DYNAMICS OF SPACE CABLE SYSTEMS

Sleep in mice has typically been determined from electroencephalograms and electromyograms recorded via cables in tethered animals. However, the relatively small physical size of mice can produce concerns in recording with cables that may not be seen in larger animals. To examine the influence of implantation and tethering on mice, we recorded activity and sleep in 2 strains while they were attached to 3 cable configurations that varied in weight and flexibility. Activity was recorded prior to surgery and after surgery without tethering. Afterward, the mice were habituated to 3 cable configurations (light [L]: 1.5 g; medium [M]: 2.2 g; heavy [H]: 3.0 g), and activity and sleep were recorded for 2 consecutive days under each configuration. N/A. Studies were conducted in 2 mouse strains that differ significantly in levels of spontaneous activity (more-active strain: BALB/cJ [C]; less-active strain: DBA/2J [D2]). N/A. Significant postsurgery reductions in activity in nontethered mice were found only in the more-active C strain. Activity in both strains was reduced in a graded manner as cable weight increased and flexibility decreased. In contrast, changes in sleep were not graded across cables, and changes in rapid eye movement sleep showed more variability. In addition, the effects of varying cables were not consistent across strains. The differential impact that variations in the weight and flexibility of recording cables can have on the amount and patterns of sleep is an important consideration in conducting and interpreting sleep studies in mice.

The paper presents the dynamic behavior of a Submerged Floating Tunnel (SFT) in the Seribu Archipelago crossing under seismic loadings by using the different cable configurations. The SFT is a tubular structure submerged in the water at a fixed depth, which features several advantages from the structural and environmental impact points of view. In particular, the structural system is suited for waterway crossings in seismicity zones. Its interaction with the water provides additional damping and inertia to the system. To evaluate the SFT structural response of seismic loadings, a response spectrum analyses were carried out, in which the ground multi-support excitation is considered. The investigation of the different cable system configurations were also carried out. Both static and dynamic analyses were carried to find the optimal configuration of the structural system. Although the paper has had a definitive conclusion yet, the results gave useful indications of responses of Submerged Floating Tunnels subjected to earthquake. The SFT with two cable diagonals perpendicular with SFT’s body (called Model C) shows the optimal structural configuration compared with others.

Equilibrium configurations of a cable drogue system towed in a helical motion

China has the world's second largest electric power industry, and is planning to modernize its power network into a strong and smart grid. Superconducting cable offers the advantages of lower loss, lighter weight and smaller dimensions, as compared to conventional cables. It will have broad application prospects in Chinese power grids, and now an 110kV HTS cable project is being planned in Beijing. This paper describes the site selection of 110kV HTS cable, and put forward some investigation about the system configuration, control and protection system of the cable.

Cable models for high-frequency studies require the calculation of per-unit-length parameters in a wide frequency range. Analytical methods, such as the ones implemented in traditional electromagnetic transient simulators, are frequently used for this purpose. However, they are accurate only for cable systems in which the cables are sufficiently apart from each other, and for specific geometries in which the presence of other wired systems and metallic structures is neglected. This hampers their application to calculate the parameters of cable systems assembled in trays or pipes, which are frequently used in industrial installations. In this context, this paper presents a methodology based on finite element analysis to overcome these limitations. This methodology is used to investigate the influence of proximity effects on parameters associated with three different installation methods often found in the industry: cables laid on or above the earth surface, cables in an enclosing pipe, and cables in a tray. The results indicate the importance of considering proximity effects in the calculation of cable parameters in practical conditions, especially for high-frequency studies.

The many applications of cable systems in the ocean environment need not be enumerated, and the importance of the knowledge of the dynamic response of such systems to hydrodynamic loadings is obvious. However, because of the complex nature of such loads and because of the nonlinear nature of the response (especially for cables with small initial tension), analytic solutions are infeasible. Even for the simplest loads, non-linear solutions to static or dynamic problems are infrequent. It is the purpose of this paper to present a numerical solution method for three-dimensional nonlinear cable problems, both static and dynamic, adequate far the proper analysis of cables in which rapid spatial and. temporal changes in geometrically material properties occur. Introduction The many applications of single cables and cable systems in the ocean environment need not be enumerated, and the importance of the knowledge of the dynamic response of such systems to hydrodynamic loadings is obvious. However, because of the complex nature of such loads and because of the nonlinear nature of the response, analytic solutions are infeasible. There is extensive literature available concerning the linear response (both static and dynamic) of cables (3,4,10,12,14,15,21, 22,25,26,27,28,29,30,31) and investigations of their static nonlinear behavior have been reported (1,3,11,16,20,23,24). Even for the simplest load systems, however, nonlinear solutions to dynamic problems are infrequent (5,19,28). It is the purpose of this paper to present a numerical solution method for three-dimensional nonlinear cable problems which is adequate for the proper analysis of cables in which rapid spatial and temporal changes in geometric and material properties may occur. The theory of incremental deformations (2,7,8) is used to reduce the governing nonlinear Hamilton's principle to a sequence of quasi-linear equations which are dependent on the prior history of the deformation. The solution method for these equations is based on the use of curved finite elements to model the geometry of the cable. The advantage of a finite element analogue is that complex geometries can be easily modeled and simple temporal redefinitions of elements can be effected. The finite element representation is valid during some time interval in which the incremental equations approximate the response of the nonlinear system. The interval size is either defined a priori or determined by the calculated stresses and displacements. The solution is extended to later time intervals by referring additional incremental deformations to a coordinate system imbedded in the new cable configuration assumed at the end of the previous time interval. In a previous work (13) a finite element model using straight tension elements was presented. Such a model is inadequate for strongly-curved cables in that a great number of straight elements are required to approximate the cable. Furthermore, unless numerous small elements are used, the existence of nodal discontinuities inherent in the use of straight elements leads to spurious results because of the membrane nature of the real problem. Therefore a curved element is presented for which continuity of slope across nodal points is enforced using direction cosine approximations.

This tri‐axial high‐temperature superconducting (HTS) cable design uses three concentric superconducting layers for the phase conductors, separated by a cold dielectric material. The design offers an efficient HTS cable configuration by reducing the amount of superconductor needed and places all three phases in a single cryostat. The tri‐axial cable cooling circuit analyzed includes heat loads at the ends for the cable terminations and cable heat loads due to ac, dielectric, and thermal losses. The HTS cable critical current and ac loss are functions of the local temperature that must be determined by the analysis. The radial heat transfer also has an influence on these parameters due to the relatively low thermal conductivity of the dielectric material separating the HTS phases. The study investigates whether the tri‐axial cable must be cooled both inside the former and outside of the cable. In this study, the range of operating parameters for a tri‐axial HTS cable system and refrigeration requirements are determined based on expected HTS tape performance.

The extension of the Dutch 380 kV high voltage grid is necessary in order to guarantee security of electricity supply to the consumers. To achieve this extension, there are two new 380 kV connections under construction in the Randstad area, a densely populated area in the western part of the Netherlands. In these 380 kV connections, underground cables are applied. The work described in this thesis forms a part of a monitoring program that is managed by the Dutch transmission grid operator TenneT. In this program, the behavior of the two new underground cable connections in the Dutch 380 kV grid is being investigated and the work described in this thesis contributes to this program. Unlike the common overhead transmission line, which has an inductive behavior, a cable acts as a capacitance when it is in operation. This difference in electrical behavior makes research on the grid behavior necessary. One of the research goals is to evaluate whether the power flows and voltage levels in the 380 kV grid stay within the prescribed limits. Another goal of this work is investigating whether the peak of the transient voltages at the cable terminals after lightning currents will stay below the Basic Insulation Level. The research is divided into two parts: steady state behavior and transient behavior. For the steady state part, PI sections are used to model the underground cable and overhead line to perform load flow studies in order to investigate the power flows and voltage levels in the 380 kV grid. For the transient part, the widely applied Frequency Dependent Phase Model (FDPM), which is a transmission line model that takes into account the frequency dependency of cable and line parameters, is used to model the cable and overhead line sections. For the transient part, the focus is on the modeling work of the complete underground cable system. Field measurements are performed for both the 380 kV cross-bonded cable and the overhead line sections and the results are used for transient cable model verification. The scientific contribution of this work is the determination of the parameters for the 380 kV cross bonding system by using reflection measurements and the validation of the FDPM transmission line model by using field measurements on the actual cross bonded 380 kV cable system. Finally, based on the studies described in this thesis, one can conclude that no remarkable overvoltages occur during the studied steady state and transient situations for the given dimensions of the observed 380 kV system.

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> This paper presents a novel wavelet-based fault-location scheme for aged cable systems when synchronized digital fault recorded data are available at the two terminals of each cable. The proposed scheme estimates the fault location in multiend-aged cable systems using the theory of wavelet singularity detection as a powerful signal processing tool. The arrival of the first and second voltage traveling waves at both ends of the power cables can be identified reliably. The developed wavelet processing scheme is applied on the modal coordinates instead of the phase coordinates. The proposed scheme has the ability to eliminate the impact of the change in the propagation velocity of the traveling waves on the fault-location calculations. This will help solve the problem of cable changing parameters, especially the change of the relative permittivity of the cable with age. The method is valid even with faults that are very close to busbars. Characteristics of the proposed fault-location scheme are analyzed by extensive simulation studies using Alternative Transients Program/Electromagnetic Transients Program. The results indicate an accepted degree of accuracy for the suggested fault locator. </para>

The technology of oil filled cable systems is reviewed as a feasible approach to electric cable systems for deep ocean use. Existing technology is adequate for shallow depths but as this technology is applied to the deep ocean, cost and reliability suffer. The framework of classical cable technology as outlined in the Naval Ship Research Development Laboratory Handbook is applied to the oil filled system used on ALVIN to provide a comparison to non-oil filled performance. Cable design considerations that resulted in the choice of systems components for ALVIN are presented. The constraints on oil filled cable systems are reviewed including material compatibility, pressure head in air and water, and system servicing. The ALVIN oil-compensated system configuration is described as well as the component parts.

A partial discharge (PD) locating system, which can automatically distinguish PD from noise and locate the PD site in power cables, has been fabricated successfully and verified in an after-laying test of a Gas Insulated transmission Line (GIL). The system provides sufficient detection accuracy to meet the requirements of the practical measurement on site. This paper presents the PD locating principle and the system configuration. A new concept of recognizing PD based on the relative distribution between PD magnitude, PD site location, and measuring time is described. The results of applying the system in the on-site test for GIL are also reported.

Calculation models for the selection of cable lines used for expansion and modernization in the energy system and energy transmission planning are recognized tools supporting decision-making in both the energy sector and energy policy. At the same time, the above calculation models contain a large number of correction factors taking into account the temperature of the external environment at various points, the mutual influence of which is not taken into account. This means limitations to today’s common approaches to solutions, especially with regard to the required safety buffer for cable line selection. To meet this challenge, this article presents a parameter that takes into account the change and difference in temperature at various points in the external environment in the analyzed cable line systems. The purpose of this paper was to develop a new approach to the selection of a cable line in order to minimize failure during operation. For this purpose, possible temperature cases that may occur during line operation in different countries and at different rated voltages have been identified. Simulation models for individual cable line layouts were developed and the extreme temperature cases of the line operation for the maximum negative and positive temperature difference between the cable core and the external environment were considered in detail. The development of the curve of the change of the correction factor for the difference in the operating temperature of the cable line will allow for a more precise selection of the cable line parameters and the shortening of the current calculation model in terms of cable selection. In addition, this article presents a comparison of the change in the value of the correction factor from the change in temperature of a selected phase of a cable line system.

This paper describes the basic concept of a future optical cable network operation system for optical subscriber loops. The problem of existing subscriber networks and the functions required of the integrated operation systems are clarified. In addition, for the optical fiber switching system in the integrated operation system, the system configuration and experimental studies are presented on switching functions. As the results, good performance has been confirmed for the development system.

This work is devoted to the study of the unmanned aerial vehicle movement model. Attention is focused on the issue of studying the forces that determine the dynamics of movement, the resultant force is considered. Based on the fact that the equation of motion depends on the structural features and purpose of aircraft, and their arsenal is quite varied and multifaceted, the basis of the study is the tactical and technical characteristics (TSH) of operational-tactical missile systems. The model on the passive part of the trajectory, where the nature of the equation of motion is determined only by gravity and aerodynamic forces, is considered in the paper. Taking into account the maximum flight height and the probabilistic nature of errors in the calculations, it is proposed to consider the force of gravity as constant along the entire trajectory. Therefore, all efforts are directed at determining the numerical values for determining the aerodynamic force. TSH missiles are of great importance here. It is worth noting that there are no real and reliable data about the rocket, in particular its design and experimental data. They are either classified, or unreliable in advance (deliberately presented with some error), or are established experimentally with a certain degree of accuracy or probability. That is why the numerical values given in the paper should be taken as probabilistic. In the active part of the movement trajectory, the main attention is paid to determining the engine's thrust. The given numerical values characterizing its force, the tabulated experimental values are conditionally correct, but the errors are insignificant. Data on the natural forces of air movement are even more uncertain. This made it necessary to compare different types of rocket and determine «conditionally» correct values. Based on the proposed mathematical model, it is possible to solve the task of predicting the navigation of an unmanned aerial vehicle with the numerical values of its main characteristics and other necessary input data. This will make it possible to study and form optimization flight trajectories.

A vertical take-off and vertical landing rocket is one of the future space transportation vehicle expected as fully reusable system. In the landing phase of vertical lander, the vehicle is decelerated by the main engine thrust and lands softly to the ground site. Then its aerodynamic characteristics are affected by the interaction between the engine plume and the subsonic free-stream against the vehicle. In order to investigate the influence of such interaction, wind tunnel tests were conducted. The aerodynamic forces and surface pressure were measured by using scale model of the Reusable Vehicle Testing (RVT) which is a small vehicle built for flight tests in ISAS/JAXA. Flowfield around the vehicle model was visualized by using Particle Image Velocimetry (PIV) method. As a result, the drag force and pitching moment acting the vehicle were affected by the change of pressure distribution due to the jet/free-stream interaction.