Parallel Tunnels Research Articles

Aqueous Mediated Synthesis of Mesostructured Manganese Germanium Sulfide with Hexagonal Order

The novel sulfidic mesophase [C14H29N(CH3)3]2MnGe4S10 forms via the surfactant-templated assembly of adamantane Ge4S104- clusters and Mn2+ ions in water. The material possesses a continuous, fully bonded framework of MnGe4S10 which is perforated with large parallel tunnels arranged with hexagonal order. The materials bear a structural resemblance to MCM-41.

Design of tray tunnels for food deep chilling

A mathematical model for the semi-batch operation of tray tunnels for food deep chilling is presented and analyzed. Design aspects are discussed involving both single tunnels and systems of parallel tunnels. In both cases, optimum flowsheet configuration and operating conditions are sought and verified by appropriate formulation of design and optimization strategies. The optimization objective is the total annual cost of the plant, subject to constraints imposed by the operation of the chilling tunnel, thermodynamics and construction. The decision variables were the number of trucks, the operating temperature and flowrate of the cooling air stream, the refrigeration cycle heat exchanger temperature, as well as the total number of sections involved. The Mixed-Integer Non-Linear Programming (MINLP) nature of the design problem required mathematical programming techniques for its solution. The optimization was carried out for a wide range of production capacities, and the optimal points, where a new truck or a new section is introduced, were evaluated. The analysis focused on the design of tray tunnels for the most popular food product treated by deep chilling – meat slabs. A characteristic case study is presented in order to demonstrate the effectiveness of the proposed approach.

K4Ni7(AsO4)6

The title compound, tetrapotassium heptanickel hexaarsenate, has a three-dimensional open anionic framework built up from As04 tetrahedra and NiO 6 octahedra sharing corners and edges. They delimit parallel tunnels, running along the a direction, where the K + ions reside. This centrosymmetric framework appears to be similar to that of Na 4 Ni 7 (PO 4 ) 6 which is claimed to be non-centrosymmetric.

Ln2Al3Si2 (Ln=Ho, Er, Tm): New Silicides from Molten Aluminum—Determination of the Al/Si Distribution with Neutron Crystallography and Metamagnetic Transitions

Highly metallic compounds with a quasi-one-dimensional structure, the new ternary compounds Ln2 Al3 Si2 (Ln=Ho, Er, Tm) are synthesized in molten aluminum from lanthanoid and silicon as reagents. Their structures show a formally [Al3 Si2 ]6- framework that contains infinite Al zigzag chains and Si-Si dimers and accommodates rows of Ln3+ ions in parallel tunnels. The compounds exhibit metamagnetic transitions at high magnetic fields.

Study of ground-tunnel interactions of four shield tunnels driven in close proximity, in relation to design and construction of parallel shield tunnels

In Japan, K yoto City has constructed four subway tunnels that run closely each other. Problems accompanying the closely running tunnels are studied during the planning and design stages prior to construction. A variety of monitoring during the construction stage resulted in the collection of numerous data including the load transmission between tunnels and characteristic behavior of theground during the construction of four tunnels. Aiming at improving the method for the evaluation of the interaction of closely running tunnels, this study attempted to analyze and assess the behavior of the tunnels and the surrounding ground through such data obtained from the above project. This paper describes the characteristics of influence from the thrust of a succeeding tunnel to a preceding tunnel and the analytical expression of the mechanism of ground behavior during the construction of closely running tunnels.

Comparison of vertical and horizontal deposition hole concept for disposal of radioactive waste based on rock mechanical in situ stress-strength analyses

In Finland, a spent fuel repository is being planned in hard, crystalline rock to the depth of 300–800 m. The repository will consist of parallel deposition tunnels which are interconnected by a central tunnel. The spent fuel canisters will be placed in holes drilled according to the tunnel floor—vertical deposition hole concept or in the tunnel wall-horizontal deposition hole concept. Based on the numerical stress-strength analyses, both concepts are found to be feasible. However, when the maximum horizontal stress is perpendicular to the axis of the deposition hole, the rock in the vicinity of the horizontal deposition hole seems to have more stable behavior than in the case of the vertical deposition hole.

Reply by the Author to M. Mokry

I like to thank Dr. Mokry for his insightful contribution to the discussion of residual drag correction, particularly his description of the flow physics. The assumption in his analysis of stagnant flow within the model/wake body retains the essential features yet avoids treating the source singularity and its added mass flow. However, Mokry's assertion that the residual drag of Eq. (6) does not include drag due to gradient effects at the model deserves reply. His definition of a control volume using far upstream and far downstream planes, together with parallel tunnel walls, implicitly

Computational investigation of host–guest chiral recognition in incommensurate 2-bromoalkane/urea inclusion compounds

In conventional urea inclusion compounds, the urea molecules form a crystalline solid host structure (space group P6122 or P6522) within which there are linear, parallel tunnels. The walls of these tunnels are formed by a spiral arrangement of urea molecules; appropriate guest molecules may be located within these tunnels. In order to investigate the extent and nature of the chiral recognition between the chiral urea tunnel structure and chiral guest molecules, computational investigations of host–guest interaction in 2-bromoalkane/urea inclusion compounds have been carried out. As the 2-bromoalkane/urea inclusion compounds have an incommensurate relationship between the periodicities of the host and guest structures along the tunnel axis, it is important to consider the way in which the chiral recognition varies as a function of the position of the 2-bromoalkane guest molecule along the tunnel. All 2-bromoalkanes from 2-bromoheptane to 2-bromohexadecane were studied; in each case, four different ‘types’ of 2-bromoalkane guest molecule were considered, representing the R and S enantiomers, both for the conformation with the Br atom trans (CH3 group gauche) and for the conformation with the Br atom gauche (CH3 group trans).

Subsurface imaging with broadband electromagnetic induction

Diffraction tomography (DT) is a quantitative technique for high-resolution subsurface imaging. In general, DT algorithms are used for subsurface imaging with propagating waves. In this study an imaging algorithm is developed and tested for use with broadband electromagnetic induction for a so-called `multimonostatic' measurement geometry; a primary and secondary coil are coincident and move in unison over a uniformly spaced grid, on or above the ground surface. The algorithm is formulated in three dimensions and tested on simulated data for inhomogeneities that are both two and three dimensional. The algorithm is also applied, in two dimensions, to data acquired over a pair of parallel tunnels. One important finding is that good images can be reconstructed when the frequency band is limited to the case where all skin depths are greater than the depth of inhomogeneities.

Groundwater Management in Central Berlin

The Spreebogen area in central Berlin is the site of a large and complex tunnelling project that calls for three parallel tunnels to serve long distance trains, a subway line and a roadway. The tunnels for the long distance and subway rail lines are shield tunnels, while the road tunnel is being built by the open-pit technique. Extensive environmental impact studies were conducted for this large project to assess the existing situation and forecast the impact of construction on the surface water and groundwater. The Tiergarten Park, with its groundwater-dependent vegetation has been given particular attention in these studies.

An investigation of deformational behaviours and stresses in a central wall of parallel tunnels

An investigation of deformational behaviours and stresses in a central wall of parallel tunnels

Lord Rayleigh revisited: Can vortices in tubes be sources of noise?

Energy can flow through tubes filled with air governed by the laws of fluid dynamics, even in the violent form of shock waves. Energy also can flow through such systems as oscillations of small amplitude, which are governed by the equations of linear acoustics. What happens in the regime between? Calculations performed upon complaint of excessive low-frequency noise during alternate blasting for two long parallel railway tunnels indicated that particle velocities were a substantial fraction of the speed of sound at the tunnels’ mouths—between the regimes of shock waves and linear resonances. A Strouhal calculation suggested that vortices were the likely source: A sequence of counter-rotating vortices was being propelled out of the tunnels’ mouths, generating a powerful monopole source at 12 Hz. Modern noise consultants were baffled, but Lord Rayleigh had solved the system a century before, as a compound nonlinear eigenvalue problem, necessarily taking viscosity into account. The blasting engineers drove small cross-bores between the tunnels, sucking circulating fluid out of the vortices, reducing power, and quieting neighbors. The experiment should be repeated at a smaller scale with better instruments under controlled conditions.

Fault spacing in the El Teniente Mine, central Chile: Evidence for nonfractal fault geometry

We utilize the excellent rock exposure provided by the network of mining tunnels in El Teniente Mine, Central Chile, to test the applicability of fractal fault spacing laws to a ∼2 km × 3 km × 1.3 km body of crystalline rock in an Andean shear zone. Fractal spacing laws can be particularly useful because they allow prediction of fault spacing at unsampled scales. Because of the restrictions of tunnel geometry in the mine we use only “scanline”, one‐dimensional, analyses. The large number of parallel tunnels allows us to assess the consistency of one‐dimensional scanline samples over a two‐dimensional area. We use two methods: 1) an interval counting technique and 2) standard cumulative statistics to test the hypothesis of fractal fault geometry in the shear zone. The interval counting method produces deceptively good fits to a fractal distribution. In fact, by analyzing the residuals and differential slopes of interval counting and cumulative statistical plots and by comparison with synthetic fractal, negative exponential, and log‐normal distribution data, we conclude that a negative exponential distribution best describes fault spatial distribution at the mine. We present three possible explanations for the negative exponential spacing distribution: 1) the rock body is at the earliest stage in a deformational path that will produce varying spacing distributions as deformation proceeds, 2) the spacing distribution is inherited through joint reactivation, and 3) the present spacing distribution is the result of a superposition of two spacing distributions each of which is not necessarily negative exponential. Additionally, we attempt to use the deviation of mean spacings in parallel scanlines (after Wu and Pollard (1995)) to further classify deformational maturity. We show that this method cannot be used to compare population development in faults which follow a negative exponential spacing distribution because of the negative exponential's equivalence of mean and standard deviation. Instead we use a relative measure of parallel scanline deviation to compare regions. The distinctly smaller standard deviation of mean spacings in one region (the T3 Isla region) may be a signature of increased local finite strain accumulation.

High-Pressure Synthesis and Structure of the New Spinel-Related Series LnCu2O4 (Ln = Nd, Gd, Er, Lu, Y)

The new spinel-related series LnCu{sub 2}O{sub 4} (Ln = Nd, Gd, Er, Lu, Y) has been prepared at pressures of 40-100 kbar using a multianvil apparatus. The structure of these phases was determined for the case of NdCu{sub 2}O{sub 4} by Rietveld profile analysis of X-ray powder diffraction data. NdCu{sub 2}O{sub 4} is monoclinic, I2/a, a = 5.822(2) {angstrom}, b = 9.695(3) {angstrom}, c = 5.748(2) {angstrom}, {beta} = 92.34-(2){degrees}, and Z = 4. The NdCu{sub 2}O{sub 4} structure can be derived from that of spinel, as the cations in both have the Cu{sub 2}Mg-type arrangement. However, the metal coordination by oxygen in NdCu{sub 2}O{sub 4} is unlike that in spinel, consisting of NdO{sub 8} polyhedra and square-coplanar CuO{sub 4}. The structure is comprised of Cu{sup II}O{sub 4} chains along (100) and Cu{sup III}O{sub 4} chains along (001). These are linked perpendicularly through the corners of CuO{sub 4} square planes, leading to an array of parallel pseudotetragonal tunnels in which the Nd cations reside. Superconductivity was not observed in any of the new LnCu{sub 2}O{sub 4} phases to 4 K. 14 refs., 3 figs., 5 tabs.

An estimation of ground settlement due to shield tunnelling by the Peck–Fujita method

In this paper, an empirical method based on Peck and Fujita's study is proposed to estimate the magnitude and extent of surface settlement associated with shield tunnelling. It is found that the ground-settlement curves calculated with the proposed method for various types of shields, ground conditions, tunnel diameters, and depths are in reasonably good agreement with field measurements. For open shields tunnelled through clayey soils, the stability ratio has a significant influence on the surface settlement induced. Field measurement data suggest that the Peck–Fujita method may be used to estimate the ground subsidence associated with the construction of parallel tunnels. Key words : empirical method, field measurement, settlement, soft ground, tunnelling.

Dynamic properties of the urea molecules in α,ω-dibromoalkane/urea inclusion compounds investigated by2H NMR spectroscopy

2 H NMR spectroscopy has been used to investigate the dynamic properties of the urea molecules in Br(CH2)nBr/[2H4]urea inclusion compounds (n= 7–10) and in pure crystalline [2H4]urea. In the Br(CH2)nBr/urea inclusion compounds, the urea molecules form an extensively hydrogen-bonded host structure, which contains linear, parallel tunnels within which the Br(CH2)nBr guest molecules are located. The urea molecules undergo a two-site 180° jump motion about their CO axes, on the 2H NMR timescale, at temperatures greater than ca. 200 K for the Br(CH2)nBr/[2H4]urea inclusion compounds and at temperatures greater than ca. 300 K for pure crystalline [2H4]urea. Quantitative details relating to the dynamic properties of the urea molecules in these solids are presented.

EXAFS spectroscopic studies of the bromine environment in the crystalline inclusion compounds formed between urea and α,ω-dibromoalkanes

EXAFS spectroscopy of the bromine K-edge has been used to investigate local structural properties of urea inclusion compounds containing α,ω-dibromoalkane ‘guest’ molecules [Br(CH2)nBr; n= 6–11]. In these inclusion compounds, the α,ω-dibromoalkane molecules are included within a urea ‘host’ substructure containing linear, parallel tunnels. For the inclusion compounds containing Br(CH2)nBr ‘guest’ molecules with n= 7–11, the host substructure is that of the conventional urea inclusion compounds, whereas the inclusion compound containing Br(CH2)6Br as the guest has a different host substructure.The principal aim of these studies was to determine the Br⋯Br distance between adjacent guest molecules in the urea tunnel. For the inclusion compounds containing Br(CH2)nBr molecules with n= 7–11, however, an accurate determination of the Br⋯Br distance has not been possible from data collected at room temperature and at 77 K (this was also found for data collected at 9 K for 1,10-dibromodecane/urea), probably because of dynamic disorder at high temperature and static positional disorder at low temperature. On the other hand, backscattering from the first three intramolecular carbon neighbours on the Br(CH2)nBr molecule is detected in the Br EXAFS, and structural parameters for these neighbours have been determined. In these inclusion compounds, the periodicities of the host and guest substructures along the tunnel axis are incommensurate, and therefore each guest molecule within a given tunnel is in a different environment with respect to the host substructure. As a consequence, no well defined features in the Br EXAFS spectra arising from backscattering by atoms in the host substructure are expected or observed.In the 1,6-dibromohexane/urea inclusion compound, the guest substructure is commensurate with the host substructure. The Br K-edge EXAFS results for 1,6-dibromohexane/urea are consistent with known structural features of this inclusion compound.

Interactions between directional and visual environmental cues in spatial learning by rats

In these experiments, we examined movement organization during spatial learning in modular mazes made of transparent Plexiglas tunnels. The orientation of adjacent tunnels provided the main direction cues, while the access to visual environmental cues was controlled by the position of a large partition. The first series of experiments was conducted in a modified eight-arm radial maze with two parallel and six radial arms. An important neglect of one of the parallel tunnels was completely prevented when these arms were separated by a partition. Removing this screen during training induced a slow development of the neglect. In a second series of experiments, spontaneous alternation behavior (SAB) was tested in asymmetrical three-arm mazes in which the two goal arms were always 45° apart. Various configurations were designed in which the angle between the start arm and the nearest goal arm varied between 0 and 135°. In these mazes, SAB was reduced by an important neglect of the nearest goal arm, which was an inverse function of the angle between the start arm and the pair of goal arms, i.e., maximum for 0° and minimum for 135°. This bias was significantly decreased when a curtain separated the start arm from the nearest arm, restoring significant SAB. These results confirm and extend previous findings that the observed neglect is a direct consequence of movement rules which favor large angle transitions during an exploratory phase.

MODEL VIBRATION TESTS AND NUMERICAL ANALYSIS ON THE UNDERWATER EMBANKMENT LAYING PARALLEL TUNNELS WITH THE SAME LARGE CROSS SECTION

MODEL VIBRATION TESTS AND NUMERICAL ANALYSIS ON THE UNDERWATER EMBANKMENT LAYING PARALLEL TUNNELS WITH THE SAME LARGE CROSS SECTION

Intrahippocampal cholinergic grafts in aged rats compensate impairments in a radial maze and in a place learning task

Age-related cognitive impairments were studied in rats kept in semi-enriched conditions during their whole life, and tested during ontogeny and adult life in various classical spatial tasks. In addition, the effect of intrahippocampal grafts of fetal septal-diagonal band tissue, rich in cholinergic neurons, was studied in some of these subjects. The rats received bilateral cell suspensions when aged 23-24 months. Starting 4 weeks after grafting, they were trained during 5 weeks in an 8-arm maze made of connected plexiglass tunnels. No age-related impairment was detected during the first eight trials, when the maze shape was that of a classical radial maze in which the rats had already been trained when young. The older rats were impaired when the task was made more difficult by rendering two arms parallel to each other. They developed an important neglect of one of the parallel tunnels resulting in a high amount of errors before completion of the task. In addition, the old rats developed a systematic response pattern of visits to adjacent arms in a sequence, which was not observed in the younger subjects. None of these behaviours were observed in the old rats with a septal transplant. Sixteen weeks after grafting, another experiment was conducted in a homing hole board task. Rats were allowed to escape from a large circular arena through one hole out of many, and to reach home via a flexible tube under the table. The escape hole was at a fixed position according to distant room cues, and olfactory cues were made irrelevant by rotating the table between the trials. An additional cue was placed on the escape position. No age-related difference in escape was observed during training. During a probe trial with no hole connected and no proximal cue present, the old untreated rats were less clearly focussed on the training sector than were either the younger or the grafted old subjects. Taken together, these experiments indicate that enriched housing conditions and spatial training during adult life do not protect against all age-related deterioration in spatial ability. However, it might be that the considerable improvement observed in the grafted subjects results from an interaction between the graft treatment and the housing conditions.