Physical Setup Research Articles

A Hopping Robot Driven by a Series Elastic Dual-Motor Actuator

In this letter, we present the kinematically redundant series elastic dual-motor actuator (SEDMA). It consists of two motors, coupled to a series spring through a planetary differential. The redundant degree of freedom of this system can be exploited to optimize a specific aspect of the actuation task. This requires a controller, which distributes the required output power among the two different inputs in an optimal way. The closed-loop control design for redundant systems is, however, a challenging topic, especially for strongly dynamic tasks like hopping. In this work, we test the abilities of the SEDMA by using it to actuate a single-leg hopping robot. Its controller features a closed-loop hopping controller and a control allocator, which minimizes the electrical energy consumption of the SEDMA. Tests on a physical setup prove that the actuator and its online controller are able to generate consistent hopping patterns. The work highlights the difficulties in achieving optimality in online control when the internal dynamics of kinematically redundant actuators become relevant.

Topology of Rayleigh–Bénard convection and magnetoconvection in plane layer

ABSTRACTThe present study aims to link the dynamics of geophysical fluid flows with their vortical structures in physical space and to study the transition of these structures due to the control parameters. The simulations are carried in a rectangular box filled with liquid gallium for three different cases, namely, Rayleigh–Bénard convection (RBC), magnetoconvection (MC) and rotating magnetoconvection (RMC). The physical setup and material properties are similar to those considered by Aurnou and Olson in their experimental work. The simulated results are validated with theoretical results of Chandrasekhar and experimental results of Aurnou and Olson. The results are also topologically verified with the help of Euler number given by Ma and Wang. For RBC, the onset is obtained at Ra greater than 1708 and at this Ra, the symmetric rolls are orientated in/along a horizontal axis. As the value of Ra increases further, the width of the horizontal rolls starts to amplify. It is observed that these two-dimensional rolls are nothing but the cross-sections of three-dimensional (3D) cylindrical rolls with wave structures. When the vertically imposed magnetic field is added to RBC, the onset of convection is delayed due to the effect of Lorentz force on the thermal buoyancy force. The presence of 3D rectangular structures is highlighted and analysed. When the magnetically influenced rectangular box rotates about vertical axis at low rotation rates in magnetoconvection model, the onset of convection gets further delayed by magnetic field, which is in general agreement with the theoretical predictions. The critical Ra increases linearly with magnetic field intensity. Coherent thermal oscillations are detected near the onset of convection, at moderate rotation rates.

Road Accident Mapping along Halsema Highway

This paper showcases the profile of the road accident rate that happened along the Halsema Highway and the determination of road accident hotspots through QGIS mapping. This research used the qualitative research design and descriptive method using documentary analysis to determine the road accident rate profiles. On-site observation was conducted to describe the physical set-up of the accident prone areas; while interviews with police officers, commuters and drivers were conducted to supplement the findings of the study. It was found that most road accidents happen during the 2 nd quarter of the year. More accidents happen during weekends between 12:00 at noon and 4:00 in the afternoon. It was also revealed that vehicle-to-vehicle is the most common type of collision. Looking at the accident map, Usok Area, Amlosong, Balili, SitioPalinga-aw, Namatec, Mount Data Cliff and Mount Data Sawmill are identified as accident prone areas. The findings indicate that road accidents choose no place, weather or person. It happens at any time regardless of vehicle type. https://doi.org/10.26803/ijhss.11.1.3

Development of a visual inspection system and the corresponding algorithm for the detection and subsequent classification of paint defects on car bodies in the automotive industry

Increasing expectations of customers on the appearance of cars force the automotive paint shops to inspect all car bodies with great care. Currently, skilled workers visually inspect each car body to detect and repair occurring paint defects. However, humans can neither detect nor judge the blemishes objectively and reliably over a longer period. Hence, this paper focuses on the development and validation of an algorithm for a surface inspection system, which improves the accuracy of detecting paint defects through an image processing system. Once they are detected, a reliable classifier is necessary to gain further information about the paint defects. The generated data can be utilized for improving the paint application process and for identifying the perpetrator of the paint defects once the defect classification is operational. As a consequence, the quality control circuit can be shortened, the surface quality of different paint formulae can be evaluated objectively, and actions can be taken in order to reduce the occurrences of certain defect types. This paper presents the physical setup of the visual inspection system and a detailed description of the algorithm for detecting the defects in the acquired images. Further research is essential to generate a classifier to differentiate the types of paint defects.

Femtosecond optical two-way time-frequency transfer in the presence of motion

Platform motion poses significant challenges to high-precision optical time and frequency transfer. We give a detailed description of these challenges and their solutions in comb-based optical two-way time and frequency transfer (O-TWTFT). Specifically, we discuss the breakdown in reciprocity due to relativity and due to asynchronous sampling, the impact of optical and electrical dispersion, and velocity-dependent transceiver calibration. We present a detailed derivation of the equations governing comb-based O-TWTFT in the presence of motion. We describe the implementation of real-time signal processing algorithms based on these equations and demonstrate active synchronization of two sites over turbulent air paths to below a femtosecond time deviation despite effective velocities of +/-25 m/s, which is the maximum achievable with our physical setup. With the implementation of the time transfer equation derived here, we find no velocity-dependent bias between the synchronized clocks to within at two-sigma statistical uncertainty of 330 attoseconds.

Technique for the measurement of picosecond optical pulses using a non-linear fiber loop mirror and an optical power meter.

A method for measuring picosecond pulse width by using only fiber components and optical power meters is presented. We have shown that the output power splitting ratio of a non-linear fiber loop mirror can be used to extract the full-width half maximum of the optical pulse, assuming a known slowly varying envelope shape and internal phase structure. Theoretical evaluation was carried out using both self-phase and cross-phase modulation approaches, with the latter showing a twofold sensitivity increase, as expected. In the experimental validation, pulses from an actively fiber mode-locked laser at the repetition rate of 10 GHz were incrementally temporally dispersed by using SMF-28 fiber, and then successfully measured over a pulse width range of 2-10 ps, with a resolution of 0.25 ps. This range can be easily extended from 0.25 to 40 ps by selecting different physical setup parameters.

Influence of dilatancy on shear band characteristics of granular backfills

This study investigates the evolution of strain localisation and resulting failure surfaces within cohesionless backfills. For this purpose, 1 g small scale model experiments are performed simulating the lateral translation of rigid retaining walls to active state using Akpinar sand. The physical model test set-up has transparent sidewalls that allow observation of soil deformations and progressive failure. Images captured at successive stages of the test are analysed using particle image velocimetry (PIV) in order to visualise the formation of shear bands. Test set-up is equipped with several pressure transducers which are used to measure the stresses within the model backfill. A well-known empirical equation is used to calculate peak dilatancy and friction angles of the backfill using the measured density and stress magnitudes. Thus, it was possible to examine the influences of dilatancy and strength characteristics of the granular backfill on localisation and shear band formation. Moreover, the evolution of shear bands with the movements of the model wall is examined and two new methods for the determination of shear band thickness are proposed. Finally, it is concluded that there is a strong correlation between shear band characteristics and the dilative properties of granular soils.

Dynamics and Control of Liquid Level in Annular Conical Tank Process: Modelling and Experimental Validation

Objectives: The present work has been carried out to prove the superiority of IMC based PID control strategy over the conventional PID, based on simulation studies and experimental validation on an annular conical tank liquid level nonlinear process. Methods/Statistical Analysis: First principles based Mathematical Model of an annular conical tank liquid level nonlinear process has been developed based on the mass balances and outlet flow hydraulic characteristics. Linearization of the nonlinear model at a specific steady-state operating point led to the theoretical development of state-space and standard first order transfer function models. Open loop and closed loop experimental studies on a computer controlled physical setup were performed to identify the parameters of a FOPDT Model with variable gain and time constant. IMC based PID controller was designed and compared to the conventional PID controller. Findings: The variation in process parameters was attributed to two factors: (a) the variation in annular cross sectional area of the conical tank at different levels, and (b) the variation in outlet flow resistance. The IMC based PID controller has been shown to exhibit superior performance in terms of quantitative performance indices such as ISE, IAE, ITAE, rise time, settling time and percentage overshoot, at four different steady-states. Application/Improvements: Study of Modelling of annular conical tank process and a systematic methodology of process system identification from experimental setup have been reported. The advantages of IMC based PID controller design over the conventional PID tuning method has been experimentally verified. Keywords: Annular Flow Conical tank process, FOPDT model, System Identification, PID controller tuning, IMC based PID.

Potential problems on surfaces: With or without boundary, subjected to discrete distributed sources

Abstract In this paper we derive analytical solutions for potential problems on different types of surfaces, such as cylinders, cones and spheres. These solutions complement the solution obtained for a sphere. Besides examining modes of truncation for a sphere, we also provide a complete coverage of all modes of truncation for cylinders and cones. Our interest focuses on two-dimensional conducting surfaces, that are fed with point sources of current. Our solution gave explicitly the voltage distribution on these surfaces, results that can straight-forwardly be applied to pressure profiles of a fluid flow in a gap between surfaces. Yet since every physical set-up takes place in the R 3 space, some adjustments were required. We focused on three types of geometric surfaces: cylinder, cone and sphere. As being effectively two-dimensional problems, the use of analytic functions and conformal maps has been used to obtain analytical solutions for all these geometries, all are mapped into the complex plane. Special attention is paid to examine particular cases of truncated ends by taking into account boundary conditions and flux considerations. We used reflections on cylinder inversions on cone and explore a spherical version of inversion on a sphere in order to satisfy the boundary conditions.

Black hole entropy from nonproper gauge degrees of freedom: The charged vacuum capacitor

The question which degrees of freedom are responsible for the classical part of the Gibbons-Hawking entropy is addressed. A physical toy model sharing the same properties from the viewpoint of the linearized theory is a charged vacuum capacitor. In Maxwell's theory, the gauge sector including ghosts is a topological field theory. When computing the grand canonical partition function with a chemical potential for electric charge in the indefinite metric Hilbert space of the BRST quantized theory, the classical contribution originates from the part of the gauge sector that is no longer trivial due to the boundary conditions required by the physical set-up. More concretely, in the benchmark problem of a planar charged vacuum capacitor, we identify the degrees of freedom that, in the quantum theory, give rise to an additional contribution to the standard black body result proportional to the area of the plates, and that allow for a microscopic derivation of the thermodynamics of the charged capacitor.

Researches regarding scale reduced models for the optimisation of the aerodynamic coefficient

Within the lifecycle of the product, the reduced models are very important for the experimental validation of the prototype. The modelling, simulation and optimization stage precedes the prototype realization, being part of the computer aided design (CAD), computer aided engineering (CAE). The physical model is a physical layout or test setup that reproduces, on a small scale, the features of the original system, in our case the vehicle body layout. The paper presents an automobile reduced model, with the aim to study the aerodynamic theory. The paper presents the algorithms of conceptual design of the scale reduced model, namely: 3D modelling, small scale modelling technology and geometric shape optimization solutions using different CAD-CAE programs.

Необходимость применения интеллектуальных систем управления в экспериментальных ядерно-физических комплексах (типа NICA). Ч.I: Проблема нештатных ситуаций

In the article (Part I) the necessity of application of end-to-end quantum technologies of intelligent computing in problems of structure elements control of complex experimental accelerator complex NICA is analyzed. Given a description of possible unforeseen situations, their classification is given to include adjustments to the decision-making application of production rules, logic knowledge bases of intelligent control systems based on emerging information risk increment. In the second part (Part II) the proposed two-level intelligent control system, a physical experimental setup of the NICA complex, in which the lower Executive level is a traditional control system based on expert control using the Tango control system Controls, while the upper (intelligent) level control actions are generated using the methods of quantum end-to-end IT design quantum fuzzy controller. Part II presents the QSCIT (Quantum Soft Computational Intelligence Toolkit), based on soft and quantum computing, to design robust knowledge bases in self-organizing intelligent control systems.

Celos, amor y venganza, o no hay mal que por bien no venga by Luis Vélez de Guevara

Reviewed by: Celos, amor y venganza, o no hay mal que por bien no venga by Luis Vélez de Guevara Xabier Granja Ibarreche Vélez de Guevara, Luis. Celos, amor y venganza, o no hay mal que por bien no venga. Edited by William R. Manson & C. George Peale, Juan de la Cuesta, 2018. 197 pp. ISBN: 987-1-58871-321-6. In this critical edition, Manson and Peale bring Vélez's lesser-studied Celos, amor y venganza, o no hay mal que por bien no venga to the limelight. The analytical approaches to this work are still in early stages throughout the critical field, as more attention has been given to other plays among the more than four hundred that Vélez authored. Manson and Peale aim to fill the void of this play's research with a fresh perspective on its implications for the literary canon. The volume is divided into three main sections. The first one is an introductory study by Paul Michael Johnson, who provides a detailed analysis about several aspects of the play. An earlier brief analysis of Celos conducted by Emilio Cotarelo y Mori considered it "más bien obra de Lope de Vega" (11). Johnson does not deem Mori's qualification a questioning of Vélez's authorship, but rather an atypical appreciation of the utmost quality of the play, as a justification of why it deserves further study. What Ignacio Arellano considers "comedias serias, de ambiente palaciego" (11) and Miguel Zugasti calls a "comedia palatina" (11) are brought together [End Page 180] in Peale's proposition of a "Comedia Siciliana" (12) subgenre: works that deal with the complications of the Salic law—at least collaterally. While Celos presents a different tone in its lyrical style, Vélez's typical dramatism in offenses, treachery, strategical marriages, and other narrative resources are all present. Johnson's preliminary study offers an outstanding contextualization of the book's subsequent sections. He begins by exploring the use of emotions in early modern Spanish works, from Aristotle's description of catharsis to A. A. Parker's conceptual pyramid that subordinates characters to dramatic action, action to plot, and plot to the 'moraleja' of the story. Johnson presents the emotionality of passions in theatrical spectacle as the "verdaderos motores de la acción dramática de Celos" (20), which he emphasizes in his approach to the play. Besides emotions, Johnson's preliminary study contextualizes the play's use of accidental actions as they are related to good or bad fortune, astutely relating 'accident' and 'emotion' to provide a perspective on the gendered discourse present in Celos. Queen Rosaura, following traditional patterns of feminine instability in the face of the sentimental realm—and unlike masculine dominion of it—is shown to let her passions get the best of her. However, in direct opposition to this statement, women in Celos also stand out for their bravery and rationality. Johnson uses this apparently contradictory representation of gender to pique readers' interest, which undeniably endows the play with a complexity that should interest critical researchers. Johnson's final commentary on the physical setup of the play offers further insight into how different actions and requirements of the plot were manifested visually in subtle ways. The second section consists of a bibliometric study by C. George Peale, in which he contextualizes the rationales employed in the editors' transcription of the play. The final product is an effort in linguistic regularization that forms what Peale calls a "transcripción… moderadamente ecléctica" (44) which nonetheless maintains a respectful treatment of the "deslices y peculiaridades" (46) inherent to the text. This segment also includes an exhaustive summary of metric resources present throughout the play. Analytic minds will find this a useful exploration of the structure and form of Vélez's language in Celos, thanks to Peale's quantification of the frequency with which redondillas, romances, tercetos, sonetos, octavas, quintillas, and other forms occur. The third section gives way to the play itself, one that would certainly not be out of place next to other well-known political works like Lope de Vega's Fuenteovejuna, Calderón de la Barca's La vida es...

Probabilistic robust design of control systems for high-fidelity cyber–physical testing

Cyber–physicalempirical methods consist in partitioning a dynamical system under study into a set of physical and numerical substructures that interact in real-time through a control system. In this paper, we define and investigate the fidelity of such methods, that is their capacity to generate systems whose outputs remain close to those of the original system under study. In practice, fidelity is jeopardized by uncertain and heterogeneous artefacts originating from the control system, such as actuator dynamics, time delays and measurement noise. We present a computationally efficient method, based on surrogate modelling and active learning techniques, to (1) verify that a cyber–physical empirical setup achieves probabilistic robust fidelity, and (2) to derive fidelity bounds, which translate to absolute requirements to the control system. For verification purposes, the method is first applied to the study of a simple mechanical system. Its efficiency is then demonstrated on a more complex problem, namely the active truncation of slender marine structures, in which the substructures’ dynamics cannot be described by an analytic solution.

Improving Measurement Sensitivity for a Displacement Sensor Based on Self-Mixing Effect

When a part of light emitted by a laser is back-reflected or back-scattered from an external target and re-enters the laser cavity, both the laser intensity and its wavelength can be modulated. This is so-called self-mixing effect (SME). An SME-based displacement sensor is featured with compact physical setup and interferometric measurement resolution. However, when a target has a surface with very low reflectivity, the sensing signal is very weak and noisy. The system may even lose its sensing capability. It is desired to develop a method for improving the sensing performance in this case. We propose a configuration of dual external cavities for the SME-based sensing system, where one of the cavities is used to provide prefeedback for improving the sensing sensitivity and the other is related to the target to be measured. First, a sensing model is derived for the proposed configuration and shows that the magnitude of the sensing signal can be enhanced by setting the prefeedback cavity with suitable location and high optical feedback strength. Then, experimental investigations are conducted to demonstrate the feasibility of the proposed approach. This paper provides an important guidance for designing an SME-based sensor with high sensitivity.

A new approach to automation of black tea fermentation process with electronic nose

ABSTRACTManufacturing of black tea is a complex process consisting of plucking, withering, curling, fermenting, drying, determining of quality, and packaging stages. Nowadays, tea quality is determined by two methods. Either chemical analysis method is used or tea tasters give quality scores by tasting, smelling, and visual inspection. By means of recent studies, tea quality can also be determined by electronic nose technology. The quality of tea is generally related with the fermentation stage. In this work, an electronic nose, which determines the quality of tea during the fermentation process in real time from only its odour, was made, and the fermentation band was controlled by this electronic nose. Fermentation bands of a tea factory in the Çayeli District of Rize, Turkey have been simulated and controlled via LabVIEW simulation software by using real odour values measured in the factory with the electronic nose. In the study, a new fermentation band system has been designed to function with the electronic nose. This section of the study has been performed in the simulation environment due to the high cost of physical system setup. With the method proposed in this study, tea factories will be able to increase their production capacity with higher quality.

Office space: a leadership challenge

Synopsis The case describes the dilemma a young leader, First Lieutenant Toomey, faces after arriving at a new organization. Toomey’s subordinate (sergeant first class Rodgers) is more experienced and accomplished and has enjoyed a degree of autonomy under Toomey’s predecessor. Rodger’s demeanor and the physical setup of the joint office space speak to a dysfunctional dynamic in an organization that values a traditional hierarchy and relatively high power distance between supervisor and subordinate. The potential for conflict exists as Toomey contemplates how to address the dysfunctional norms he has observed while maintaining a functional relationship and reputation as an effective leader in his new unit. Research methodology The case was created via an interview of the protagonist. Relevant courses and levels This case is designed for use in undergraduate and graduate level courses on leadership and management. The case is useful for teaching lessons (or electives) on power, influence, conflict management, culture and leading change.

Comparing Seven Variants of the Ensemble Kalman Filter: How Many Synthetic Experiments Are Needed?

AbstractThe ensemble Kalman filter (EnKF) is a popular estimation technique in the geosciences. It is used as a numerical tool for state vector prognosis and parameter estimation. The EnKF can, for example, help to evaluate the geothermal potential of an aquifer. In such applications, the EnKF is often used with small or medium ensemble sizes. It is therefore of interest to characterize the EnKF behavior for these ensemble sizes. For seven ensemble sizes (50, 70, 100, 250, 500, 1,000, and 2,000) and seven EnKF variants (damped, iterative, local, hybrid, dual, normal score, and classical EnKF), we computed 1,000 synthetic parameter estimation experiments for two setups: a 2‐D tracer transport problem and a 2‐D flow problem with one injection well. For each model, the only difference among synthetic experiments was the generated set of random permeability fields. The 1,000 synthetic experiments allow to calculate the probability density function of the root‐mean‐square error (RMSE) of the characterization of the permeability field. Comparing mean RMSEs for different EnKF variants, ensemble sizes and flow/transport setups suggests that multiple synthetic experiments are needed for a solid performance comparison. In this work, 10 synthetic experiments were needed to correctly distinguish RMSE differences between EnKF variants smaller than 10%. For detecting RMSE differences smaller than 2%, 100 synthetic experiments were needed for ensemble sizes 50, 70, 100, and 250. The overall ranking of the EnKF variants is strongly dependent on the physical model setup and the ensemble size.

Tracking the quantized information transfer at the edge of a chiral Floquet phase

Two-dimensional arrays of periodically driven qubits can host inherently dynamical topological phases with anomalous chiral edge dynamics. These chiral Floquet phases are formally characterized by a dynamical topological invariant, the chiral unitary index. Introducing a quantity called the chiral mutual information, we show that this invariant can be precisely interpreted in terms of a quantized chiral transfer of quantum information along the edge of the system, and devise a physical setup to measure it.

A canonical hidden-variable space

The hidden-variable question is whether or not various properties — randomness or correlation, for example — that are observed in the outcomes of an experiment can be explained via introduction of extra (hidden) variables which are unobserved by the experimenter. The question can be asked in both the classical and quantum domains. In the latter, it is fundamental to the interpretation of the quantum formalism (Bell [1], Kochen and Specker [9], and others). In building a suitable mathematical model of an experiment, the physical set-up will guide us on how to model the observable variables — i.e., the measurement and outcome spaces. But, by definition, we cannot know what structure to put on the hidden-variable space. Nevertheless, we show that, under a measure-theoretic condition, the hidden-variable question can be put into a canonical form. The condition is that the σ-algebras on the measurement and outcome spaces are countably generated. An argument using a classical result on isomorphisms of measure algebras then shows that the hidden-variable space can always be taken to be the unit interval equipped with the Lebesgue measure on the Borel sets.