Single Tunnel Research Articles

Estimation of surface crack dimensional characteristics by an eddy current method using a single magnetic tunnel junction device

Eddy current testing plays a significant role in detecting surface defects in a nondestructive testing field. The magnetoresistive sensors based on magnetic tunnel junction devices attracted considerable attention for their use in eddy current testing owing to their high sensitivity and capability of being miniaturized. We investigated the detection of surface cracks in eddy current testing using a single magnetic tunnel junction. A perpendicular component with a secondary magnetic field from an eddy current was measured by using an optimized rectangular magnetic tunnel junction device with an aspect ratio of 4 (20 × 80 µm2). Furthermore, according to the extracted ΔX and ΔV from the sensor output signal, surface cracks with various widths (0.1, 0.3, and 0.5 mm) and depths (0.5, 1.0, 1.5, and 3.0 mm) in aluminum specimens were successfully estimated using the magnetic tunnel junction device in eddy current testing when an excitation frequency of 1000 Hz was used.

Analysis and optimization of mutual influence of single channel tunnel construction blasting

In the current urban rail transit project in the vigorous development of the community, due to the needs of the site environment or line selection, it has been a common phenomenon in the actual construction of the tunnel encountered in the parallel operation and tunnel overlap situation, the new tunnel or tunnel group on the existing tunnel or other structure of the interaction problem has become very prominent! Based on the blasting excavation of the single-channel caverns in the first phase of the Chongqing Rail Transit Line 10 project, this paper makes a detailed investigation of the actual engineering, and uses ANSYS/LS-DYNA to simulate to comparative analysis and optimization the tunnel lining.

The forewing of the Aphis fabae (Scopoli 1763) (Hemiptera, Sternorrhyncha): a morphological and histological study

Dorsal and ventral sides of the forewing of Aphis fabae (Scopoli 1763) (Sternorrhyncha, Hemiptera) were examined by scanning electron microscopy. Reinforcement elements on their surface as well as scale-like elements were described. Using histological methods, cross-sections of the material were done. They showed a two-layered membrane with a circular foramen inside. The course of veins and places of their bifurcation were followed. Common stem of radius (R), media (M), and cubitus anterior (CuA) veins were composed of separate tracheae, which ran separately at the beginning, then continued in a single tunnel, and finally disappeared. Nerves were not observed. Neither were tracheae visible on the further course of those veins. The presence of a devoid-of-trachea costal vein was confirmed. Under scanning electron microscope, convex reinforcements on dorsal side of the wing turned out to be more sclerotized parts of chitin, not giving a zigzag-like profile of the wing on sections. In this paper, we show for the first time a cross-section of a very delicate wing of an aphid representative.

Combined Anatomic Reconstruction of the Anterior Cruciate and Anterolateral Ligaments Using Hamstring Graft Through a Single Femoral Tunnel and With a Single Femoral Fixation

Patients with complete anterior cruciate ligament (ACL) injury have different degrees of rotational (internal rotation) laxity. A residual pivot shift has been found to be positive in more than 15% of cases after an accurate ACL reconstruction. Improved understanding of the existence, function, and biomechanical role of the anterolateral ligament (ALL) in controlling rotational instability of the knee has redirected and refocused attention on a supplemental extra-articular reconstruction of the ALL in conjunction with the intra-articular ACL reconstruction so as to restore normal kinematics of the knee. This Technical Note describes a technique that allows for a combined ACL and ALL reconstruction using autogenous hamstring graft (semitendinosus and gracilis tendons). One femoral tunnel is used connecting the anatomic femoral attachment of the ALL on the lateral wall of the lateral femoral condyle to the anatomic femoral ACL footprint on the medial wall of the lateral femoral condyle. The remaining part of the graft is fixed to the proximal tibia midway between Gordy's tubercle and the head of the fibula. This Technical Note describes a technique of both ACL and ALL reconstruction with a continuous hamstring graft.

Dual delta tunnel FET: An energy efficient switch with improved current switching ratio and steeper subthreshold slope

In this paper, a single gate tunnel FET has been designed with two delta layers in both the source and channel regions. The width, position and doping concentration of both the delta regions are optimized to maximize the current switching ratio. The simulation work of the present DD-TFET device has been carried out by 2-D TCAD device simulator from Synopsys and the results are compared with the results of source delta doped TFET (SD-TFET), channel delta doped TFET (CD-TFET) and conventional TFET. The proposed device exhibits its superiority over other designs in terms of ON-state current, current switching ratio and subthreshold swing. Thus DD-TFET can be used as an energy efficient switch and has the potential to replace MOSFETs in high-speed and low-power applications.

Change in PM10 Concentration by Train Operation in a Single Tunnel Section

Daily operation of urban railways is a major source of large particles affecting PM10 concentration in underground tunnel environments. In this study, temporal variation of PM10 and PM2.5 concentrations were measured using a DustTrak DRX aerosol monitor at the shelter located between adjacent stations on Seoul Metropolitan Railway Line 5. A one-way single tunnel section was chosen to isolate effect of train operation in opposite direction. The monitoring location was about 570 m away from the starting station, where trains traveled at the constant speed. Time-series PM10 and PM2.5 concentrations were categorized by four time periods such as no operation, morning rush-hour, midday, and evening rush-hour periods for both summer and winter. It was found that the train passing caused to increase both PM10 and PM2.5 concentrations shortly. As a result, both PM10 and PM2.5 concentrations were increased steadily during the morning and evening rush-hour periods, on the other hand they remained constantly during the midday period due to the difference in train operation interval.

Combined All-Inside Anterior Cruciate Ligament Reconstruction and Minimally Invasive Posterolateral Corner Reconstruction Using Ipsilateral Semitendinosus and Gracilis Autograft

The anterior cruciate ligament (ACL) is the most commonly injured knee ligament, particularly among adolescents and young adults. Unrecognized posterolateral laxity is understood as a major cause of ACL reconstruction failure, and concomitant injury to the posterolateral corner (PLC) is prevalent and underdetected. We advocate screening all ACL-deficient knees for PLC injury and present a technique combining minimally invasive PLC reconstruction with anatomic all-inside ACL reconstruction. The combined procedure uses only the ipsilateral hamstring tendons representing a major surgical advantage over traditional management approaches. The semitendinosus is quadrupled and attached to 2 adjustable suspensory cortical fixation devices to form the ACL graft. The gracilis tendon is looped through the fibula head and secured in a single femoral tunnel for the PLC reconstruction via 2 minimally invasive incisions. The use of a single femoral PLC tunnel combined with a single femoral ACL socket minimizes the risk of tunnel convergence.

Outcomes and Complications After All-Epiphyseal Anterior Cruciate Ligament Reconstruction in Skeletally Immature Patients.

Background:The safest and most effective technique for anterior cruciate ligament (ACL) reconstruction in skeletally immature patients is currently unknown.Purpose:To evaluate the functional and patient-reported outcomes of a specific all-epiphyseal ACL reconstruction technique in which the graft, bone tunnels, and fixation do not cross the knee growth plates.Study Design:Case series; Level of evidence, 4.Methods:Twenty-seven patients (23 boys, 4 girls; mean age, 11 years; range, 8-15 years) underwent an all-epiphyseal ACL reconstruction with a single femoral transverse epiphyseal tunnel and primarily split tibial epiphyseal tunnels. Outcomes were evaluated in terms of the manual Lachman test, range of motion, pain, return to activity, angular or leg-length deformity on imaging, and International Knee Documentation Committee (IKDC) or Pedi-IKDC score an average of 3.8 years postoperatively, with a minimum 2-year follow-up.Results:The mean IKDC score was 94 ± 11. There were no growth arrests, but 3 patients had knee overgrowth, and 2 required a subsequent guided growth procedure. The ACL graft failed in 4 patients (15%), and 2 patients had contralateral ACL tears (7%). There were 5 subsequent ipsilateral meniscal tears, 4 of which were retears of a repaired meniscus. Ipsilateral knee reinjury significantly correlated with the number of associated injuries at the time of index surgery (P = .040) and the number of sports played (P = .029).Conclusion:All-epiphyseal ACL reconstruction resulted in excellent long-term functional outcomes, despite a high rate of complications (48%) and secondary procedures (37%) in this highly active cohort. The incidence of graft failure was similar to other standard ACL reconstruction techniques for patients younger than 20 years.

An evaluation of two traps and sets for trapping the plains pocket gopher

We investigated the efficiency of DK-1 and Macabee ® pocket gopher (Geomys bursarius) traps placed in lateral tunnels in both open and closed tunnel sets in rangeland and nonirrigated alfalfa fields in Nebraska. We observed no statistical difference between the traps in capture efficiency when used in open, versus closed, tunnel sets. Trapping of pocket gophers was more effective in rangeland (probability of capture in a single tunnel system using 3 traps; 63%) than nonirrigated alfalfa fields (26%). We did not determine whether this variance was due to behavioral differences between Geomys bursarius and Geomys lutescens. We found that trapping pocket gophers was species specific with only 1 nontarget animal harmed. We suggest modifications to the traps to improve gopher capture rate and lethality .

Synchronous Ipsilateral High Submuscular Placement of Prosthetic Balloons and Reservoirs

IntroductionSynchronous ipsilateral high submuscular placement of artificial urinary sphincter (AUS) pressure-regulating balloons (PRBs) and inflatable penile prosthesis (IPP) reservoirs in a single submuscular tunnel is a novel strategy that could be advantageous for patients who have had major pelvic surgery. AimTo report our initial experience with synchronous ipsilateral vs bilateral placement of AUS PRBs and IPP reservoirs in men undergoing implant surgery. MethodsWe retrospectively reviewed all patients undergoing synchronous AUS and IPP placement from 2007 through 2015 by a single surgeon at our tertiary center. Patients were stratified according to ipsilateral vs bilateral placement of the AUS PRB and IPP reservoir. Main Outcome MeasuresReoperation rates because of infectious or erosive complications and mechanical failure were assessed. ResultsOf the 968 implant surgeries during the study period, 47 men had synchronous device placement, of whom 17 (36%) underwent ipsilateral placement of the PRB and reservoir. During a median follow-up of 19 months (range = 1–84 months), reoperations were necessary in 12 of 47 (26%) and were similar between groups (ipsilateral, 5 of 17, 29%; bilateral, 7 of 30, 23%; P = .73). Most reoperations were due to AUS-related complications (10 of 12, 83%) and nearly all patients with reoperation (10 of 12, 83%) had compromised urethras (ie, prior urethral surgery, radiation, or prior AUS implantation). The most common indication for reintervention was cuff erosion (4 of 47, 9%), with no difference between groups (ipsilateral, 3 of 17, 18%; bilateral, 1 of 30, 3%; P = .13). ConclusionSynchronous ipsilateral high submuscular placement of urologic prosthetic balloons could safely facilitate prosthetic surgery in patients with a history of major pelvic and inguinal surgery.

Transport in a Single Self-Doped Nanocrystal.

Addressing the optical properties of a single nanoparticle in the infrared is particularly challenging, thus alternative methods for characterizing the conductance spectrum of nanoparticles in this spectral range need to be developed. Here we describe an efficient method of fabricating single nanoparticle tunnel junctions on a chip circuit. We apply this method to narrow band gap nanoparticles of HgSe, which band structure combines the inverted character of the bulk semimetal with quantum confinement and self-doping. Upon tuning the gate bias, measurement reveals the presence of two energy gaps in the spectrum. The wider gap results from the interband gap, while the narrower gap results from intraband transitions. The observation of the latter near zero gate voltage confirms the doped character of the nanoparticle at the single particle level, which is in full agreement with the ensemble optical and transport measurements. Finally we probe the phototransport within a single quantum dot and demonstrate a large photogain mechanism resulting from photogating.

Patellar complications in single versus double tunnel medial patellofemoral ligament reconstruction

Hamstring graft fixation on the patellar side during medial patellofemoral ligament (MPFL) reconstruction is usually with transosseous tunnels and can frequently lead to further problems. The aim of our study was to compare and analyse patellar complications in single patellar tunnel versus double tunnel hamstring graft fixation. Twenty-nine knees with MPFL reconstructions (group S) in which the hamstring tendon graft was transfixed using a suspensory fixation method in a single tunnel drilled across the patella were analysed in comparison with 29 knees (group D) with interference fixation of the graft through two tunnels drilled up to a predetermined depth in the patella. Primary outcome measured was any patellar complication like anterior knee pain and patella fracture. Secondary outcomes assessed were future functional instability and failure of reconstruction. Anterior knee pain was noted in six patients in group S, of which three patients had removal of the irritating metalwork on the patella. In all, nine surgical interventions were needed in six patients in this group. Three patients in group D complained of knee pain, but no one in this group needed any further surgical interventions ( p value 0.02). Symptomatic instability requiring revision surgery or realignment surgery was required in two patients in the group S and none in group D. No patellar fractures were seen in either group. Our study showed increasing problems with single tunnel patellar fixation, with more reoperation and failure rates compared to double tunnel fixation. The evidence supports the move towards anatomical double bundle MPFL reconstructions.

Theory of Spin Torque Switching Current for the Double Magnetic Tunnel Junction

A single-domain model for spin-transfer torque switching of double magnetic tunnel junctions with perpendicularly magnetized layers is developed. An analytical formula is derived for the switching current threshold, I c0 . Surprisingly, the model predicts that the switching current can be reduced by a factor of 10 compared to single magnetic tunnel junctions, for sufficiently large spin-polarizations. This effect is explained in terms of the “enhanced antiparallel-to-parallel” spin torque, familiar from single magnetic tunnel junctions.

Semianalytical Solution and Parameters Sensitivity Analysis of Shallow Shield Tunneling-Induced Ground Settlement

The influence of boundary soil properties on tunneling-induced ground settlement is generally not considered in current analytic solutions, and the hypothesis of equal initial stress in vertical and horizontal makes the application of the above solutions limited. Based on the homogeneous half-plane hypothesis, by defining the boundary condition according to the ground loss pattern in shallow tunnel, and with the use of Mohr-Coulomb plastic yielding criteria and classic Lame and Kiersch elastic equations by separating the nonuniform stress field to uniform and single-direction stress field, a semiempirical solution for ground settlement induced by single shallow circular tunnel is presented and sensitivity to the ground parameters is analyzed. The methods of settlement control are offered by influence factors analysis of semiempirical solution. A case study in Beijing Metro tunnel shows that the semiempirical solution agrees well with the in situ measured results.

Arthroscopic trans-osseous rotator cuff repair.

Mechanical factors are at the basis of any tendon healing process, being pressure an aspect able to positively influence it. For this reason transosseous rotator cuff repair represents the gold standard procedure for patients affected by a cuff tear, maximizing the tendon footprint contact area and reducing motion at the tendon to bone interface. The Authors present an all arthroscopic suture bridge-like transosseous repair with the preparation of a single transosseous tunnel perfor med thanks to a precise dedicated instrument (Compasso®) and one implant (Elite-SPK®) with the use of only 3 suture wires. In addition this technique permits to accurately prepare the bony side of the lesion without any risk or complication, such as anchor pull-out and greater tuberosity bone osteolysis. However, even if this technique seems less demanding, the arthroscopic transosseous repair is still an advanced procedure, and should be performed only by well prepared arthroscopic shoulder surgeons. V.

Ipsilateral hamstring tendon graft reconstruction for chronic patellar tendon ruptures: surgical technique.

Patellar tendon chronic ruptures are more debated to manage that acute injuries as the patella tends to retract proximally (after 2 weeks), and surrounding soft tissues may make the repair more complicate. We propose a novel technique in which the patellar tendon is reconstructed using ipsilateral hamstring tendons. This surgical procedure implies to drill a single tunnel through the patella and another through the tibia to reduce the risk of bony breakage. In addition, the tendon is secured to the bone, at the tunnel exit points, by periostium sutures without requiring any additional surgery for hardware removal. We assessed 19 patients (16 men and 3 women) who underwent PT reconstruction at an average of 5.8 years (range, 4 to 7.8 years, SD: 3.5) from the index surgery. The mean age at surgery was 46 ± 9.2 years (range, 38-59 years). All patients had a complete tear of the patellar tendon. The main indication for this procedure is the reconstruction of the PT in patients with chronic rupture (>6 weeks) in which the tendon gap is greater than 2 centimeters and the scar tissues and degenerated tendon ends do not allow to juxtapose the tendon stumps to each other. Level IV.

Model test to investigate failure mechanism and loading characteristics of shallow-bias tunnels with small clear distance

Based on the similarity theory, a tunnel excavation simulation testing system under typical unsymmetrical loading conditions was established. Using this system, the failure mechanism of surrounding rock of shallow-bias tunnels with small clear distance was analyzed along with the load characteristics. The results show that: 1) The failure process of surrounding rock of shallow-bias tunnels with small clear distance consists of structural and stratum deformation induced by tunnel excavation; Micro-fracture surfaces are formed in the tunnel surrounding rock and extend deep into the rock mass in a larger density; Tensile cracking occurs in shallow position on the deep-buried side, with shear slip in deep rock mass. In the meantime, rapid deformation and slip take place on the shallow-buried side until the surrounding rocks totally collapse. The production and development of micro-fracture surfaces in the tunnel surrounding rock and tensile cracking in the shallow position on the deep-buried side represent the key stages of failure. 2) The final failure mode is featured by an inverted conical fracture with tunnel arch as its top and the slope at tunnel entrance slope as its bottom. The range of failure on the deep-buried side is significantly larger than that on the shallow-buried side. Such difference becomes more prominent with the increasing bias angle. What distinguishes it from the "linear fracture surface" model is that the model proposed has a larger fracture angle on the two sides. Moreover, the bottom of the fracture is located at the springing line of tunnel arch. 3) The total vertical load increases with bias angle. Compared with the existing methods, the unsymmetrical loading effect in measurement is more prominent. At last, countermeasures are proposed according to the analysis results: during engineering process, 1) The surrounding rock mass on the deep-buried side should be reinforced apart from the tunnel surrounding rock for shallow-buried tunnels with small clear distance; moreover, the scope of consolidation should go beyond the midline of tunnel (along the direction of the top of slope) by 4 excavation spans of single tunnel. 2) It is necessary to modify the load value of shallow-bias tunnels with small clear distance.

Undrained stability of a single circular tunnel in spatially variable soil subjected to surcharge loading

The stability of tunnels is an important problem in geotechnical engineering. Most of the previous studies dealing with the stability of unlined tunnels are deterministic in nature and do not consider the soil spatial variability. This study investigates the influence of spatial variability on the undrained stability of an unlined circular tunnel, using Random Adaptive Finite Element Limit Analysis (RAFELA). The effect of spatial variability is investigated for tunnels having two different ratios of γD/cu, for different spatial correlation lengths and tunnel depths. The results indicate that the effect of spatial variability depends on γD/cu and the depth of the tunnel.

Real-space coherent manipulation of electrons in a single tunnel junction by single-cycle terahertz electric fields

Carrier-envelope-phase-controlled single-cycle terahertz pulses can induce coherent electron tunnelling either from a Pt/Ir nanotip to a graphite sample or vice versa. The pulses enable ultrafast nonlinear manipulation of electrons at the atomic scale. The ultrafast coherent manipulation of electrons using waveform-controlled laser pulses1,2,3,4,5,6,7,8,9 is a key issue in the development of modern electronics10,11. Developing such an approach for a tunnel junction will provide a new platform for governing ultrafast currents on an even smaller scale, which will be indispensable for the advancement of next-generation quantum nanocircuits12,13,14,15 and plasmonic devices16,17,18. Here, we demonstrate that carrier-envelope-phase-controlled single-cycle terahertz electric fields can coherently drive electron tunnelling either from a nanotip to a sample or vice versa. Spatially confined electric fields of more than 10 V nm–1 strongly modulate the potential barrier at a nanogap in a scanning tunnelling microscope (STM) on the subpicosecond timescale and can steer a large number of electrons in an extremely nonlinear regime, which is not possible using a conventional STM. Our results are expected to pave the way for the future development of nanoscale science and technologies.

Determination of tunnel support pressure under the pile tip using upper and lower bounds with a superimposed approach

This study aimed to develop upper and lower bounds to predict the tunnel support pressure under the pile tip during the circular tunnel excavation. Most previous studies on the upper and lower bound methods were carried out for the single ground structures, e.g., retaining wall, foundation, ground anchor and tunnel, in the homogeneous ground conditions, since the pile-soil-tunnel interaction problem is very complicated and sophisticated to solve using those bound methods. Therefore, in the lower bound approach two appropriate stress fields were proposed for single pile and tunnel respectively, and then they were superimposed. In addition, based on the superimposition several failure mechanisms were proposed for the upper bound solution. Finally, these upper bound mechanisms were examined by shear strain data from the laboratory model test and numerical analysis using finite element method.