Frame Of Reference In Terms Research Articles

The relationship between flux coordinates and equilibrium-based frames of reference in fusion theory

The properties of two local reference frames based on the magnetic field and the current density are investigated for magnetized plasmas in toroidal geometry with a symmetric angle. The magnetic field-based local frame of reference has been well-studied, for example, by Dewar and colleagues [Phys. Fluids 27, 1723 (1984)]. An analogous frame based on the current density vector is possible because it is also divergence free and perpendicular to the gradient of the poloidal flux. The concept of straightness of a vector is introduced and used to elucidate the Boozer and Hamada coordinate systems. The relationship of these local frames to the more well-known Frenet frame of reference, which specifies a curve in terms of curvature and torsion, is given. As an example of the usefulness of this formal relationship, we briefly review the ideal MHD theory and its use. We also present a new annihilation operator, useful for eliminating shorter time scales than the time scale of interest, for deriving the inner layer equations of Glasser et al. [Phys. Fluids 18, 875 (1975)]. Compared to the original derivation that is based on the local frame of reference in terms of the magnetic field, the new annihilation operator that is based on the local frame of reference in terms of the current density simplifies the derivation.

Patient-Reported Outcome Measures of Total Knee Arthroplasties for Post-Traumatic Arthritis versus Osteoarthritis: A Short-Term (5- to 10-year) Retrospective Matched Cohort Study

BackgroundThe objective of the study was to compare the patient-reported outcome measures (PROM) of patients with post-traumatic arthritis (PTA) versus patients with osteoarthritis (OA) undergoing total knee arthroplasty (TKA) and compare the rates of revision among these two groups. MethodsUsing a prospectively held institutional registry, we retrospectively reviewed patients ≥60 years of age who underwent unilateral TKA between May 2007 and February 2012. Patients with previous or concomitant diagnosis of inflammatory arthropathy or an initial open fracture were excluded. PTA patients were matched 1:5 with OA patients undergoing TKA. Validated PROMs were recorded at baseline before index TKA and the last follow-up. Reason and time to revision surgery was reported, and survivorship was compared using Kaplan-Meier curves. ResultsSeventy-five PTA patients were matched to 375 OA patients. There was no difference between these groups with respect to age (67.7 ± 5.6 vs 67.8 ± 5.5 years; P = .876), body mass index (28.6 ± 5.4 vs 28.7 ± 5.3 kg/m2; P = .948), sex (65.3% vs 65.3% females; P = .999), Charlson Comorbidity Index (21.3% vs 21.3% Index 1-2, P = .999), and time to follow-up (93.0 ± 13.4 vs 88.2 ± 13.7 months; P = .999). No statistically significant difference was found in PROMs at baseline and the last follow-up (P > .05), the rate or time to revision surgery between the two groups (P-value = .635; log-rank test). ConclusionUnlike previous studies, TKA for PTA does not pose lower PROMs or higher revision rates when compared to TKA for OA. These results could help provide surgeons with a frame of reference in terms of expectations for patients with PTA undergoing TKA.

Quantum Walks, Weyl Equation and the Lorentz Group

Quantum cellular automata and quantum walks provide a framework for the foundations of quantum field theory, since the equations of motion of free relativistic quantum fields can be derived as the small wave-vector limit of quantum automata and walks starting from very general principles. The intrinsic discreteness of this framework is reconciled with the continuous Lorentz symmetry by reformulating the notion of inertial reference frame in terms of the constants of motion of the quantum walk dynamics. In particular, among the symmetries of the quantum walk which recovers the Weyl equation--the so called Weyl walk--one finds a non linear realisation of the Poincar\'e group, which recovers the usual linear representation in the small wave-vector limit. In this paper we characterise the full symmetry group of the Weyl walk which is shown to be a non linear realization of a group which is the semidirect product of the Poincar\'e group and the group of dilations.

Context Effects in the Evaluation of Bodily Symptoms: Comparing Three Versions of the Health Norms Sorting Task

The illness-related evaluation of bodily symptoms is considered to be an important maintaining factor in somatoform disorders. However, little is known about context variables that could influence this evaluation process. In the current study, participants completed three versions of the Health Norms Sorting Task (HNST) and evaluated bodily symptoms in different contexts (i.e., different evaluation perspectives and time frames of evaluation). Additionally, the three HNST versions were presented in different orders. Bodily symptoms were evaluated more often as a sign of illness when a specific time frame (i.e., one week) was given. However, this context effect was only large when participants had previously evaluated symptoms existing without a concrete duration. Thus, previously completed symptom evaluations appear to represent an important frame of reference in terms of a cue that makes specific context variables salient. The results further suggested that these cueing effects might be less relevant for participants with elevated somatic symptom reports.

Engineering Metrology and Measurements

The main purpose of Metrology is to increase awareness of metrology and to establish a common metrological frame of reference in terms of quality of products. It is meant to provide easy techniques to users of different tools and techniques in measurement with a transparent and handy tool to obtain metrological information. Today’s global economy depends on reliable measurements and tests, which are trusted and accepted internationally. They should not create technical barriers to trade and a precondition for this is a widely utilized and robust metrological infrastructure. The content of this book is a description of scientific, industrial and legal metrology. The technical subject fields of metrology and metrological units are described. A list of metrological terms is collected primarily from internationally recognized standards.

In-plane elastic response of two-segment circular-axis symmetric notch flexure hinges: The right circular design

Abstract This work presents a general analytical model of the planar compliances for two-segment circular-axis symmetric notch flexure hinges. Compared to a similar straight-axis flexure design, the circular-axis configuration enhances the design parameter domain by adding the median circle radius. Six compliances are formulated with respect to a central reference frame and to an end reference frame in terms of a smaller number of half-flexure compliances. The model covers both relatively large radius-to-thickness ratio designs (thin flexures) and small radius-to-thickness ratio configurations (thick flexures). The new circular-axis right circular flexure is introduced to illustrate the general model. Predictions of the analytical compliance model for this flexure were confirmed by finite element analysis and experimental testing. The analytical model is further utilized to investigate the influence of normal and shear forces in the thick-member model and to assess the accuracy of the simpler thin-beam model, which considers only bending. A comparison is also performed between the corresponding compliances of the new circular-axis flexure design and the existing straight-axis right circular flexure hinge in terms of defining geometric parameters.

Constructing Professional Portfolios: Sense‐Making and Professional Identity Development for Engineering Undergraduates

BackgroundWhile previously researching the educational impacts of single‐course and cross‐curricular portfolios, investigators noted that student participants described their portfolio activities as positively impacting their growing identities as engineering professionals. These impacts were seen particularly in studies regarding cross‐curricular portfolios. Purpose (Hypothesis)This study was designed to explicitly investigate identity‐related impacts of cross‐curricular portfolios and to explore the processes students employed during portfolio construction to identify themselves as budding engineers and as future professionals.Design/MscethodEngineering undergraduate students attended four weekly workshops where they wrote a professional statement, selected artifacts that demonstrated their engineering abilities, and wrote annotations that explained how the artifacts served as concrete examples of their claims for professional standing. Online surveys were administered at each workshop asking participants about their ongoing experiences of creating their portfolios and sharing these portfolios with their peers.ResultsAnalysis of the survey responses revealed that participants had two primary frames of reference for the construction of professional identity during portfolio creation. The external frame of reference focused on students' understanding of the expectations of potential employers and recruiters. The internal frame of reference, which accounted for twice as many responses as the external frame coding, focused on students' emerging realizations of their own values and interests as professional engineers.ConclusionsAs engineering educators, we often support the external frame of reference in terms of building professional identity. We need to provide students with opportunities to engage the internal frame of reference with which our participants were particularly concerned.

Gravitational radiation and angular momentum flux from a slowly rotating dynamical black hole

A four-dimensional asymptotic expansion scheme is used to study the next-order effects of the nonlinearity near a spinning dynamical black hole. The angular-momentum flux and energy flux formula are then obtained by constructing the reference frame in terms of the compatible constant spinors and the compatibility of the coupling leading-order Newman-Penrose equations. By using the slow rotation and small-tide approximation for a spinning black hole, the horizon cross-section we chose is spherical symmetric. It turns out the flux formula is rather simple and can be compared with the known results. Directly from the energy flux formula of the slow-rotating dynamical horizon, we find that the physically reasonable condition on requiring the positivity of the gravitational energy flux yields that the shear will monotonically decrease with time. Thus a slow-rotating dynamical horizon will asymptotically approach an isolated horizon during late time.

Age and sex differences in a virtual version of the reorientation task

Previous studies on allocentric frame of reference (FoR) have shown a substantial deficit in elderly spatial navigation. (e.g. Moffat and Resnick 2002). We referred to allocentric FoR in terms of the absence of reckoning cues in solving a spatial navigation task. Although age-related effect on navigational behaviour has been already evaluated in previous studies (e.g. Driscoll et al. 2005), rarely the impact of both layout and featural information has been systematically assessed. Acquisition and use of knowledge regarding the environment are fundamental to effective everyday functioning and, consequently, have a critical impact on the quality of life, particularly for elderly adults. A general aim of this study is to investigate the different weight of layout and featural information in a virtual version of reorientation paradigm (VReor) adopting an individual difference perspective. Virtual environments have been successfully employed in research involving both children (e.g. Newhouse et al. 2007) and elderly (Moffat and Resnick 2002). Benefits in the employment of virtual reality technologies can be summed as follows: (a) improvement in experimental control, with the advantage to create realistic, interactive three-dimensional environments, and to collect a large amount of reliable data, (b) maintained ecological validity with respect to real-world settings, (c) opportunity to investigate spatial navigation strategies in samples showing different characteristics, such as aged people and people with cognitive impairments and psychopathological conditions. In line with the aforementioned theoretical framework, this paper accounted for the following ideas: first, the layout information remains stable along lifespan, because it seems to be linked to a more implicit perception of space, the use of featural information is less stable along life-span, and it tends to corrupt earlier with age. Second, males rely predominantly on layout information, while featural information is used equally by both males and females.

A multigrid Navier-Stokes CFD code for rotor computations

This paper presents the development of a multigrid Navier-Stokes code TLNS3DR for rotary wing calculations. The TLNS3DR is developed from the fixed-wing TLNS3D code by including a rotation term and making necessary modifications on boundary conditions. The TLNS3D code solves the thin-layer Navier-Stokes equations using an explicit multistage Runge-Kutta type of time stepping with multigrid method. The TLNS3DR code reformulates the TLNS3D code in the rotor blade-fixed moving frame of reference and solves relative motion of fluids. In this paper, the formulation of the Navier-Stokes equations in the moving frame of reference in terms of relative velocity is given. Several numerical examples are then presented. The results of rotor blade in hover calculated by the new TLNS3DR code seem quantitative correct. The computation also shows that this multigrid code is efficient.

Effects of frame of reference on the judgments of whole-body vibration intensity

Although the concept of the term 'riding comfort' is ambiguous, in the present paper it means a perceptual experience derived from the vibrational factors of a running railway vehicle. When we regard riding comfort evaluation as a perceptual judgment process, we must consider that what is perceived is dependent not only on the physical properties of the stimuli, but also on the frame of reference. The purpose of the present study is to examine the effect of the frame on the judgments of vibration intensity in the anchoring effect paradigm. Using the four-axis vibration apparatus, we conducted experiments for eighty subjects, in which frequencies and lateral accelerations of vibrations were changed. As the result, we found a clear anchoring effect. This suggests that we must take into consideration effects of frame of reference in terms of riding comfort criterion of railway vehicles.

SIMULATION OF NITRIFICATION AND DENITRIFICATION PROCESSES IN A TIDAL RIVER

Nitrification and denitrification processes in a well mixed tidal river in Japan are modeled, based on results of long term field observation on water quality and sediments in the river. Laboratory test results and values in references are used for the determination of parameters and coefficients in the model. In modeling of the processes, sediments, suspended solids, and overlying water are taken as elements and in computation a Lagrangian reference frame in terms of accumulated water volume is employed for reduction in numerical dispersion. Simulation results on ammonium and nitrate nitrogen, showing good agreement with long term field observation results, qualitatively explain well the processes in the river. The results indicate some countermeasures to reduce nitrate more such as the increase in the area of sediment surface. The simulation model is available for the estimation of water quality in well mixed tidal rivers and applicable for water quality control.

Nuclear shape and pairing vibrations in the presence of fast rotation

First, the nuclear shape vibrations of a liquid drop in the presence of fast rotation are analysed. Second, the RPA dispersion equations are derived for a rotating nuclear system. Third, the interplay between nuclear shape- and pairing vibrations is studied in the rotating frame of reference in terms of an exactly solvable model. As a result, some qualitative conclusions concerning the vibrations in a rotating nucleus are drawn.

A general mathematical model for balanced global isostasy

A general mathematical model of balanced global isostasy is presented that describes the geometrical relationships among atmospheric, oceanic, lithospheric, and asthenospheric components relative to a fixed, external frame of reference in terms of 19 parameters of mass, density, area, and thickness in five basic equations and various corollaries. The model is applicable and necessary for evaluating lithospheric processes that operate on a global scale or that affect globally oriented parameters such as sea level, freeboard, and ocean basin depth. It also provides a means of testing the internal consistency of a given set of mass, density, volume, and area parameters relative to present crustal geometry by showing how well they combine to predict present continental free-board. With modification, the basic model can be used to examine more complex questions involving glacially induced sea level fluctuations and long-term crustal evolution resulting from differential energy flux to Earth, short-term modulation of heat flux from the asthenosphere, and long-term monotonic cooling.

Time Domain Response of Induction Motors with PWM Supplies

Induction motors may be excited by rectangular voltage waves which are pulsewidth modulated according to a wide variety of strategies. The determination of performance directly in the time domain has hitherto been regarded as a complex task requiring considerable mathematical knowledge, and solution in the frequency domain has been preferred. The way is described in which the time domain response can be generated by any engineer with some programming experience provided there is access to a computer with subroutines which produce system eigenvalues and eigenvectors and which permit the manipulation of complex matrices. The solution is generated directly in the stator three-phase reference frame in terms of the stator phase currents. Transformation of stator variables to an orthogonal reference frame or so as to diagonalize the system matrix is not required. A key to the solution is the generation of two switching arrays which define the switching instants and voltage levels of the voltage waveforms applied to the machine. The switching instants can be random, pseudorandom, or follow a specific pattern. The method can therefore be applied to sinusoidally modulated waves where the ratio of carrier-to-signal frequency is nonintegral or even irrational and to the transition from pure PWM to pure six-step through the intermediate stages involving dwell time limiting. The solution can either be transient, following the behavior from some specified starting point, or steady-state where the starting point is unknown but the excitation follows a recurring sequence of arbitrary length. Sample computations are given.

Bereavement: the Contribution of Phenomenological and Existential Analysis to a Greater Understanding of the Problem

SUMMARY Theoretical approaches to grief and mourning have emphasized the instinctual and biological elements of a person's response to bereavement. The behaviour of bereaved individuals has therefore been interpreted on the basis of these theoretical models. This paper argues that an appreciation of the social context in which bereavement occurs leads to a fuller understanding of observed responses in such a situation. It thus em phasizes the social nature of individuals rather than their biological make-up and provides a theoretical frame of reference in terms of which this may be understood. Such an analysis also has implications for the kind of help which is seen to be appropriate to the needs of bereaved people. It is suggested that social workers should develop a greater understanding of this approach and that, on the basis of this, they would then have a particular role to play in relation to this area of need.

Doppler Shift in a Plasma*

It is first shown that the ideal electron plasma (presence of protons neglected) is unique among all dispersive media in that it does not distinguish any inertial frame of reference in terms of utility. The theory of the Doppler shift in an ideal plasma is then developed by simultaneous employment of two inertial frames of reference. In this way, certain remnants of paradoxes in the literature, such as energy dissipation for emitter frequencies greater than the plasma frequency, are removed. The theory is then extended by applying the principle of conservation of frequency. This makes it possible to establish the relation between the emitted and received frequency of an emitter and receiver which move at arbitrary speeds through a plasma that may be heterogeneous and may display unremovable anisotropy because of flow fields that cannot be eliminated by transformations.

Methodological Problems in Social Disorganization

T HE FIRST problem which confronts one in the study of social disorganization is that of finding a suitable frame of reference in terms of which to make the analysis. This involves both the definition of what constitutes social disorganization and the setting up of a conceptual scheme in terms of which all the several forms of social disorganization become explainable as variations upon a common theme. In the attempt to define what constitutes social disorganization two divergent philosophical premises operate: one leads to the definition of social disorganization as a condition; the other to its definition as a process. The consequence is that the conception and definition of social disorganization differs radically in terms of the basic assumptions with regard to the nature of social reality. As a condition, social disorganization has been analyzed in terms of social problems, social pathology, and social disease. The distinctive characteristic of this approach is that certain conditions are looked upon as inimical to social welfare and call for concerted action on the part of the group in order to eliminate these conditions. What constitutes a social problem is, therefore, a matter of judgment as to what constitutes social welfare. In turn, social welfare tends to be a subjective concept unless some device can be evolved for eliminating its evaluative character. In general, the various attempts to eliminate the subjective character of the distinction between what is and is not a social problem may be differentiated into three approaches: (i) definition in terms of group consciousness, (2) the operational approach, and (3) the cultural lag hypothesis. Each of these approaches leads to greater objectivity than that obtained through the naive definition of a social problem as any condition which someone judges to be contrary to social welfare. None of the three, however, entirely eliminates the necessity of making subjective judgments. The identification of a social problem in terms of group awareness that a social situation exists about which something ought to be done is obviously more objective in character than the isolated judgment of an individual, yet it is quite apparent that group awareness in most instances, if not in all, is generated out of individual awareness. This raises the question, accordingly, how are the essential conditions of social reality changed in the process of converting an individual judgment into a collective judgment? Furthermore, what proportion of the group has to come to accept the situation as a