Underground Electric Research Articles

Obstacle Detection Method of Underground Electric Locomotive Rail Based on Instance Segmentation

Real-time and accurate obstacle detection is a vital technology for electric locomotives, especially as driverless vehicles are introduced. A method of obstacle detection for underground electric locomotive rail based on instance segmentation is developed to solve the problems of misdetection and missing detection, low detection accuracy, and slow detection speed of rail obstacles. The method of locating the track mask, demarcating the effective driving boundary, expanding the track mask, and forming the effective driving area is adopted to verify whether the target is an obstacle based on whether the target is located in the effective driving area, to avoid the problem of misdetection and missing detection of the target obstacle. The YOLACT++ (You Only Look At CoefficienTs) model is improved, and path augmentation and target classification loss function replacement strategies are adopted to enhance the model’s ability to detect target details and increase the accuracy of target segmentation. Compared with traditional image processing, this method can detect both straight rail and turnout. The mean average precision of boundary box mAP0.5(box) and mask mAP0.5(mask) of the improved YOLACT++ model reaches 98.52% and 98.55%, which is higher than that of the YOLACT++ model, and the detection frame rate reaches 21.9 frames per second.

Mobile Sensor Networks: What Can Underground Electric Transport Vehicles do in Underground Mine Monitoring?

According to our previous work, we have found that the ZigBee WSN technology and sensors are actually suitable for the underground monitoring, but there are still many problems. So in this viewpoint paper, we showed our viewpoint that the underground driver-less electric transport vehicles could also play an important role in the underground monitoring, that is, underground electric transport vehicles running in the mine roadway could carry mobile sensors to monitor the environmental conditions in the transport roadway. If it could be realized, it will save the number of sensors installed around the mine so as to reduce costs. If it could be realized, the monitoring of underground mines will become more convenient.

Preliminary Evaluation of the Earthquake Hazard for Underground Electric Facility Lines in Pohang City based on ArcGIS

Pohang, a big city of Gyeongbuk province, South Korea, is developing rapidly in every aspect, containing many important infrastructures such as seaports, industrial factories, commercial centers, and underground electric facility systems that play an integral part in the contribution of electricity stemming from nuclear power plants. The main purpose of this research is a preliminary assessment of the earthquake hazard for underground electric facility lines (UEFL) located beneath Pohang city by using ArcGIS program. About 1000 drilling boreholes were collected as a database. All of the data were processed by filtering with respect to the depths, then the SPT-N values of unknown points were estimated by interpolation. Four interpolation methods (e.g., Inverse Distance Weighting (IDW), Kriging, Natural Neighbor, and Spline) were evaluated to find the method which gives the best representation of the SPT-N value for unknown points. The IDW method was finally selected. Afterwards, the border surface between soft- and hard-soil layers, the ground rock zonation map, the dramatic change of soil condition, and the depth of structure were determined as important scales to evaluate primarily whether the structures might be in danger or not when an earthquake occurs. In this way, proposed method can be applied to whole South Korea with over 100,000 available borehole data.

Underground Electric Signal at the Occurrence of the Niigataken Chuetsu-oki Earthquake in 2007, Japan

The electric field mill in our underground observation room detected a co-seismic electromagnetic signal in the vertical electrostatic field ca. 8s after the origin time of the Niigataken Chuetsu-oki Earthquake in 2007, but ca. 30s before the arrival time of the P-waves.

Tube Centenary: 100 Years of Underground Electric Railways Exhibition at the London Transport Museum, 18 May 1990 to 6 October 1991

Tube Centenary: 100 Years of Underground Electric Railways Exhibition at the London Transport Museum, 18 May 1990 to 6 October 1991

Tube Centenary: 100 Years of Underground Electric Railways Exhibition at the London Transport Museum, 18 May 1990 to 6 October 1991

Tube Centenary: 100 Years of Underground Electric Railways Exhibition at the London Transport Museum, 18 May 1990 to 6 October 1991

地震直前先行現象としての極低周波地中電界変動

地震直前先行現象としての極低周波地中電界変動

Lorenzo of the Underground

BENEATH the smog and the traffic jams, cheerful, colourfully-dressed people glide down escalators, through clean white tunnels and in sleek silent bright , carriages are carried to every corner of the city. Their motion is effortless; there are no delays. This was the vision of travel as it might be, not a daily inconvenience, but a means to a richer life and itself a spiritual and uplifting experience. And such it was hoped London's Underground railways might become, a transport system fit for the celestial city. In spite of the present realities of staff shortages, dirt and mechanical failures, one can still glimpse the optimism as one stands in the faded glory of a suburban Piccadilly line station; and it is still true that of all the transport systems in the world, London's came closest to realising that dream of celestial perfection. Much of the character of London Transport was due to the dedication of one man in particular, Frank Pick, who between 1906 and 1940 managed successive parts and ultimately the whole of London's transport system. The centenary of his birth was 'celebrated at the Victoria & Albert Museum by a small exhibition organised jointly by the Museum and London Transport. Called Teaspoons to Trains, it covered his'interest in design both in his official capacity as manager of London Transport, and in his personal support of the Design and Industries Association.* 'London Transport as we know it today was formed out of the many different underground railway, bus and tram companies that were merged with the Underground Electric Railway Company of London (UERL) between 1912 and 1933 under the chairmanship of A. H. Stanley (created Lord Ashfield in 1920). In 1933, the combine became a public corporation, the London Passenger Transport Board (LPTB). The very remarkable story of the mergers and the ultimate formation of the LPTBis told by T. C. Barker and Michael Robbins in volume two of their History of London Transport, published in 1974. Pick joined the UERL in 1906 and from 1912, as commercial manager and subsequently managing director, had the job of making this miscellany of companies work. Pick's own view was that the whole of London's transport should be run as one united operation, under a single management, a goal which was partly though not fully achieved with the LPTB. While it was Ashfield who engineered the mergers and made the ideal of a single management possible, it

Flow and Heat Transfer in Convectively Cooled Underground Electric Cable Systems: Part 2—Temperature Distributions and Heat Transfer Correlations

Temperature distributions and heat transfer correlations have been obtained experimentally for a wide range of physical, flow and thermal parameters in three models of oil-cooled underground electric cable systems. The results show that in the laminar range, with the oils used, the thermal boundary layer thickness around the heated cables is only of the order of 2–3 mm over the entire length of the test section. Consequently, the best correlation of the heat transfer results is obtained if the Nusselt number, based on the cable diameter, is plotted against Re·Pr0.4, where the Reynolds number is based on the overall hydraulic diameter of the cross section of the flow. For laminar flows, the oil temperatures in the restricted flow channels between three cables or two cables and the pipe wall are about 11°C higher than corresponding bulk temperatures. As the flow becomes turbulent, the thermal boundary layer tends to vanish and the oil temperature becomes uniform over the entire flow cross section. Laminar Nusselt numbers are independent of the skid wire roughness ratio and the flow Reynolds number, but increase with increasing Rayleigh number and axial distance from the inlet, indicating significant natural convection effect. The range of laminar Nusselt numbers was 5–16. Turbulent Nusselt numbers increase with increasing roughness ratios. The Nusselt numbers at Re = 3000 are 30 and 60 for roughness ratios of 0.0216 and 0.0293, respectively.

Flow and Heat Transfer in Convectively Cooled Underground Electric Cable Systems: Part 1—Velocity Distributions and Pressure Drop Correlations

Velocity distributions and pressure drop correlations have been obtained experimentally for a wide range of physical, flow, and thermal parameters in three models of oil-cooled underground electric cable systems. The flow can be considered as consisting of several, interconnected, parallel channels. If one of these is significantly larger in cross section, it will dominate the behavior of the entire system with velocities up to an order of magnitude greater than in the other channels. Laminar, fully developed flow exists at a dimensionless entrance length as low as x/DH = 100. The turbulent velocity profiles are essentially uniform in the larger, main channel, but not in the small channels with lower velocities. Laminar friction factors can be correlated with an equivalent Reynolds number, based on the main flow channel alone, as fe·Ree = 30. Turbulent friction factors increase with increasing skid wire roughness ratios and approach the asymptotic values of 0.013 and 0.021 for roughness ratios 0.0216 and 0.0293, respectively. Cable heating had no noticeable effect on the friction factor correlations.

Book Review: Underground Electric Haulage (Locomotives)

Book Review: Underground Electric Haulage (Locomotives)

Grounding and Corrosion Protection on Underground Electric Power Cable Sheaths and Oil-or Gas-Filled Pipe Lines [includes discussion

Grounding and Corrosion Protection on Underground Electric Power Cable Sheaths and Oil-or Gas-Filled Pipe Lines [includes discussion

Heat Flow from Underground Electric Power Cables

The heat resistance of the soil surrounding underground cable ducts is usually large, and the path of the heat through the soil is not simple, especially when there are several adjacent ducts. This heat resistance and the path of the heat flow may be determined graphically, but except in the simpler cases, this method becomes very difficult. The heat resistance of any one of several ducts can be calculated theoretically by making assumptions of unknown magnitudes. To check these calculations by testing actual installations would be slow and expensive. Advantage may be taken of the similarity between the flow of heat and the flow of electricity to set up and test the electrical equivalent of any duct system. In this way the theoretical results can be checked readily with a minimum outlay of equipment. Results obtained by this method show the theoretical calculations to be accurate even for close spacing and also give a picture of the actual path of the heat from a group of several ducts, Thus, the heat resistance of a duct may be found quite accurately if the specific heat resistance of the soil is known.

The Atmosphere of the Underground Electric Railways of London: A Study of its Bacterial Content in 1920

1. The bacterial content of the air of the Underground Railways, when the average of all results of the bacteriological investigations is taken, does not numerically compare unfavourably with the outside air of London.2. The ratio of the number of organisms growing at room temperature appears to be about 14 for railway air to 10 outside air. For those growing at body temperature the ratio is considerably higher, namely 2 to 1 respectively. The mean per litre, for room temperature organisms, is about 9 in railway air, 6·3 in the outside air; for body temperature organisms 4·6 for railway air, 2·2 for outside air.3. The bacterial content of platform air, except on the City and South London Railway, would appear to be higher than that of carriage air; the total mean for platform air being 52 and for carriage air 42·8 organisms per 5 litres, or a ratio of 16·4 and 13·5 respectively to 10 of the open air. The higher proportion in platform air is generally speaking to be accounted for by the greater amount of draught and dust disturbance.4. The ratios of the total bacterial content of railway carriage air and carriage and platform air on the six lines to open air are estimated in the following proportions:

Underground Electric Railways Abroad

Underground Electric Railways Abroad