Journal articles on the topic 'Large Size Tunnel'
To see the other types of publications on this topic, follow the link: Large Size Tunnel.
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 journal articles for your research on the topic 'Large Size Tunnel.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse journal articles on a wide variety of disciplines and organise your bibliography correctly.
1
Gravish, Nick, Mateo Garcia, Nicole Mazouchova, Laura Levy, Paul B. Umbanhowar, Michael A. D. Goodisman, and Daniel I. Goldman. "Effects of worker size on the dynamics of fire ant tunnel construction." Journal of The Royal Society Interface 9, no. 77 (August 22, 2012): 3312–22. http://dx.doi.org/10.1098/rsif.2012.0423.
Full textAbstract:
Social insects work together to complete tasks. However, different individuals within a colony may vary in task proficiency. We investigated if fire ant ( Solenopsis invicta ) worker body size influenced the ability to construct tunnels—a key component of subterranean nests. We monitored excavation by worker groups in a substrate of small wetted glass particles in quasi-two-dimensional arenas. Morphological and network features of the tunnel system were measured. Total tunnel area did not differ significantly between groups of large and small workers, although the tunnel area of control sized workers was significantly larger than that of large workers. Moreover, large workers created wider but shorter tunnels, with slower growth rate of tunnel number. However, edge–vertex scaling and degree distribution of the tunnel network were similar across all treatments. In all cases, the amount of excavated material was correlated with the number of active workers. Our study reveals that morphological features of excavated tunnels show modest variation when constructed by workers of varying sizes, but topological features associated with the tunnel network are conserved. These results suggest that important behavioural aspects of tunnel construction—and thus nest building—are similar among morphologically distinct members of fire ant societies.
2
Liu, Li Yu, Zhi Yi Chen, and Yong Yuan. "Seismic Design and Analysis of Large-Size Shield Tunnels. Part I: Parametric Study." Applied Mechanics and Materials 105-107 (September 2011): 1299–303. http://dx.doi.org/10.4028/www.scientific.net/amm.105-107.1299.
Full textAbstract:
According to the extensive application of shield tunnel, large-diameter shield tunnel in particular, structure stiffness of shield tunnels varies in a large rang. In this paper, shield tunnels with different diameters and thicknesses are analyzed and calculated by time-history method. Stiffness ratio is identified to measure the relationship of structure’s stiffness and soil’s stiffness. The results indicate that dynamic moment and shear forces of shield tunnels have positive correlation with the stiffness ratio. Axial forces have positive correlation with thickness and diameter of lining structure.
3
Liu, Li Yu, Zhi Yi Chen, and Yong Yuan. "Seismic Design and Analysis of Large-Size Shield Tunnels. Part II: Modified Stiffness Solution." Applied Mechanics and Materials 105-107 (September 2011): 1308–12. http://dx.doi.org/10.4028/www.scientific.net/amm.105-107.1308.
Full textAbstract:
According to the extensive application of shield tunnel, large-diameter shield tunnel in particular, a simplified seismic design method is in urgent need. The equivalent static method is more suitable for the rigid underground structure, rather than flexible structure such as large-diameter shield tunnel. In this paper, shield tunnels with different diameters and thicknesses are analyzed and calculated by time-history method and free field deformation method. The calculation and analysis above help to identify the stiffness ratio to measure the relationship of structure’s stiffness and soil’s stiffness and the derivation of a revised stiffness solution based on the free field deformation method. The results indicate that this method can calculate seismic stress of shield tunnels with different diameters and thicknesses accurately.
4
Wu, Lin, Xiedong Zhang, Wei Wang, Xiancong Meng, and Hong Guo. "Comparison of Dynamic Characteristics between Small and Super-Large Diameter Cross-River Twin Tunnels under Train Vibration." Applied Sciences 11, no. 16 (August 18, 2021): 7577. http://dx.doi.org/10.3390/app11167577.
Full textAbstract:
Train vibration from closely aligned adjacent tunnels could cause safety concerns, especially given the soaring size of the tunnel diameter. This paper established a two-dimensional discrete element model (DEM) of small (d = 6.2 m) and super-large (D = 15.2 m) diameter cross-river twin tunnels and discussed the dynamic characteristics of adjacent tunnels during the vibration of a train that runs through the tunnel at a speed of 120 km/h. Results in the D tunnel showed that the horizontal walls have the same horizontal displacement (DH) and the vertical walls have the same vertical displacement (DV). The stress state of the surroundings of the D tunnel is the decisive factor for DH, and the distance from the vibration point to the measurement point is the decisive factor for DV. Results in the comparison of the d and D tunnels showed that the D tunnel is more stable than the d tunnel with respect to two aspects: the time the tunnel reaches the equilibrium state and the vibration amplitude of the structure’s dynamic and static responses. The dynamic characteristic of the d and D tunnel is significantly different. This research is expected to guide the design and construction of large diameter twin tunnels.
5
Zhang, Zhien, Mingli Huang, Chunbo Yu, and Xiaojian Fu. "Study on the Face Stability of a Metro Tunnel in a Silty Clay Layer Constructed Using the Full-Face Method." Symmetry 13, no. 6 (June 15, 2021): 1069. http://dx.doi.org/10.3390/sym13061069.
Full textAbstract:
The horizontal displacement of the soil at the face of the subway tunnel is symmetrically distributed along the central axis of the tunnel, which is larger in the middle and smaller at both sides. The displacement is related to the size of the excavation face. If the excavation area is too great, the horizontal displacement of the tunnel face will be too large, easily leading to tunnel face collapse. For this reason, tunnel builders often use the core-keeping ring-cut method to build subway tunnels. A large section is divided into several small sections to reduce the soil displacement caused by soil excavation. With the continuous promotion and application of mechanized construction in the field of tunnels, mechanized full-section construction will gradually be performed in urban subway tunnels. Once the change in construction method from the core-keeping ring-cut method to the full-face method is made, the issue of how to maintain the stability of the tunnel working face (especially the soft soil stratum) becomes the focus of attention. Taking silty clay as the research object, this paper studies the displacement law of core soil with regard to the tunnel face under the condition of full-face excavation by using theoretical analysis, numerical simulations, and outdoor tests. According to the research results, the extrusion displacement of the tunnel face is the main cause of tunnel displacement. We optimize the construction parameters of glass fiber anchors to strengthen the tunnel face and provide theoretical guidance for the safe construction of subway tunnels.
6
Jaecker, Vera, Mirco Herbort, Bertil Bouillon, Daniel Günther, and Sven Shafizadeh. "High incidence of tunnel collision in combined ACL reconstruction and LET." Orthopaedic Journal of Sports Medicine 8, no. 5_suppl4 (May 1, 2020): 2325967120S0031. http://dx.doi.org/10.1177/2325967120s00313.
Full textAbstract:
Aims and Objectives: Lateral extra-articular tenodesis (LET) procedures are being increasingly performed as concomitant procedures to both primary and revision intra-articular ACL reconstructions with the purpose of controlling excessive anterolateral rotatory instability and to reduce tension on the ACL graft. There is, however, a lack of evidence on benefits and pitfalls of different femoral LET attachment positions. The purpose of this study was to assess the risk of tunnel convergence in combined ACL and LET procedures comparing two different femoral attachment sites (Lemaire and MacIntosh). Materials and Methods: 10 fresh-frozen cadaver knees were examined. In each specimen an anatomic ACL femoral tunnel and two LET tunnels were drilled applying the Lemaire and MacIntosh position. Following knee dissection, minimal distances between ACL and LET tunnels were directly measured on the lateral femoral cortex. Furthermore, computed tomography (CT) scans were obtained to measure inter-tunnel convergence and lateral femoral condyle (LFC) width. Based on the average LFC width, knees were divided into large and small knees to determine a relationship between knee size and tunnel convergence. Results: Convergence of ACL and LET tunnels occurred in 7 of 10 cases (70%) using the Lemaire attachment position. All tunnel collisions occurred directly on the lateral femoral cortex, while inter-tunnel conflicts were not observed. Collisions emerged in both, small (n=4) and large (n=3) knees. Critical tunnel convergence did not occur using the MacIntosh position. The mean minimal distance between the LET and ACL tunnel using the Lemaire and MacIntosh position was 3.1±4.6 mm and 9.8±5.4 mm, respectively. Conclusion: A high risk of tunnel convergence was observed in combined ACL and LET reconstruction using the Lemaire technique, independent of the knee size. LET femoral tunnel positioning according to the MacIntosh reconstruction can significantly reduce the risk of tunnel collision. These findings help to intraoperatively raise the awareness for the risk of tunnel convergence in combined ACL and LET procedures. Adjustments on ACL reconstruction techniques and especially on the femoral fixation have to be considered when applying an additional Lemaire reconstruction.
7
Jaecker, Vera, Philip Ibe, Christoph H. Endler, Thomas R. Pfeiffer, Mirco Herbort, and Sven Shafizadeh. "High Risk of Tunnel Convergence in Combined Anterior Cruciate Ligament Reconstruction and Lateral Extra-articular Tenodesis." American Journal of Sports Medicine 47, no. 9 (June 13, 2019): 2110–15. http://dx.doi.org/10.1177/0363546519854220.
Full textAbstract:
Background: Lateral extra-articular tenodesis (LET) is being increasingly added to primary and revision anterior cruciate ligament (ACL) reconstruction to address residual anterolateral rotatory instability. However, currently there is a lack of knowledge on how close the femoral tunnels are when combining these procedures. Purpose/Hypotheses: To assess the risk of tunnel convergence in combined ACL and LET procedures using 2 different surgical techniques (Lemaire and MacIntosh). It was hypothesized that the risk of tunnel convergence would be greater when using the more distally located Lemaire position. The authors further hypothesized that tunnel proximity would be influenced by knee size. Study Design: Controlled laboratory study. Methods: Ten fresh-frozen cadaveric knees were used for this study. In each specimen, an anatomic ACL femoral tunnel and 2 LET tunnels were drilled using the Lemaire and MacIntosh positions, respectively. After knee dissection, minimal distances between each ACL and LET tunnel were directly measured on the lateral femoral cortex. Furthermore, computed tomography scans were obtained to measure intertunnel convergence and lateral femoral condyle (LFC) width. On the basis of the average LFC width, knees were divided into large and small knees to determine a relationship between knee size and tunnel convergence. Results: Convergence of ACL and LET tunnels occurred in 7 of 10 cases (70%) using the Lemaire attachment position. All tunnel collisions occurred directly on the lateral femoral cortex, while intertunnel (intramedullary) conflicts were not observed. Collisions emerged in both small (n = 4) and large (n = 3) knees. Critical tunnel convergence did not occur using the MacIntosh position. The mean minimal distance between the LET and ACL tunnel using the Lemaire and MacIntosh positions was 3.1 ± 4.6 mm and 9.8 ± 5.4 mm, respectively. Conclusion: Tunnel convergence was more frequently observed in combined ACL and LET reconstruction using the Lemaire technique, independent of the knee size. LET femoral tunnel positioning according to the MacIntosh reconstruction was not associated with tunnel collision. Clinical Relevance: These findings help to raise the awareness for the risk of tunnel convergence in combined ACL and LET procedures. Surgeons may contemplate adjustments on the ACL femoral tunnel drilling technique or fixation device when applying an additional Lemaire procedure. However, in the absence of clinical outcome studies comparing different LET techniques, it remains unclear which technique is superior in a clinical setting.
8
Owandkar, Asha, Jayashree Jogi, Tejas Sangle, Vivekanand Bachche, and Dr A. W. Dhawale. "Flood Control Strategy Chandoli Reservoir Using Tunnel Construction Approach a Case Study of Warna River in Kolhapur." International Journal for Research in Applied Science and Engineering Technology 10, no. 5 (May 31, 2022): 337–40. http://dx.doi.org/10.22214/ijraset.2022.42116.
Full textAbstract:
Abstract: Floods are the most frequent and damaging of all types of natural disasters and annually affect the lives of millions all over the globe. Against this background, enhanced climate variability and climate change are expected to increase the frequency and intensity of floods. There are growing demands for deep tunnels to mitigate severe rural flooding by providing a large tunnelling capacity for excess storm runoff. This study aims to assess the flooding mitigation effect of a deep tunnel system proposed in the old downtown of Kolhapur, India. By providing a sufficient tunnel of a particular type of size, we can reduce the flood force on the downstream side for minimizing the negative impacts of floods, often making the difference between life and death Keywords: Flood, River, Tunnel, Dam, Diversion, Rainfall
9
Peterie, Shelby L., and Richard D. Miller. "Near-surface scattering phenomena and implications for tunnel detection." Interpretation 3, no. 1 (February 1, 2015): SF43—SF54. http://dx.doi.org/10.1190/int-2014-0088.1.
Full textAbstract:
Tunnel locations are accurately interpreted from diffraction sections of focused mode converted P- to S-wave diffractions from a perpendicular tunnel and P-wave diffractions from a nonperpendicular (oblique) tunnel. Near-surface tunnels are ideal candidates for diffraction imaging due to their small size relative to the seismic wavelength and large acoustic impedance contrast at the tunnel interface. Diffraction imaging algorithms generally assume that the velocities of the primary wave and the diffracted wave are approximately equal, and that the diffraction apex is recorded directly above the scatterpoint. Scattering phenomena from shallow tunnels with kinematic properties that violate these assumptions were observed in one field data set and one synthetic data set. We developed the traveltime equations for mode-converted and oblique diffractions and demonstrated a diffraction imaging algorithm designed for the roll-along style of acquisition. Potential processing and interpretation pitfalls specific to these diffraction types were identified. Based on our observations, recommendations were made to recognize and image mode-converted and oblique diffractions and accurately interpret tunnel depth, horizontal location, and azimuth with respect to the seismic line.
10
Zhu, Lin-Lin, Jun-Chao Wu, Yi-Ping Wang, Du He, Wen-Yan Zhang, Tao Gan, and Jin-Lin Yang. "Endoscopic Submucosal Single- or Multi-tunnel Dissection for Near-Circumferential and Circumferential Superficial Esophageal Neoplastic Lesions." Gastroenterology Research and Practice 2019 (March 12, 2019): 1–7. http://dx.doi.org/10.1155/2019/2943232.
Full textAbstract:
This study reports the outcomes of endoscopic submucosal single-tunnel dissection or endoscopic submucosal multi-tunnel dissection for the treatment of esophageal neoplastic lesions of at least three-quarters of the esophageal circumference, including circumferential superficial esophageal neoplastic lesions. From July 2014 to February 2018, a total of 124 lesions underwent endoscopic submucosal tunnel dissection at our hospital. One to four submucosal tunnels were created in the oral to anal direction. Of the 124 lesions, there were 83 noncomplete circumferential lesions and 41 circumferential lesions. Endoscopic submucosal single-tunnel dissection was performed in 54 patients, two-tunnel dissection in 43 patients, three-tunnel dissection in 19 patients, and four-tunnel dissection in 8 patients. The mean dissection speed was 22.8±12.7 mm2/min. En bloc dissection was achieved in all lesions, and the R0 resection rate was 70.2 percent. No matter how large the lesion area was, there were no significant differences in the dissection speed and the R0 resection rate when lesions were at least three-quarters of the esophageal circumference. Esophageal stricture was observed in 54 patients and was relieved by placement of a retrievable metal stent or by endoscopic water balloon dilation. No recurrence was noted after 19.1±12.4 months of follow-up. Our large sample size study showed that endoscopic submucosal tunnel dissection showed effectiveness and safety for the treatment of large superficial esophageal neoplastic lesions at least three-quarters of the esophageal circumference, including circumferential superficial esophageal neoplastic lesions.
11
Zhang, Gang, and Hong Bing Liu. "The Simulation Analysis of Large Cross-Section Soft Rock Tunnel Excavation under the Bias Terrain." Applied Mechanics and Materials 90-93 (September 2011): 1853–58. http://dx.doi.org/10.4028/www.scientific.net/amm.90-93.1853.
Full textAbstract:
Abstract: Taking a High-speed railway tunnel as the background, This paper analyses not only the stress and displacement of surrounding rock , the plastic area distribution and size, but also the size and distribution of initial support internal force in two excavation schemes, based on the criterion of underground engineering structure design theory and rock elastic-plastic succumb Drucker-Prager, Under the guidance of New Austria Tunneling Method, this paper makes numerical simulation of soft rock tunnel excavation in large sections and initial support with the finite software ANSYS11.0. The stress and displacement of surrounding rock and the plastic area distribution and size under two excavation schemes are analyzed, the size and distribution of initial support internal force under two excavation schemes are also investigated .By comprehensive comparing advantages and disadvantages of two schemes, this paper makes some significant conclusions and gives reference for the similar tunnel design and construction.
12
Zhang, Ye, Min, and Xu. "Effect of Voids behind Lining on the Failure Behavior of Symmetrical Double-Arch Tunnels." Symmetry 11, no. 10 (October 21, 2019): 1321. http://dx.doi.org/10.3390/sym11101321.
Full textAbstract:
The presence of voids behind lining seriously affects the safety of the symmetrical double-arch tunnels during service life. It is essential to find out the impact of voids on tunnel safety due to the increasing demand for the construction and maintenance of symmetrical double-arch tunnels. Model tests and numerical analyses were conducted in this research. The results attained were explored including earth pressure, internal force, and lining failure. Results reveal that the presence of voids has a large influence on the internal force in the lining of symmetrical double-arch tunnels, generally in the form of asymmetrical failure patterns of the lining. The failure patterns of the lining are greatly influenced by the size and location of voids with respect to the symmetrical double-arch tunnel circumference. Significant changes in the lining internal forces were found at the areas in the close vicinity of the void whereas a few changes were found at the bottom of the sidewall, the invert, and the central wall far away from the void. The propagation laws of lining cracks of asymmetrical double-arch tunnels are more complicated than symmetrical tunnels with a void behind the central wall. The location of the initial cracking of symmetrical and asymmetrical double-arch tunnels is the same, while the lining failure of the large-section tunnel is the most complicated.
13
Shannak, B., U. Corsmeier, Ch Kottmeier, and T. Al-azab. "Wind tunnel study of twelve dust samples by large particle size." Atmospheric Environment 98 (December 2014): 442–53. http://dx.doi.org/10.1016/j.atmosenv.2014.08.062.
Full text
14
Zhang, Zheng Yu, Xu Hui Huang, Jiang Yin, and Han Xuan Lai. "Videogrammetric Techniques for Wind Tunnel Testing and Applications." Advanced Materials Research 986-987 (July 2014): 1629–33. http://dx.doi.org/10.4028/www.scientific.net/amr.986-987.1629.
Full textAbstract:
Videogrammetric measurement is a research focus for the organizations of wind tunnel test because of its no special requirements on the test model, its key techniques for the vibration environment of the high speed wind tunnel are introduced by this paper, such as the solution of exterior parameters with big-angle large overlap, the algorithm of image processing for extracting marked point, the method of camera calibration and wave-front distortion field measurement. The great requirements and application prospects of videogrammetry in wind tunnel fine testing have been demonstrated by several practice experiments, including to measure test model’s angle of attack, dynamic deformations and wave-front distortion field in high speed wind tunnels whose test section size is 2 meters.
15
Zhang, Qingsong, Peng Li, Xiao Zhang, Shucai Li, Weijie Zhang, and Qian Wang. "Exploration and Grouting of Large-Scale Water Capsule in the Fault Fracture Zone of Yonglian Tunnel." Open Civil Engineering Journal 9, no. 1 (March 10, 2015): 32–43. http://dx.doi.org/10.2174/1874149501509010032.
Full textAbstract:
A large-scale water capsule was formed after 8 times inrush of mud and water in Yonglian tunnel. The capsule seriously inhabited the construction of the tunnel. By combining with the geological conditions in tunnel site, the causes and characteristics of the water capsule were analyzed. Its spatial location and size were explorated by comprehensive exploration methods. In order to control the water capsule, the treatment scheme composed by full-face curtain grouting in left tunnel and decompression by drainage in right tunnel was made, and the composite and controlling grouting methods were proposed. The composite and controlling grouting technology was applied in the treatment. It was composed by grouting parameters selection, grouting material and technology optimization by means of numerical simulation, model experiment and SEM microscopic experiment. By means of the grouting effect examination methods including P-Q-t curve, examination holes, surrounding rock deformation monitoring and excavation, the water capsule was proved to be treated successfully. The engineering case provides a reference for the similar engineering to some extent.
16
Cheng, Yuh-Jiuh, Bor-Tauo Chen, Cheng-Ping Wu, and Yu-Yun Lee. "Design of Optical Tunnel Switching Networks for Big Data Applications." Applied Sciences 10, no. 6 (March 20, 2020): 2098. http://dx.doi.org/10.3390/app10062098.
Full textAbstract:
In this paper, we proposed large-scale optical tunnel switching networks based on the Torus topology network with WSS (Wavelength Selective Switch) for future big data applications. All nodes of the large-scale optical tunnel switching networks use WSS switch modules, and the communications between nodes use multiple λs (wavelengths), where a tunnel is established with a wavelength which can be reused. The widely used MEMS (Micro-Electro-Mechanical Systems) and LCoS (Liquid Crystal on Silicon) technologies are all millisecond-level switching speeds, so the frame size of the optical frame switch is very large, and this will reduce switching performance. Therefore, they are only suitable for optical tunnel switching networks design, but are not suitable for optical frame switch design. This multi-plane Torus topology network architecture not only increases network throughput, but also has fault tolerance to increase network reliability. When the traffic is changed, the number of tunnels between nodes can be scheduled in time to balance the load traffic and avoid traffic loss. Therefore, it can not only schedule the number of tunnels in time to balance the load traffic, in order to avoid traffic loss, but also because the channel is fixedly established, this does not generate any buffer delay, and this because of the transmission using optical transmission unlimited speed, so it is a good choice for future big data applications that require high speed, high bandwidth and low latency.
17
Chen, Qizhi, Luju Liang, Baoping Zou, Changjie Xu, Bowen Kong, and Jingyuan Ma. "Analytical Solutions of Steady a Seepage Field for Deep-Buried Tunnel with Grouting Ring Considering Anisotropic Flow." Journal of Marine Science and Engineering 10, no. 12 (December 2, 2022): 1861. http://dx.doi.org/10.3390/jmse10121861.
Full textAbstract:
Difficulties related to seepage are frequently encountered in tunnel design and construction, especially in deep-buried tunnels. Nowadays, analytical solutions of steady seepage fields for deep-buried tunnel usually assume that the surrounding rock mass is homogeneous. In this study, analytical solutions of a steady seepage field for a deep-buried tunnel with grouting ring considering anisotropic flow are proposed. The proposed analytical solutions are verified by numerical simulations and parameter analysis are carried out. Results show that the seepage field of surrounding rocks around the deep buried circular tunnel is no longer uniformly distributed and presents elliptical distribution. The change of permeability coefficient of the lining structure has a great influence on the hydraulic head when the difference between permeability coefficient of lining structure and surrounding rock is not very large. The results show that the size of the grouting ring has more significant influence on the grouting effect.
18
Guo, Qi, Aerik Carlton, Spencer E. Quiel, and Clay J. Naito. "Stochastic Thermal Demand and Resulting Capacity Loss of Concrete Tunnel Liners Subjected to Vehicle Fires." Transportation Research Record: Journal of the Transportation Research Board 2674, no. 5 (May 2020): 293–304. http://dx.doi.org/10.1177/0361198120914612.
Full textAbstract:
Fire resistant design of both structural and non-structural components in road tunnels is predicated on the determination of fire demand intensity. Current practice typically uses a conservative, deterministic fire curve that does not necessarily provide a representative evaluation of the spatial and temporal distribution of thermal demands in tunnels that are caused by large vehicle fires. This paper proposes a tunnel-specific probabilistic framework for evaluating vehicle fire frequency and intensity based on tunnel geometry and traffic information. The framework leverages a fast-running computational tool that has been previously developed by the authors for calculating fire-induced heat flux exposure on tunnel liners because of enclosed vehicle fires. The likelihood of a vehicular fire and the associated fire size distribution are used to generate probabilistic distributions of total fire exposure for the reinforced concrete tunnel liner. Critical heat flux values according to these probabilistic distributions are then used to assess reductions in concrete material strength and resulting losses in the structural performance of the system. A case study of the Fort Pitt Tunnel in Pittsburgh, PA, is included for demonstration. The proposed framework enables decision making regarding design and renovation of tunnels for fire resistance as well as post-fire inspection by quantifying the risk of capacity reduction in the concrete liner because of a realistic range of fire hazard intensities.
19
Yang, Sun, Zhang Chengke, Yu Junping, Wu Jiangpeng, and Zhu Liqing. "Research on Influence of Road Tunnels with Different Lanes on Surrounding Rock Characteristic Curve." E3S Web of Conferences 198 (2020): 02009. http://dx.doi.org/10.1051/e3sconf/202019802009.
Full textAbstract:
Convergence confinement method is an important guidance method for tunnel construction and support design. Numerical simulation method was used to comparatively analyze the ground reaction curve and the plastic zone under different rock grade and roadway tunnel size. The results show that the change of tunnel size has different effects on the maximum deformation of the tunnel arch crown, the ground reaction curve and the plastic zone range. Finally, some suggestions were put forward for the construction and optimization of the large span arch tunnel support structure. The research results may provide some guidance for related engineering
20
Canet, H., P. Bortolotti, and CL Bottasso. "Gravo-aeroelastic scaling of very large wind turbines to wind tunnel size." Journal of Physics: Conference Series 1037 (June 2018): 042006. http://dx.doi.org/10.1088/1742-6596/1037/4/042006.
Full text
21
Zhou, Hao, Xinghua Wang, Changdi He, and Changxi Huang. "Seismic Response of a Tunnel Embedded in Compacted Clay through Large-Scale Shake Table Testing." Shock and Vibration 2018 (November 1, 2018): 1–17. http://dx.doi.org/10.1155/2018/5968431.
Full textAbstract:
To investigate the seismic response of large-scale tunnel in compacted clay and effect of shock absorbing layer to the tunnel, a series of three dimensional (3D) shaking table model tests were carried out. The similarity ratio of the model is 1 : 8 and the size of the model container is 9.3 m (length) × 3.7 m (width) × 2.5 m (height). The cross-sectional diameter of the model tunnel is 0.9 m, and the thickness of the tunnel lining is 0.06 m. To simulate the clay soil surrounding condition, the container was filled with clay soil. During the tests, the concrete strain, acceleration, and dynamic soil pressure on the surface of the model tunnel were measured. The results show the existence of tunnel can decrease the maximum acceleration of the model in the X direction; the shock absorbing layer can further decrease the maximum acceleration, however, cannot change the dominant frequency of the ground motion. The longitudinal and hoop strain of the model tunnel with excitation of the input motion is mainly in tension state and the maximum hoop deformation of the model tunnel is located at the conjugate 45°. In addition, the shock absorbing layer has an effect on the strain and dynamic earth pressure of the model tunnel.
22
Dohkoh, Tatsuki, Shinya Suzuki, and Masaru Miyayama. "Proton Storage Properties of Manganese Oxides with Tunnel Structures." Key Engineering Materials 566 (July 2013): 145–48. http://dx.doi.org/10.4028/www.scientific.net/kem.566.145.
Full textAbstract:
The electrochemical capacitors (ECs) have attracted a great attention as a rechargeable strage device with a high power density and high safety. An increase in specific capacity is demanded to use ECs in various applications. MnO2 are expected as electrodes of ECs because of their large oxidation state change (Mn4+ Mn2+), low cost and environmental compatibility. When all manganese ions in the MnO2 are completely reduced to Mn2+ from Mn4+ over a potential window of 1.1 V, the theoretical capacity is estimated to about 2000 Fg-1. However, the reported capacity of MnO2 electrodes are 100250 Fg-1 [1-2] for powders and around 700 Fg-1 [3] for thin films. Tunnel structured MnO2 are expected to show high capacities by utilizing high ionic mobility in the tunnel and high surface area of tunnel walls. Fig. 1 shows crystal structures of (a) Pyrolusite (Tunnel size: 1×1), (b) Hollandite (Tunnel size: 2×2) and (c) OMS-5 (Tunnel size: 2×4) and (d) MnO6 unit. In the present study, the relationship between the tunnel size and the specific capacity was investigated for those tunnel structured MnO2. In addition, Hollandite /carbon composites were synthesized to improve the electrode properties of Hollandite.
23
Harikai, Souichi, Susumu Kubota, and Shintaro Hotta. "WIND TUNNEL STUDY OF SAND TRANSPORT ON SURFACES COMPOSED OF BI-MODAL GRAIN-SIZE DISTRIBUTION." Coastal Engineering Proceedings 1, no. 32 (January 29, 2011): 108. http://dx.doi.org/10.9753/icce.v32.sediment.108.
Full textAbstract:
The transports rates on a sandy bed that grain sizes were bi-modally distributed were experimented in a wind tunnel. The results showed that the transport rate followed a power law and the power was 2.5, and that the threshold shear velocities were the same or somewhat larger than those of the large diameter sand in the mixture.
24
Xue, Fei, Minjun Cai, Tianzuo Wang, and Tongyang Zhao. "Characteristics of Karst Cave Development in Urban Karst Area and Its Effect on the Stability of Subway Tunnel Construction." Advances in Civil Engineering 2021 (May 7, 2021): 1–12. http://dx.doi.org/10.1155/2021/8894713.
Full textAbstract:
The existence of karst caves poses a large threat to safe tunnel construction in a karst area. This paper presents a synthetic method to evaluate the collapse risk before subway tunnel construction with Yang-Jian interval tunnel as a case study. The crosshole seismic Computed Tomography (CT) integrated with Geological Drilling (Geo-D) was first applied to accurately delineate the karst location and its scale. Then, 483 groups of seismic wave CT images were recorded, and 524 karst cave anomalies were found. The height of karst caves in the study area is 1–20 m and mainly concentrated at approximately 5 m. The vertical distance between the karst cave and the tunnel is mainly within 15 m. According to the detection results, a series of numerical models were built and calculated using FLAC3D to investigate the effect of different sizes and locations of karst caves on the displacement and stability of the surrounding rock in tunnels. Afterwards, based on the simulation results, the disturbance degree evaluation index was established to quantitatively evaluate the risk level of karst caves. The evaluation results indicate that the buried depth of the karst cave greatly affects the disturbance degree. No treatment is required for the deeply buried karst cave that is more than 7 m from the tunnel. When the distance between the cave and the tunnel is less than 7 m, there is a critical size of the cave. Karst caves that are larger than that critical value must be filled with a single slurry or binary slurry before tunnel construction to eliminate the risk of tunnel collapse. This study can be used to provide a more efficient and economical program for metro tunnel construction above a karst cave.
25
Fridayani, Ni Kadek Yuni, Ni Luh Nopi Andayani, and Ni Wayan Tianing. "THE A CORRELATION STUDY ABOUT SIZE OF SMARTPHONE AND PARESTHESIA IN PALMAR CAUSED BY CONSTRICTION AT CARPAL TUNNEL IN STUDENTS OF MEDICAL FACULTY UDAYANA UNIVERSITY." Majalah Ilmiah Fisioterapi Indonesia 6, no. 3 (September 15, 2018): 43. http://dx.doi.org/10.24843/mifi.2018.v06.i03.p12.
Full textAbstract:
ABSTRACT
Using smartphone in different size can give different effectwhilehold and swipe smartphone so, this study was to analyze the relationship between the size of smartphone and paresthesia in palmar caused by constriction at carpal tunnel. Cross sectional analytic study with subjects were 109 students of Medical Faculty Udayana University. The sample of this study is the students who scored SAS (Smartphone Addiction Scale) ? 84, inclusion and exclusion. The participants asked to use a smartphone for 30 minutes, one-handed while maintaining comfortable sitting postures on a chair. The result showed no significant correlation between the size of smartphone and paresthesia in palmar caused by constriction at carpal tunnel and also was found that smartphone large more cause paresthesia in palmar (46,5%) than small category (39,5%) and medium (14,0%). Subjects were more fatigue in thumb and finger after using smartphone than paresthesia. So, the use of smartphones with large category can caused paresthesia and continued with musculoskeletal problem especially in thumb.
Keywords: size of smartphone, paresthesia, constriction at carpal tunnel
26
Oshima, Takeshi, Sven Putnis, Samuel Grasso, Antonio Klasan, and David Anthony Parker. "Graft Size and Orientation Within the Femoral Notch Affect Graft Healing at 1 Year After Anterior Cruciate Ligament Reconstruction." American Journal of Sports Medicine 48, no. 1 (November 15, 2019): 99–108. http://dx.doi.org/10.1177/0363546519885104.
Full textAbstract:
Background: The combined influence of anatomic and operative factors affecting graft healing after anterior cruciate ligament (ACL) reconstruction within the femoral notch is not well understood. Purpose: To determine the influence of graft size and orientation in relation to femoral notch anatomy, with the signal/noise quotient (SNQ) of the graft used as a measure of graft healing after primary single-bundle ACL reconstruction. Study Design: Case series; Level of evidence, 4. Methods: A total of 98 patients with a minimum 2-year follow-up after primary single-bundle ACL reconstruction with hamstring tendon autografts were included. Graft healing was evaluated at 1 year on magnetic resonance imaging (MRI) scan as the mean SNQ measured from 3 regions situated at sites at the proximal, middle, and distal graft. Patient characteristics, chondropenia severity score, tunnel sizes, tunnel locations, graft bending angle (GBA), graft sagittal angle, posterior tibial slope (PTS), graft length, graft volume, femoral notch volume, and graft-notch volume ratio (measured using postoperative 3-T high-resolution MRI) were evaluated to determine any association with 1-year graft healing. The correlation between 1-year graft healing and clinical outcome at minimum 2 years was also assessed. Results: There was no significant difference in mean SNQ between male and female patients ( P > .05). Univariate regression analysis showed that a low femoral tunnel ( P = .005), lateral tibial tunnel ( P = .009), large femoral tunnel ( P = .011), large tibial tunnel ( P < .001), steep lateral PTS ( P = .010), steep medial PTS ( P = .004), acute graft sagittal angle ( P < .001), acute GBA ( P < .001), large graft volume ( P = .003), and high graft-notch volume ratio ( P < .001) were all associated with higher graft SNQ values. A multivariate regression analysis showed 2 significant factors: a large graft-notch volume ratio ( P = .001) and an acute GBA ( P = .004). The 1-year SNQ had a weak correlation with 2-year Tegner Activity Scale score ( r = 0.227; P = .026) but no other clinical findings, such as International Knee Documentation Committee subjective and Lysholm scores and anterior tibial translation side-to-side difference. Conclusion: The 1-year SNQ value had a significant positive association with graft-notch volume ratio and GBA. Both graft size and graft orientation appeared to have a significant influence on graft healing as assessed on 1-year high-resolution MRI scan.
27
Han, Zhirong, Jiangtao Si, and Dawei Wu. "Contrast Icing Wind Tunnel Tests between Normal Droplets and Supercooled Large Droplets." Aerospace 9, no. 12 (December 18, 2022): 844. http://dx.doi.org/10.3390/aerospace9120844.
Full textAbstract:
In order to compare and analyze the similarities and differences between normal droplet icing shapes and supercooled large droplet icing shapes, SADRI carried out normal droplet and supercooled large droplet icing wind tunnel tests in the NRC−AIWT icing wind tunnel. Taking the typical glaze ice in normal droplet icing conditions as the reference, the freezing drizzle and freezing rain icing tests under the supercooled large droplet conditions were carried out. The test results show that compared with normal droplets, the ice horn height of supercooled large droplets decreases with the increase in droplet particle size, and even the ice horn characteristics are not obvious when the icing condition is freezing rain. At the same time, the range and height of rough element ice shape after the main ice horn of supercooled large droplets are significantly larger and higher than those of the normal droplets, while the difference in the rough element in different supercooled large droplet icing conditions is small.
28
Chan, Calvin, Kevin Dale, Ryan J. Koehler, Theodore J. Ganley, and J. Todd Lawrence. "REDUCTION IN HAMSTRING AUTOGRAFT DIAMETER AS A RESULT OF ACL RECONSTRUCTION PREPARATION USING LONGITUDINAL TENSION AND CIRCUMFERENTIAL COMPRESSION." Orthopaedic Journal of Sports Medicine 7, no. 3_suppl (March 1, 2019): 2325967119S0012. http://dx.doi.org/10.1177/2325967119s00120.
Full textAbstract:
Background: Previous studies have investigated the effect of tension and circumferential compression on the diameter of fresh-frozen anterior cruciate ligament (ACL) allografts, but no study has described the effect on soft tissue ACL autografts harvested for implantation in the operating room for ACL reconstruction. The purpose of this study was to elucidate how hamstring autograft diameter changes during preparation for ACL reconstruction with compression in addition to tensioning. We hypothesized that autograft diameter would decrease as the graft was prepared with both tension and circumferential compression. Operative complications related to graft compression were also investigated. Methods: 100 ACL reconstruction surgeries (Age M = 15.3 ± 2.2 years; 53% male) were identified among two orthopedic surgeons. Hamstring tendon grafts were prepared in a standardized procedure to produce a looped graft for all-inside ACL reconstruction. Autografts were tensioned to 15-20 lbs and then their tibial and femoral diameters were measured using cylindrical sizing blocks. The graft diameters were measured again after placement under a saline soaked gauze for 10 minutes with the sizing blocks in place. A Wilcoxon signed rank test with correction for continuity was performed to detect significant change in autograft diameters after compression. Results: Treatment of hamstring autografts with longitudinal tension and circumferential compression significantly decreased the median tibial and femoral graft diameters by 0.75 mm. The median tibial diameter decreased from 9.50 mm to 8.75 mm (p < 0.0001) and the median femoral diameter decreased from 9.50 mm to 8.50 mm (p < 0.0001). 72% of all autografts had the same tibial and femoral diameters at implant. No intraoperative complications were noted with implantation of compressed grafts in smaller diameter tunnels. Conclusions: Median diameters of ACL hamstring autografts harvested in the OR decreased by 0.75 mm after treatment with circumferential compression using cylindrical sizing blocks. This decreased the socket size by one to two 0.5 mm sizes with no adverse events noted intra-operatively due to the compression of the grafts or the smaller sockets. Clinical Relevance: Graft integration in a bone tunnel is dependent on optimal fit of the graft inside the tunnel. If the tunnel is too small, the graft will not fit and if it is too large, it may allow joint fluid into the tunnel leading to tunnel widening and incomplete integration. Pre-tensioning a graft has been noted for many years to be an important way to properly establish the length-tension relationship of a graft. Here, we show that circumferential compression of the graft prior to implantation significantly changes the size of the graft, and thus the size of the tunnels required for implantation. In addition to providing better graft tunnel match, using smaller tunnels requires less bone removal which is particularly advantageous for pediatric, revision, and double bundle ACL reconstruction techniques where space for tunnel drilling is limited.
29
Han, Zili, Weibin Ma, Jinfei Chai, Zhenyu Zhu, Chuannian Lin, Zeli An, Chaofeng Ma, Xueliang Xu, and Tianyuan Xu. "A Treatment Technology for Optimizing the Stress State of Railway Tunnel Bottom Structure." Shock and Vibration 2021 (July 20, 2021): 1–13. http://dx.doi.org/10.1155/2021/9191232.
Full textAbstract:
With the continuous increase of railway transportation volume, the aging problem of railway tunnel bottom structure is becoming more and more serious, which seriously threatens the safe operation of trains. Based on the cause analysis and field detection of the defects at the railway tunnel bottom structure, the “Anchor-Grouting-Drainage” treatment technology of the railway tunnel bottom structure is summarized. The research shows that (1) the technology is simple and can effectively repair the defects of railway tunnel bottom structure under the conditions of the narrow site, short time of maintenance skylight, strict requirements of track size variation, and no interference with the normal operation of the train, which has great significance and broad application prospect. (2) The drainage system of the existing railway tunnel bottom structure can be applied to the reconstruction of the railway tunnel bottom structure. The high-strength transverse diversion structure at the bottom of the tunnel has the advantages of strong bearing capacity, large drainage capacity, and corrosion resistance, which can provide a reference for the subsequent implementation of the reconstruction project at the railway tunnel bottom structure.
30
Lin, Tingting, Yujing Yang, Xiaofeng Yi, Chuandong Jiang, and Tiehu Fan. "First Evidence of the Detection of an Underground Nuclear Magnetic Resonance Signal in a Tunnel." Journal of Environmental and Engineering Geophysics 23, no. 1 (March 2018): 77–88. http://dx.doi.org/10.2113/jeeg23.1.77.
Full textAbstract:
During the excavation of underground tunnels and ore mining, accidents related to sudden water inflows often occur. As the only technique used for the direct detection of groundwater, nuclear magnetic resonance (NMR) has advantages for the detection of disaster-inducing water flows. However, NMR has commonly been applied only at the ground surface using large-size loop with several turns (typically tens of meters). For the first time, we demonstrate that the water signal in a tunnel can be directly detected using an underground nuclear magnetic resonance (UNMR) experiment. Specifically, we describe the design of a six-meter multi-turn transmitting coil and receiving coil. By conducting UNMR measurements in the Dadushan Tunnel, located in southwestern China, we not only verified the ability to detect the UNMR signal, but also matched the observed data using a 1D inverse model. [Figure: see text]
31
GRAHAM, JEFFREY B., HEIDI DEWAR, N. C. LAI, WILLIAM R. LOWELL, and STEVE M. ARCE. "Aspects of Shark Swimming Performance Determined Using a Large Water Tunnel." Journal of Experimental Biology 151, no. 1 (July 1, 1990): 175–92. http://dx.doi.org/10.1242/jeb.151.1.175.
Full textAbstract:
A large, sea-going water tunnel was used in various studies of shark swimming performance. The critical swimming velocity (Ucrit, an index of aerobically sustainable swimming speed) of a 70 cm long lemon shark (Negaprion brevirostris Poey) was determined to be 1.1 Ls−1, where L is body length. The Ucrit of the leopard shark (Triakis semifasciata Girard) was found to vary inversely with body size; from about 1.6Ls−1in 30–50cm sharks to 0.6LS−1 in 120cm sharks. Large Triakis adopt ram gill ventilation at swimming speeds between 27 and 60cms−1, which is similar to the speed at which this transition occurs in teleosts. Analyses of tail-beat frequency (TBF) in relation to velocity and body size show that smaller Triakis have a higher TBF and can swim at higher relative speeds. TBF, however, approaches a maximal value at speeds approaching Ucrit, suggesting that red muscle contraction velocity may limit sustained swimming speed. The TBF of both Triakis and Negaprion rises at a faster rate with swimming velocity than does that of the more thunniform mako shark (Isurus oxyrinchus Rafinesque). This is consistent with the expectation that, at comparable relative speeds, sharks adapted for efficient swimming should have a lower TBF. The rates of O2 consumption of swimming lemon and mako sharks are among the highest yet measured for elasmobranchs and are comparable to those of cruise-adapted teleosts.
32
Brito, J., L. V. Rizzo, P. Herckes, P. C. Vasconcellos, S. E. S. Caumo, A. Fornaro, R. Y. Ynoue, P. Artaxo, and M. F. Andrade. "Physical–chemical characterisation of the particulate matter inside two road tunnels in the São Paulo Metropolitan Area." Atmospheric Chemistry and Physics 13, no. 24 (December 17, 2013): 12199–213. http://dx.doi.org/10.5194/acp-13-12199-2013.
Full textAbstract:
Abstract. The notable increase in biofuel usage by the road transportation sector in Brazil during recent years has significantly altered the vehicular fuel composition. Consequently, many uncertainties are currently found in particulate matter vehicular emission profiles. In an effort to better characterise the emitted particulate matter, measurements of aerosol physical and chemical properties were undertaken inside two tunnels located in the São Paulo Metropolitan Area (SPMA). The tunnels show very distinct fleet profiles: in the Jânio Quadros (JQ) tunnel, the vast majority of the circulating fleet are light duty vehicles (LDVs), fuelled on average with the same amount of ethanol as gasoline. In the Rodoanel (RA) tunnel, the particulate emission is dominated by heavy duty vehicles (HDVs) fuelled with diesel (5% biodiesel). In the JQ tunnel, PM2.5 concentration was on average 52 μg m−3, with the largest contribution of organic mass (OM, 42%), followed by elemental carbon (EC, 17%) and crustal elements (13%). Sulphate accounted for 7% of PM2.5 and the sum of other trace elements was 10%. In the RA tunnel, PM2.5 was on average 233 μg m−3, mostly composed of EC (52%) and OM (39%). Sulphate, crustal and the trace elements showed a minor contribution with 5%, 1%, and 1%, respectively. The average OC : EC ratio in the JQ tunnel was 1.59 ± 0.09, indicating an important contribution of EC despite the high ethanol fraction in the fuel composition. In the RA tunnel, the OC : EC ratio was 0.49 ± 0.12, consistent with previous measurements of diesel-fuelled HDVs. Besides bulk carbonaceous aerosol measurement, polycyclic aromatic hydrocarbons (PAHs) were quantified. The sum of the PAHs concentration was 56 ± 5 ng m−3 and 45 ± 9 ng m−3 in the RA and JQ tunnel, respectively. In the JQ tunnel, benzo(a)pyrene (BaP) ranged from 0.9 to 6.7 ng m−3 (0.02–0.1‰ of PM2.5) whereas in the RA tunnel BaP ranged from 0.9 to 4.9 ng m−3 (0.004–0. 02‰ of PM2.5), indicating an important relative contribution of LDVs emission to atmospheric BaP. Real-time measurements performed in both tunnels provided aerosol size distributions and optical properties. The average particle count yielded 73 000 cm−3 in the JQ tunnel and 366 000 cm−3 in the RA tunnel, with an average diameter of 48 nm in the former and 39 nm in the latter. Aerosol single scattering albedo, calculated from scattering and absorption observations in the JQ tunnel, indicates a value of 0.5 associated with LDVs. Such single scattering albedo is 20–50% higher than observed in previous tunnel studies, possibly as a result of the large biofuel usage. Given the exceedingly high equivalent black carbon loadings in the RA tunnel, real time light absorption measurements were possible only in the JQ tunnel. Nevertheless, using EC measured from the filters, a single scattering albedo of 0.31 for the RA tunnel has been estimated. The results presented here characterise particulate matter emitted from nearly 1 million vehicles fuelled with a considerable amount of biofuel, providing a unique experimental site worldwide.
33
Shi, Jianjun, Wei Zhang, Shucheng Guo, and Huaming An. "Numerical Modelling of Blasting Dust Concentration and Particle Size Distribution during Tunnel Construction by Drilling and Blasting." Metals 12, no. 4 (March 23, 2022): 547. http://dx.doi.org/10.3390/met12040547.
Full textAbstract:
In order to reduce the blasting dust concentration in the tunnel during the drilling and blasting, accelerate the tunnel excavation process, and improve the working environment for the construction workers, a three-dimensional geometric model of dust transport was established based on the gas-solid two-phase flow model using the DesginModeler software, and the discrete phase model (DPM) in the FLUENT software was used to simulate the variation of dust concentration and the distribution of dust particle size at different locations along the tunnel route within 1200 s after tunnel blasting. The results showed that the concentration of blasting dust gradually decreased over time, with the fastest decrease in the range of 2 s to 120 s, and after 900 s, the dust concentration stabilized. The overall spatial distribution of the dust concentration showed a trend of decreasing from the palm face to the tunnel entrance and from the bottom plate to the upper part. The distribution pattern of dust with different particle sizes was not the same along the length of the tunnel. The large particles settled in the area of 25 m from the palm face under the action of gravity. With the increases of distance, the mass flow rate decreased, and the dust particle size became smaller, but the proportion of small particles gradually increased, while the R-R distribution index increased. The results in this study were confirmed to be reliable by comparing the measured data to provide guidance for the dust reduction technology in tunnel blasting, so as to quickly remove the dust generated during the blasting process and improve the engineering construction efficiency.
34
Mulvaney, Joshua J., Andrew L. Sullivan, Geoffrey J. Cary, and Glenys R. Bishop. "Repeatability of free-burning fire experiments using heterogeneous forest fuel beds in a combustion wind tunnel." International Journal of Wildland Fire 25, no. 4 (2016): 445. http://dx.doi.org/10.1071/wf15068.
Full textAbstract:
Combustion wind tunnels are often used to investigate the propagation of free-moving fires through solid-phase fuels, typically standardised ‘artificial’ fuel beds. However, the results of such studies are difficult to apply directly to wildland fire situations primarily due to the disparity between the generally uniform artificial fuel and the heterogeneous fuel found in nature. To explore the feasibility of using heterogeneous ‘natural’ fuel beds in subsequent combustion wind tunnel experiments, this study quantified the variability in forward rate of fire spread resulting from the use of heterogeneous fuel beds in a combustion wind tunnel under a given set of burning conditions. The experiment assessed the effects of fuel type and air speed, and controlled for the effects of fuel moisture content, fuel load and fuel particle size. It was found that the variability in rate of spread increased with its mean, but the overall residual variance (σ2e <0.025, s.e. 0.011) was low compared with the effects of air speed and fuel type. This demonstrates that heterogeneous fuel beds can be used in combustion wind tunnel experiments without introducing a large degree of variability.
35
Mutama, K. R., and A. E. Hall. "The Experimental Investigation of Jet Fan Aerodynamics Using Wind Tunnel Modeling." Journal of Fluids Engineering 118, no. 2 (June 1, 1996): 322–28. http://dx.doi.org/10.1115/1.2817380.
Full textAbstract:
Jet fan aerodynamic behavior was investigated using wind tunnel modeling. Conditions were created to simulate mine and vehicular tunnel ventilation where these fans are finding increased application. Results showed that the ability of a jet fan to entrain air depends on its proximity to the tunnel wall. Moving the jet fan toward the wall increased the initial pressure drop below ambient in a significant length of the tunnel. This increased the volume of air entrained despite the existence of a large recirculation eddy or back flow whose size diminished as the jet fan was traversed toward the tunnel axis. When the jet fan was located at the tunnel axis the flow was very unstable close to the walls of the tunnel and it had a tendency to reverse itself with periods coinciding with the jet oscillation behavior. The complete set of measurements obtained are suitable for CFD code validation and modeling.
36
Wu, Yimin, Haiping Wu, Dinghai Chu, Sheng Feng, Junjian Zhang, and Haoran Wu. "Failure Mechanism Analysis and Optimization Analysis of Tunnel Joint Waterstop Considering Bonding and Extrusion." Applied Sciences 12, no. 11 (June 5, 2022): 5737. http://dx.doi.org/10.3390/app12115737.
Full textAbstract:
In waterproofing mountain tunnels, the tunnel joint is the weak link. To explore the waterproof failure mechanism of the tunnel joint waterstop belt and to propose an optimization method for the waterstop belt, this paper combines tests and numerical simulations, summarizes the waterproofing mechanism of the waterstop belt, establishes a finite element model of the waterstop belt considering bonding and extrusion, and studies the waterproofing ability and mechanical properties of the waterstop. The main conclusions are as follows: (1) The waterproofing capacity of the water stop belt depends on its surface contact pressure and bonding force. (2) Waterstop deformation will partially destroy the bonding between the waterstop and concrete, reducing the reliability of the waterproofing mechanism. (3) When the deformation of the waterstop belt reaches a certain degree, its stress value is too large to meet the requirements of its service life. (4) The design can be optimized from two aspects: the bond between the waterstop and concrete, and the size of the waterstop.
37
Yan, Shumeng, Meixin Feng, Shizhao Fan, Rui Zhou, Yongjun Tang, Tianhao Jiang, Jianxun Liu, Yu Zhou, Qian Sun, and Hui Yang. "Activation of buried p-GaN through nanopipes in large-size GaN-based tunnel junction LEDs." Nanotechnology 32, no. 30 (May 4, 2021): 30LT01. http://dx.doi.org/10.1088/1361-6528/abf969.
Full text
38
Andersson, L. Robin, J. Gunnar I. Hellström, Patrik Andreasson, and T. Staffan Lundström. "Numerical Investigation of a Hydropower Tunnel: Estimating Localised Head-Loss Using the Manning Equation." Water 11, no. 8 (July 29, 2019): 1562. http://dx.doi.org/10.3390/w11081562.
Full textAbstract:
The fluid dynamics within a water tunnel is investigated numerically using a RANS approach with the k- ε turbulence model. The computational model is based on a laser scan of a hydropower tunnel located in Gävunda, Sweden. The tunnel has a typical height of 6.9 m and a width of 7.2 m. While the average cross-sectional shape of the tunnel is smooth the local deviations are significant, where some roughness elements may be in the size of 5 m implying a large variation of the hydraulic radius. The results indicate that the Manning equation can successfully be used to study the localised pressure variations by taking into account the varying hydraulic radius and cross-sectional area of the tunnel. This indicates a dominant effect of the tunnel roughness in connection with the flow, which has the potential to be used in the future evaluation of tunnel durability. ANSYS-CFX was used for the simulations along with ICEM-CFD for building the mesh.
39
Yamamoto, Kentaro, Andrei V. Lyamin, Daniel W. Wilson, Scott W. Sloan, and Andrew J. Abbo. "Stability of a single tunnel in cohesive–frictional soil subjected to surcharge loading." Canadian Geotechnical Journal 48, no. 12 (December 2011): 1841–54. http://dx.doi.org/10.1139/t11-078.
Full textAbstract:
This paper focuses mainly on the stability of a square tunnel in cohesive–frictional soils subjected to surcharge loading. Large-size noncircular tunnels are quickly becoming a widespread building technology by virtue of the development of advanced tunneling machines. The stability of square tunnels in cohesive–frictional soils subjected to surcharge loading has been investigated theoretically and numerically, assuming plane strain conditions. Despite the importance of this problem, previous research on the subject is very limited. At present, no generally accepted design or analysis method is available to evaluate the stability of tunnels or openings in cohesive–frictional soils. In this study, a continuous loading is applied to the ground surface, and both smooth and rough interface conditions between the loading and soil are modelled. For a series of tunnel geometries and material properties, rigorous lower and upper bound solutions for the ultimate surcharge loading of the considered soil mass are obtained by applying recently developed numerical limit analysis techniques. The results obtained are presented in the form of dimensionless stability charts for practical convenience, with the actual surcharge loads being closely bracketed from above and below. As a handy practical means, upper bound rigid-block mechanisms for square tunnels have also been developed, and the obtained values of collapse loads were compared with the results from numerical limit analysis to verify the accuracy of both approaches. Finally, an expression that approximates the ultimate surcharge load of cohesive–frictional soils with the inclusion of shallow square tunnels has been devised for use by practicing engineers.
40
Berisio, Rita, Natascia Corti, Peter Pfister, Ada Yonath, and Erik C. Böttger. "23S rRNA 2058A→G Alteration Mediates Ketolide Resistance in Combination with Deletion in L22." Antimicrobial Agents and Chemotherapy 50, no. 11 (August 21, 2006): 3816–23. http://dx.doi.org/10.1128/aac.00767-06.
Full textAbstract:
ABSTRACT Resistance to macrolides and ketolides occurs mainly via alterations in RNA moieties of the drug-binding site. Using an A2058G mutant of Mycobacterium smegmatis, additional telithromycin resistance was acquired via deletion of 15 residues from protein L22. Molecular modeling, based on the crystal structure of the large ribosomal subunit from Deinococcus radiodurans complexed with telithromycin, shows that the telithromycin carbamate group is located in the proximity of the tip of the L22 hairpin-loop, allowing for weak interactions between them. These weak interactions may become more important once the loss of A2058 interactions destabilizes drug binding, presumably resulting in a shift of the drug toward the other side of the tunnel, namely, to the vicinity of L22. Hence, the deletion of 15 residues from L22 may further destabilize telithromycin binding and confer telithromycin resistance. Such deletions may also lead to notable differences in the tunnel outline, as well as to an increase of its diameter to a size, allowing the progression of the nascent chain.
41
Kim, Jonguk, Jung-joo Kim, Hafeezur Rehman, and Hankyu Yoo. "Ground Stability Analysis in Non-Open-Cut Tunneling Method Using Small-Diameter Steel Pipe Piles." Applied Sciences 10, no. 19 (October 2, 2020): 6906. http://dx.doi.org/10.3390/app10196906.
Full textAbstract:
The non-open-cut method is used for constructing tunnels under existing roads without blocking traffic. Various non-open-cut methods use pipe roofs made of medium- and large-diameter steel pipe piles. However, the risk of ground settlement or heave is involved during the application of such piles. Therefore, research is conducted through model tests and numerical analysis on the non-open-cut method to investigate these problems using small-diameter piles. The progress of tunnel construction is divided into two repetitive steps. The first step (Stage 1) involves pulling back the pressure panel, and the second step involves propelling the precast structure (Stage 2). The behaviors of the pipe piles and ground displacement are analyzed according to the cover depth, tunnel size, existence and nonexistence of the shoe structure, and progress of tunnel construction. Small-diameter piles reduce the displacement during both stages. With a decrease in cover depth, the stress acting on the pile decreases during Stage 1 and increases during Stage 2. The presence of the shoe structure reduces the stress on the pile during both stages. The ground behavior based on the construction progress indicates that the ground settlement increases during Stage 1; however, no correlation is observed during Stage 2 at low depth.
42
Venkert, A., P. R. Guduru, and G. Ravichandran. "Effect of Loading Rate on Fracture Morphology in a High Strength Ductile Steel." Journal of Engineering Materials and Technology 123, no. 3 (November 17, 2000): 261–67. http://dx.doi.org/10.1115/1.1371231.
Full textAbstract:
Fracture experiments in a high-strength ductile steel (2.3Ni-1.3Cr-0.17C) were conducted under static and dynamic loading conditions in a three-point bend and a one-point bend configurations. A qualitative description of the influence of loading rate on the microscopic features of the fracture surfaces and their role in the fracture initiation process was considered. The fracture surfaces consist of tunneled region and shear lips. The size of the shear lips increases with increasing loading rate and is characterized by micro-voids and cell structures. The tunneled region consists of large voids and micro-voids that coalesce by impingement. At high loading rates, localized molten zones are observed at the tunnel-shear lip interface.
43
Luo, Ciyou, Zihai Yan, Zijuan Wang, and Hao Cui. "Study on Lining Mechanical Behavior of Super Large Diameter Shield Tunnel during Segment Opening." Journal of Physics: Conference Series 2185, no. 1 (January 1, 2022): 012072. http://dx.doi.org/10.1088/1742-6596/2185/1/012072.
Full textAbstract:
Abstract The mechanical behavior and risks of the lining of the super large shield tunnel during segment opening are still unclear. In order to study the characteristics of the mechanical behavior of the lining of the super-large-diameter shield tunnel during segment opening, Take the cross-passage project of Hangzhou Zhijiang Road Water Conveyance Corridor and Road Improvement Project as the engineering background. The MIDAS finite element numerical calculation model of the opening on the double-track main tunnel lining is established. The influence of the opening size and support stiffness on the mechanical behavior of the lining is analyzed separately. The main conclusions are: (1) The maximum deformation of the lining when opening occurs in the middle area directly above the opening. It is necessary to strengthen the deformation monitoring of the segment in this area during construction to prevent excessive deformation or even damage and accidents; (2) The reduction of the opening area within a certain range and the increase of the stiffness of the temporary support can reduce the deformation of the lining after the opening. Based on the determined parameters of the main tunnel lining and opening, the stiffness of the temporary support can be increased to reduce the deformation of the lining opening; (3) Setting up temporary supports and increasing the stiffness of the temporary supports cannot affect the final deformation of the lining after the temporary supports are removed. Therefore, to stabilize the lining in the open area, it is necessary to rely on pouring ring beams.
44
Chakraverty, Mayank, and Harish M. Kittur. "First Principle Study of Tunnel Currents through CeO2, Y2O3, TiO2 and Al2O3 Dielectrics in MOSFETs for Ultra Large Scale Integration." Advanced Materials Research 584 (October 2012): 428–32. http://dx.doi.org/10.4028/www.scientific.net/amr.584.428.
Full textAbstract:
High gate leakage current, as a central problem, has decelerated the downscaling of minimum feature size of the field effect transistors In this paper, a combination of density functional theory and non equilibrium Green’s function formalism has been applied to the atomic scale calculation of the tunnel currents through CeO2, Y2O3, TiO2 and Al2O3 dielectrics in MOSFETs. The tunnel currents for different bias voltages applied to Si/Insulator/Si systems have been obtained along with tunnel conductance v/s bias voltage plots for each system. The results are in agreement to the use of high dielectric constant materials as gate dielectric so as to enable further downscaling of MOSFETs with reduced gate leakage currents thereby enabling ultra large scale integration. When used as dielectric, TiO2 exhibits extremely low tunnel currents followed by Y2O3 while CeO2 and Al2O3 exhibit high tunnel currents through them at certain bias voltages.
45
Gordon, Robert, and Mohammed S. Imbabi. "CFD Simulation and Experimental Validation of a New Closed Circuit Wind/Water Tunnel Design." Journal of Fluids Engineering 120, no. 2 (June 1, 1998): 311–18. http://dx.doi.org/10.1115/1.2820650.
Full textAbstract:
A new closed-circuit wind/water tunnel to support flow visualization research was designed and constructed at The University of Aberdeen. Review of existing closed-circuit tunnel designs revealed that they are large, expensive, difficult to set up and maintain, and typically employ a single working fluid. Key objectives of the work reported here were to reduce the overall cost and size of the tunnel, facilitate the use of alternative working fluids (air or water), and provide high quality flow within the test section. Conventional design methods were used initially, and computational fluid dynamics (CFD) was then employed to simulate the flow within critical sections of the tunnel. The results from CFD played a decisive role in identifying the modifications needed to achieve the compact, cost-effective tunnel design eventually built and tested. Flow quality within the test section was established using measured velocity profiles, and these are also presented.
46
Yan, Mei, De Yun Ding, Xiu Ren Yang, Xiu Ren Yang, Wei Dong Lu, Wei Ning Liu, and Ai Min Li. "3D Numerical Analysis of Metro Station by PBA Method to Enlarge Existing Large-Size Shield Tunnel." Applied Mechanics and Materials 170-173 (May 2012): 1673–78. http://dx.doi.org/10.4028/www.scientific.net/amm.170-173.1673.
Full textAbstract:
There is no engineering experience for metro station construction by the PBA (Pile-Beam-Arch) method to enlarge an existing large-size shield tunnel in China. During enlarging construction by the PBA method, the spatial mechanical and deformational characteristics of metro station structure are still not clear. In this paper, the Gaojiayuan station is taken as an engineering background to study the spatial mechanical and deformational characteristics during enlarging construction by the PBA method. Based on soil-structure interaction theory, a three-dimensional finite element model is built to simulate the enlarging construction by the PBA method. The three-dimensional numerical results can be regarded as a valuable reference for enlarging construction by the PBA method in Beijing metro line 14.
47
Fujisawa, Y., G. Fujii, M. Ukibe, S. Shiki, M. Naruse, H. Myoren, and T. Taino. "Development of High Throughput X-ray detectors using Superconducting Tunnel Junctions with a large area size." Journal of Physics: Conference Series 1293 (September 2019): 012052. http://dx.doi.org/10.1088/1742-6596/1293/1/012052.
Full text
48
Flaga, Andrzej, and Łukasz Flaga. "Wind tunnel tests and analysis of snow load distribution on three different large size stadium roofs." Cold Regions Science and Technology 160 (April 2019): 163–75. http://dx.doi.org/10.1016/j.coldregions.2019.02.002.
Full text
49
Guo, Huihui, Xiong Wang, Tingting Liu, Zhijiang Guo, and Yang Gao. "MEMS Skin Friction Sensor with High Response Frequency and Large Measurement Range." Micromachines 13, no. 2 (January 30, 2022): 234. http://dx.doi.org/10.3390/mi13020234.
Full textAbstract:
Micro-electromechanical system (MEMS) skin friction sensors are considered to be promising sensors in hypersonic wind tunnel experiments owing to their miniature size, high sensitivity, and stability. Aiming at the problem of short test duration (a few milliseconds) and heavy load in a shock wind tunnel, the fast readout circuit and the sensor head structures of a MEMS skin friction sensor are presented and optimized in this work. The sensor was fabricated using various micro-mechanical processes and micro-assembly technology based on visual alignment. Meanwhile, the sensor head structure was integrated with the fast readout circuit and tested by using a centrifugal force equivalent method. The calibration results show that this sensor provides good linearity, sensitivity, and stability. The measurement ranges are 0–2000 Pa with good performance. The resolution is better than 10 Pa at 3000 Hz detection frequency of the readout circuit for the sensor in ranges from 0 to 1000 Pa. In addition, the repeatability and linearity of static calibration for sensors are better than 1%.
50
Yang, Zhaopeng, and Linbing Wang. "Fractal Analysis of Tunnel Structural Damage Caused by High-Temperature and Explosion Impact." Buildings 12, no. 9 (September 8, 2022): 1410. http://dx.doi.org/10.3390/buildings12091410.
Full textAbstract:
The tunnel is one of the most important components in modern underground engineering. Due to long and narrow shape constraints, it very easily results in large-scale fire and explosion when deflagration is caused by the accidents of vehicles that transport dangerous goods in the tunnel. Previously, the studies on the damage to tunnel lining caused by high-temperature impacts in these kinds of disasters were often limited to a discussion of only one influencing factor, either fire or explosion, but they rarely considered the two factors simultaneously. In this work, the damage properties of full-size tunnel lining induced by high temperature and impact were evaluated, and the concrete samples from the whole lining arch were selected for CT scanning. The improved differential box-counting method was used for the fractal analysis of the CT images to obtain the damage-distribution properties of the tunnel lining structure under the two coupled influencing factors: the high temperature caused by fire, and the impact caused by deflagration.