Presence Of Tunneling Research Articles

Air quality on UK diesel and hybrid trains

Concentrations of particulate matter (PM10, PM2.5), ultrafine (UFP), particle number (PNC), black carbon (BC), nitrogen dioxide (NO2) and nitrogen oxides (NOX) were measured in train carriages on diesel and bi-mode trains on inter-city and long-distance journeys in the United Kingdom (UK) using a high-quality mobile measurement system. Air quality on 15 different routes was measured using highly-time resolved data on a total of 119 journeys during three campaigns in winter 2020 and summer 2021; this included 13 different train classes. Each journey was sampled 4–10 times with approximatively 11,000 min of in-train concentrations in total. Mean-journey concentrations were 7.552 µg m−3 (PM10); 3.936 µg m−3 (PM2.5); 333–11,300 # cm−3 (PNC); 225–9,131 # cm−3 (UFP); 0.6–11 µg m−3 (BC); 28–201 µg m−3 (NO2); and 130–3,456 µg m−3 (NOX). The impact of different factors on in-train concentrations was evaluated. The presence of tunnels was the factor with the largest impact on the in-train particle concentrations with enhancements by a factor of 40 greater than baseline for BC, and a factor 6 to 7 for PM and PNC. The engine fuel mode was the factor with the largest impact on NO2 with enhancements of up to 14-times larger when the train run on diesel compared to the times running on electric on hybrid trains. Train classes with an age < 10 years observed the lowest in-train PM, BC and NOX concentrations reflecting improvements in aspects of rail technology in recent years. Air quality on UK diesel trains is higher than ambient concentrations but has lower PM2.5 and PNC than most other transport modes, including subway systems, diesel and petrol cars. This paper adds significantly to the evidence on exposure to poor air quality in transport micro-environments and provides the industry and regulatory bodies with reference-grade measurements on which to establish in-train air quality guidelines.

Optical-pumping enantio-conversion of chiral mixtures in presence of tunneling between chiral states

Enantio-conversion of chiral mixtures, converting the mixtures composed of left- and right-handed chiral molecules into the homochiral ensembles, has become an important research topic in chemical and biological fields. In previous studies on enantio-conversion, the tunneling interaction between the left- and right-handed chiral states was often neglected. However, for certain chiral molecules, this tunneling interaction is significant and cannot be ignored. Here we propose a scheme for enantio-conversion of chiral mixtures through optical pumping based on a four-level model of chiral molecules, comprising two chiral ground states and two achiral excited states, with a tunneling interaction between the chiral states. Under one-photon large detuning and two-photon resonance conditions, one of the achiral excited states is eliminated adiabatically. By well designing the detuning and coupling strengths of the electromagnetic fields, the tunneling interaction between two chiral states and the interaction between one of the chiral states and the remaining achiral excited state can be eliminated. Consequently, one chiral state remains unchanged, while the other can be excited to an achiral excited state, establishing chiral-state-selective excitations. By numerically calculating the populations of two chiral ground states and the enantiomeric excess, we observe that high-efficiency enantio-conversion is achieved under the combined effects of system dissipation and chiral-state-selective excitations.

Unitary p-wave interactions between fermions in an optical lattice.

Exchange-antisymmetric pair wavefunctions in fermionic systems can give rise to unconventional superconductors and superfluids1-3. The realization of these states in controllable quantum systems, such as ultracold gases, could enable new types of quantum simulations4-8, topological quantum gates9-11 and exotic few-body states12-15. However, p-wave and other antisymmetric interactions are weak in naturally occurring systems16,17, and their enhancement via Feshbach resonances in ultracold systems has been limited by three-body loss18-24. Here we create isolated pairs of spin-polarized fermionic atoms in a multiorbital three-dimensional optical lattice. We spectroscopically measure elastic p-wave interaction energies of strongly interacting pairs of atoms near a magnetic Feshbach resonance. The interaction strengths are widely tunable by the magnetic field and confinement strength, and yet collapse onto a universal curve when rescaled by the harmonic energy and length scales of a single lattice site. The absence of three-body processes enables the observation of elastic unitary p-wave interactions, as well as coherent oscillations between free-atom and interacting-pair states. All observations are compared both to an exact solution using a p-wave pseudopotential and to numerical solutions using an ab initio interaction potential. The understanding and control of on-site p-wave interactions provides a necessary component for the assembly of multiorbital lattice models25,26 and a starting point for investigations of how to protect such systems from three-body recombination in the presence of tunnelling, for instance using Pauli blocking and lattice engineering27,28.

33181 C5a and C5aR is prominently associated with tunnels in severe hidradenitis suppurativa

Complement dysregulation and neutrophil activation have been implicated in the pathogenesis of hidradenitis suppurativa (HS). The presence of tunnels (subcutaneous cavities lined with squamous epithelium) is a feature of the moderate and severe forms of HS. The complement 5a (C5a) receptor (C5aR) is highly expressed on neutrophils and is a major driver of the proinflammatory functions. Avacopan is a potent and specific inhibitor of human C5aR, and was shown to be efficacious and well tolerated in patients with severe HS in a recent phase 2 clinical trial.

Faraday-imaging-induced squeezing of a double-well Bose-Einstein condensate

We examine how nondestructive measurements generate spin squeezing in an atomic Bose-Einstein condensate confined in a double-well trap. The condensate in each well is monitored using coherent light beams in a Mach-Zehnder configuration that interacts with the atoms through a quantum nondemolition Hamiltonian. We solve the dynamics of the light-atom system using an exact wave-function approach, in the presence of dephasing noise, which allows us to examine arbitrary interaction times and a general initial state. We find that monitoring the condensate at zero detection current and with identical coherent light beams minimizes the backaction of the measurement on the atoms. In the weak atom-light interaction regime, we find the mean spin direction is relatively unaffected, while the variance of the spins is squeezed along the axis coupled to the light. Additionally, squeezing persists in the presence of tunneling and dephasing noise. For long atom-light interaction time, we equally show our methods can be used to prepare non-Gaussian correlated spin states.

Evaluation of the compatibility of the power traction supply system with a use of a “virtual coupling” technology

This article will propose the practical use of the interval control technology that will reduce the interval of passing trains and will increase the capacity of railway lines. Controlled approbation of the technology was carried out on railway sections for freight traffic: Shkotovo - Nakhodka, Novonezhino - Krasnoarmeysky of the Far Eastern railway and Koshurnikovo-Shchetinkino of the Krasnoyarsk railway in terms of “push locomotives” transferring to the opposite direction using the “virtual coupling” system; Mogocha - Urusha of the Trans-Baikal railway in terms of traffic organizing using the “virtual coupling” system for empty trains during long “Windows” on infrastructure; Slyudyanka - Bolshoy Lug of the East Siberian railway in terms of testing interval control technology to ensure the return of odd freight trains “push locomotives” using the “virtual coupling” system. The practical experience of the system use considered in the article allowed us to identify the main directions for its further development: protected radio channel stability improvement in obstacles of the rough terrain and the presence of tunnels; auto-driving algorithms operation.

Centrifuge modeling of normal faulting and underground tunnel in sandy soil deposit

Earthquakes of large magnitudes cause fault ruptures propagation in soil layers and lead to interactions with subsurface and surface structures. The emergence of fault ruptures on or adjacent to the position of existing tunnels cause significant damage to the tunnels. The objective of this paper is to study the interaction of an embedded tunnel within a soil layer and the soil deformations imposed upon by normal faulting. A centrifuge modeling under 80-g acceleration was conducted to investigate the rupture propagation pattern for different relative tunnel positions. Compared with the free field condition, due to tunnel and normal fault rupture interactions, focused on soil relative density and tunnel rigidity in this research, found that they can dramatically modify the rupture path depending on the tunnel position relative to the fault tip. The tunnel diverts the rupture path to its sides. This study presents the normal fault-tunnel interaction with the tunnel axis parallel to the normal fault line, to examine the changes that take place in fault rupture plane locations, the vertical displacement of the ground surface with tunnel presence and the effect of tunnel rigidity and soil density on fault tunnel interaction.

High-efficiency asymmetric diffraction based on PT-antisymmetry in quantum dot molecules

We present preparation of asymmetric grating with higher diffraction efficiency in quantum dot molecules by combining the tunneling effect and parity-time antisymmetry. In the presence of tunneling between two quantum dots, the system exhibits the striking PT antisymmetry via spatially modulating the driving field and the detuning with respect to the driven transition. For this reason, the asymmetric grating could be achieved. The results show that the diffraction efficiency can be adjustable via changing the driving intensity, detuning, tunneling strength, and interaction length, and then the high-order diffraction can be reached. The scheme provides a feasible way to obtain the direction-controlled diffraction grating, which can be helpful for optical information processing and realization of controllable optical self-image.

Quench Dynamics of a Fermi Gas with Strong Nonlocal Interactions.

We induce strong nonlocal interactions in a 2D Fermi gas in an optical lattice using Rydberg dressing. The system is approximately described by a t - V model on a square lattice where the fermions experience isotropic nearest-neighbor interactions and are free to hop only along one direction. We measure the interactions using many-body Ramsey interferometry and study the lifetime of the gas in the presence of tunneling, finding that tunneling does not reduce the lifetime. To probe the interplay of nonlocal interactions with tunneling, we investigate the short-time-relaxation dynamics of charge-density waves in the gas. We find that strong nearest-neighbor interactions slow down the relaxation. Our work opens the door for quantum simulations of systems with strong nonlocal interactions such as extended Fermi-Hubbard models.

Numerical Investigations on the Resistance and Longitudinal Motion Stability of a High-Speed Planing Trimaran

The planing trimaran is a novel kind of aerodynamic alleviated marine vehicle and possesses a unique hybrid hydrodynamic and aerodynamic characteristics. In this paper, to investigate the hull behavior of a planing trimaran under the effect of tunnel forces, the tunnel and demihull are treated as appendages mounted on the slender main hull. Numerical simulations were carried out for planing trimaran and a monohull which was built according to the main hull configuration. Mesh convergence studies were implemented based on the public experimental data of a similar planing trimaran. Calculated results show that the presence of tunnel and demihull could decrease the resistance of the main hull and improve the longitudinal motion stability at high speeds. Flow evolutions of waves, velocity vector, wetted length and lift distribution were performed to explain the variation of the tunnel lift and its moment and their influence on hull behavior. Parameter studies on demihull length were carried out as well. It was found that, as the demihull length is increased, the tunnel trimming moment would decrease especially in the final stage of ventilation, making resistance reduced but the motion stability weakened.

Experimental characterization of aero-acoustic performance of micro-perforated materials in a wind tunnel

Mitigating the propagation of low frequency noise in ducted flows represents a challenging task since wall treatments have often limited dimensions. Micro-perforated panels have been successfully used backed by a cavity constituting a bulk-reacting resonator or in combination with honeycomb for a locally reacting system. In this work, a cost-efficient methodology for the study and characterization of the aero-acoustic properties of flush-mounted micro-perforated resonators has been developed. Although Laser Doppler Velocimetry is a non-intrusive technique, it requires delicate instrumentation to obtain an estimation of the acoustic velocity and pressure fluctuations at several points over a wall liner. Here, the attenuation has been estimated from sound pressure level measurements performed with two nosecone microphones positioned along a vertical line centered on the resonator axis. Experiments have been performed in a wind tunnel in presence of a low-speed turbulent boundary layer of air fully developed over different samples made up of micro-perforated sheets or porous materials with surface roughness. The micro-perforates have been flush-mounted over a cylindrical cavity of depth 30 mm situated on the floor of the test section. The ability of bulk-reacting resonators for reducing the acoustic or flow-induced noise has been assessed in comparison with locally reacting treatments.

Monitoring Land Surface Deformation Associated with Gold Artisanal Mining in the Zaruma City (Ecuador)

Underground mining can produce subsidence phenomena, especially if orebodies are surficial or occur in soft rocks. In some countries, illegal mining is a big problem for environmental, social and economic reasons. However, when unauthorized excavation is conducted underground, it is even more dangerous because it can produce unexpected surficial collapses in areas not adequately monitored. For this reason, it is important to find quick and economic techniques able to give information about the spatial and temporal development of uncontrolled underground activities in order to improve the risk management. In this work, the differential interferometric synthetic aperture radar (DInSAR) technique, implemented in the SUBSOFT software, has been used to study terrain deformation related to illegal artisanal mining in Ecuador. The study area is located in Zaruma (southeast of El Oro province), a remarkable site for Ecuadorian cultural heritage where, at the beginning of the 2017, a local school collapsed, due to sinkhole phenomena that occurred around the historical center. The school, named “Inmaculada Fe y Alegria”, was located in an area where mining activity was forbidden. For this study, the surface deformations that occurred in the Zaruma area from 2015 to 2019 were detected by using the Sentinel-1 data derived from the Europe Space Agency of the Copernicus Program. Deformations of the order of five centimeters were revealed both in correspondence of known exploitation tunnels, but also in areas where the presence of tunnels had not been verified. In conclusion, this study allowed to detect land surface movements related to underground mining activity, confirming that the DInSAR technique can be applied for monitoring mining-related subsidence.

Polynomial potentials and coupled quantum dots in two and three dimensions

Polynomial potentials V(x)=x4+O(x2) and V(x)=x6+O(x4) were introduced, in the Thom’s purely geometric classification of bifurcations, as the benchmark models of the so called cusp catastrophes and of the so called butterfly catastrophes, respectively. Due to their asymptotically confining property, these two potentials are exceptional, viz., able to serve similar purposes even after quantization, in the presence of tunneling. In this paper the idea is generalized to apply also to quantum systems in two and three dimensions. Two related technical obstacles are addressed, both connected with the non-separability of the underlying partial differential Schrödinger equations. The first one [viz., the necessity of a non-numerical localization of the extremes (i.e., of the minima and maxima) of V(x,y,…)] is resolved via an ad hoc reparametrization of the coupling constants. The second one [viz., the necessity of explicit construction of the low lying bound states ψ(x,y,…)] is circumvented by the restriction of attention to the dynamical regime in which the individual minima of V(x,y,…) are well separated, with the potential being locally approximated by the harmonic oscillator wells simulating a coupled system of quantum dots (a.k.a. an artificial molecule). Subsequently it is argued that the measurable characteristics (and, in particular, the topologically protected probability-density distributions) could bifurcate in specific evolution scenarios called relocalization catastrophes.

Influence of properties of hematite films on electrical characteristics of isotype heterojunctions Fe2O3/n-CdTe

Conditions for the production of straightening isotype heterostructures n-Fe2O3/n-CdTe by spray-pyrolysis of thin films of hematite n-Fe2O3 onto n-CdTe crystalline substrates were investigated. The presence of tunneling and space charge limits of the mechanisms of motion of electrons in the forward and reverse currents through the energy barrier of the heterojunction is established on the basis of the analysis of temperature dependences of I–V-characteristics. The role of energy states at the boundary of n-Fe2O3/n-CdTe in the formation of barrier parameters is determined. On the basis of the C–V-characteristics, the manifestation of the dielectric properties of the hematite film in a wide range of voltages is investigated. A model of the energy diagram of the heterostructure, which describes the experimental electrophysical phenomena well, has been proposed.

Spin-charge coupled transport in van der Waals systems with random tunneling

We study the electron and spin transport in a van der Waals system formed by one layer with strong spin-orbit coupling and a second layer without spin-orbit coupling, in the regime when the interlayer tunneling is random. We find that in the layer without intrinsic spin-orbit coupling spin-charge coupled transport can be induced by two distinct mechanisms. First, the gapless diffusion modes of the two isolated layers hybridize in the presence of tunneling, which constitutes a source of spin-charge coupled transport in the second layer. Second, the random tunneling introduces spin-orbit coupling in the effective disorder-averaged single-particle Hamiltonian of the second layer. This results in non-trivial spin transport and, for sufficiently strong tunneling, in spin-charge coupling. As an example, we consider a van der Waals system formed by a two-dimensional electron gas (2DEG)--such as graphene--and the surface of a topological insulator (TI) and show that the proximity of the TI induces a coupling of the spin and charge transport in the 2DEG. In addition, we show that such coupling can be tuned by varying the doping of the TI's surface. We then obtain, for a simple geometry, the current-induced non-equilibrium spin accumulation (Edelstein effect) caused in the 2DEG by the coupling of charge and spin transport.

Tunnelling in landslide areas connected to deep seated gravitational deformations: An example in Central Alps (northern Italy)

Tunnel excavation in mountainous regions often interacts with landslide phenomena. This paper deals with potential hazards arising from tunnelling in presence of a Deep-Seated Gravitational Slope Deformation (DSGSD), with specific reference to a case study located in Valtellina (northern Italy, Central Alps). In the study area a landslide has shown evidences of activation along the border of a wide DSGSD, where a tunnel has recently been excavated. The conceptual model of both the slope dynamics and the tunnel construction was first reconstructed, by integrating surface and subsurface surveys (from drillings and geophysical investigations to convergence tunnelling measurements, from topographic and inclinometric monitoring to radar interferometry and dendrogeomorphology). Data interpretation showed the presence within the slope of a thick shear zone, characterised by very weak rocks and significant water flows. When the tunnel intercepted this zone, convergences and face instabilities occurred, as well as tunnel inflow; in the meantime, slope deformation developed along the slope. These latter were probably the result of the superimposition of different effects, arising also from the long and heavy rainfall of that period. The investigation of the landslide activity based on dendrochronological analysis confirmed its correlation with rainfall, as well as the contribution of tunnelling. A similar behaviour is also confirmed by the results of stress-strain numerical simulations. Numerical results showed that groundwater rising due to long and heavy rainfall can contribute to slope instability much more than tunnelling itself. Moreover, they showed that the existence of shear and fracture zones connected to the DSGSD determines both an increase in tunnel inflow as well as in tunnel convergences. Actually, fracture and shear zones act as high permeability flow paths within the slope, draining groundwater towards the tunnel and increasing the surface settlements in a wide zone of the slope, worsening the slope stability conditions without triggering the collapse.

An approach to support traffic engineering in IPv6 networks based on IPv6 facilities

IPv6 is an Internet protocol with the ability to provide a large number of addresses to allow the connectivity of each existing thing to the global network. It also allows the deployment of many technologies and services of the next generation. One of the major changes that occurred in the IP header with this new version is the addition of the IPv6 flow label field, which was created with the intention of labeling packets that belong to a particular flow to provide an appropriate treatment by routers. However, this field has not been widely exploited yet, and it is being set to zero in almost all IPv6 packets. The main Internet routing problem is that said routing is based on the shortest path algorithm, which leads to the possibility of some paths being congested while others are underused. To solve the congestion problem, many solutions aiming at traffic engineering support have been proposed, but this topic remains an open issue. This paper describes a new solution to support traffic engineering based on the usage of the IPv6 flow label for providing fast packet switching, which we have called PSA-TE6. In this document, we present the PSA-TE6 operation and evaluation regarding the label space reduction, label stacking cost and its minimization. The results show that PSA-TE6 is cheaper compared to the IP/MPLS solution when there is no label stacking, and that PSA-TE6 also outperforms IP/MPLS when the stacking is enabled until achieving a 40% presence of tunnels for encapsulation levels greater than 1.

Semiclassical theory of Landau levels and magnetic breakdown in topological metals

The Bohr-Sommerfeld quantization rule lies at the heart of the modern semiclassical theory of a Bloch electron in a magnetic field. This rule is predictive of Landau levels and quantum oscillations for conventional metals, as well as for a host of topological metals which have emerged in the recent intercourse between band theory, crystalline symmetries and topology. The essential ingredients in any quantization rule are connection formulae that match the semiclassical (WKB) wavefunction across regions of strong quantum fluctuations. Here, we propose (a) a multi-component WKB wavefunction that describes transport within degenerate-band subspaces, and (b) the requisite connection formulae for saddlepoints and type-II Dirac points, where tunneling respectively occurs within the same band, and between distinct bands. (a-b) extend previous works by incorporating phase corrections that are subleading in powers of the field; these corrections include the geometric Berry phase, and account for the orbital magnetic moment and the Zeeman coupling. A comprehensive symmetry analysis is performed for such phase corrections occurring in closed orbits, which is applicable to solids in any (magnetic) space group. We have further formulated a graph-theoretic description of semiclassical orbits. This allows us to systematize the construction of quantization rules for a large class of closed orbits (with or without tunneling), as well as to formulate the notion of a topological invariant in semiclassical magnetotransport -- as a quantity that is invariant under continuous deformations of the graph. Landau levels in the presence of tunneling are generically quasirandom, i.e., disordered on the scale of nearest-neighbor level spacings but having longer-ranged correlations; we develop a perturbative theory to determine Landau levels in such quasirandom spectra.

Analysis of the effect of ultraviolet irradiation on varroa mite

We presented theoretical and experimental material on the influence of UV irradiation on a Varroa mite in the range of UVB and UVC in the study. We obtained mathematical expressions that simulate dependencies of electrical and structural characteristics of protective devices. Such devices implement the operation of HEA-1 hive entrance attachments equipped with LED modules of UV radiation powered by solar photocells. We substantiated parameters of protective devices, which provide a harmful effect of UV radiation on physiological functions of a Varroa mite. These parameters include power and an amount of UV light emitting diodes, their placement in a tunnel of a hive entrance attachment, a wavelength, exposure and geometric parameters of HEA-1 hive entrance attachment. A use of a hive entrance attachment ensures rejuvenation of bees from varroatosis without disrupting their natural rhythm of life, preventing a premature release of a bee colony to a first treatment flight under adverse temperature conditions. Extension of a path of bees from a hive entrance to an exit from a tunnel of an attachment make possible for bees to adapt to meteorological conditions and feel a low temperature of the outside air and return to a hive. In addition, the study of the proposed hive entrance attachment showed a functional ability to prevent penetration of wasps, hornets and rodents to a hive. This happens due to the presence of a tunnel with a calibrated internal opening, which limits direct access to a hive entrance, from which an appealing flavor of honey products spreads. The described device makes it possible to prevent the infection of bees of healthy bee colonies by the exception of possibility of penetration of ill bees-villains into hive entrance. This happens due to the presence of a grid tunnel. Sources of electromagnetic radiation of the optical range of the ultraviolet spectrum (LEDs) irradiate its inner surface.

A Study on the Wiedemann-Franz Law in a Granular s-Wave Superconductor, Given the Tunneling Between the Grains in Cooper Pair Fluctuation Propagator and Impurity Vertex

The present study tries to investigate Wiedemann-Franz law near and far from the critical temperatures, given the tunneling between the grains in Cooper pair fluctuation propagator and impurity vertex. By means of Dyson’s equation, the Cooper pair fluctuation propagator, L(q kΩ μ ) and the Cooperon (impurity vertex), λ(q, k, e 1, e 2), are initially calculated in the presence of tunneling between the grains. Then, the three distinct contributions of density of states, Maki-Thompson, and Aslamazov-Larkin, are calculated in the frameworks of the Green’s functions formalism and the Kubo formula technique. The evaluation is conducted under the limited tunneling conductance between the grains. Findings show that although the tunneling is efficient near the critical temperature, it is not effective when it is far from the critical temperature Compared to that in high temperatures, moreover, the deviation from the Wiedemann-Franz law is much more evident in low temperatures.