The selection of anti‐corrosive protective materials for metal pipelines is generally based upon a consideration of three basic factors. Briefly, we can list them as follows: the…
Abstract
The selection of anti‐corrosive protective materials for metal pipelines is generally based upon a consideration of three basic factors. Briefly, we can list them as follows: the atmospheric conditions or, in the case of an underground or underwater structure, the soil or water conditions that will be encountered by the line; the ease and economy with which the protection can be applied; and lastly the durability of the material in the face of not only corrosive shock but mechanical stresses. The problem is complicated by the fact that few such pipelines meet with uniform conditions throughout their length.
Paul Clérico, Xavier Mininger, Laurent Prévond, Thierry Baudin and Anne-Laure Helbert
This paper aims to investigate the efficiency of a laminated composite for shielding applications. The solution has to be efficient not only for the shield against static magnetic…
Abstract
Purpose
This paper aims to investigate the efficiency of a laminated composite for shielding applications. The solution has to be efficient not only for the shield against static magnetic fields but also “for low-frequency ones, in order to be well-suited for applications with electromagnetic perturbations in the frequency range DC to 100 kHz.”
Design/methodology/approach
The composite constituted of a steel sheet taken in a sandwich between two aluminum (Al) sheets is produced by cold roll bonding. A good adherence between Al and steel sheets, ensuring a good mechanical resistance, is obtained with a specific process. A previous study has shown that the optimal trade-off between adherence and magnetic shielding effectiveness (SEH) is obtained with a 230 µm composite produced with an initial thickness of Al and steel sheets, respectively, of 250 and 100 µm. In this paper, the 230 µm Al/steel/Al composite is used in three applications modelized by two-dimensional numerical simulations. To obtain reasonable computation time for the simulations, a homogenization method is applied to the composite. Studied applications are a cylindrical box containing a coil, a square box under an external magnetic field and a high voltage cable.
Findings
In each application, SEH is calculated at low frequency and different materials (Al/steel/Al, Al, steel and copper) are compared. It is observed that, in each application, the composite presents higher SEH at equal mass, especially for frequencies between 5 and 100 kHz.
Originality/value
The proposed approach, from the material point of view to the system consideration, shows that the thin bimetallic composite is an innovative and promising solution for magnetic shielding in the case of applications with both DC and low-frequency perturbations.
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Disons‐le d'entrée de jeu, je préférerais, quant à moi, inverser les termes et vous entretenir du thème: tourisme et remontées mécaniques. Il me paraît, en effet, qu'en mettant…
Abstract
Disons‐le d'entrée de jeu, je préférerais, quant à moi, inverser les termes et vous entretenir du thème: tourisme et remontées mécaniques. Il me paraît, en effet, qu'en mettant l'accent sur les remontées mécaniques, on se retrouve comme transporté quelque dix ou quinze ans en arrière à cette époque d'investissements fiévreux où l'on croyait qu'il suffisait de construire une ou plusieurs installations — téléphérique, télésiège ou monte‐pente — pour ouvrir une vallée ou une région au tourisme. On cédait à une illusion simpliste: Le tourisme sidvra!
Zehui Zhang, Qian Huang, Lewen Li, Dan Li, Xueping Luo and Xiaohong Zeng
The purpose of this study is to address the deficiency in safety monitoring technology for 27.5 kV high-voltage cables within the railway traction power supply by analyzing the…
Abstract
Purpose
The purpose of this study is to address the deficiency in safety monitoring technology for 27.5 kV high-voltage cables within the railway traction power supply by analyzing the grounding methods employed in high-speed railways and developing an effective monitoring solution.
Design/methodology/approach
Through establishing a mathematical model of induced potential in the cable sheath and analyzing its influencing factors, the principle of grounding current monitoring is proposed. Furthermore, the accuracy of data collection and alarm function of the monitoring equipment were verified through laboratory simulation experiments. Finally, through practical application in the traction substation of the railway bureau on site, a large amount of data were collected to verify the stability and reliability of the monitoring system in actual environments.
Findings
The experimental results show that the designed monitoring system can effectively monitor the grounding current of high-voltage cables and respond promptly to changes in cable insulation status. The system performs excellently in terms of data collection accuracy, real-time performance and reliability of alarm functions. In addition, the on-site trial results further confirm the accuracy and reliability of the monitoring system in practical applications, providing strong technical support for the safe operation of high-speed railway traction power supply systems.
Originality/value
This study innovatively develops a 27.5kV high-voltage cable grounding current monitoring system, which provides a new technical means for evaluating the insulation status of cables by accurately measuring the grounding current. The design, experimental verification and application of this system in high-speed railway traction power supply systems have demonstrated significant academic value and practical significance, contributing innovative solutions to the field of railway power supply safety monitoring.
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To the Editor. DEAR SIR, In the June issue of AIRCRAFT ENGINEERING, Mr V. D. Naylor rightly asserts that, according to one‐dimensional theory, the velocity at the throat of a…
Abstract
To the Editor. DEAR SIR, In the June issue of AIRCRAFT ENGINEERING, Mr V. D. Naylor rightly asserts that, according to one‐dimensional theory, the velocity at the throat of a Laval nozzle is the local sonic velocity, whether friction is present or not. However his proof rests on an expansion law pvn=constant, when n≠y, and the throat velocity which he obtains differs according to the value of n. Both the assumption and the conclusion are false. The confusion which has existed on this point is, therefore, deepened.
After dealing in Part 1 with the actual corrosion of pipelines under the varied atmospheric and ground conditions in the Middle East, Mr. Sparrow deals with practical problems in…
Abstract
After dealing in Part 1 with the actual corrosion of pipelines under the varied atmospheric and ground conditions in the Middle East, Mr. Sparrow deals with practical problems in the construction of groundbeds in the desert, their siting, and the siting of terminals and tank farms. Stress is laid on the importance of regular and thorough checking of pipeline protection methods, both pipe wrapping and cathodic protection.
This paper provides a brief historical sketch of cable and telephone regulation in the USA, the purpose of which is to demonstrate the legacy that precedes contemporary debates…
Abstract
Purpose
This paper provides a brief historical sketch of cable and telephone regulation in the USA, the purpose of which is to demonstrate the legacy that precedes contemporary debates over competing models of digital networks, and to question the justifications offered for regulating such networks as private property with no corresponding public service obligations.
Design/methodology/approach
The paper relies on historical research to examine the rationales that have been used for cable and telephone regulation, based on the use of legal documents (statutes, regulations, court rulings).
Findings
The historic justifications that have been used to protect telecommunications from competition amounts to what is known as “corporate welfare”. Today's cable and telephone networks, and the accumulated wealth of the corporations that own them, would not have been possible without the willingness of regulators to favor particular firms and business models, and to protect these firms from competition under the rationale that these networks are “natural monopolies”.
Originality/value
Today's digital networks have been built on the wealth and market dominance that was made possible by protection from competition and the guaranteed rates of return that regulation permitted. Consequently, the property rights that have been afforded to network owners should be accompanied by responsibilities, namely, in the form of public service obligations.
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La région du haut‐lac Léman doit sa réputation mondiale non seulement à la beauté de ses sites, à la douceur de son climat et à l'excellente organisation de ses hôtels bien…
Abstract
La région du haut‐lac Léman doit sa réputation mondiale non seulement à la beauté de ses sites, à la douceur de son climat et à l'excellente organisation de ses hôtels bien aménagés. Montreux est encore le pays classique des chemins de fer de montagne. En effet, les Montreusiens ont, dans ce domaine, accompli un vrai travail de pionnier.
Hao Guo, Feng Ju, Ning Wang, Bai Chen, Xiaoyong Wei, Yaoyao Wang and Dan Wang
Continuum manipulators are often used in complex and narrow space in recent years because of their flexibility and safety. Vision is considered to be one of the most direct…
Abstract
Purpose
Continuum manipulators are often used in complex and narrow space in recent years because of their flexibility and safety. Vision is considered to be one of the most direct methods to obtain its spatial shape. However, with the improvement of the cooperation requirements of multiple continuum manipulators and the increase of space limitation, it is impossible to obtain the complete spatial shape information of multiple continuum manipulators only by several cameras.
Design/methodology/approach
This paper proposes a fusion method using inertial navigation sensors and cameras to reconstruct the shape of continuum manipulators in the whole workspace. The camera is used to obtain the position information, and the inertial navigation sensor is used to obtain the attitude information. Based on the above two information, the shape of the continuum manipulator is reconstructed by fitting Bézier curve.
Findings
The experiment result of single continuum manipulator shows that the cubic Bézier curves is applicable to curve fitting of variable curvature, the maximum fitting error is about 2 mm. Meanwhile, the experiment result shows that this method is not affected by obstacles and can still reconstruct the shape of the continuum manipulators in 3-D space by detecting the position and attitude information of the end.
Originality/value
According to the authors’ knowledge, this is the first study on spatial shape reconstruction of multiple continuum manipulators and the first study to introduce inertial navigation sensors and cameras into the field of shape reconstruction of multiple continuum manipulators in narrow space. This method is suitable for shape reconstruction of manipulator with variable curvature continuum manipulator. When the vision of multiple continuum manipulators is blocked by obstacles, the spatial shape can still be reconstructed only by exposing the end point. The structure is simple, but it has certain accuracy within a certain range.