Tunnel End Research Articles

Fluid-structure interaction of submerged floating tunnel in wave field

The aspect ratio of submerged floating tunnel (SFT), i.e. the ratio of length to diameter, is usually as large as 102 to 103, which means the behavior of SFT would like a slender cylinder restrained by tethers. Although SFT is usually placed under the water surface at a certain depth, surface wave has important influence on its dynamic response due to the slenderness. This paper performs analyses on the fluid-structure interaction of SFT in wave field. Potential fluid theory is adopted to describe the wave field. Boundary element method is used to solve the interaction between SFT and surface wave. Wave potential is divided into three parts, including incident wave potential, diffraction wave potential and radiation wave potential. SFT is discretized into finite elements and its dynamic response is finally solved in frequency domain. As a case study, the values of design parameters for SFT prototype in Qiandao Lake are adopted. Two different tunnel end connectors are used to compare the distributions of tunnel deflections, axial membrane forces at the tube segment connectors and tunnel end connectors.

トンネル坑口上方のまさ土斜面の崩壊による土砂流動災害の事例

2002年7月11日の台風6号に伴う豪雨で, 羅生トンネル坑口の上方斜面が崩壊し, 道路に土砂流出し災害となった. ここでは, この崩壊経緯とその特徴および今後の対策検討のために実施した周辺斜面の調査結果を報告する. (1) 周辺の地質は, 北上山地南部の花崗岩類で, 崩土はまさ土を主体としていた. (2) 複数時期の空中写真により崩壊発生と植生変化状況を追跡した結果, 今回の崩壊箇所と同様な地質・植生箇所で, 崩壊が頻発していた. (3) 隣接斜面 (S-2) に簡易貫入試験を行った結果, 崩壊の危険性箇所を特定した. (4) 隣接斜面は今回崩壊斜面と類似の特徴を持っていた.

Connecting IPvX Networks Over IPvY with a P2P Method

During the transition from IPv4 to IPv6, the IPv6 islands inside the IPv4 networks need to communicate with each other and with the native IPv6 network. The drawback of existing IPv6 transition methods is that relay gateways become potential communication bottlenecks. In this paper, a new method--PS64--is presented to connect IPv6 islands together over IPv4 network and reduce the reliance on these relays by shifting the burden to edge gateways on each island. In this method, direct tunnels are set up between the IPv6 islands, and a P2P network is maintained between edge gateways of these islands to propagate information of tunnel end points. After describing the algorithm, we analyze the connectivity of the P2P network, the scalability of this algorithm, and present the prototype and experiments. The results of our analysis and experiments show that the proposed method is reliable, scalable and effective. Obviously, this technique works for all IPvX over IPvY situations.

Computational Fluid Dynamics (CFD) Use InThe Simulation Of The Death End Ventilation InTunnels And Galleries

In the framework of the Research Project CTM2005-00187/TECNO, “Prediction models and prevention systems in the particle atmospheric contamination in an industrial environment” of the Spanish National R+D Plan of the Ministry of Education and Science, 2004-2007 period, a CFD model has been developed to simulate air flows in tunnels and galleries, including its detailed comparison with available experimental data. Taking into account the importance of the air velocity distribution in the tunnels or galleries where there is continuous transport of particulated material by means of conveyor belts, and where PM10 or PM50 particulated material can be easily thrown in suspension, we quickly identify the necessity of studying the air behaviour using CFD software. Several models were developed using the commercial code Ansys CFX 10.0, starting from several 3D meshes of different resolutions generated using ICEM CFD 10.0. Medium complexity turbulence models were selected in order to obtain acceptable resolution times in single processor machines, as well as following advices contained in related bibliography. Zero Equation (constant turbulent eddy viscosity), k-epsilon and Spallart-Allmaras models were used, comparing their results with detailed experimental measurements obtained from the use of hot wire anemometers. Results show good agreement between the simulated data and the experimental measurements depending on the turbulence model: areas close to the tunnel end are best simulated using k-e, but areas far from the tunnel end, in the developed flow area, are best simulated using Spalart-Allmaras. As was expected the constant turbulent eddy viscosity model gave results which were not very approximated.

Preparation of hollandite-type K xGa xSn 8− xO 16 thin film and NO adsorption behavior

Thin films of hollandite-type K x Ga x Sn 8− x O 16 (KGSO) were fabricated on YSZ substrate by spin-coating method. Those are colorless and transparent, and about 100–150 nm thick at minimum, consisting of KGSO primary particles with about 20 nm in average size. The adsorption behavior of NO on the thin film was examined by diffuse reflectance infrared fourier transform spectroscopy and temperature programmed desorption method. The sample was preheated at 973 K in a mixture gas of N 2 and O 2 prior to NO adsorption. As the oxygen ratio in the mixture gas increased up to 40%, absorption bands appeared and got stronger an around 1400 cm −1, and the amount of desorption in the range from 650 to 850 K increased. Those bands were assigned to NO 2 species in the chelating and nitrito form, respectively, referring to the literature about NO on La 2O 3. The amount of desorption was equal to the number of tunnel end face per unit cell. It was found that the coexistence of oxygen remarkably improves the adsorption ability of NO on KGSO thin films.

Role of monocytes and macrophages in adult angiogenesis: a light at the tunnel's end.

In spite of sustained efforts, there are still gaps in our understanding of angiogenesis as it takes place in vivo. Older observations and a number of recent developments strongly involve the blood mononuclear cell population, collectively known as monocytes (MC), in the normal and pathological adult angiogenesis. An emerging paradigm should eventually incorporate the established biochemical cross talk between MC and their descendents, tissular macrophages (Mph), and the endothelial cells (EC); additionally, it should account for both the intercellular cooperation at the morphological level and the phenotypic overlap between the two cell populations. This focused review puts together the pieces of this puzzle in such a way as to suggest an alternative angiogenic model applicable to adult animals, and particularly to pathological conditions. A working hypothesis is put forward, which is centered on the preformation of capillary lumen as a "tunnel" drilled by penetrating MC/Mph. The tunnels may be colonized in a later stage by sprouts, circulating progenitor endothelial cells (CPEC) or transdifferentiated EC. Thus, MC/Mph are suggested to be included among the targets of therapeutic manipulation of angiogenesis.

Spanwise variation in the unsteady stalling flowfields of two-dimensional airfoil models

Recent investigations of two-dimensional airfoil stalling characteristics have revealed low-frequency and highly unsteady flow in some cases and large-scale three-dimensional structures in other cases. The latter were referred to as stall cells and can form on two-dimensional configurations where the ends of the airfoil model are flush with tunnel side walls or end plates. We present results of detailed investigations of the stalling characteristics of several airfoils that exhibited both low-frequency unsteadiness and large-scale three-dimensional structures. The airfoils were wind-tunnel tested in a two-dimensional configuration. The primary measurements were spanwise wake velocity and mini-tuft flow visualization. The results showed that airfoils with trailing-edge separations at and above maximum lift (static stall) exhibited stall-cell patterns. Conversely, airfoils that had leading-edge separation bubbles that grew in size as the angle of attack was increased into stall developed the low-frequency, highly unsteady flow

Precise leveling of the very long Qinling mountain tunnel

The Qinling tunnel with length of 18. 488km is located on the railway line from Xi’an (Shanxi Province) to Ankan (Sichuan Province) in the middle of Qinling mountain. It is the longest double track railway tunnel in China and takes the third place in the world. According to the design, the break-through error in vertical direction caused by the altimetric control surveying is limited to 18mm for the case of one piercing face. Because the leveling route reaches over 120km in length and must go over two mountains in 2 800m height, the first-order precise leveling and precise gravity measurement should be carried out in the construction stage. In this paper the field leveling approach, the application of new technology, some experience as well as the office calculation with final results analysis are introduced. By meticulous planning, organization and observation, the final accuracy of vertical difference between two tunnel end points is only 8mm, and it provides reliable surveying guarantee for this great tunnel engineering. Finally it is pointed out that this vertical difference distinguishes obviously from the primary measurement result as high as 114mm. It means that the primary result is not accurate enough.

Pediatric near-death experiences.

Article reviewing one previously reported and three new pediatric near-death experiences (NDEs), in which the experiencers were interviewed as children, and which suggests that the childhood core NDE as described by Melvin Morse and colleagues may be expanded to include feeling pain-free, seeing a light at the tunnel's end, entering the light, and time alteration.

Pediatric near-death experiences

A review of one previously reported and three new pediatric near-death experiences (NDEs), in which the experiencers were interviewed as children, suggests that the childhood core NDE as described by Melvin Morse and colleagues may be expanded to include feeling pain-free, seeing a light at the tunnel's end, entering the light, and time alteration. These cases also suggest that the life review may be a function of chronological age.

Stern Thruster Installation on the SS John Sherwin

This paper describes the first retrofitting of a stern thruster on an existing Great Lakes carrier. Description of the machinery involved along with the method of overcoming space restrictions is provided. Sea trial results utilizing the stern thruster alone and in combination with the bow thrusterare tabulated. Economic aspects of the installation are discussed briefly. The paper is illustrated with photographs of the installation and includes arrangement drawings and a description of tunnel end closures.

The response of isolated digging worker ants [Formica lemani bondroit andLasius niger (L.)] to tunnels

1. In laboratory experimentsF. lemani andL. niger preferred to begin tunnels where moist sand met a solid surface. 2. Both species were, however, attracted to dig in artificial tunnels (made by pushing a wire into the sand). The effect of these was greater onF. lemani than onL. niger. 3. The tunnels whichL. niger dug, starting from an artificial tunnel, were usually at an angle to it; those ofF. lemani in line with it. 4. Where an ant was digging in two tunnels during a given period it was more likely to make two successive trips to the same tunnel than was expected. 5. About half the total of digging acts were not made at the end of the tunnel. The proportion of these «deficit» grabs did not differ between species. 6. The distance from the tunnel end at which «deficit» grabs were made was greater inL. niger than inF. lemani. 7. There was no evidence that this distance depended on the length of the tunnel. 8. The dispersion of grabs in a line at right-angles to the tunnel length was greater inL. niger than inF. lemani. 9. These differences may explain the differences in tunnel form between these species.