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"tunneling."
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Roslyn Rutabaga and the biggest hole on earth
Roslyn Rutabaga is a rabbit. One day she has a plan to dig the biggest hole on earth. Will she succeed?
Book
Moiréless correlations in ABCA graphene
Atomically thin van der Waals materials stacked with an interlayer twist have proven to be an excellent platform toward achieving gate-tunable correlated phenomena linked to the formation of flat electronic bands. In this work we demonstrate the formation of emergent correlated phases in multilayer rhombohedral graphene—a simple material that also exhibits a flat electronic band edge but without the need of having a moiré superlattice induced by twisted van der Waals layers. We show that two layers of bilayer graphene that are twisted by an arbitrary tiny angle host large (micrometer-scale) regions of uniform rhombohedral four-layer (ABCA) graphene that can be independently studied. Scanning tunneling spectroscopy reveals that ABCA graphene hosts an unprecedentedly sharp van Hove singularity of 3–5-meV half-width. We demonstrate that when this van Hove singularity straddles the Fermi level, a correlated many-body gap emerges with peak-to-peak value of 9.5 meV at charge neutrality. Mean-field theoretical calculations for model with short-ranged interactions indicate that two primary candidates for the appearance of this broken symmetry state are a charge-transfer excitonic insulator and a ferrimagnet. Finally, we show that ABCA graphene hosts surface topological helical edge states at natural interfaces with ABAB graphene which can be turned on and off with gate voltage, implying that small-angle twisted double-bilayer graphene is an ideal programmable topological quantum material.
Journal Article
A dog named Doug
Egged on by a ground squirrel, a dog named Doug digs miles underground--taking a detour through the White House--until he returns home, goes to bed, and dreams of digging some more.
Book
Coupling Quantum Tunneling with Cavity Photons
Tunneling of electrons through a potential barrier is fundamental to chemical reactions, electronic transport in semiconductors and superconductors, magnetism, and devices such as terahertz oscillators. Whereas tunneling is typically controlled by electric fields, a completely different approach is to bind electrons into bosonic quasiparticles with a photonic component. Quasiparticles made of such light-matter microcavity polaritons have recently been demonstrated to Bose-condense into superfluids, whereas spatially separated Coulomb-bound electrons and holes possess strong dipole interactions. We use tunneling polaritons to connect these two realms, producing bosonic quasiparticles with static dipole moments. Our resulting three-state system yields dark polaritons analogous to those in atomic systems or optical waveguides, thereby offering new possibilities for electromagnetically induced transparency, room-temperature condensation, and adiabatic photon-to-electron transfer.
Journal Article
Tunnels
Follow the developments of tunnels, as they have gone deeper underground, have traveled further and helped us transport people, energy and goods through engineering skill, design, and ambition.
Book
A novel LSTM-autoencoder and enhanced transformer-based detection method for shield machine cutterhead clogging
Shield tunneling machines are paramount underground engineering equipment and play a key role in tunnel construction. During the shield construction process, the “mud cake” formed by the difficult-to-remove clay attached to the cutterhead severely affects the shield construction efficiency and is harmful to the healthy operation of a shield tunneling machine. In this study, we propose an enhanced transformer-based detection model for detecting the cutterhead clogging status of shield tunneling machines. First, the working state data of shield machines are selected from historical excavation data, and a long short-term memory-autoencoder neural network module is constructed to remove outliers. Next, variational mode decomposition and wavelet transform are employed to denoise the data. After the preprocessing, nonoverlapping rectangular windows are used to intercept the working state data to obtain the time slices used for analysis, and several time-domain features of these periods are extracted. Owing to the data imbalance in the original dataset, the
k
-means-synthetic minority oversampling technique algorithm is adopted to oversample the extracted time-domain features of the clogging data in the training set to balance the dataset and improve the model performance. Finally, an enhanced transformer-based neural network is constructed to extract essential implicit features and detect cutterhead clogging status. Data collected from actual tunnel construction projects are used to verify the proposed model. The results show that the proposed model achieves accurate detection of shield machine cutterhead clogging status, with 98.85% accuracy and a 0.9786
F
1 score. Moreover, the proposed model significantly outperforms the comparison models.
Journal Article
Tunnel Engineering Handbook
The Tunnel Engineering Handbook, Second Edition provides, in a single convenient volume, comprehensive coverage of the state of the art in the design, construction, and rehabilitation of tunnels. It brings together essential information on all the principal classifications of tunnels, including soft ground, hard rock, immersed tube and cut-and-cover, with comparisons of their relative advantages and suitability. The broad coverage found in the Tunnel Engineering Handbook enables engineers to address such critical questions as how tunnels are planned and laid out, how the design of tunnels depends on site and ground conditions, and which types of tunnels and construction methods are best suited to different conditions. Written by the leading engineers in the fields, this second edition features major revisions from the first, including: * Complete updating of all chapters from the first edition * Seven completely new chapters covering tunnel stabilization and lining, difficult ground, deep shafts, water conveyance tunnels, small diameter tunnels, fire life safety, tunnel rehabilitation and tunnel construction contracting *New coverage of the modern philosophy and techniques of tunnel design and tunnel construction contracting The comprehensive coverage of the Tunnel Engineering Handbook makes it an essential resource for all practicing engineers engaged in the design of tunnels and underground construction. In addition, the book contains a wealth of information that government administrators and planners and transportation officials will use in the planning and management of tunnels.
eBook
Dark terror
Alec Shorecross is 14 and has already left school to work in the local mine. He's paid 13 cents an hour to toil in the underground darkness. When war breaks out, Alec ships overseas in search of a different life and a way to contribute. He dreams of doing something heroic but soon Alec finds himself underground again. While soldiers and aircraft engage in battles on the ground and in the sky, down, deep below the surface Alec joins the invisible crew of combatants who risk their lives building tunnels so that they can place mines beneath enemy territory. This dramatic and realistic story shows us a little-known side of war and the role of one brave and determined young man.
Book
Bistability in Atomic-Scale Antiferromagnets
Control of magnetism on the atomic scale is becoming essential as data storage devices are miniaturized. We show that antiferromagnetic nanostructures, composed of just a few Fe atoms on a surface, exhibit two magnetic states, the Néel states, that are stable for hours at low temperature. For the smallest structures, we observed transitions between Néel states due to quantum tunneling of magnetization. We sensed the magnetic states of the designed structures using spin-polarized tunneling and switched between them electrically with nanosecond speed. Tailoring the properties of neighboring antiferromagnetic nanostructures enables a low-temperature demonstration of dense nonvolatile storage of information.
Journal Article