Current Reference Frame Research Articles

Investigation of crustal motion in Europe by analysing the European VLBI sessions

Since 1990 the International VLBI Service for Geodesy and Astrometry (IVS) has been performing geodetic Very Long Baseline Interferometry (VLBI) observations within the European geodetic VLBI network. In this work, 114 European VLBI sessions from January 1990 to September 2011 are analysed using the Vienna VLBI Software (VieVS). A total of 58 baselines with lengths ranging from 59 m to 4581 km are investigated and the lengths of most of them indicate repeatabilities at the sub-centimetre level. The horizontal station motions which describe the motion of the Eurasian plate are compared to the NUVEL-1A and MORVEL tectonic plate models. Intraplate crustal motions are investigated by estimating the station velocities with respect to Wettzell (Germany), a station on the geodynamically stable part of Eurasia. The northern part of Europe is dominated by the postglacial isostatic rebound, confirmed by four VLBI sites in this region with an uplift from 2.89±0.71 mm/yr (Svetloe, Russia) to 7.23±1.00 mm/yr (Ny-Alesund, Norway) with respect to the central part of the European plate. Besides the vertical uplift, these radio telescopes evidence a horizontal motion from the centre of the former ice sheet towards its border. In the southern part of Europe the motion of the VLBI sites is caused by the collision of the African plate with the Eurasian plate, while the stations on the stable part of Europe do not present any significant relative motions. Our results are compared against those by Haas et al. (J. Geodyn. 35:391–414, 2003) and with velocities of the current reference frame of the International Global Navigation Satellite Systems Service.

A decade of horizontal deformation from great earthquakes

The 21st Century has seen the occurrence of 17 great earthquakes (Mw >8), including some of the largest earthquakes ever recorded. Numerical modeling of the earthquakes shows that nearly half of the Earth's surface has undergone horizontal coseismic deformation >1 mm, with the 2004 Sumatra‐Andaman earthquake dominating the global deformation field. This has important implications for both the realization of a terrestrial reference frame and in the interpretation of regional tectonic studies based on GPS velocities. We show that far‐field coseismic deformations from great earthquakes will, if unaccounted for, introduce errors in estimates of linear site velocities of at least 0.1‐0.3 mm/yr across most of the surface of the Earth. The accumulated global deformation field shows that two regions, Australia and the north Atlantic/Arctic Ocean, have been largely undeformed by these great earthquakes, with accumulated deformations generally <0.5 mm. Using GPS estimates of surface deformation, we show that the majority of the Australian continent is deforming at <0.2 mm/yr, the northern part of New Zealand is rotating clockwise relative to the Australian Plate with relative horizontal velocities of ∼2 mm/yr, while the southeastern coast of Australia is undergoing post‐seismic relaxation caused by the 2004 Mw = 8.1 Macquarie Ridge earthquake. The presence of ongoing post‐seismic relaxation thousands of kilometers from plate margins violates the secular/linear assumption made in current terrestrial reference frame definitions. These effects have significant ramifications for regional tectonic interpretations and global studies such as sea level rise that require reference frame accuracy greater than this level.

Ventromedial Prefrontal and Anterior Cingulate Cortex Adopt Choice and Default Reference Frames during Sequential Multi-Alternative Choice

Although damage to the medial frontal cortex causes profound decision-making impairments, it has been difficult to pinpoint the relative contributions of key anatomical subdivisions. Here we use function magnetic resonance imaging to examine the contributions of human ventromedial prefrontal cortex (vmPFC) and dorsal anterior cingulate cortex (dACC) during sequential choices between multiple alternatives--two key features of choices made in ecological settings. By carefully constructing options whose current value at any given decision was dissociable from their longer term value, we were able to examine choices in current and long-term frames of reference. We present evidence showing that activity at choice and feedback in vmPFC and dACC was tied to the current choice and the best long-term option, respectively. vmPFC, mid-cingulate, and posterior cingulate cortex encoded the relative value between the chosen and next best option at each sequential decision, whereas dACC encoded the relative value of adapting choices from the option with the highest value in the longer term. Furthermore, at feedback we identify temporally dissociable effects that predict repetition of the current choice and adaptation away from the long-term best option in vmPFC and dACC, respectively. These functional dissociations at choice and feedback suggest that sequential choices are subject to competing cortical mechanisms.

LUNAR CARTOGRAPHY: PROGRESS IN THE 2000S AND PROSPECTS FOR THE 2010S

LUNAR CARTOGRAPHY: PROGRESS IN THE 2000S AND PROSPECTS FOR THE 2010S

Changing teachers’ perceptions about the writing abilities of emerging bilingual students: towards a holistic bilingual perspective on writing assessment

This study explored the application of a holistic bilingual view to assess the writing of emerging bilingual children. The study is part of a 5-year longitudinal research and intervention project that explores the biliteracy development of Spanish–English emerging bilingual students who are receiving instruction in both languages. Participants included 36 bilingual teachers who were part of the project. Teachers evaluated student writing samples using a writing rubric developed for the project. They were trained to evaluate students’ Spanish and English language writing samples in a manner that allowed for cross-language comparison and analysis. A total of 216 writing samples produced by students from grades 1–5 were analyzed. Findings from this study suggest the need to train teachers to evaluate the writing of emerging bilingual children in ways that both challenge and expand on their current frames of reference. This paper posits that the utilization of a holistic bilingual lens to evaluate the writing of Spanish–English emerging bilingual children is a more robust and valid means of understanding language and biliteracy development in these children. Furthermore, a holistic bilingual lens can be useful in changing teacher perceptions about children's biliteracy, thereby enhancing instruction.

Construction clients’ ability to manage uncertainty and equivocality

While risk and uncertainty management have received much attention within construction management research, management of information interpretation remains unexplored. Situations that are generally overlooked are those where increased amounts and flow of information are not the solution to the human problem of managing multiple meanings of information and conflicting interpretations, i.e. ‘equivocality’. The aim is to identify and differentiate between construction clients’ uncertainty and equivocality about industrialized construction in Sweden, and, in the light of those findings, to evaluate clients’ current information processing practice on investment decisions in new-build in order to assess and discuss clients’ ability to manage uncertainty and equivocality. Based on information processing theory, analysis of aggregated data from three previous studies shows that there is a need to manage both uncertainty and equivocality. At the same time, clients’ ability to do this is found to be limited. Consequently, when industrialized construction moves clients beyond their current frame of reference, clients’ information processing practice does not support decision making. It is also proposed that differentiating between uncertainty and equivocality will enable a more profound understanding of the sequential order for information processing, i.e. that one must define questions (reduce equivocality) before one can find answers to the questions (reduce uncertainty).

Value, Impact, and the Transcendent Library: Progress and Pressures in Performance Measurement and Evaluation

Libraries are under pressure to prove their worth and may not have achieved this fully successfully. There is a resultant growing requirement for value and impact measurement in academic and research libraries. This essay reviews the natural history of library performance measurement and suggests that proof of worth will be measured by the higher-order beneficial effects that libraries deliver. Evaluation within current frames of reference will therefore be insufficient. Compelling proof will reside in transcendent contribution beyond immediate temporal, spatial, and influential boundaries of libraries. Answers to value contribution will not arise from goals but from values, as concepts of value depend on values systems. A reflection on the meaning of value for libraries is presented. A new, higher-order framework for evaluation and performance measurement based on a values scorecard is suggested. The concept of the transcendent library is offered as a route to further progress.

Recommendations for construction of a nonlinear international Terrestrial Reference Frame

The problems of ITRF2008, the latest International Terrestrial Reference Frame, are pointed out and analyzed as follows: (1) ITRF is not a mm-level Terrestrial Reference Frame; (2) the origin of ITRF is neither the Earth’s center of mass (CM) nor the center of figure (CF); (3) the scale of ITRF is not a uniform system in the sense of the gravitational theory of relativity. These problems result from the linear hypothesis used in the establishment and maintenance of ITRF, which includes the linear hypothesis of the coordinates definition of the ITRF reference stations, and the seven coordinate transformation parameters (three translation parameters, three rotation parameters, and one scale parameter) when the ITRF combine solution is constructed. The linear hypothesis of the ITRF construction leads to the current terrestrial reference frame only at the cm-level, which cannot satisfy the requirements of monitoring mm-level crust movements as well as the global environment. This article points out that the construction of a mm-level Terrestrial Reference Frame is actually a leap from linear to nonlinear. Therefore, according to the main characteristics of nonlinear changes of the crust’s deformation, the geocenter motion and the overall height fluctuation of the Earth, the new ITRF station coordinates definition and the new observation equations of combined solutions are constructed for the realization of a mm-level nonlinear ITRF, which can solve the problems of the current ITRF.

Continuing Nursing Education: Enhancing Professional Development

Are you aware of current issues that will have an impact on the future of continuing nursing education? It is easy to get focused on day-to-day operations and lose sight of the bigger picture of the evolving role of continuing nursing education in enhancing professional development. This column reviews current frames of reference for continuing nursing education and foundational work that is guiding our future.

A New Power-Factor-Based Vector Control Method for Sensorless Drive of Permanent-Magnet Synchronous Motors -Simplification and Conversion to Voltage Reference Frame-

As a simple vector control method for sensorless drives of permanent-magnet synchronous motors, the so-called “Power-Factor-Based (PFB) Vector Control Method” has been proposed. The conventional PFB method directly estimates the phase of the quasi-optimal stator current through a control of the power factor phase, instead of the estimation of the rotor phase. The stator current is controlled in the current reference frame whose secondary axis phase is the same as the stator current phase. This paper proposes a new PEB method where the stator current is controlled in the voltage reference frame whose secondary axis phase is the same as the voltage phase rather than the current phase. It is shown that the similar quasi-optimal stator current control can be attained through the current control with appropriate current commands taking the power factor phase into account. This paper also shows a practical method for generating the current commands and a practical guideline for the design parameters of the new PFB method.

A fast mode decision method for H.264/AVC using the spatial-temporal prediction scheme

In the H.264/AVC coding standard, seven motion estimation modes from 4 × 4 to 16 × 16 are used to find the minimum motion compensation error for each macroblock. However, the high computation cost of the full search method in the reference software JM-9.3 makes the encoding process inefficient. Therefore, the methods of applying the SAD (sum of absolute difference), homogeneous region analysis, and edge detection are developed to determine the optimum motion estimation mode. Nevertheless, the additional computation cost of image processing still reduces the efficiency of the motion compensation process. In this paper, the spatial-temporal correlations between the current frame and reference frame are analyzed to develop a fast mode decision method in which no extra image processes are used. Furthermore, the concept of drift compensation is adopted to avoid the error accumulation phenomenon during the mode decision process. The experimental results show that the computation cost may be reduced above 60% and the average PSNR is only dropped about 0.04db.

Galilean invariance and stabilized methods for compressible flows

AbstractIn a recent work (Comput. Methods Appl. Mech. Eng. 2007; 196(4–6):966–978), it was observed that lack of Galilean invariance led to catastrophic instabilities when stabilized methods were used in Lagrangian shock hydrodynamics computations. By means of an arbitrary Lagrangian–Eulerian (ALE) formulation, Galilean invariant SUPG operators were consistently derived in (Comput. Methods Appl. Mech. Eng. 2007; 196(4–6):1108–1132), and their Lagrangian and Eulerian limits were compared to the most commonly used stabilized formulations. In the particular case of Eulerian meshes, it was shown that most of the SUPG operators designed to date for compressible flow computations are not invariant. However, due to the significant overhead of algebraic manipulations, the use in (Comput. Methods Appl. Mech. Eng. 2007; 196(4–6):1108–1132) of the referential form of the ALE equations made the presentation of the main ideas quite involved. The present paper addresses this particular issue, since the invariance analysis is presented with the aid of the intuitive current configuration reference frame, more familiar to computational fluid dynamicists. Copyright © 2007 John Wiley & Sons, Ltd.

An Adaptive Dead-Time Compensation Strategy for Voltage Source Inverter Fed Motor Drives

This paper presents an adaptive dead-time compensation strategy to obtain fundamental phase voltage for inverter fed vector controlled permanent magnet synchronous motor drives. The amplitude of phase dead-time compensation voltage (DTCV) to compensate disturbance voltage due to undesirable characteristics of inverter, such as dead-time, turn-on/off time of switching devices, and on-voltages of switching devices and diodes is adaptively determined according to a dead-time compensation time (DTCT). DTCT is identified on-line with using a /spl delta/-axis disturbance voltage in the current reference frame that is synchronized with current vector. The /spl delta/-axis disturbance voltage is estimated by a disturbance observer. The accuracy of identified DTCT is experimentally confirmed by calculating the mean absolute percentage error (MAPE) between a calculated active power and a measured one. MAPE for adaptive DTCT is almost within 5% at any operating point.

Multiple ophiolite generation preserved in the northern Philippines and the growth of an island arc complex

Although all oceanic arcs grow through the addition of subduction-generated magmas, the geology of the northern Philippines demonstrates that a major contribution to arc crustal growth can come from repeated, episodic, intra-arc, back-arc, and/or fore-arc oceanic crust generation with subsequent preservation of the basic–ultrabasic units in the arc complex. At least five episodes of oceanic crust generation are represented in the northern Philippines by preserved ophiolitic sequences and recent intra-arc seafloor spreading. Each episode is distinct in age as confirmed by modern dating techniques, with the ages ranging from pre(?)-Jurassic to ∼Quaternary. Although the Philippines is widely regarded as an amalgamation of allochthonous terranes, a review of the available data shows that there is currently no compelling evidence that these ophiolites are of exotic origin and that they have been tectonically accreted to the Philippine arc complex. Rather, the evidence suggests that most—and possibly all—of the ophiolites were generated as back-arc, fore-arc, or intra-arc crust within the Philippine arc complex. Hence, there is a close spatial association of several ophiolitic terranes of diverse ages spanning ∼150 Myr that formed as part of the arc complex. Such an association may have arisen from episodic generation of oceanic crust during periods of local extension in a suprasubduction zone setting, which has experienced changing and possibly overlapping subduction from the east and west sides (in the current reference frame). Disruption of the ophiolitic basement terranes has been, and continues to be, effected primarily by wrench faulting. This style of arc growth has implications for the paleotectonic interpretation of ancient ophiolite-arc terranes in continents and the petrologic evolution of island arcs.

Instabilité psychomotrice chez l'enfant. Histoire des idées et réflexions actuelles

Psychomotor instability in children is now described in two different ways that share many clinical characteristics but contrast sharply with each other in terms of the underlying nosographic and etiopathogenic concepts. To cast a clearer picture of these two currents of thought, we present a classic historical overview of psychomotor instability followed by a description of what is now called attention deficit hyperactivity disorder. The clinical descriptions corresponding to each of these two approaches are reviewed in a way that highlights the key role of the child psychiatrist in listening to and working through the symptoms, as well as in determining which therapeutic steps may be appropriate. Finally, a few considerations on the issues underlying psychomotor instability and on its current frames of reference are put forward to paint a more detailed picture of the complexity of the problem and to improve the quality of care of affected children.

Sensorless IFOC of induction motor with current regulators in current reference frame

In this paper, a new current vector control method combined with an indirect-field-orientation feedforward algorithm is presented for shaft-sensorless induction motor drives. The new current control technique is based on the concept that the angular speed and the magnitude of the stator current vector can be controlled by two stator voltage components relative to the stator current vector. In the proposed solution, the current regulators are rotating together with the stator current vector. The new topology drive has improved low-speed performance compared to the conventional solutions.

The Rule of Opposites: A Paradigm for Counseling Native Americans

The Rule of Opposites offers a cultural lesson in perspective that is useful for counselors working with Native American clients. The Rule of Opposites, based on the concept of the Circle of Life, is presented as a worldview that allows individuals to move beyond their current frame of reference toward an understanding of universal truths and underlying meanings. Use of the Rule's 7 lessons helps both the counselor and the client to recognize and resolve conflict, to ask more effective questions, to seek harmony and balance in life for greater purpose and direction, and to explore personal decision making and choices.

Legacies of Saleem Shah: Correctional and legal psychology.

Saleem A. Shah made seminal and substantive contributions to psychological knowledge, theory, and practice in corrections and the law. He assumed a role as instigator of research and generous colleague in a vast range of psychological-legal activities. Current clinical practices and conceptual frames of reference in legal and correctional psychology reflect the conscience, involvements, and ideas of Saleem Shah.

An Advanced Criminology Based on Psychology-of-Mind

The field of criminology has been living within its own theoretical views. It has become increasingly dependent upon the content of its own logical reasoning to produce the progress and outcomes it seeks. It has maintained the status quo by re-cycling variations of its current thought patterns. Thus, the search for unknown or new knowledge has become re-search at previously established levels of understanding. This paper attempts to move beyond the current criminological frames of reference in order to examine how the field has evolved into its present state and proposes the need for an advanced criminology based on a deeper understanding of the psychological function that is used to create all patterns of thought.

Frames of Reference and Modalities Used by Occupational Therapists in the Treatment of Patients with Eating Disorders

Eating disorders are complex conditions which continue to present serious problems to those who have them and the health professionals who try to treat them. Although the development of effective treatment programs has been slow, it is now recognized that a multidisciplinary approach, including occupational therapy services, is indicated for optimal treatment. A study was conducted to examine the current frames of reference and modalities utilized by occupational therapists treating patients with eating disorders. It was found that the majority of the respondents used the psychoanalytic, familial, and cognitive frames of reference as their primary theoretical bases. Preferred modalities included art therapy, cooking/menu planning, crafts, stress maangement training, and group discussions/activities. Implications to the field, limitations of the study, and the need for further research are discussed.