Cable Deployment Research Articles

Novel Grid Concepts for Urban Area Power Supply

Abstract This paper presents results of a study investigating a permanent grid deployment of medium voltage superconductor cables in combination with superconducting fault current limiters within a typical urban area power system. A completely new grid concept, which only becomes feasible through the use of superconductor cable systems, is shown. Further, several different cable options, including superconducting and conventional cables, are compared

Geostationary station keeping control of a space elevator during initial cable deployment

This paper presents a basic concept to derive an orbital control strategy to achieve the full deployment and the geostationary station keeping of a space elevator during its initial cable deployment. The space elevator model is composed of a main spacecraft, a sinker mass and a massive cable connecting them. The cable elasticity, flexibility and taper of the cross-sectional area are omitted for simplification. A reference trajectory is designed so that the space elevator and its center of mass ascend vertically along the geostationary position with keeping the geostationary orbital rate. From the reference trajectory analyses, an orbital control that leads the space elevator orbit to the reference one is derived. However it is found that the reference trajectory is unstable throughout the deployment and a linear feedback control is introduced for stabilization. It is also clarified that the libration destabilizes the orbital control because the orbital acceleration caused by the libration always acts in the opposite direction to the orbital control. Therefore, a libration control is also introduced to stabilize the coupled orbital and librational motions. Numerical simulation result clearly shows that these controls facilitate the full deployment and the geostationary station keeping of the space elevator within the feasible thrust force and amount of propellant.

Tracking sperm whales with a towed acoustic vector sensor

Passive acoustic towed linear arrays are increasingly used to detect marine mammal sounds during mobile anthropogenic activities. However, these arrays cannot resolve between signals arriving from the port or starboard without vessel course changes or multiple cable deployments, and their performance is degraded by vessel self-noise and non-acoustic mechanical vibration. In principle acoustic vector sensors can resolve these directional ambiguities, as well as flag the presence of non-acoustic contamination, provided that the vibration-sensitive sensors can be successfully integrated into compact tow modules. Here a vector sensor module attached to the end of a 800 m towed array is used to detect and localize 1813 sperm whale "clicks" off the coast of Sitka, AK. Three methods were used to identify frequency regimes relatively free of non-acoustic noise contamination, and then the active intensity (propagating energy) of the signal was computed between 4-10 kHz along three orthogonal directions, providing unambiguous bearing estimates of two sperm whales over time. These bearing estimates are consistent with those obtained via conventional methods, but the standard deviations of the vector sensor bearing estimates are twice those of the conventionally-derived bearings. The resolved ambiguities of the bearings deduced from vessel course changes match the vector sensor predictions.

A Survey on Scheduling in IEEE 802.16 Mesh Mode

IEEE 802.16 standard (also known as WiMAX) defines the wireless broadband network technology which aims to solve the so called last mile problem via providing high bandwidth Internet even to the rural areas for which the cable deployment is very costly. The standard mainly focuses on the MAC and PHY layer issues, supporting two transmission modes: PMP (Point-to-Multipoint) and mesh modes. Mesh mode is an optional mode developed as an extension to PMP mode and it has the advantage of having an improving performance as more subscribers are added to the system using multi-hop routes. In 802.16 MAC protocol, mesh mode slot allocation and reservation mechanisms are left open which makes this topic a hot research area. Hence, the focus of this survey will mostly be on the mesh mode, and the proposed scheduling algorithms and performance evaluation methods.

Deployment/Retrieval Modeling of Cable-Driven Parallel Robot

A steady-state dynamic model of a cable in air is put forward by using some tensor relations. For the dynamic motion of a long-span Cable-Driven Parallel Robot (CDPR) system, a driven cable deployment and retrieval mathematical model of CDPR is developed by employing lumped mass method. The effects of cable mass are taken into account. The boundary condition of cable and initial values of equations is founded. The partial differential governing equation of each cable is thus transformed into a set of ordinary differential equations, which can be solved by adaptive Runge-Kutta algorithm. Simulation examples verify the effectiveness of the driven cable deployment and retrieval mathematical model of CDPR.

Effect of Optical Loss and Antenna Separation in 2$\,\times\,$2 MIMO Fiber-Radio Systems

We study the impact of fiber-optic loss due to realistic cable deployment and optical connector loss variation and distance between the transmitter antennas in a radio-over-fiber transmission system with 2 × 2 MIMO. We evaluate an upper bound on the system capacity based on measured values of the error vector magnitude and the condition number of the channel matrix. For this, assuming a Rayleigh fading environment, we derive conditional probability density functions of eigenvalues of a 2 × 2 Wishart matrix. We compare the obtained results with another approach, which is based on IEEE 802.11 relations between the allowed relative constellation error and the achievable data rate for an individual stream. Trends predicted by both models agree very well. Our analysis shows that (i) about 1 meter spatial separation of fiber-fed transmitter antennas is optimum and results in the maximized system performance and (ii) the maximum tolerable optical power imbalance in two fiber optic links is about 6 dB.

Dynamics and control of multi-connected satellites aligned along local horizontal

The paper presents dynamics and control of multi-connected satellites aligned along an unstable local horizontal configuration. The satellites are modeled as point masses and they are connected through cables. The cables are assumed to be flexible but massless. The governing equations of motions of the system moving in an elliptic orbit are obtained through a Lagrangian approach. The control laws are developed and the cable deployment and retrieval laws are stated for an N-body system. Results of numerical simulations of the nonlinear governing equations of motion of two- and three-body systems and approximate closed-form solutions indicate the feasibility of controlling multi-connected satellites along the local horizontal. Finally, the effects of various system parameters as well as the cable deployment and retrieval on the system response have been investigated. It is important to mention that the multi-connected satellites system outperforms the free flyer multi-satellite system and the controller only requires force in the order of a Millinewton for multi-satellites in geostationary orbit with a desired inter-satellite separation distance of 100 m.

Cable consolidation and deployment of advanced broadband service

PurposeThe primary purpose of this study is to examine the implications of consolidation in the US cable industry in terms of deployment of advanced broadband services in local markets.Design/methodology/approachThis study estimates a cable operator's deployment of advanced broadband services using a binary probit model of profits from advance broadband services.FindingsThis study finds that larger and more powerful multiple system operators are limited in the transfer of efficiency deployment of advanced broadband services in local markets; therefore, the implications of the efficiency of horizontal integration do not have significant meaning.Originality/valuePrevious literature examined the relationship between horizontal integration, rates and the quality of traditional video services. By examining the relationship between horizontal integration and deployment of advanced cable services in local markets and making a policy suggestion for further consolidations in the US cable industry, this study fills a gap in extant cable industry research.

Constrained path-planning for an aerial-towed cable system

This paper studies the coupled motion of an aircraft towing a cable for applications such as precision deployment or retrieval of payloads, or close surveying of land/ocean environments. There is a complex interaction between the motion of the cable tow-point, aerodynamic drag, and tension forces on the motion of the cable tip. The path-planning algorithm involves determining the motion of the aircraft, as well as the cable deployment rate, to achieve precision “hits” of the cable tip with known ground targets in a three-dimensional space. By utilizing the motion of the towed-body as a differentially flat output, the aircraft controls and/or reel rate are computed via an inverse technique. The motion of the towed-body is approximated using Chebyshev polynomials so as to pass through the desired points while minimizing its overall acceleration. The technique is implemented in a nonlinear programming environment to constrain the aircraft dynamics to within acceptable limits.

Broadband adoption in Europe

The widespread availability and adoption of high-speed broadband Internet access by consumers is increasingly viewed in all developed nations not only as a key driver of information and communication technology (ICT) capabilities, but also of the overall prosperity and well being of the economy of a developed nation. Developed nations are seeking to promote rapid deployment of broadband, coupled with rapid adoption by consumers. Some countries, notably the United States, have sought to rely on competition among multiple broadband media to achieve broadband deployment. Since cable deployments tend to be limited in most European countries, the European approach has been heavily dependent on procompetitive regulation in order to achieve intramodal competition. In this paper, the author discussed the broadband adoption in Europe. It details the upsurge in broadband technology as well as the regulatory and policy issues.

Fluid and lithology identification using high-resolution 3D seismic data

BP acquired its first high-resolution 3D survey data in late 2000 over their Greater Plutonio development area in Block 18, offshore Angola. The seismic acquisition and processing parameters were designed to maximize temporal and spatial resolution of the reservoir sands. A compact and shallow source was used in conjunction with shallow cable deployment. The data were processed at 2 ms to a bin size of 6.25 m. AVO imaging and inversion technology were used to provide fluid and lithological impedance cubes. The survey was designed to aid development well drilling as well as providing a baseline 4D survey. The final datasets have significantly improved resolution compared to the previous conventional 3D survey. The new data show sharply defined fluid contacts, which allows the identification of potential pressure barriers within the reservoir.

Comparison of Field Measurements and Statistical Estimation of Link PMD Coefficients in Optical Systems

Prediction of polarization-mode dispersion (PMD) values of installed links based on manufacturers' data on the delivered short cable sections are biased by the instruments' sensitivity, thus overestimating power penalties. Field distributions of link PMD coefficients display an unexpected long tail toward high PMD coefficients indicating that the hypothesis of random concatenation of fibers in standard procedures for PMD evaluation is not being obeyed in the field. Better instrument sensitivity is required for correct predictions and we suggest that the link simulation methods shall be revised to account for the color pattern in fibers splicing in cable deployment.

Telecommunication Reform: The History and Conditions Leading to Political Action

No abstract available.

Simulation of unsteady oceanic cable deployment by direct integration with suppression

An improved algorithm is developed for predicting the transient response of a system of serially connected cables and bodies during unsteady deployment from a surface vessel. The governing equations of a cable-body system are derived with dependent variables of cable velocities, direction cosines and tension magnitude to form a nonlinear combined initial-value and boundary-value problem. The problem is then solved by introducing a stable Newmark-like implicit integration scheme in time and by a direct integration method with suppression of extraneous erroneous solutions. Special boundary conditions simulating actively controlled payout and slack-cable/ocean-bottom contact boundary conditions are included in the present model.

Bringing fiber optics to america: The cable television experience

Abstract Fiber optic technology is now being deployed on a large scale by cable television companies. Fiber brings unique benefits to cable system design in terms of improved reliability, reduced operating costs, and upgrades of channel capacity. The increased deployment of fiber will also enable cable companies to offer new services to take advantage of the increased functionality of the resulting network design. A survey of cable companies' deployment of fiber is presented.

Global cooperation in an era of deregulation

This article examines the International Telecommunications Satellite Organization (Intelsat), the world's foremost satellite carrier and non-profit global cooperative, and the strategic issues facing this organization in the light of international deregulatory changes in the field of telecommunications. Intelsat faces new competitive challenges from two distinct sources, including private satellite systems and the continued deployment of sub-oceanic fibre-optic cable by a consortium of international common carriers.

Present and future perspectives of mass-splicing technologies in local-distribution networks

Abstract The costs of future local-distribution networks will be determined, for the most part, from the deployment and installation of the fiber-optic cable. The expenditure for the installation, which affects cost and time, can be minimized by utilizing techniques that allow simultaneous splicing of up to 12 single-mode fibers. The two main techniques employ the principles of direct fusing (butt welding) and of mechanical clamping in holding structures of very high geometrical precision. The various feasible methods are discussed and compared in detail.

Simulation of tension controlled cable deployment

The theory and a numerical algorithm were developed for the deployment of cable from a ship traveling with constant speed and direction in a flowing fluid. Attention was focused on steady-state conditions, i.e., horizontal, steady horizontal flow varying in magnitude and direction with depth but uniform in plan, and on tension controlled payout of the cable.

Vortex Shedding in a Linear Shear Flow From a Vibrating Marine Cable With Attached Bluff Bodies

The present study examines the vortex street wake behavior of a flexible, helically wound, high aspect ratio marine cable in a linear shear flow. Particular attention is paid to the lock-on phenomena associated with uniform and sheared flow past the cable when it is forced to vibrate in the first mode, normal to the flow. An analysis is given of the effects on the vortex shedding and synchronization phenomena that are generated by placing distributions of spherical bluff body shapes along the span of the cable in uniform and sheared flow. The latter geometry is representative of a number of cable system deployments and has special consequencies for strumming in a shear flow. The effectiveness of these attached spheres as strumming-suppression devices is evaluated. Synchronized vibration and/or the presence of the bluff bodies significantly affected the spanwise character of the near wake cellular vortex shedding structure. The spanwise extent of the resonant, vortex-excited oscillations was significantly extended by the presence of the spheres along the cable span. This finding was particularly significant because it meant that the undesirable effects that accompanied synchronization would be extended over a longer portion of the cable span.