Narrow Results

In 2D mesh Network on Chips (NoCs), fault-tolerant algorithms usually deactivate healthy nodes to form rectangular or convex fault blocks. However, the deactivated nodes can possibly form an available tunnel in a faulty block. We propose a method to discover these tunnels, and propose a fault-tolerant routing algorithm to route messages through such paths such that the overall communication performance is improved. In addition, the algorithm is deadlock-free by prohibiting some turns. Simulation results demonstrate that the reuse of the sacrificed nodes in fault blocks can significantly reduce the average message latency.

We show that any tunnel number one knot group has a two generator one relator presentation in which the relator is a palindrome in the generators. We use this fact to compute the character variety for this knot groups and we show that it is an affine algebraic set .

There are exactly four mutually non-isotopic unknotting tunnels τ_i, i = 1,2,3,4 for the pretzel knot P(-2,3,7). Moreover, there are at most 3 non-stabilized genus 3 Heegaard splittings.

We show that every tunnel number 1 genus 1 knot can be changed into a genus 3 fibered knot by a crossing change.

We report a novel method of debridement for penetrating trauma to the hand involving bone using a sterile hand drill. This provides a means for adequate clearance of debris which may otherwise be left in-situ due to poor access to the contaminants when conventional techniques of debridement are used.

A finite element approach is extended to study the ground vibrations induced by metro trains and their propagation properties. Two dynamic interaction models are established: the two-dimensional train-track interaction model, which provides the excitation loads of moving trains onto the tunnel structure, and the three-dimensional track-tunnel-ground interaction model, by which the propagation properties of ground accelerations and velocities are analyzed. The results show that there exists a vibration amplifying area in certain distance away from the tunnel center, and the dominant frequencies of the ground vibration concentrate in a certain range. Buildings located in that area with their natural frequencies falling in the specific frequency range will be sensitive to the ground vibrations induced by metro trains.

Presented herein is a computationally efficient 2D theoretical model for simulating the steady response of a floating slab track-tunnel-soil system. The track-tunnel coupled system is simplified as a beam-spring system and embedded in soil layers. The tunnel is modeled by a Timoshenko beam with its interaction with the soil layers accounted for by two transfer matrices, with each derived for the soil layer above and beneath the tunnel. The approach as proposed herein has been referred to as the Timoshenko beam-transfer matrix method (TTMM), that allows one to analyze the response of the coupled system, including the tunnel motion and soil stresses. The results obtained were compared with those furnished by the pipe-in-pipe (PIP) approach, and were found to be consistent for exciting frequencies smaller than the tunnel second-mode cut-on frequency. The origin of discrepancies was investigated by the dispersion characteristic analysis, which is attributed to the absence of several in-plane modes when the tunnel is simplified as a Timoshenko beam.

A layered rock mass is a special type of geological body. The existence of a bedding surface may lead to a poor cutting effect (over/under-excavation of the surrounding rock), falling of blocks, or collapse, thereby affecting most constructions in areas with such rocks. Given the lack of a proper quantitative analysis method for surrounding rock damages, the construction process of layered surrounding rock tunnels becomes difficult. To address these problems, three types of cut blasting models with single, double, and four holes are studied in this paper. With this, the LS-DYNA program is used to analyze the behaviors of stress wave propagation, crack propagation, and fracture modes, as well as fracture mechanisms of mudstone, sandstone, and layered rock. Using the image processing technology and fractal theory, the fractal dimension change trend and progressive damage evolution behavior of the three types of rocks under different cut blasting conditions are determined. Also determined is the corresponding relationship between the fractal dimension and the rock damage degree. The results indicate that crack initiation, propagation, bifurcation, and fractal dimension evolution are more closely related to the phenomenon where the compression wave is ahead of the tension wave, and the$\setminus$incompatible deformation of the bedding under single-hole blasting. Under double-hole and four-hole blasting, the phenomena, such as spalling, bedding crack penetration, and fracture connection between the explosive holes are caused mainly by the effects of stress concentration, reflected tension waves, and stress wave superposition. Moreover, under different blasting conditions, the rocks exhibit a similar progressive damage process, i.e. a rapid increase at first, then a slow rise, and finally a stabilization phase. The dynamic damage degree of the rock exhibits a linear increasing trend under different blasting holes. The study results provide a useful reference for blasting scheme design and optimization of underground engineering projects.

An analytical solution for consolidation around spherical cavity contraction is developed. This solution has the potential to evaluate consolidation around tunnel heads. The initial excess pore water pressure immediately after the creation of the cavity is estimated from the cavity expansion/contraction theory using a linear-elastic-perfectly-plastic soil model. Expressions for the decay of pore water pressure with time are obtained using elasticity. Curves showing the variation of pore water pressure with time are plotted in nondimensional form. Comparison with two-dimensional coupled stress-pore pressure finite element analysis shows that the proposed semi-analytical solution can successfully predict the poro-elasto-plastic behavior around spherical cavity.

Installing flexible layer is one kind of supporting techniques to deal with the large deformation in tunnels excavated in viscoelastic rocks. The role of flexible layer is to absorb rock deformation due to rock rheology. For further understanding the effect of flexible layer on mechanical behavior of tunnels, a three-layered model is established to study the mechanical behavior of tunnel where flexible layer is installed between surrounding rock and primary support. Visco-elastic analytical solutions for displacements and interaction forces in the rock/flexible layer interface and in the flexible layer/primary support interface are provided. Numerical calculation by use of finite element software Abaqus is carried out to verify the effectiveness and reliability of theoretical analysis. It could be found that flexible layer has a good ability to absorb rock deformation. Compared with rigid support structure, pressure and displacement of primary support in tunnels employing flexible layer could achieve a good improvement. This improvement is dramatically affected by the thickness and deformability of reserved flexible layer.

Dynamic response of road tunnels against internal explosions can vary depending on the types and cover depths of surrounding rock mass. However, the influences of cover depth and rock type on dynamic response of road tunnels under internal explosions are very less investigated. Based on the calibrated numerical model of road tunnel, the present study investigates the dynamic response of an arched road tunnel subjected to an internal Boiling Liquid Expansion Vapour Explosion (BLEVE) and its equivalent TNT explosion under varied cover depths and different rock types. The results indicate that the increment of the cover depth can reduce the lining response (e.g., strain energy and damage) against the internal BLEVE. However, beyond a certain cover depth, the TNT explosion-induced lining response (e.g., strain energy) escalates with the increased cover depth due to the enlarged rebound deformations of the lining with the increased in-situ stress. In addition, the rock mass with better mechanical properties is beneficial to reduce the tunnel response under the internal BLEVE but leads to more severe tunnel response under the internal TNT explosion. Using equivalent TNT explosion loads may not give reliable predictions of tunnel responses subjected to BLEVE loads.

The lining incorporating yielding elements has been proved to be the most effective solution for tunneling through severe squeezing ground. Unfortunately, there has not been a well-organized method to transfer its beneficial effects into the practical tunnel design. This study aims to provide an analytical model for predicting the behavior of yielding lining supported tunnel. The internal force analysis of the lining is first carried out to determine the optimal installation positions of the yielding elements. Second, the lining incorporating yielding elements is processed as a simplified shell using the equivalent deformation principle. The equation for calculating the elastic modulus of the simplified shell is presented. The analytical solutions for the tunnel displacement and lining pressure are provided in the viscoelastic Burgers rocks, where the installation delay of the lining and the tunnel face advancement effect are taken into account. The proposed analytical model is applied in the Saint Martin La Porte access adit of Lyon-Torino Base tunnel, where the yielding lining was employed. The analytical result provides a good prediction of the time-dependent tunnel convergences in the Saint Martin La Porte access adit. Finally, a comprehensive parametric investigation is performed, including the influences of installation time of yielding lining, yield stress and length of yielding elements. Some inspiring results for the tunnel design are provided.

The long-term stability of tunnel structures is significantly influenced by the time-dependent behavior of the surrounding rock. Existing constitutive models often deviated from surrounding deformation due to the anisotropic nature of rock mass. In response, this study introduces a novel reinforced learning fusion constitutive model to accurately capture the time-dependent behaviors of soft rock. The framework and methodologies are first outlined, followed by the instantiation of the constitutive model of Burgers and creep parameters using laboratory testing data. To enhance accuracy, an XGBoost model is trained to reinforce the results of the constitutive model. The reliability of the proposed model is then validated against the original constitutive model and other representative machine learning models. Experimental findings demonstrate the superior characterization ability and stability of the presented reinforced model, where the calculation error reduces by 7.2E−06 at least, and $R^2$ score is improved by at least 1% to others. Consequently, the proposed model is reliable, offering a promising approach to capturing the actual time-dependent behaviors of tunnel surroundings in practical field applications.

Tunnel–medium interaction problems are one of the important problems in engineering. Because it has a high risk in terms of reliability, tunnel structures should be modeled in detail. The modeling of tunnel structures under static and dynamical loads is a difficult problem in engineering because of consists of a lot of conditions and effects, such as heterogeneous medium, soil layers, porosity, soil–structure interaction, groundwater, earthquake, etc. In this paper, aims to investigate the tunnel–medium interaction problems for nonlinear static and dynamic analyses. This study includes nonlinear static and dynamic analyses for layered porous semi-infinite viscoelastic medium with twin tunnels. The constitutive property of each layer of medium is considered in bilinear stress–strain relation with uniform porosity and Kelvin–Voigt viscoelastic property. The considered study is solved via the finite element method within the two-dimensional (2D) model. Layered medium is modeled as finite and infinite elements. In the solution process, the incremental force method is implemented and, for each load step, finite element equations are solved according to the bilinear stress–strain relation. In nonlinear dynamic analysis, the dynamic loads are divided by a certain finite number and applied incrementally depending on the time-dependent load function. At each load step, the final displacement, velocity and acceleration of that load step, obtained as a result of applying the Newmark $\beta$ method procedure, are assigned as the starting value of the next load step according to the bilinear stress–strain relation. Influences of porosity and position of tunnels on the nonlinear static and dynamic deflections of the system are investigated. Also, differences between linear and nonlinear responses are compared and discussed.

Shaking table tests were conducted on typical models of subway structures subjected to several seismic shaking time histories to study seismic response of subway structures in soft ground as well as to provide data for validation of seismic design methods for underground structure. Three types of tests were presented herein, namely green field test, subway station test, and test for joint structure between subway station and tunnel. The similitude and modeling aspects of the 1g shaking table test are discussed. The seismic response of Shanghai clay in different depths was examined under different input waves to understand the acceleration amplification feature in both green field and in the presence of underground structure. Damage situation was checked on internal sections of both subway station and tunnels by halving the model structure. Structure deformation was investigated in terms of element strain under different earthquake loadings. The findings from this study provides useful pointers for future shaking table tests on underground structures/facilities, and the seismic response characteristic of underground structure derived from the shaking table test could be helpful for validating seismic design method for subway station.

Sodium-ion batteries (SIBs) are promising candidates for large-scale energy storage applications. High-performance cathode material with high-energy density and long cycle life is of great interest. Here, an F-doped Na_x${\text{MnO}}_{2-y}$F_y with layered-tunnel intergrowth structure is synthesized by a facile solid-state reaction method. The microstructure and composition of prepared material was confirmed by X-ray diffraction, field emission scanning electron microscope and transmission electron microscopy. The aim of the structure design is to combine the complementary features of high capacity from P2 phase and excellent structural stability from tunnel phase, as well as to improve rate performance by F doping. When investigated as high-rate and long-life cathode materials for Na-ion batteries, the layered-tunnel intergrowth structure exhibits synergistic effect including high discharge capacity (194.0mAh${\text{g}}^{-1}$), good rate capability (86mAh${\text{g}}^{-1}$ at 15 C) as well as good cycling stability (81.2% capacity retention after 100 cycles). The as-prepared layered-tunnel intergrowth Na_x${\text{MnO}}_{2-y}$F_y provides new insight into the development of intergrowth electrode materials and their application in rechargeable SIBs.

The anatomic variations of the median nerve and of the muscles of the wrist have been widely reported in literature. It is essential for the surgeon to be familiar with these variations in order to avoid accidental injury to the nerve during surgery. We report a rare case of bifid median nerve accompanied by an anomalous tendon of palmaris profundus discovered during the surgical release of carpal tunnel. The transverse carpal ligament was dissected and the anomalous tendon was left in situ because any direct compression over the median nerve was noticed intraoperatively. The patient was evaluated one year postoperatively clinically and radiologically (with MRI). At the follow up the resolution of symptoms was complete and the sleep disturbance was solved. The patient achieved a postoperative QuickDASH score of 9.1 and a Michigan Hand Questionnaire outcome score of 90 points.

Cubital tunnel syndrome is the second most common nerve compression syndrome seen in the upper limb. Paresthesia and weakness are the two most common presentations in the hand. If left untreated, compression can lead to irreversible nerve damage, resulting in a loss of function of the forearm and hand. Therefore, recognizing the various clinical presentations of cubital tunnel syndrome can lead to early detection and prevention of nerve damage. Conservative management is usually tried first and involves supporting the elbow using a splint. If this fails and symptoms do not improve, surgical management is indicated. There are 3 main surgical techniques used to relieve compression of the nerve. These are simple decompression, anterior transposition and medial epicondylectomy. Studies comparing the techniques have demonstrated particular advantages to using one or another. However, the overall technique of choice is based on both the clinical scenario and the surgeon’s digression. Following primary cubital tunnel surgery, recurrent symptoms can often occur due to a variety of pathological and non-pathological causes and revision surgery is usually warranted. This article provides a complete review of cubital tunnel syndrome.

One new similar materical for the expansive soil tunnel in model test is researched and defined which can simulate the most features of expansive soil during wetting and drying cycles. Then, the failure mechanism and deformation rules of expansive soil tunnel are investigated based on the new similar material. Through the research and development of new similar material, those are able to obtain that the new similar material is good at simulate the expansive soil and is able to use for model test to investigate the features of expansive soil tunnel subjected to wetting and drying cycles.