Cable Movement Research Articles

Uncertainties of S-Parameter Measurements in Rectangular Waveguides at PTB

Abstract. In this work the determination of measurement uncertainties in scattering parameter measurements for waveguide interfaces ranging from R 100 (WR 90) to R 2.6k (WR 3, WM-864) is presented. For each waveguide band a Thru Reflect Line calibration is performed including uncertainties for calibration standards, cable movement, interface repeatability and the characteristics of the vector network analyzer. For reflection and transmission coefficients, envelopes of uncertainties are determined for magnitude and phase angle respectively. In addition, an experiment on connection (interface) repeatability for R 140 was carried out to systematically investigate the influence of shifting and rotating of waveguide flanges. Translation values in steps of 0.3 mm up to 1.5 mm are examined in simulation as well as measurement. The findings of these investigations can be extended and applied to other waveguide bands.

Influence of LO cable movements on VNA measurements using Frequency Extensions

Abstract. In this study, the impact of local oscillator cable movements or drift during VNA measurements using frequency extenders is investigated. A non-reciprocal measurement error caused by alterations of the local oscillator signal in R 900 (WR 10) waveguide measurements from 75 to 110 GHz is observed and systematically analyzed. Furthermore, the theory behind this effect and its implications on measurement results are discussed, as well as possible corrections for both calibrated and raw measurement data.

Monitoring acoustic vibrations in optical fibers by estimating polarization matrix variation with the integration of coherent optical communication and sensing.

In this paper, we propose a novel architecture called as the Direct-Computation-Sensing Architecture (DCSA) to directly calculates the polarization state changes caused by optical fiber vibrations with training data, offering a more accurate and responsive method than that with adaptive filter-based sensing architectures. We detected the distinct fiber vibration induced by piezoelectric ceramics in an established experimental platform, and recovered a song melody played near the optical fiber buddle from the fiber's polarization changes. We locate the source of the vibration by comparing data from both ends of a bidirectional transmission setup. Lastly, we conducted field tests under conditions involving machine-induced vibrations and natural cable movements.

On the modal characteristics and stability of translating cable: Application to an overall line of cable transport systems

Moving cables are used for many applications in engineering structures such as cable-supported transport systems that involves mobile cables suspended between supports for moving attached vehicles. Advantages of such systems in terms of cost, footprint and energy efficiency make its urban integration as one of the solutions to meet the need for new mobilities. Because of the inherent cable’s flexibility and the modification of dynamic properties during the cable movement, such systems are sensitive to the effects of perturbations and self-sustaining oscillations. The methods commonly used to describe cable dynamics are restricted to small static sag case with a predominant vertical dynamics. To accurately analyse a multi-segment mobile cable, this paper proposes an hybrid analytical–numerical strategy to deal with a general mechanical elementary model of a cable in unsteady translation formulated in curvilinear abscissa derived from the formalism of continuum mechanics. An assembly procedure permits to deal with a more complex system considering a cable loop in contact with intermediary supports and punctual loads according to different boundary conditions, considering the coupling between the vertical dynamics activated at the local scale of a span and the longitudinal dynamics activated at the scale of the whole cable loop. The translation speed and acceleration gyroscopic effects on the system’s complex modes are studied and design rules are provided to guide an optimal conception avoiding strong oscillations of the system.

Comparison of S-Parameter Measurement Methods for Adapters

Abstract. In this work two methods for the characterization of adapters meaning reciprocal two-ports with different connector styles on both ports are analyzed and compared in detail. The focus is on the comparison of these approaches in terms of required effort and obtained measurement uncertainty. The first method is based on two one-port calibrations and it is compared to a two-port approach. Both methods are carried out in simulation as well as in measurement under very comparable conditions using a 2.4 to 3.5 mm adapter in the frequency range up to 33 GHz as an example. The obtained measurement uncertainties of the results are presented and analyzed, the required measurement time in terms of the necessary number of separate connections is compared, and the influence of cable movements is discussed.

Theory of rain–wind induced vibration of stay cables: Toward unsteady and fully coupled modeling

Large-amplitude rain–wind induced vibration (RWIV) is a complex fluid–structure interaction process that may develop if light rainfall and moderate wind act concurrently on long stay cables of a cable-stayed bridge. However, its dynamic characteristics and excitation mechanism are remained an open question. Recently, a theoretical framework for the analysis of RWIV was proposed, based on a quasi-steady-state approximation of the movement of upper rivulet, to reveal the main features of the dynamic process of RWIV. In the present study, we further consider the unsteady and dynamic behaviors of the moving upper rivulet and its coupling effects with the cable movement. The periodic mass, circumferential movement of the upper rivulet was modeled based on experimental observations. The theoretical results are then validated by comparison with experimental results. In addition, some parameters that influence RWIV are investigated in detail. The augmented theory in the present study gives a more accurate model and promotes more reliable evaluations of the dynamic behaviors of RWIV of stay cables.

Computer-assisted assembly process planning for the installation of flexible cables modeled according to a viscoelastic Cosserat rod model

Available computer-aided assembly process planning methods fail to provide the necessary level of accuracy required by modern complex planning processes owing to the neglect of the internal friction arising in the process of cable movement and large cable deformation conditions. The present study addresses this issue by developing a computer-aided assembly process planning method that inherently considers the tensile, bending, and torsional deformations of cables based on a dynamic viscoelastic Cosserat model describing cable motion. The simulation module of the virtual cable assembly process integrates and optimizes an efficient and robust algorithm for rapidly solving the dynamic cable model based on a semi-implicit Euler method. The performance of the proposed method is verified by demonstrating the rationality and accuracy of the assembly path planning and multi-cable assembly sequence obtained by the virtual assembly simulation module for a modeled prototype of a complex electromechanical product produced in the aerospace industry.

On the mechanism of divergent cable movement: Contribution of the bistable flow activity in the critical flow regime

This paper studies the contribution of the bistable flow activity on the installation of incipient conditions to provoke divergent stayed-cable movement. The experiment consists of performing dynamic tests on a long (6.1 m) and genuine inclined and smooth-surfaced cable in a wind tunnel. The cable has an outer diameter of 0.219 m and is equipped with 128 pressure taps distributed on seven (7) rings. The range of the Reynolds numbers is covering the critical flow regime around a circular cylinder. The evolution of mean and instantaneous aerodynamic coefficients is discussed and Proper Orthogonal Modes of the pressure pattern are created. The results indicate that both transitory regimes in the critical flow regime could contribute to install cable instability incipient conditions. Seemingly, only the unsteady states in the critical flow regime appear to participate on imposing large cable displacement. The influence of the circularity defect on disturbing flow fields around the circular cylinder has also been confirmed. Furthermore, the bistable flow activity has been clearly identified to contribute strongly in the installation of large-amplitude wind-induced vibrations.

High-precision digital Faraday cups for FEEP thrusters

The number of scientific missions that require an extremely precise alignment of spacecraft achieved by electric thrusters has increased significantly in recent years. This requires a highly accurate knowledge of the thrust vector misalignment and the thrust intensity variation over time. In order to be able to resolve this high accuracy of the thruster beam, a high-precision plasma diagnostics system is required. For example, for upcoming missions like NGGM, it is required to get a spatial resolution of the ion beam current measurements <0.5° in polar and azimuthal direction. FOTEC's plasma diagnostics system based on Faraday cup analysis was optimised in order to be able to analyse the thrust vector misalignment with high spatial resolution. On the one hand, the geometry was adapted to keep the reduction of the signal due to secondary electron emission at a minimum. On the other hand, the entire measuring electronics were built into the head of each Faraday cup. This completely eliminates signal interference due to the cable length and movement of the diagnostics arm. Measurements of the digital Faraday cup diagnostics system will be presented, which were carried out at an IFM Nano Thruster. In particular, the signal-to-noise ratio could be significantly improved.

Evaluating the electromagnetic forces on the electric arc furnaces’ power cables under various operation conditions

Studies of the electrical, thermal, and mechanical stresses on power cables have received much attention in recent years. However, there is a research gap in studying the electromagnetic forces of the power cables of electric arc furnaces (EAFs). The challenges of studying the EAF's power cable are highlighted because of the special cyclic operations, inrush currents, current harmonics, and short circuit faults of the EAF. The electromagnetic forces are influenced by the magnitude current and behavior of the current passing through the cable. The main purpose of this paper is to respond to a research gap about studying the electromagnetic forces of EAF's power cables under different normal and abnormal conditions. The proposed study is implemented in the COMSOL Multiphysics environment. Test results of applying the proposed method to an actual test system highlight the advantages of the proposed study. Simulation results imply that current harmonics, particularly the 7th harmonic order, intensify the electromagnetic forces. Test results emphasize the impacts of short circuit currents on the induced electromagnetic force. Furthermore, test results show that although cable clips limit the cable movement, internal von Mises cable stress increase due to the deployment of cable clips.

CT Assessment of Intraorbital Cable Movement of Electronic Subretinal Prosthesis in Three Different Surgical Approaches.

PurposeElectronic retinal implants restore some visual perception in patients blind from retinitis pigmentosa. Eye movements cause mechanical stress in intraorbital power supply cables leading to cable breaks. By using computer tomography (CT) scans at the extreme positions of the four cardinal gaze directions, this study determined in vivo, which of three surgical routing techniques results in minimal bending radius variation and favors durability.MethodsNine patients received the first-generation subretinal implant Alpha IMS (Retina Implant AG, Reutlingen, Germany) in one eye. Three techniques for intraorbital cable routing were used (straight cable route (A), parabulbar loop (B), and encircling band (C)), each in three patients. All patients underwent computer tomography of the orbital region. The bending radius of the intraorbital cable was measured with the DICOM viewer Osirix v4.1.2 (Pixmeo SARL, Bernex, Switzerland) and served as indicator for mechanical stress.ResultsAverage bending radius variation was 87% for method A, 11% for method B, and 16% for method C. Methods A and B (P = 0.005) and methods A and C (P = 0.007) differed significantly, while method B and C showed no statistical difference (P = 0.07).ConclusionsCompared to straight routes, arcuated cable routes significantly reduce cable movement and bending. Due to an easier surgical procedure, a parabulbar loop is the preferred method to minimize bending radius variation and prolong survival time of electronic subretinal implants.Translational RelevanceCT analysis of cable bending of implanted medical devices allows to determine which surgical routing technique favors durability in vivo.

A WSN system for high-precision cable manhole cover movement detection uses TDOA ranging method

In the research of the power cable anti-theft problem, the demand for high-precision positioning of the cable manhole cover is proposed. For this reason, a wireless sensor WSN node with ranging function is studied. The system uses the Stm32 chip as the MCU core, uses 433MH radio frequency signals and ultrasonic signals to implement a ranging circuit based on the TODA principle of arrival time difference, and sends data to the cloud server through the NB-IoT module to achieve the purpose of alarming. The system has the characteristics of good real-time performance and high positioning accuracy. It can be applied to the theft prevention of cable manhole covers, and can also be extended to the detection of indoor moving objects.

Cable-Movable Rolling Joint to Expand Workspace Under High External Load in a Hyper-Redundant Manipulator

Hyper-redundantmanipulators (HRMs) are widely used in minimally invasive surgery (MIS) because of their flexibility, dexterity, and compactness. However, when an external load acts on an HRM, its bending motion is disturbed and the workspace decreases. In addition, the external load increases the cable tension, and thin cables may break due to their low breaking strengths. This article proposes a cable-movable rolling joint that increases the workspace for MIS under an external load and reduces the actuating cable tension through cable movement. Furthermore, it presents an optimized motion estimation analysis method that verifies the manipulator performance by finding the equilibrium position and predicting the shape and tip position. The simulated manipulator exhibited a shape similar to that of the prototype and an average tip position difference of 4.59&#x0025; based on the prototype length. Under an external load of 150 g, the workspace and cable tension of the prototype were 27.32&#x0025; larger and 1.79 N lower than those of the conventional rolling joint, respectively. The new cable-movable mechanism and estimation analysis method will help improve the bending performance and position accuracy of HRMs for MIS.

Impact of Wind Gust on High-Speed Characteristics of Polarization Mode Dispersion in Optical Power Ground Wire Cables.

Polarization mode dispersion is recognized as a key factor limiting optical transmission systems, particularly those fiber links that run at bit rates beyond 10 Gbps. In-line test and characterization of polarization mode dispersion are thus of critical importance to evaluate the quality of installed optical fibers that are in use for high-speed signal traffics. However, polarization-based effects in optical fibers are stochastic and quite sensitive to a range of environmental changes, including optical cable movements. This, in turn, gives rise to undesired variations in light polarization that adversely impair the quality of the signal transmission in the link. In this work, we elaborate on experimental testing and theoretical analysis to asses changes of polarization mode dispersion in optical fibers that are caused by environmental variations, here wind gusts in particular. The study was performed on commercially harnessed optical fibers installed within optical power ground wire cables, taking into account different weather conditions. More specifically, we showed that changes caused by wind gusts significantly influence the differential group delay and the principal state of polarization in those optical fibers. For this, we experimentally measured a number of parameters to characterize light polarization properties. Measurements were carried out on C-band operated fiber-optic link formed by 111-km-long power ground wire cables and 88 spectral channels, with a test time step of 1 min during 12 consecutive days. Variations in differential group delay allowed for sensitive testing of environmental changes with measured maxims up to 10 ps under the worst wind conditions. Moreover, measured parameters were used in a numerical model to assess the quality of transmitted high-bit-rate optical signals as a function of wind conditions. The analysis revealed a negligible impact of wind on a 10 Gbps transmission, while substantial influence was noticed for higher bit rates up to 100 Gbps. These results show promises for efficient sensing of environmental changes and subsequent monitoring of the quality of recently used fiber-optic link infrastructures.

Human myoelectric spatial patterns differ among lower limb muscles and locomotion speeds.

The spatial distribution of myoelectric activity within lower limb muscles is often nonuniform and can change during different stationary tasks. Recent studies using high‐density electromyography (EMG) have suggested that spatial muscle activity may also differ among muscles during locomotion, but contrasting electrode array sizes and experimental designs have limited cross‐study comparisons. Here, we sought to determine if spatial EMG patterns differ among lower limb muscles and locomotion speeds. We recorded high‐density EMG from the vastus medialis, tibialis anterior, biceps femoris, medial gastrocnemius, and lateral gastrocnemius muscles of 11 healthy subjects while they walked (1.2 and 1.6 m/s) and ran (2.0, 3.0, 4.0, and 5.0 m/s) on a treadmill. To overcome the detrimental effects of cable, electrode, and soft tissue movements on high‐density EMG signal quality during locomotion, we applied multivariate signal cleaning methods. From these data, we computed the spatial entropy and center of gravity from the total myoelectric activity within each recording array during the stance or swing phases of the gait cycle. We found heterogeneous spatial EMG patterns evidenced by contrasting spatial entropy among lower limb muscles. As locomotion speed increased, mean entropy values decreased in four of the five recorded muscles, indicating that EMG signal amplitudes were more spatially heterogeneous, or localized, at faster speeds. The EMG center of gravity location also shifted in multiple muscles as locomotion speed increased. Contrasting myoelectric spatial distributions among muscles likely reflect differences in muscle architecture, but increasingly localized activity and spatial shifts in the center of gravity location at faster locomotion speeds could be influenced by preferential recruitment of faster motor units under greater loads.

Measuring electrical activity in the brain during exercise: A review of methods, challenges, and opportunities

Background:During the last decade, the use of mobile electroencephalography (EEG) devices has furthered understanding of the mechanisms that underlie psychophysical and affective responses during the execution of gross movements (e.g. walking and cycling). Such devices can also be used to shed new light on the mechanisms that underlie attention allocation, fatigue-related symptoms, emotional reactions, and behavioural outcomes associated with physical activity programmes. This advancement could, potentially, herald a new era for the field of sport and exercise psychology, wherein researchers will be able to investigate athletic performance and exercise behaviour from a different perspective.Objective:In this review, we explore some of the most recent approaches used to measure electrical activity in the brain during exercise.Practical recommendations:We provide an overview of the practical issues that researchers face in this field, such as dealing with artefacts elicited by body and cable movements and how to process the biological signal. We also review methods that researchers can employ to prevent electrical artefacts from compromising the fidelity of data. We make a case for assessing psychological and psychobiological parameters in tandem with EEG in order to arrive at a fuller understanding of exercise-related phenomena.

Mechanical evaluation of the Bravos afterloader system for HDR brachytherapy

PurposeThe Bravos afterloader system was released by Varian Medical Systems in October of 2018 for high-dose-rate brachytherapy with 192Ir sources, containing new features such as the CamScale (a new device for daily quality assurance and system recalibration), channel length verification, and different settings for rigid and flexible applicators. This study mechanically evaluated the Bravos system precision and accuracy for clinically relevant scenarios, using dummy sources. Methods and MaterialsThe system was evaluated after three sets of experiments: (1) The CamScale was used to verify inter- and intra-channel dwelling variability and system calibration; (2) A high-speed camera was used to verify the source simulation cable movement inside a transparent quality assurance device, where dwell positions, dwell times, transit times, speed profiles, and accelerations were measured; (3) The source movement inside clinical applicators was captured with an imaging panel while being exposed to an external kV source. Measured and planned dwell positions and times were compared. ResultsMaximum deviations between planned and measured dwell positions and times for the source cable were 0.4 mm for the CamScale measurements and 0.07 seconds for the high-speed camera measurements. Mean dwell position deviations inside clinical applicators were below 1.2 mm for all applicators except the ring that required an offset correction of 1 mm to achieve a mean deviation of 0.4 mm. ConclusionsFeatures of the Bravos afterloader system provide a robust and precise treatment delivery. All measurements were within manufacturer specifications.

Wake-induced vibration of the hanger of a suspension bridge: Field measurements and theoretical modeling

The underlying mechanism of the wind-induced vibration of the hangers of the suspension bridges is still not fully understood at present and hence is comprehensively examined in this study. More specifically, a series of field measurements on the No. 2 hanger of the Xihoumen Bridge was first carefully conducted. Large amplitude vibrations of the hanger were found and the oscillation amplitude of the leeward cable was obviously larger than that of the windward cables. Furthermore, the trajectory of the leeward cable was close to an ellipse, which agreed well with the major characteristics of wake-induced vibration. Then, a theoretical model for the wake-induced vibration based on a 3-D continuous cable was established. To obtain the responses of the leeward cable, the finite difference method (FDM) was adopted to numerically solve the established motion equation. Finally, numerical simulations by using the structural parameters of the No. 2 hanger of the Xihoumen Bridge were carried out within the spatial range of 4 4<=X<=10 and 0<=Y<=4 with a uniform interval of delta X= delta Y=0.25. The results obtained from numerical simulations agreed well with the main features obtained from the field observations on the Xihoumen Bridge. This observation indicates that the wake-induced vibration might be one of the reasons for the hanger oscillation of the suspension bridge. In addition, the effects of damping ratio and windward cable movement on the wake-induced vibration of the leeward cable were numerically investigated.

Predicting Damage and Life Expectancy of Subsea Power Cables in Offshore Renewable Energy Applications

Subsea power cables are critical assets within the distribution and transmission infrastructure of electrical networks. Over the past two decades, the size of investments in subsea power cable installation projects has been growing significantly. However, the analysis of historical failure data shows that the present state-of-the-art monitoring technologies do not detect about 70% of the failure modes in subsea power cables. This paper presents a modeling methodology for predicting damage along the length of subsea cables due to environmental conditions (e.g., seabed roughness and tidal flows) which result in the loss of the protective layers on the cable due to corrosion and abrasion (accounting for over 40% of subsea cable failures). For a defined cable layout on different seabed conditions and tidal current inputs, the model calculates the cable movement by taking into account the scouring effect and then it predicts the rate at which the material is lost due to corrosion and abrasion. Our approach integrates accelerated aging data using a Taber test which provides abrasion wear coefficients for the cable materials. The models have been embedded into a software tool that predicts the life expectancy of the cable and demonstrated for narrow conditions, where the tidal flow is unidirectional and perpendicular to the power cable. The paper also provides discussion on how the developed models can be used with other condition monitoring data sets in a prognostics framework.

Comparison of Two Models for Prediction of Seismic Streamer State Using the Ensemble Kalman Filter

Towed marine seismic streamers are extensively utilized for petroleum exploration. With the increasing demand for efficiency, leading to longer and more densely spaced streamers, as well as four-dimensional (4D) surveys and more complicated survey configurations, the demand for optimal streamer steering has increased significantly. Accurate streamer state prediction is one important aspect of efficient streamer steering. In the present study, the ensemble Kalman filter (EnKF) has been used with two different models for data assimilation including parameter estimation followed by position prediction. The data used are processed position data for a seismic streamer at the very start of a survey line with particularly large cable movements due to currents. The first model is a partial differential equation (PDE) model reduced to two-dimensional (2D), solved using a finite difference method (FDM). The second model is based on a path-in-the-water (PIW) model and includes a drift angle. Prediction results using various settings are presented for both models. A variant of the PIW method gives the overall best results for the present data.