a rectangular prism. Using the chain rule of partial differentiation, a new set of governing equations is derived in the , -coordinate from the original NSE defined in the Cartesian coordinate. The operator splitting method (Li and Yu, Int. J. Num. Meth. Fluids 1996; 23: 485,501), which splits the solution procedure into the advection, diffusion, and propagation steps, is used to solve the modified NSE. The model is first tested for mass and energy conservation as well as mesh convergence by using an example of water sloshing in a confined tank. Excellent agreements between numerical results and analytical solutions are obtained. The model is then used to simulate two- and three-dimensional solitary waves propagating in constant depth. Very good agreements between numerical results and analytical solutions are obtained for both free surface displacements and velocities. Finally, a more realistic case of periodic wave train passing through a submerged breakwater is simulated. Comparisons between numerical results and experimental data are promising. The model is proven to be an accurate tool for consequent studies of wave-structure interaction. Copyright © 2002 John Wiley & Sons, Ltd. [source] A Lagrangian boundary element approach to transient three-dimensional free surface flow in thin cavitiesINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Issue 4 2001Jie Zhang Abstract The lubrication theory is extended for transient free-surface flow of a viscous fluid inside a three-dimensional thin cavity. The problem is closely related to the filling stage during the injection molding process. The pressure, which in this case is governed by the Laplace's equation, is determined using the boundary element method. A fully Lagrangian approach is implemented for the tracking of the evolving free surface. The domain of computation is the projection of the physical domain onto the (x,,y) plane. This approach is valid for simple and complex cavities as illustrated for the cases of a flat plate and a curved plate. It is found that the flow behavior is strongly influenced by the shape of the initial fluid domain, the shape of the cavity, and inlet flow pressure. Copyright © 2001 John Wiley & Sons, Ltd. [source] A Randomized, Controlled Trial of Fall Prevention Programs and Quality of Life in Older FallersJOURNAL OF AMERICAN GERIATRICS SOCIETY, Issue 4 2007Mau-Roung Lin PhD OBJECTIVES: To compare the effects of three fall-prevention programs (education (ED), home safety assessment and modification (HSAM), and exercise training (ET)) on quality of life (QOL), functional balance and gait, activities of daily living (ADLs), fear of falling, and depression in adults aged 65 and older. DESIGN: A 4-month randomized trial. SETTING: Randomized, controlled trial. PARTICIPANTS: One hundred fifty participants who had experienced a recent fall. MEASUREMENTS: QOL was assessed according to the brief version of the World Health Organization Quality of Life instrument (WHOQOL-BREF), functional balance and gait according to functional reach and Tinetti balance and gait, ADLs according to the Older Americans Resources and Services questionnaire, fear of falling according to a visual analog scale, and depression level according to the Geriatric Depression Scale. RESULTS: The score changes for the ET group were 2.1 points greater on the physical domain (95% confidence interval (CI)=,1.2,5.3), 3.8 points greater on the psychological domain (95% CI=0.7,7.0), and for the WHOQOL-BREF, 3.4 points greater on the social domain (95% CI=0.7,6.1) and 3.2 points greater on the environmental domain (95% CI=0.6,5.7) than for the ED group. The score change for each domain of the WHOQOL-BREF for the HSAM group was greater than that for the ED group, although these results were not statistically significant. The ET group also had greater improvements in functional reach, Tinetti balance and gait, and fear of falling than the ED group. CONCLUSION: The QOL outcome supports the superiority of ET over the other two interventions in older people who have recently fallen. This finding also parallels those gathered from the functional measures. [source] Doing social volcanology: exploring volcanic culture in IndonesiaAREA, Issue 1 2010Katherine Donovan Social volcanology refers to the integration of social science research methods into the traditionally physical domain of volcanology. This emerging multi-methodological research area draws from many disciplines in order to examine hazard-mitigation strategies that are community focused. A key facet of social volcanology is the role of culture and this paper explores the influence of traditional cultural values in relation to the 2006 volcanic crisis at Mt Merapi (Java). This paper describes the complex amalgam of cultural and socio-economic factors that influence community reactions to volcanic hazards and demonstrates the need for interdisciplinary hazard research. [source] Perceptual Causality in ChildrenCHILD DEVELOPMENT, Issue 6 2002Anne Schlottmann Three experiments considered the development of perceptual causality in children from 3 to 9 years of age (N= 176 in total). Adults tend to see cause and effect even in schematic, two,dimensional motion events: Thus, if square A moves toward B, which moves upon contact, they report that A launches B,physical causality. If B moves before contact, adults report that B tries to escape from A,social or psychological causality. A brief pause between movements eliminates such impressions. Even infants in the first year of life are sensitive to causal structure in both contact and no,contact events, but previous research with talking,age children found poor verbal reports. The present experiments used a picture,based forced,choice task to reduce linguistic demands. Observers saw eight different animations involving squares A and B. Events varied in whether or not these agents made contact; whether or not there was a delay at the closest point; and whether they moved rigidly or with a rhythmic, nonrigid "caterpillar" motion. Participants of all ages assigned events with contact to the physical domain and events without contact to the psychological domain. In addition, participants of all ages chose causality more often for events without delay than with delay, but these events became more distinct over the preschool range. The manipulation of agent motion had only minor and inconsistent effects across studies, even though children of all ages considered only the nonrigid motion to be animal,like. These results agree with the view that perceptual causality is available early in development. [source] Patients with Hip Fracture: Subgroups and Their OutcomesJOURNAL OF AMERICAN GERIATRICS SOCIETY, Issue 7 2002Elizabeth A. Eastwood PhD OBJECTIVES: To present several alternative approaches to describing the range and functional outcomes of patients with hip fracture. DESIGN: Prospective study with concurrent medical records data collection and patient and proxy interviews at the time of hospitalization and 6 months later. SETTING: Four hospitals in the New York metropolitan area. PARTICIPANTS: Five hundred seventy-one hospitalized adults aged 50 and older with hip fracture between July 1997 and August 1998. MEASUREMENTS: Rates of return to function in four physical domains, mortality, and nursing home residence at 6 months. Cluster analysis was used to describe the heterogeneity among the sample and identify variations in 6-month mortality, nursing home residence, and level of functioning and to develop a patient classification tree with associated patient outcomes at 6 months postfracture. RESULTS: In locomotion, transfers, and self-care, 33% to 37% of patients returned to their prior level of function by 6 months, including those needing assistance, but only 24% were independent in locomotion at 6 months. Cluster analysis identified eight patient subgroups that had distinct baseline features and variable outcomes at 6 months. The patient classification tree used four variables: atypical functional status (independent in locomotion but dependent in other domains); nursing home residence; independence/dependence in self-care; and age younger than 85 or 85 and older that identified five subgroups with variable 6-month outcomes that clinicians may use to predict likely outcomes for their patients. CONCLUSION: Patients with hip fracture are heterogeneous with respect to baseline and outcome characteristics. Clinicians may be better able to give patients and caregivers information on expected outcomes based on presenting characteristics used in the classification tree. [source] Systematic review: impact of constipation on quality of life in adults and childrenALIMENTARY PHARMACOLOGY & THERAPEUTICS, Issue 9 2010J. BELSEY Aliment Pharmacol Ther,31, 938,949 Summary Background, Comparison of quality of life (QoL) across disease areas requires the use of appropriate tools. Although many studies have investigated QoL in constipation, most used disease-specific tools that are inappropriate for cross-comparisons. Aims, To identify studies of QoL in constipation and to compare these results with other chronic conditions. Methods, A comprehensive literature search identified studies in constipation that used a generic QoL tool. Results were statistically pooled where possible and compared with published results using the same tools in other chronic conditions. Results, A total of 13 qualifying studies were identified, 10 in adults and three in children. Results from eight studies using the SF-36/12 tools were pooled; the remaining five were narratively reported. Mental and physical components of QoL scores were consistently impaired in both adult and child populations, with the greatest impact being seen in secondary care studies. Mental health effects predominated over physical domains. The magnitude of impact was comparable with that seen in patients with allergies, musculoskeletal conditions and inflammatory bowel disease. Conclusions, The impact of constipation on QoL is significant and comparable with other common chronic conditions. Improving management may prove to be an effective way of improving QoL for a substantial number of patients. [source] Properties of discrete Chebyshev collocation differential operators in curvilinear geometriesNUMERICAL LINEAR ALGEBRA WITH APPLICATIONS, Issue 8 2008P. Pironkov Abstract The properties of discrete systems resulting from spectral Chebyshev collocation discretizations are investigated with respect to the solution efficiency of corresponding solvers. Complex geometries are encountered by a mapping technique to connect computational and physical domains. Several representative transformation techniques are considered. The influences of the differential operators, the boundary conditions, the geometry, and the number of grid points are systematically studied. The convergence properties of the BiCGSTAB method when iteratively solving the discrete systems are investigated. Copyright © 2008 John Wiley & Sons, Ltd. [source] Does Externalism Entail the Anomalism of the Mental?THE PHILOSOPHICAL QUARTERLY, Issue 211 2003Nicholas Shea In ,Mental Events' Donald Davidson argued for the anomalism of the mental on the basis of the operation of incompatible constitutive principles in the mental and physical domains. Many years later, he has suggested that externalism provides further support for the anomalism of the mental. I examine the basis for that claim. The answer to the question in the title will be a qualified ,Yes'. That is an important result in the metaphysics of mind and an interesting consequence of externalism. [source] Believing in the purpose of events,why does it occur, and is it supernatural?APPLIED COGNITIVE PSYCHOLOGY, Issue 2 2010Annika M. Svedholm What is the cognitive basis for the common belief that random events have a purpose, and are these beliefs a form of supernatural thinking, as Bering has suggested? Two questionnaire studies with Finnish volunteer participants (N,=,2650, 1830 females, mean age 26) used structural equation modelling (SEM) to test the hypotheses that beliefs in the purpose of events are part of the same phenomenon as paranormal beliefs and that confusions of core knowledge of the psychological, biological and physical domains predict both sets of beliefs. In Study 1, participants were not given a definition of purpose, and in Study 2, purpose was explicitly defined as entailing planning by a supernatural agent. The results from both studies supported the predictions. The results indicate that construing events in terms of purpose is not a universal tendency but an individual cognitive bias that can be accounted for by false analogies from intuitive psychology, biology and physics. Copyright © 2009 John Wiley & Sons, Ltd. [source] Factors influencing quality of life in multiple sclerosis patients: disability, depressive mood, fatigue and sleep qualityACTA NEUROLOGICA SCANDINAVICA, Issue 1 2004I. S. Lobentanz Objectives , In a series of 504 patients with multiple sclerosis (MS), quality of life (QOL) and its main clinical and demographic determinants were assessed in comparison with healthy individuals. Materials and methods , A postal questionnaire with self-completed measures of disability (Expanded Disability Status Scale, EDSS), QOL (Quality of Life Index, QLI), depressive mood (Self-rating Depression Scale, SDS), fatigue severity (Fatigue Severity Scale, FSS) and sleep quality (Pittsburgh Sleep Quality Index, PSQI) was sent to this sample of MS patients. Results , Most patients were severely disabled; almost half were mildly to severely depressed, suffering from reduced sleep quality and/or fatigue. The multiple sclerosis patients had significantly lower QLI scores than healthy controls. EDSS and SDS scores were found to be predictors of global QLI score. Regarding the different QLI domains, mean SDS scores remained predictive for all QLI items, while mean EDSS, PSQI and FSS scores were only predictive for physical domains. Conclusion , Our study clearly demonstrates that depressive mood is the main factor influencing QOL. The disability status, fatigue and reduced sleep quality have an impact mainly on physical domains of life quality. [source] Agreement between parent and child report of quality of life in children with attention-deficit/hyperactivity disorderCHILD: CARE, HEALTH AND DEVELOPMENT, Issue 4 2006A. F. Klassen Abstract Background There is little information in the research literature of agreement between parent and child in reports of child quality of life (QOL) for a sample of children diagnosed with attention-deficit/hyperactivity disorder (ADHD). The aim of our study was to determine whether parent and child concordance is greater for physical domains of QOL than for psychosocial domains; whether parents rate their child's QOL better or poorer than their child's ratings; and whether concordance is related to demographic, socioeconomic or clinical factors. Methods The study was a questionnaire survey of children aged 10,17 referred to the ADHD clinic and diagnosed with ADHD in the province of British Columbia (Canada) between November 2001 and October 2002 and their parent. Results Fifty-eight children diagnosed with ADHD and their parents completed our study questionnaire. The main outcome measure was the Child Health Questionnaire, which permitted comparisons on eight QOL domains and one single item. Intraclass correlation coefficients were moderate for five domains (range from 0.40 to 0.51), and good for three domains (range from 0.60 to 0.75). Children rated their QOL significantly better than their parents in four areas and poorer in one. Standardized Response Means indicated clinically important differences in mean scores for Behaviour and Self-esteem. Compared with population norms, across most domains, children with ADHD reported comparable health. Discrepancies between parent,child ratings were related to the presence of a comorbid oppositional/defiant disorder, a psychosocial stressor and increased ADHD symptoms. Conclusions Although self-report is an important means of eliciting QOL data, in children with ADHD, given the discrepancies in this study between parent and child report, measuring both perspectives seems appropriate. [source] | |||||||||||||||||||