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Articoli di riviste sul tema "Tunnelling"

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Autore: Grafiati

Pubblicato: 4 giugno 2021

Ultima modifica: 28 luglio 2024

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1

Karataglidis, S., K. Amos, B. G. Giraud e B. A. Robson. "Is "friction" responsible for the reduction of fusion rates far below the Coulomb barrier?" HNPS Proceedings 13 (20 febbraio 2020): 24. http://dx.doi.org/10.12681/hnps.2954.

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Observed rates of the fusion of interacting heavy ions well below the Coulomb barrier are considerably lower than estimates obtained from penetration factors. An interpretation of this discrepancy has been in terms of tunnelling in semiclassical models, with the observed depletion being taken as evidence of a "friction" under the barrier. An extension of that approach is to consider tunnellin in fully quantal models. We consider tunnelling in one-dimensional models to investigate possible sources for such a friction. Under certain conditions, we find that tunnelling may be enhanced or diminished by up to 50%, which finds analogy with observation, without the invocation of a friction under the barrier.

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2

Maji, Kaushik, C. K. Mondal e S. P. Bhattacharyya. "Tunnelling time and tunnelling dynamics". International Reviews in Physical Chemistry 26, n. 4 (ottobre 2007): 647–70. http://dx.doi.org/10.1080/01442350701619689.

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3

W.J.O-T. "Tunnelling". Journal of Molecular Structure: THEOCHEM 164, n. 1-2 (febbraio 1988): 195. http://dx.doi.org/10.1016/0166-1280(88)80018-6.

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4

Tan, Zhongsheng, Zonglin Li, Zhenliang Zhou, Haixiang Lai, Yifeng Jiao, Fengyuan Li e Liming Wang. "Research on an Evaluation Method for the Adaptability of TBM Tunnelling". Applied Sciences 12, n. 9 (30 aprile 2022): 4590. http://dx.doi.org/10.3390/app12094590.

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When a TBM carries out tunnelling in complex strata, there is often low tunnelling efficiency and an increase in tunnelling costs due to the improper selection of tunnelling parameters, the wrong estimation of geological conditions, or adverse geology, so it is necessary to evaluate the tunnelling adaptability of TBM construction. In this paper, based on hydraulic engineering in Xinjiang, 11 evaluation indexes of TBM tunnelling adaptability are determined by comprehensively considering the influence of tunnelling parameters, geological conditions, and adverse geological factors on TBM tunnelling adaptability. After that, the membership function of each evaluation index is determined by referring to the existing research results and fuzzy mathematics method, and the weight of each evaluation index is determined and adjusted by the analytic hierarchy process (AHP)–entropy weight (EW) method. Finally, the adaptability evaluation method and evaluation model of TBM tunnelling are put forward. The TBM tunnelling adaptability evaluation model proposed in this paper is verified by relying on the actual situation of three interval tunnels in the project, and good effects are obtained. This study can provide a reference for the evaluation of TBM tunnelling adaptability in similar strata.

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5

Ng, C. W. W., e H. Lu. "Effects of the construction sequence of twin tunnels at different depths on an existing pile". Canadian Geotechnical Journal 51, n. 2 (febbraio 2014): 173–83. http://dx.doi.org/10.1139/cgj-2012-0452.

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Any tunnelling process inevitably induces changes in stress in the ground and may adversely affect nearby pile foundations. The interaction between tunnelling and an existing pile has been investigated by researchers and a certain amount of fundamental understanding has been gained. However, the effects of different tunnel excavation sequences on an adjacent pile remain to be understood. In this paper, a series of three-dimensional centrifuge model tests and numerical back-analyses were carried out to investigate the effects of construction sequence of twin tunnels on an existing pile in dry sand. Two tunnelling sequences were investigated: (i) a sequence involving tunnelling near the pile toe followed by tunnelling near the mid-depth of the pile shaft (i.e., test TS); (ii) sequence involving tunnelling near the mid-depth of the pile shaft followed by tunnelling near the pile toe (i.e., test ST). The measured cumulative pile settlement was about 33% larger for tunnelling sequence ST than for tunnelling sequence TS. Due to different tunnelling sequences, the apparent losses of pile capacity were 40% and 29% for sequences ST and TS, respectively. Although the computed reductions in normal stress acting on the pile induced by twin tunnelling were almost the same in tests TS and ST, tunnelling near the pile toe induced a larger decrease in the end-bearing and shaft resistances at the lower part of the pile in test ST than in test TS. In contrast to the measured pile head settlements, different tunnelling sequences had a limited effect on measured ground surface settlements and additional bending moments in the pile.

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6

Guo, Ziqi, Huipeng Zhang, Xiaoyang Shi, Zhi Huang, Yiyong Xu e Zhiqiang Zhang. "Research on Shield Tunnelling Parameters Correlation in Composite Strata". Advances in Materials Science and Engineering 2022 (1 aprile 2022): 1–11. http://dx.doi.org/10.1155/2022/3973469.

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Shield tunnelling has become the development direction of tunnel construction due to its safety, economy, and speed. The complex formation has complicated geological changes, including soft rock, hard rock, and soft and hard inhomogeneous formation. It is particularly difficult to select and control the tunnelling parameters in shield tunnelling, while the reasonable selection and control of the tunnelling parameters play an important role in the excavation efficiency, tool wear, and surface settlement. Based on the tunnel project between the Dinggong Road North Station and the People’s Park Station online 4 of Nanchang Metro during shield tunnelling construction, this paper collects thrust, torque, and revolution speed of the cutterhead during shield tunnelling in the complex strata with differentiated argillaceous siltstone and gravel and analyzes these parameters by means of mathematical statistics analysis, in order to explore the interrelationship between shield tunnelling parameters under different stratigraphic conditions and put forward optimization suggestions for tunnelling parameters, which can provide a reference for control of tunnelling parameters of earth pressure shield in composite strata.

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7

Joshi, G., M. Singh e M. Chauhan. "Analysis of gate tunnelling currents in nanoscale metal—oxide—semiconductor field effect transistors (MOSFETs) with SiO2 and high-K gate dielectrics". Proceedings of the Institution of Mechanical Engineers, Part N: Journal of Nanoengineering and Nanosystems 223, n. 1 (1 marzo 2009): 19–24. http://dx.doi.org/10.1243/17403499jnn159.

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In this paper, an analytical model for gate tunnelling current has been deployed by solving the Schrödinger equation using the Wentzel—Kramer—Brillouin approximation method for a trapezoidal potential barrier. The gate tunnelling current has been computed for direct tunnelling from channel to gate as well as for tunnelling from source drain extension region to gate. The effect of temperature variation on gate tunnelling current with an SiO2 thickness of 4nm down to 1nm has been studied at various gate voltages. Gate tunnelling in the case of high-K gate dielectrics and high-K stacks has also been analysed. In order to study the effect of temperature on gate tunnelling current in SiO2 and in high-K dielectrics, the related parameters have been modelled based on physics. The effect of variation of substrate doping concentration (Na) on gate tunnelling current in an n-type metal—oxide—semiconductor field effect transistor (n-MOSFET) with SiO2 has also been studied These studies have been used to bring out the design margins available in equivalent oxide thickness and Na.

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8

-, Fitriyadi. "A Modelling of Tunnelling Current through a Trapezoidal Potential Barrier by Using Exponential Wavefunction Approach". Indonesian Journal of Physics 32, n. 1 (14 novembre 2021): 29–31. http://dx.doi.org/10.5614/ijp.v32i1.304.

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A tunnelling current through a trapezoidal barrier potential has been modelled. The transmittance is determined using the exponential wavefunction approach method. Furthermore, the transmittance is used to calculate the tunnelling current density by applying the Gauss-Laguerre quadrature method. The simulation results show the increasing bias voltage causes the raising tunnelling current, and an increase of temperature is proportional to the tunnelling current.

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9

-, Fitriyadi. "A Modelling of Tunnelling Current through a Trapezoidal Potential Barrier by Using Exponential Wavefunction Approach". Indonesian Journal of Physics 32, n. 1 (14 novembre 2021): 29–31. http://dx.doi.org/10.5614/itb.ijp.2021.32.1.4.

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A tunnelling current through a trapezoidal barrier potential has been modelled. The transmittance is determined using the exponential wavefunction approach method. Furthermore, the transmittance is used to calculate the tunnelling current density by applying the Gauss-Laguerre quadrature method. The simulation results show the increasing bias voltage causes the raising tunnelling current, and an increase of temperature is proportional to the tunnelling current.

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10

Sutcliffe, Michael J., Laura Masgrau, Anna Roujeinikova, Linus O. Johannissen, Parvinder Hothi, Jaswir Basran, Kara E. Ranaghan, Adrian J. Mulholland, David Leys e Nigel S. Scrutton. "Hydrogen tunnelling in enzyme-catalysed H-transfer reactions: flavoprotein and quinoprotein systems". Philosophical Transactions of the Royal Society B: Biological Sciences 361, n. 1472 (12 luglio 2006): 1375–86. http://dx.doi.org/10.1098/rstb.2006.1878.

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It is now widely accepted that enzyme-catalysed C–H bond breakage occurs by quantum mechanical tunnelling. This paradigm shift in the conceptual framework for these reactions away from semi-classical transition state theory (TST, i.e. including zero-point energy, but with no tunnelling correction) has been driven over the recent years by experimental studies of the temperature dependence of kinetic isotope effects (KIEs) for these reactions in a range of enzymes, including the tryptophan tryptophylquinone-dependent enzymes such as methylamine dehydrogenase and aromatic amine dehydrogenase, and the flavoenzymes such as morphinone reductase and pentaerythritol tetranitrate reductase, which produced observations that are also inconsistent with the simple Bell-correction model of tunnelling. However, these data—especially, the strong temperature dependence of reaction rates and the variable temperature dependence of KIEs—are consistent with other tunnelling models (termed full tunnelling models), in which protein and/or substrate fluctuations generate a configuration compatible with tunnelling. These models accommodate substrate/protein (environment) fluctuations required to attain a configuration with degenerate nuclear quantum states and, when necessary, motion required to increase the probability of tunnelling in these states. Furthermore, tunnelling mechanisms in enzymes are supported by atomistic computational studies performed within the framework of modern TST, which incorporates quantum nuclear effects.

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11

Gousset, Karine, e Chiara Zurzolo. "Tunnelling nanotubes". Prion 3, n. 2 (aprile 2009): 94–98. http://dx.doi.org/10.4161/pri.3.2.8917.

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12

Phillips, W. A. "Advanced tunnelling". Nature 317, n. 6032 (settembre 1985): 25. http://dx.doi.org/10.1038/317025a0.

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13

Kemp, Martin. "Turrell's tunnelling". Nature 391, n. 6663 (gennaio 1998): 131. http://dx.doi.org/10.1038/34313.

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14

Burstal, Richard. "Epidural Tunnelling". Acute Pain 5, n. 2 (novembre 2003): 73. http://dx.doi.org/10.1016/j.acpain.2003.07.001.

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15

Baski, A. A., T. R. Albrecht e C. F. Quate. "Tunnelling accelerometer". Journal of Microscopy 152, n. 1 (ottobre 1988): 73–76. http://dx.doi.org/10.1111/j.1365-2818.1988.tb01363.x.

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16

Füllenbach, Christel. "Smarter Tunnelling". Geomechanics and Tunnelling 11, n. 6 (dicembre 2018): 722–28. http://dx.doi.org/10.1002/geot.201800048.

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17

Shi, Jun-jie, B. C. Sanders e Shao-hua Pan. "Coherent and Phonon-assisted Tunnelling in Asymmetric Double Barrier Resonant Tunnelling Structures". Australian Journal of Physics 53, n. 1 (2000): 35. http://dx.doi.org/10.1071/ph99037.

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We present a theory for calculating the phonon-assisted tunnelling current in asymmetric double barrier resonant tunnelling structures (DBRTS), in which all of the phonon modes including the interface modes and the confined bulk-like LO phonons and the conduction band nonparabolicity are considered. An important physical picture about coherent and phonon-assisted tunnelling is given. The coherent tunnelling current can be directly determined by both the width of the resonant level and the peak value of the transmission coecient at the resonant level. The phonon-assisted tunnelling current mainly comes from electron interaction with higher frequency interface phonons (especially the interface phonons localised at either interface of the left barrier). Phonon-assisted tunnelling makes a significant contribution to the valley current. The subband nonparabolicity strongly influences on electron?phonon scattering and current-to-voltage characteristics. A specially designed asymmetric DBRTS may have an improved performance over the symmetric DBRTS.

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18

Soldatov, Eugene S., Artem S. Trifonov, Vladimir V. Khanin, Sergei P. Gubin, S. A. Yakovenko e G. V. Khomutov. "Correlated electron tunnelling in a tunnelling cluster structure". Uspekhi Fizicheskih Nauk 166, n. 8 (1996): 903. http://dx.doi.org/10.3367/ufnr.0166.199608m.0903.

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19

Soldatov, Eugene S., Artem S. Trifonov, Vladimir V. Khanin, Sergei P. Gubin, S. A. Yakovenko e G. V. Khomutov. "Correlated electron tunnelling in a tunnelling cluster structure". Physics-Uspekhi 39, n. 8 (31 agosto 1996): 844. http://dx.doi.org/10.1070/pu1996v039n08abeh001538.

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20

Chitta, V. A., R. E. M. de Bekker, J. C. Maan, S. J. Hawksworth, J. M. Chamberlain, M. Henini e G. Hill. "Photon-assisted tunnelling in sequential resonant tunnelling devices". Semiconductor Science and Technology 7, n. 3 (1 marzo 1992): 432–35. http://dx.doi.org/10.1088/0268-1242/7/3/028.

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21

Klinman, Judith P. "Linking protein structure and dynamics to catalysis: the role of hydrogen tunnelling". Philosophical Transactions of the Royal Society B: Biological Sciences 361, n. 1472 (14 luglio 2006): 1323–31. http://dx.doi.org/10.1098/rstb.2006.1870.

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Early studies of enzyme-catalysed hydride transfer reactions indicated kinetic anomalies that were initially interpreted in the context of a ‘tunnelling correction’. An alternate model for tunnelling emerged following studies of the hydrogen atom transfer catalysed by the enzyme soybean lipoxygenase. This invokes full tunnelling of all isotopes of hydrogen, with reaction barriers reflecting the heavy atom, environmental reorganization terms. Using the latter approach, we offer an integration of the aggregate data implicating hydrogen tunnelling in enzymes (i.e. deviations from Swain–Schaad relationships and the semi-classical temperature dependence of the hydrogen isotope effect). The impact of site-specific mutations of enzymes plays a critical role in our understanding of the factors that control tunnelling in enzyme reactions.

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22

Sun, Lianwei, Zhong-chao Li e Rong-zhu Liang. "Simplified Analytical Method for Predicting the Lateral Ground Displacements due to Shield Tunnelling". Advances in Civil Engineering 2021 (21 giugno 2021): 1–10. http://dx.doi.org/10.1155/2021/5524557.

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Earth pressure balance or slurry shield tunnelling will squeeze the subsoils and lead to lateral outward ground displacement. However, current methods to estimate the shield tunnelling-induced ground displacements generally use the methods based on the face unsupported tunnelling (e.g., New Austrian tunnelling and open shield excavation), which cannot predict the lateral ground movement due to shield tunnelling. In this paper, a novel simplified analytical method is proposed to predict the ground lateral displacement during the shield advancing process. The key shield tunnelling operation factors, including the additional pressure of cutter head, the friction forces around shield body, the back-fill grouting pressure, and the soil volume loss are all considered. The lateral ground displacements induced by the four former factors are calculated by using Mindlin’s solutions. The soil volume loss-induced lateral ground displacement is calculated by employing the expression introduced by Pinto and Whittle. Combining with the displacement obtained from all the factors, the analytical method for lateral ground displacement induced by shield tunnelling is obtained. The applicability of the proposed analytical approach is verified with three well-documented case histories involving slurry shield and EPB shield machines.

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23

Lalowicz, Z. T., Ulrike Werner e W. Müller-Warmuth. "Rotational Tunnelling of CD3Groups in Molecular Crystals as Studied by NMR Spectra". Zeitschrift für Naturforschung A 43, n. 3 (1 marzo 1988): 219–27. http://dx.doi.org/10.1515/zna-1988-0307.

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Abstract Tunnelling frequencies of rotating CD3 groups in solids between about 20 kHz and 2 MHz may be obtained from the 2H NMR spectra. The theory of the spectral response is developed where quadrupole and dipole-dipole interactions as well as rotational tunnelling are taken into account. Features characteristic of tunnelling, which distinguish the spectra from those of rapidly reorienting deuterated methyl groups, are found from analytically calculated spectra even for the case of very large tunnel splittings. Numerical calculations have been performed for various conditions to deter mine the tunnel frequency. Experimental spectra measured at 45 MHz and low temperatures have revealed the appearance of rotational tunnelling in CD3I, CD3COONa, and (CD3COO)2Cu • H2O. In the latter case, a tunnelling frequency of 608 kHz has been extracted from the spectrum at 27 K.

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24

Zhang, Zihan. "Analysis of One-dimensional Double-potential Barrier Structures Resonant Tunnelling Based on Transmission Matrices". Highlights in Science, Engineering and Technology 104 (11 giugno 2024): 21–26. http://dx.doi.org/10.54097/smk0rt84.

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The comprehension of the tunnel effect, the passage of matter waves and particles across a high potential barrier, was the most astounding of all discoveries in quantum mechanics. Research on tunnelling in semiconductors and superconductors, as well as the development of scanning tunnelling microscopy, garnered five Nobel prizes in physics. In this study, the resonant tunnelling effect of electron tunnelling through a one-dimensional double-potential barrier was found and verified by solving the time-independent Schrödinger equation and calculating the transmittance rate of the electron tunnelling through the two potential barriers by using the transmission matrix technique performed by MATLAB. According to the analysis, the transmittance rate was one under certain specific conditions (under some specific incident energy values or some specific distance between two potential barriers), which was called as resonant tunnelling. However, in this study, square potential wells were analyzed, which can be considered merely as ideal models in real life, and therefore all results are idealized. For further investigations, researchers can use more realistic parameters to set up potential wells and analyze real-life problems.

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25

Guo, Enyi, e David R. McKenzie. "A post Gurney quantum mechanical perspective on the electrolysis of water: ion neutralization in solution". Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 473, n. 2207 (novembre 2017): 20170371. http://dx.doi.org/10.1098/rspa.2017.0371.

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Electron fluxes crossing the interface between a metallic conductor and an aqueous environment are important in many fields; hydrogen production, environmental scanning tunnelling microscopy, scanning electrochemical microscopy being some of them. Gurney (Gurney 1931 Proc. R. Soc. Lond. 134 , 137 (doi:10.1098/rspa.1931.0187)) provided in 1931 a scheme for tunnelling during electrolysis and outlined conditions for it to occur. We measure the low-voltage current flows between gold electrodes in pure water and use the time-dependent behaviour at voltage switch-on and switch-off to evaluate the relative contribution to the steady current arising from tunnelling of electrons between the electrodes and ions in solution and from the neutralization of ions adsorbed onto the electrode surface. We ascribe the larger current contribution to quantum tunnelling of electrons to and from ions in solution near the electrodes. We refine Gurney's barrier scheme to include solvated electron states and quantify energy differences using updated information. We show that Gurney's conditions would prevent the current flow at low voltages we observe but outline how the ideas of Marcus (Marcus 1956 J. Chem. Phys. 24 , 966–978 (doi:10.1063/1.1742723)) concerning solvation fluctuations enable the condition to be relaxed. We derive an average barrier tunnelling model and a multiple pathways tunnelling model and compare predictions with measurements of the steady-state current–voltage relation. The tunnelling barrier was found to be wide and low in agreement with other experimental studies. Applications as a biosensing mechanism are discussed that exploit the fast tunnelling pathways along molecules in solution.

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Chatterjee, Bhramar, A. Ghosh e P. Mitra. "Tunnelling from black holes and tunnelling into white holes". Physics Letters B 661, n. 4 (marzo 2008): 307–11. http://dx.doi.org/10.1016/j.physletb.2008.02.034.

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Liang, Yu, Kai Jiang, Shijun Gao e Yihao Yin. "Prediction of Tunnelling Parameters for Underwater Shield Tunnels, Based on the GA-BPNN Method". Sustainability 14, n. 20 (18 ottobre 2022): 13420. http://dx.doi.org/10.3390/su142013420.

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Reasonable tunnelling parameters for underwater shield tunnels play an important role in maintaining driving efficiency and safety. In this paper, a neural network method was developed to predict tunnelling parameters. Soil properties and geometric parameters were taken as inputs for the neural network, which output the tunnelling parameters, such as advancing thrust, rotation, penetration, torque of the cutter head, and support pressure. In order to improve the stability of the neural network, a genetic algorithm (GA) with a global searching ability was used to optimize the initial weight of the neural network (GA-BPNN). The accuracy of the algorithm, based on GA-BPNN, was studied through an underwater shield tunnel project. The results showed that the integration of GA into the neural network significantly improves the prediction ability for shield tunnelling parameters, especially for adjustable parameters. Later, the developed GA-BPNN model was further utilized to predict and set the range of shield tunnelling parameters in fine sand stratum of high risk. Through a comparative analysis of tunnelling parameters, the reasons leading to ground instability have been found out, and the effectiveness of ground pre-reinforcement has been verified.

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Onuchic, José N., Chigusa Kobayashi, Osamu Miyashita, Patricia Jennings e Kim K. Baldridge. "Exploring biomolecular machines: energy landscape control of biological reactions". Philosophical Transactions of the Royal Society B: Biological Sciences 361, n. 1472 (14 luglio 2006): 1439–43. http://dx.doi.org/10.1098/rstb.2006.1876.

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For almost 15 years, our Pathway model has been the most powerful model in terms of predicting the tunnelling mechanism for electron transfer (ET) in biological systems, particularly proteins. Going beyond the conventional Pathway models, we have generalized our method to understand how protein dynamics modulate not only the Franck–Condon factor, but also the tunnelling matrix element. We have demonstrated that when interference among pathways modulates the electron tunnelling interactions in proteins (particularly destructive interference), dynamical effects are of critical importance. Tunnelling can be controlled by protein conformations that lie far from equilibrium—those that minimize the effect of destructive interference during tunnelling, for example. In the opposite regime, electron tunnelling is mediated by one (or a few) constructively interfering pathway tubes and dynamical effects are modest. This new mechanism for dynamical modulation of the ET rate has been able to explain and/or predict several rates that were later confirmed by experiment. However, thermal fluctuations can also affect these molecular machines in many other ways. For example, we show how global transformations, which control protein functions such as allostery, may involve large-scale motion and possibly partial unfolding during the reaction event.

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Cvitaš, Marko T., e Jeremy O. Richardson. "Quantum tunnelling pathways of the water pentamer". Physical Chemistry Chemical Physics 22, n. 3 (2020): 1035–44. http://dx.doi.org/10.1039/c9cp05561d.

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Ochmański, Maciej. "Long-term settlement induced by EPB tunnelling studied with numerical simulations". Annals of Warsaw University of Life Sciences – SGGW. Land Reclamation 50, n. 2 (1 giugno 2018): 139–57. http://dx.doi.org/10.2478/sggw-2018-0012.

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Abstract Long-term settlement induced by tunnelling in soft cohesive subsoil is rarely considered as a subject for research despite substantial evidence that it increases considerably after construction. The paper aims to investigate the time effects of tunnelling with an earth pressure balance (EPB) shield by means of analysing subsoil deformation with the most up-to-date numerical tool. A three-dimensional numerical model with a detailed description of the geometrical and mechanical characteristics of the tunnelling process and the various materials involved was built. The computational model validated on a real-case was then used to simulate tunnelling in different groundwater conditions prior to construction. That was followed by a simulation of groundwater drawdown conditions after tunnelling with impermeable and permeable tunnel linings. The calculations show the development of the settlement over time in different groundwater conditions together with the significant influence of the permeability of the tunnel.

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Song, Tian Tian, e Xiang Sheng Chen. "A Mechanical Model of EPB-TBM Tunnelling in Mixed Face Strata". Applied Mechanics and Materials 204-208 (ottobre 2012): 1472–79. http://dx.doi.org/10.4028/www.scientific.net/amm.204-208.1472.

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The forces on TBM druing tunnelling are analyzed in detail based on the characteristics of mixed face strata. Suitable parameters of TBM are choosed according to the characteristics of the strata ahead. The studies are focused on both the acting posture of TBM and the points of the main forces. A systemic model is consequently set up, which can provide ones with analysis of TBM stability, parameter calculation and tunnelling design in mixed strata. Two cases are finally analyzed of TBM tunnelling in different mixed strata by using this model. Then some of countermeasures is given as reference for TBM tunnelling in such mixed strata in the further.

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Chan, Lucas Kwan Lok, e Alan Kwok Lun Kwong. "Geotechnical risks, mitigation measures and performance of tunnel boring machine (TBM) tunnels for the Tuen Mun – Chek Lap Kok Link Project, Hong Kong". Special Issue with Awarded and Shortlisted Papers from the HKIE Outstanding Paper Award for Young Engineers/Researchers 2019 26, n. 4 (20 dicembre 2019): 175–89. http://dx.doi.org/10.33430/v26n4thie-2019-0017.

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The Tuen Mun – Chek Lap Kok Link (TM-CLKL) project implemented latest innovation designs and ground improvement techniques in large slurry tunnel boring machines (TBM) tunnelling for constructing the sub-sea TBM tunnel in Hong Kong. Face stability, ground settlement, blow out, water ingress and ovalisation are always the major geotechnical risks for TBM tunnelling in the industry. This paper summarises the design considerations in terms of ground improvement and special arrangements of TBM tunnelling to mitigate the geotechnical risks and the improvement of the overall performance of TBM tunnelling under the TM-CLKL project. Field monitoring data such as surface settlement, ovalisation of segmental lining and ground improvement technique such as barrettes are presented.

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Soe, We-Hyo, Corentin Durand e Christian Joachim. "Low temperature two STM tip tunneling measurements of a floating chemical potential Pb(111) surface". European Physical Journal Applied Physics 87, n. 3 (settembre 2019): 31001. http://dx.doi.org/10.1051/epjap/2019190122.

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On a Pb(111) superconducting surface, low temperature dI/dV tunnelling spectra are recorded between two scanning tunnelling microscopes (STM) metallic tips with the Pb(111) sample metallic support non-grounded. The tunnelling current intensity I passing between the 2 tips through the sample is controlled by changing one or both STM vacuum tunnelling junction resistances. The chemical potential of this floating Pb(111) surface depends on the normalized ratio between those two quantum resistances. When ungrounded, the Pb(111) sample chemical potential balances between those of the 2 STM tips while tuning their respective tip end atomic apex to Pb(111) surface distances with a picometer precision without any physical contact between the STM tips and the surface.

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34

Cui, Jian, Wang-Hao Xu, Yong Fang, Li-Ming Tao e Chuan He. "Performance of Slurry Shield Tunnelling in Mixed Strata Based on Field Measurement and Numerical Simulation". Advances in Materials Science and Engineering 2020 (8 gennaio 2020): 1–14. http://dx.doi.org/10.1155/2020/6785260.

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There are severe challenges for slurry pressure balance tunnel boring machine (TBM) tunnelling in sandy cobble soil of Beijing, Chengdu, and Lanzhou in China. And the problems caused by tunnelling from silty clay to sandy cobble stratum are more serious. With the change of stratum, the key parameters and surface settlement will change correspondingly. Controlling the key parameters and predicting the surface settlement accurately and efficiently is important for hazard mitigation and risk management. In this study, based on the Tsinghuayuan Tunnel project in Beijing, the key parameters and surface settlement while tunnelling from silty clay to sandy cobble stratum are studied. Firstly, the difference of key parameters while tunnelling in two different strata is analyzed. The analysis shows that immediate responses to changes in the stratum are recommended in order to ensure construction efficiency. Then, a refined 3D finite difference model is developed to simulate the slurry TBM tunnelling in different strata. For refined simulation, three key parameters obtained from measurement data were applied to the 3D models, and the simulation results were compared with the field data. Results show that the refined model has good performance in terms of the accuracy and efficiency. This study provides a good engineering practice reference for slurry TBM tunnelling in mixed strata.

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35

Mu, Linlong, e Maosong Huang. "Analytical Method for Evaluation of Coupled Responses of a Multidirectionally Loaded Pile-Raft Foundation Induced by Tunnelling in Layered Soils". Mathematical Problems in Engineering 2015 (2015): 1–18. http://dx.doi.org/10.1155/2015/540804.

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The tunnelling effect on a pile-raft foundation is usually studied in either the horizontal or vertical direction separately, while, in practice, the responses of a pile-raft foundation induced by tunnelling in the horizontal and vertical directions occur simultaneously. Typically, a pile-raft foundation is usually loaded by vertical and horizontal loads and moments when a tunnel is constructed. Since little effort has been conducted to evaluate the coupled responses of multidirectionally loaded pile-raft foundations subjected to tunnelling, a modified two-stage method is proposed in this paper to evaluate the coupled responses of a multidirectionally loaded pile-raft foundation in layered soil. After careful verification of the method, a parametric study was carried out to evaluate whether it is necessary to consider the influences of tunnelling on a loaded pile-raft foundation from the design stages. Our study showed that it is more necessary to consider the influence of tunnelling on a pile-raft foundation when the working load on the pile-raft foundation is small. When there was only a vertical load working on the raft, the horizontal deformation and the rotation of the raft, as well as any horizontal deformation and moment along the piles, were controlled by tunnelling.

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36

Ren, Dong-Jie, Shui-Long Shen, Arul Arulrajah e Huai-Na Wu. "Evaluation of ground loss ratio with moving trajectories induced in double-O-tube (DOT) tunnelling". Canadian Geotechnical Journal 55, n. 6 (giugno 2018): 894–902. http://dx.doi.org/10.1139/cgj-2017-0355.

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Abstract (sommario):

This paper investigates the influence of moving trajectories on ground loss ratio (GRL) due to the double-O-tube (DOT) tunnelling method. DOT tunnelling has three moving trajectories: pitching, yawing, and rolling, which have different behaviours during tunnel construction compared with those from single circular shield tunnelling. These moving trajectories cause overexcavation during tunnelling. The calculation method of gap area between the DOT shield machine and linings is evaluated in this research. Based on the superposition concept, the modification equation of GLR is proposed, which takes both moving trajectory and grouting volume into consideration. A field DOT tunnelling case is analysed to determine the correlation between moving trajectories and ground settlement. The influence of tail grouting is discussed by adjusting the grouting volume in different periods. The finite element method is also employed by setting the modified ground loss ratio (GLR′) as the contraction increment of linings. Results from both the measured and simulated settlements verify the reasonability of the proposed equation and the effect of moving trajectories on ground loss.

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37

Shin, J. H., e D. M. Potts. "Time-based two dimensional modelling of NATM tunnelling". Canadian Geotechnical Journal 39, n. 3 (1 giugno 2002): 710–24. http://dx.doi.org/10.1139/t02-009.

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Abstract (sommario):

A two dimensional model is commonly employed in practice for the analysis of tunnelling. Such analyses are computationally cheap and are useful for assessing the sensitivity of the problem to the construction method, studying the influence of varying soil conditions, and (or) finding appropriate locations for placing measuring instruments. However, simulating the three dimensional nature of tunnelling in two dimensions requires certain simplifications, including the use of empirical parameters to represent the construction sequence. In many cases the choice of parameter values are arbitrary and often not fully explained. In addition, the modelling methods are often only applicable for undrained or fully drained soil conditions where no time-dependent behaviour is involved during tunnel construction. In this paper an alternative two dimensional approach termed the "time-based modelling method" is proposed that can simulate both the three dimensional effects at the tunnel heading and the time-dependent behaviour during construction. It is proposed that the new approach is appropriate for the analysis of tunnelling in a relatively permeable soil and, as an example, the method is applied to the analysis of a new Austrian tunnelling method (NATM) tunnelling problem in decomposed granite soil. The results are compared with field data and excellent agreement is obtained.Key words: numerical modelling, time-dependent behaviour, NATM tunnelling, decomposed granite soil.

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38

Saraswati, Ade Maya. "Determinants of Transfer Pricing Decisions in Mining Companies Listed on the Indonesian Stock Exchange". Jurnal Economia 17, n. 2 (30 ottobre 2021): 151–61. http://dx.doi.org/10.21831/economia.v17i2.33818.

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Abstract (sommario):

Abstract: This research aims to analyse the effect of tax and tunnelling incentive to transfer pricing with good corporate governance as a moderating variable. This research focuses on all mining companies listed on the Indonesian Stock Exchange in the period from 2014-2018 by using the purposive sampling technique to determine the sample. There are 90 data observations used as the sample and analysed by using logistic regression and moderation regression analysis, with the help of the SPSS 20 program. The research result shows that tax has a positive effect on the decision of transfer pricing; tunnelling incentive does not have an effect on the decision of transfer pricing. Good corporate governance moderates the effect of tax to transfer pricing, meanwhile good corporate governance does not moderate the effect of tunnelling incentive to the decision of transfer pricing. Keywords: Good corporate governance; Tax; Transfer pricing; Tunnelling incentive Determinan Keputusan Transfer Pricing pada Perusahaan Pertambangan yang Terdaftar di Bursa Efek IndonesiaAbstrak: Penelitian ini bertujuan untuk menganalisis pengaruh pajak dan tunnelling incentive terhadap transfer pricing dengan good corporate governance sebagai variabel pemoderasi. Populasi dari penelitian ini adalah seluruh perusahaan pertambangan yang terdaftar di Bursa Efek Indonesia tahun 2014-2018 dengan penentuan sampel menggunakan teknik purposive sampling. Sampel dalam penelitian berjumlah 90 observasi data yang kemudian dianalisis menggunakan regresi logistik dan analisis regresi moderasi dengan bantuan program SPSS 20. Hasil penelitian menunjukkan bahwa pajak berpengaruh positif terhadap keputusan transfer pricing, tunneling incentive tidak berpengaruh terhadap keputusan transfer pricing, good corporate governance memoderasi pengaruh pajak terhadap transfer pricing, sedangkan good corporate governance tidak memoderasi pengaruh tunnelling incentive terhadap keputusan transfer pricing.Kata kunci: Good corporate governance; Pajak, Transfer pricing, Tunnelling incentive

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39

Goulimari, Pelagia. "SHREDDING, BURNING, TUNNELLING". Angelaki 27, n. 3-4 (4 luglio 2022): 163–81. http://dx.doi.org/10.1080/0969725x.2022.2093973.

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40

Akter, Habiba, e Chris Phillips. "Tunnelling the Internet". Journal of Telecommunications and the Digital Economy 7, n. 1 (30 marzo 2019): 20–36. http://dx.doi.org/10.18080/jtde.v7n1.175.

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Abstract (sommario):

Despite a considerable increase in Internet capacity, regional congestion is still an issue at certain times of day. Dimensioning the system to provide minimal delay under these transient conditions would be uneconomical. We therefore investigate a scheme that allows end-users to selectively exploit a sequence of mini-tunnels along a path from their origin to a chosen destination. Such tunnels can be advertised centrally through a broker, with the cooperation of the Autonomous System (AS) domain operators, similar to a driver choosing to use a toll road to avoid potential congestion. It is thus a type of loose source routing. The approach avoids the need for inter-operator cooperation, although such cooperation could enable extending tunnels across AS peers. We explore the benefit in delay reduction for a given concentration of tunnels within a portion of the Internet. We show that a relatively small number of tunnels can provide worthwhile improvements in performance. We consider both when tunnels are randomly distributed and when they are provided close to an AS domain of interest, where traffic congestion is more likely. In this latter case, even a relatively small number of tunnels can benefit a reasonable number of users across a large region.

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41

Canzi, M., H. De Baz e F. Roman. "Roman Tunnelling Tool". Journal of Vascular Access 3, n. 4 (ottobre 2002): 154–57. http://dx.doi.org/10.1177/112972980200300404.

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Abstract (sommario):

The aim of this paper is to present an instrument that helps to create a subcutaneous path for central catheters used for hemodialysis, as well as a non traumatic internal introduction of Tesio's catheters and other systems (Dacron cap). We have designed a tunneling tool which consists of a solid but light weight hand set, connected to an extension that ends with an olive shape dilator to be connected to a trocar. Thus, precise tunneling is guaranteed through a non traumatic procedure, allowing exact anchorage of catheters.

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42

Price, Peter J. "A tunnelling formalism". Semiconductor Science and Technology 19, n. 4 (8 marzo 2004): S241—S243. http://dx.doi.org/10.1088/0268-1242/19/4/081.

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43

Varoquaux, Eric. "Superfluid quantum 'tunnelling'". Physics World 1, n. 11 (novembre 1988): 32–34. http://dx.doi.org/10.1088/2058-7058/1/11/21.

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44

Pedatzur, O., G. Orenstein, V. Serbinenko, H. Soifer, B. D. Bruner, A. J. Uzan, D. S. Brambila et al. "Attosecond tunnelling interferometry". Nature Physics 11, n. 10 (24 agosto 2015): 815–19. http://dx.doi.org/10.1038/nphys3436.

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45

Chakraborty, B., P. Hedegard e M. Nylen. "Tunnelling and phonons". Journal of Physics C: Solid State Physics 21, n. 18 (30 giugno 1988): 3437–46. http://dx.doi.org/10.1088/0022-3719/21/18/009.

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46

Elberfeld, W., M. Kleber, W. Becker e M. O. Scully. "Laser-assisted tunnelling". Journal of Physics B: Atomic and Molecular Physics 19, n. 16 (28 agosto 1986): 2589–97. http://dx.doi.org/10.1088/0022-3700/19/16/017.

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47

Macilwain, Colin. "Supercollider tunnelling stops". Nature 364, n. 6440 (agosto 1993): 751. http://dx.doi.org/10.1038/364751b0.

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48

Stamp, P. C. E. "Tunnelling secrets extracted". Nature 383, n. 6596 (settembre 1996): 125–27. http://dx.doi.org/10.1038/383125a0.

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49

Leemput, L. E. C. van de, e H. van Kempen. "Scanning tunnelling microscopy". Reports on Progress in Physics 55, n. 8 (1 agosto 1992): 1165–240. http://dx.doi.org/10.1088/0034-4885/55/8/002.

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50

Wagt, J. P. A. van der. "Tunnelling-based SRAM". Nanotechnology 10, n. 2 (1 gennaio 1999): 174–86. http://dx.doi.org/10.1088/0957-4484/10/2/312.

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