Single Reference Frame Research Articles

On Bell's dynamical route to special relativity

This paper develops the approach to special relativity put forward by John S. Bell. The classical dynamics of an electron orbiting a nucleus in uniform motion is solved analytically and compared to numerical simulations for an accelerated nucleus. The relativistic phenomena of length contraction and time dilation are shown to result from the electric and magnetic forces on the electron when its motion is analyzed in a single frame of reference. The relevance of these results for understanding the theory of special relativity is discussed.

How we perceive the width of grasped objects: Insights into the central processes that govern proprioceptive judgements.

Low-level proprioceptive judgements involve a single frame of reference, whereas high-level proprioceptive judgements are made across different frames of reference. The present study systematically compared low-level (grasp grasp) and high-level (vision grasp, grasp vision) proprioceptive tasks, and quantified the consistency of grasp vision and possible reciprocal nature of related high-level proprioceptive tasks. Experiment 1 (n = 30) compared performance across vision grasp, a grasp vision and a grasp grasp tasks. Experiment 2 (n = 30) compared performance on the grasp vision task between hands and over time. Participants were accurate (mean absolute error 0.27 cm [0.20 to 0.34]; mean [95% CI]) and precise ( = 0.95 [0.93 to 0.96]) for grasp grasp judgements, with a strong correlation between outcomes (r = -0.85 [-0.93 to -0.70]). Accuracy and precision decreased in the two high-level tasks ( = 0.86 and 0.89; mean absolute error = 1.34 and 1.41 cm), with most participants overestimating perceived width for the vision grasp task and underestimating it for grasp vision task. There was minimal correlation between accuracy and precision for these two tasks. Converging evidence indicated performance was largely reciprocal (inverse) between the vision grasp and grasp vision tasks. Performance on the grasp vision task was consistent between dominant and non-dominant hands, and across repeated sessions a day or week apart. Overall, there are fundamental differences between low- and high-level proprioceptive judgements that reflect fundamental differences in the cortical processes that underpin these perceptions. Moreover, the central transformations that govern high-level proprioceptive judgements of grasp are personalised, stable and reciprocal for reciprocaltasks. KEY POINTS: Low-level proprioceptive judgements involve a single frame of reference (e.g. indicating the width of a grasped object by selecting from a series of objects of different width), whereas high-level proprioceptive judgements are made across different frames of reference (e.g. indicating the width of a grasped object by selecting from a series of visible lines of different length). We highlight fundamental differences in the precision and accuracy of low- and high-level proprioceptive judgements. We provide converging evidence that the neural transformations between frames of reference that govern high-level proprioceptive judgements of grasp are personalised, stable and reciprocal for reciprocal tasks. This stability is likely key to precise judgements and accurate predictions in high-level proprioception.

Fast and Curious: ‘The Swiss Development Puzzle’. The Institutional Roots of the Success of Industrialization

ABSTRACT The article investigates the institutional roots of the Swiss organized capitalism that contributed to the success of its industrialization and its subsequent economic growth during the second industrial revolution (1880–1913). Recent literature underlines the link between public and private actors and shows that the second industrial revolution in Switzerland owed its success to state-led organized capitalism. If the majority of studies analysed in detail one or more components of the Swiss organized capitalism, to our knowledge, there are no works seeking to explain the (institutional) construction of this organized capitalism by mobilizing a large number of factors in a single theoretical frame of reference. Using the Regulation Theory approach, this article sheds light on the institutional construction of the Swiss organized capitalism. We show that it rested on original institutional arrangements driven by the necessity to survive on external markets. We therefore demonstrate that these arrangements also enabled Switzerland to successfully deal with the production of essential public goods supporting both industrialization and national social bonds required to promote political unity.

Semantic Mapping of the Geologic Time Scale: A temporal reference

The Geologic Time Scale is an ordered hierarchical set of terms representing specific time intervals in Earth's history. The hierarchical structure is correlated to the geologic record and major geologic events in Earth’s history (Gradstein et al. 2020). In the absence of quantitative numeric age values from absolute dating methods, the relative time intervals in the geologic time scale provide us with the vocabulary needed for deciphering Earth’s history and chronological reconstruction. This temporal frame of reference is critical to establishing correlations between specimens and how they fit within the Earth’s 4.567 Ga (giga annum) history. Due to spatial and temporal variations in the stratigraphic record, the terminology used in conjunction with geologic time scales is largely inconsistent. For a detailed discussion regarding term use in geologic timescales, see Cohen et al. (2013). As a result, published values for geologic timescale terms are often ambiguous and highly variable, limiting interoperability and hindering temporal correlations among specimens. A solution is to map verbatim geologic timescale values to a controlled vocabulary, constructing a single temporal frame of reference. The harmonization process is governed by an established set of business rules that can ultimately become fully or partially automated. In this study, we examined the Global Biodiversity Information Facility’s (GBIF) published distinct verbatim values for Darwin Core terms in the GeologicalContext Class of Darwin Core to assess the the use of chronostratiphic terms, a process highlighted in Sahdev et al. (2017). Preservation of these verbatim values, the initial unmapped set of published values, is important. Many are derived directly from primary source material and possess special historical and regional significance. These include land mammal ages (e.g., Lindsay (2003)), biostratigraphic zones, regional terms, and terms with higher granularity than the International Commission of Stratigraphy’s (ICS) timescale allows (e.g., subages/substages). For the purposes of this study, we selected the 2023/6 version of the ICS chronostratigraphic timescale as the controlled vocabulary (Cohen et al. 2023). The ICS is the most widely adopted timescale, comprising the most generalized and universally applicable intervals of geologic time. After semantic analysis of the verbatim values (see Table 1 for comparative statistics), we established a comprehensive set of business rules to map to the ICS timescale controlled vocabulary. This process yielded a collection of documented procedures to transform the heterogeneous collection of published terms into a semantically consistent dataset. The end result is a single temporal frame of reference for published geologic and paleontological specimens through semantic mapping to improve the temporal correlations between geologic specimens globally through data interoperability. This talk will highlight the process of harmonizing a heterogeneous collection of published verbatim Geologic Time Scale values with an established controlled vocabulary through semantic mapping.

CSR managers as hybrid professionals: managing at the intersection of coexisting logics

Corporate Social Responsibility (CSR) is evolving, with new sustainability issues and related tasks emerging as priorities for large hotel groups. Within this institutionally complex environment, the role of CSR manager (a relatively new professional role) is becoming ever more diverse and contextualised. We unveil how CSR managers advance their work amidst logic plurality in the early stages of institutionalising CSR. Through interviews (with eight senior managers responsible for sustainability and eight sustainability experts) and pattern-inducing interpretive analysis of the resulting data, we gain a practical understanding of CSR under four institutional logics: corporate, market, professional and sustainability. Three micro-level strategies - anchoring, switching and interlinking - allow individuals to advance organisational CSR work where multiple logics are pertinent for legitimate actions. Adherence to a single frame of reference (e.g. one logic) guides most organisational practices, with managers rarely switching between logics to adapt to situations and audiences, or linking practices enacted from different logics. This results in low problematisation of the work of CSR managers, and avoidance of tensions. Implications are discussed for organisations engaging in CSR, including the organisational advantages and risks that emerge as CSR managers evolve to become hybrid professionals.

METRIC—Multi-Eye to Robot Indoor Calibration Dataset

Multi-camera systems are an effective solution for perceiving large areas or complex scenarios with many occlusions. In such a setup, an accurate camera network calibration is crucial in order to localize scene elements with respect to a single reference frame shared by all the viewpoints of the network. This is particularly important in applications such as object detection and people tracking. Multi-camera calibration is a critical requirement also in several robotics scenarios, particularly those involving a robotic workcell equipped with a manipulator surrounded by multiple sensors. Within this scenario, the robot-world hand-eye calibration is an additional crucial element for determining the exact position of each camera with respect to the robot, in order to provide information about the surrounding workspace directly to the manipulator. Despite the importance of the calibration process in the two scenarios outlined above, namely (i) a camera network, and (ii) a camera network with a robot, there is a lack of standard datasets available in the literature to evaluate and compare calibration methods. Moreover they are usually treated separately and tested on dedicated setups. In this paper, we propose a general standard dataset acquired in a robotic workcell where calibration methods can be evaluated in two use cases: camera network calibration and robot-world hand-eye calibration. The Multi-Eye To Robot Indoor Calibration (METRIC) dataset consists of over 10,000 synthetic and real images of ChAruCo and checkerboard patterns, each one rigidly attached to the robot end-effector, which was moved in front of four cameras surrounding the manipulator from different viewpoints during the image acquisition. The real images in the dataset includes several multi-view image sets captured by three different types of sensor networks: Microsoft Kinect V2, Intel RealSense Depth D455 and Intel RealSense Lidar L515, to evaluate their advantages and disadvantages for calibration. Furthermore, in order to accurately analyze the effect of camera-robot distance on calibration, we acquired a comprehensive synthetic dataset, with related ground truth, with three different camera network setups corresponding to three levels of calibration difficulty depending on the cell size. An additional contribution of this work is to provide a comprehensive evaluation of state-of-the-art calibration methods using our dataset, highlighting their strengths and weaknesses, in order to outline two benchmarks for the two aforementioned use cases.

Computational investigation of NREL Phase-VI rotor: Validation of test sequence-S measurements

A CFD-based assessment and validation of the NREL Phase-VI Sequence-S rotor at seven wind speeds presented here. The ability of a three-dimensional, unstructured, unsteady RANS solver in successfully predicting the wind flow interactions with a rotating, twisted and tapered rotor is described. The uRANS equations were coupled with SST κ-ω turbulence model and a correlation-based Gamma-Theta transition model. The simulations were performed in ANSYS CFX using both Single Reference Frame (SRF) and Multiple Reference Frame (MRF) modelling approaches. A good agreement with measurements is observed at six of seven wind speeds when comparing the integral quantities, the spanwise and chordwise distributions. The only exception is the 10 m/s wind speed case, attributed to the onset of a massive leading edge stall around the mid-span region. It is successfully demonstrated here how uRANS-based CFD computations can be effectively employed in the study of wind turbine rotor aerodynamics.

Learning Cross-Scale Weighted Prediction for Efficient Neural Video Compression.

Neural video codecs have demonstrated great potential in video transmission and storage applications. Existing neural hybrid video coding approaches rely on optical flow or Gaussian-scale flow for prediction, which cannot support fine-grained adaptation to diverse motion content. Towards more content-adaptive prediction, we propose a novel cross-scale prediction module that achieves more effective motion compensation. Specifically, on the one hand, we produce a reference feature pyramid as prediction sources and then transmit cross-scale flows that leverage the feature scale to control the precision of prediction. On the other hand, for the first time, a weighted prediction mechanism is introduced even if only a single reference frame is available, which can help synthesize a fine prediction result by transmitting cross-scale weight maps. In addition to the cross-scale prediction module, we further propose a multi-stage quantization strategy, which improves the rate-distortion performance with no extra computational penalty during inference. We show the encouraging performance of our efficient neural video codec (ENVC) on several benchmark datasets. In particular, the proposed ENVC can compete with the latest coding standard H.266/VVC in terms of sRGB PSNR on UVG dataset for the low-latency mode. We also analyze in detail the effectiveness of the cross-scale prediction module in handling various video content, and provide a comprehensive ablation study to analyze those important components. Test code is available at https://github.com/USTC-IMCL/ENVC.

NECESSARY AND SUFFICIENT CONDITION FOR THE EXISTENCE OF INTERNAL TIME ON AN ORIENTED SET

The notion of oriented set is the most elementary technical notion of the theory of changeable sets, which is needed for the general definition of changeable set notion. The main motivation for building the theory of changeable sets was the sixth Hilbert problem, that is, the problem of mathematically rigorous formulation of the fundamentals of theoretical physics. From the formal point of view oriented set is the simplest relation system with one reflexive binary relation. Oriented sets may be interpreted as simplest abstract models of sets of changing objects, evolving in the framework of the single (specified) reference frame. From the other hand in the framework of oriented sets we can give the mathematically strict and abstract definition of the notion of time as some mapping from some linearly ordered set to the power set of the set of elementary states of oriented set. Internal time may be considered as most natural time for an oriented set. From intuitive point of view internal time is the time, which can be “observed from the inside” of the oriented set. In the present paper we solve the problem of the existence of internal time on an oriented set without any synchronization. We prove necessary and sufficient condition for the existence of such time.

Spatiotemporal Calibration of Camera-LiDAR Using Nonlinear Angular Constraints on Multiplanar Target

The combinations of data captured from diverse sensors can yield reliable geometric and semantic information. However, calibration process must be preceded to make use of combined data. Calibration methods are classified by the adjusted parameters. Spatial calibration, which merges data to a single spatial reference frame, adjusts spatial parameters. Moreover, temporal offset parameter must be adjusted for sensors to acquire data under dynamic conditions, which is known as temporal calibration. In this study, a novel constraint adjustment method was proposed for spatiotemporal calibration, which combines mobile light detection and ranging (LiDAR) sensor with visual camera. It estimates seven parameters–three lever arm parameters, three bore-sight parameters, and temporal offset parameter–simultaneously. A nearly orthogonal multiplanar chessboard target was built for nonlinear angular constraints. B-spline interpolation method was employed to interpolate the plane parameters obtained from the camera and facilitate estimation of the temporal offset. Additionally, the calibration results were evaluated using correlation values and standard errors of the estimated parameters. The sequential quadratic programming method, which yields robust results for nonlinear optimization problem, was used to optimize a point-to-plane distance model subjected to nonlinear angular constraints. Assorted experiments with different sensor motions were conducted to evaluate the effects of the nonlinear angular constraints. Compared to the results of nonconstrained calibration methods, the results of the proposed method indicate lower correlation values between the calibration parameters, reduced standard errors, and fewer iterations in the optimization process, which validates the superiority of the proposed calibration method.

Transforming social perspectives with cognitive maps.

Growing evidence suggests that cognitive maps represent relations between social knowledge similar to how spatial locations are represented in an environment. Notably, the extant human medial temporal lobe literature assumes associations between social stimuli follow a linear associative mapping from an egocentric viewpoint to a cognitive map. Yet, this form of associative social memory does not account for a core phenomenon of social interactions in which social knowledge learned via comparisons to the self, other individuals or social networks are assimilated within a single frame of reference. We argue that hippocampal–entorhinal coordinate transformations, known to integrate egocentric and allocentric spatial cues, inform social perspective switching between the self and others. We present evidence that the hippocampal formation helps inform social interactions by relating self vs other social attribute comparisons to society in general, which can afford rapid and flexible assimilation of knowledge about the relationship between the self and social networks of varying proximities. We conclude by discussing the ramifications of cognitive maps in aiding this social perspective transformation process in states of health and disease.

Mix Frame Visual Servo Control Framework for Autonomous Assistive Robotic Arms.

Assistive robotic arms (ARAs) that provide care to the elderly and people with disabilities, are a significant part of Human-Robot Interaction (HRI). Presently available ARAs provide non-intuitive interfaces such as joysticks for control and thus, lacks the autonomy to perform daily activities. This study proposes that, for inducing autonomous behavior in ARAs, visual sensors integration is vital, and visual servoing in the direct Cartesian control mode is the preferred method. Generally, ARAs are designed in a configuration where its end-effector’s position is defined in the fixed base frame while orientation is expressed in the end-effector frame. We denoted this configuration as ‘mixed frame robotic arms’. Consequently, conventional visual servo controllers which operate in a single frame of reference are incompatible with mixed frame ARAs. Therefore, we propose a mixed-frame visual servo control framework for ARAs. Moreover, we enlightened the task space kinematics of a mixed frame ARAs, which led us to the development of a novel “mixed frame Jacobian matrix”. The proposed framework was validated on a mixed frame JACO-2 7 DoF ARA using an adaptive proportional derivative controller for achieving image-based visual servoing (IBVS), which showed a significant increase of 31% in the convergence rate, outperforming conventional IBVS joint controllers, especially in the outstretched arm positions and near the base frame. Our Results determine the need for the mixed frame controller for deploying visual servo control on modern ARAs, that can inherently cater to the robotic arm’s joint limits, singularities, and self-collision problems.

Parametric Analysis Using CFD to Study the Impact of Geometric and Numerical Modeling on the Performance of a Small Scale Horizontal Axis Wind Turbine

The reliance on Computational Fluid Dynamics (CFD) simulations has drastically increased over time to evaluate the aerodynamic performance of small-scale wind turbines. With the rapid variability in customer demand, industrial requirements, economic constraints, and time limitations associated with the design and development of small-scale wind turbines, the trade-off between computational resources and the simulation’s numerical accuracy may vary significantly. In the context of wind turbine design and analysis, high fidelity simulation under full geometric and numerical complexity is more accurate but pose significant demands from a computational standpoint. There is a need to understand and quantify performance deterioration of high fidelity simulations under reduced geometric or numerical approximation on a single small scale turbine model. In the present work, the flow past a small-scale Horizontal Axis Wind Turbine (HAWT) was simulated under various geometric and numerical configurations. The geometric complexity was varied based on stationary and rotating turbine conditions. In the stationary case, simple 2D airfoil, 2.5D blade, 3D blade sections are evaluated, while rotational effects are introduced for the configuration 3D blade, rotor only, and the full-scale wind turbine with and without the inclusion of a nacelle and tower. In terms of numerical complexity, the Single Reference Frame (SRF), Multiple Reference Frames (MRF), and the Sliding Meshing Interface (SMI) is analyzed over Tip Speed Ratios (TSR) of 3, 6, 10. The quantification of aerodynamic coefficients of the blade (Cl, Cd) and turbine (Cp, Ct) was conducted along with the discussion on wake patterns in comparison with experimental data.

The Naming of Parts: Integrating Urban Difference

As with Anomalocaris, urbanism is one label for many phenomena. However, the varied phenomena of urbanism are defined locally yet talked about universally, while local traditions are entitled to their own definitions. What we have is immense variety and a risk that the category will become so malleable that it loses integration or has lost meaning and interpretative value. To integrate a consistent analytic approach to the varied forms of settlement which are included in the category ‘urban’ and allow different but complementary questions to be asked about their variety, we need to recognize them as representatives of different trajectories which can be comprehended in relation to each other within a single frame of reference - the interaction and communication constraints which affect the communities in all settlements.

Interactive Exploration of Physically-Observable Objective Vortices in Unsteady 2D Flow.

State-of-the-art computation and visualization of vortices in unsteady fluid flow employ objective vortex criteria, which makes them independent of reference frames or observers. However, objectivity by itself, although crucial, is not sufficient to guarantee that one can identify physically-realizable observers that would perceive or detect the same vortices. Moreover, a significant challenge is that a single reference frame is often not sufficient to accurately observe multiple vortices that follow different motions. This paper presents a novel framework for the exploration and use of an interactively-chosen set of observers, of the resulting relative velocity fields, and of objective vortex structures. We show that our approach facilitates the objective detection and visualization of vortices relative to well-adapted reference frame motions, while at the same time guaranteeing that these observers are in fact physically realizable. In order to represent and manipulate observers efficiently, we make use of the low-dimensional vector space structure of the Lie algebra of physically-realizable observer motions. We illustrate that our framework facilitates the efficient choice and guided exploration of objective vortices in unsteady 2D flow, on planar as well as on spherical domains, using well-adapted reference frames.

Removing multi-frame Gaussian noise by combining patch-based filters with optical flow

Patch-based approaches such as 3D block matching (BM3D) and non-local Bayes (NLB) are widely accepted filters for removing Gaussian noise from single-frame images. In this work, we propose three extensions for these filters when there exist multiple frames of the same scene. The first of them employs reference patches on every frame instead of a commonly used single reference frame method, thus utilizing the complete available information. The remaining two techniques use a separable spatio-temporal filter to reduce interactions between dissimilar regions, hence mitigating artifacts. In order to deal with non-registered datasets we combine all our extensions with robust optical flow computation. Two of our proposed multi-frame filters outperform existing extensions on most occasions by a significant margin while also being competitive with a state-of-the-art neural network-based technique. Moreover, one of these two strategies is the fastest among all due to its separable design.

Reactive Power Management in Solar PV System using Matlab

Photovoltaic (PV) systems propose attractive alternative source of generation because these can be placed near to the load centers when compared with other renewable source of generation. It is therefore rooftop PV is the center of attraction for majority PV systems. The rooftop PV system in general is grid connected and supports the off-grid load with battery backup. The designed system must ensure total evacuation of generated power and with high efficiency of conversion, and utilizes the resource adequately to maximize the utilization of energy. This paper proposes single phase synchronous reference frame (SRF) theory based current controlled PWM controller for the voltage source converter (VSC) to realize maximum generated power evacuation by maintaining the DC link voltage constant without battery support, low THD sinusoidal line synchronized current output, and limited reactive power compensation based on the unutilized capacity of the inverter. PV power is being tracked always at MPP through incremental conductance (IC) method. MATLAB based simulation results shows the efficient working of rooftop PV with proposed control algorithms in grid connected mode with limited reactive power conditioning.

The six faces of ignorance in online piracy: How not knowing shapes the practices of media consumption

The aim of this study is to explore the interrelation between online piracy and ignorance. It brings together literature on both piracy and ignorance and theorizes the role that ignorance plays in media consumption. The empirical analysis first demonstrates how ignorance is used by the members of the Czech Pirate Party to avoid liability for operating a website that streams copyright content. Then, it draws upon interviews with the members of convergent audiences to account for six dimensions of ignorance that are employed by users at the end of the media distribution chain. An argument is made that the concept of ignorance accounts for a set of seemingly paradoxical findings, providing a single frame of reference within which they might be explained. Finally, a perspective is put forth that invites the study of ignorance outside of formal organizations and questions the prevailing association of strategic ignorance with established positions of power.

Heterogeneous Persecution: Lesbianism and the Nazi State

AbstractIn recent years scholars have shown increasing interest in lesbianism under National Socialism. But because female homosexuality was never criminalized in Nazi Germany, excluding Austria, historians have few archival sources through which to recount this past. That lack of evidence has led to strikingly different interpretations in the scholarly literature, with some historians claiming lesbians were a persecuted group and others insisting they were not. This article presents three archival case studies, each of which epitomizes a different mode in the relationship between lesbians and the Nazi state. In presenting these cases, the article contextualizes them with twenty-seven other cases from the literature, arguing that these different modes illustrate why different women met with such radically different fates. In so doing, it attempts to bridge the divide in the scholarship, putting persecution and tolerance into a single frame of reference for understanding the lives of lesbians in the Third Reich.

Explaining the importance of Euler’s method in rigid-body dynamics

The purpose of this study is essentially pedagogical and aims to provide an additional argument in clarification of a question often raised by first-year undergraduate mechanical engineering students concerning the reason for using two frames of reference—one fixed in space and one fixed in the rigid-body—to describe its motion. The reasoning employed to illustrate the inappropriateness of using a single reference frame entails showing that the equations of motion, thus obtained, are far more complex than the equations resulting from application of the traditional Euler Method. This point is illustrated through the well-known frictionless symmetrical spinning top problem.