Lateral Gap Research Articles

Comparison of the Shielding Properties of Superconducting and Superconducting/Ferromagnetic Bi- and Multi-layer Systems

This paper compares the shielding properties of superconducting (SC) and superimposed superconducting/ferromagnetic (SC/FM) systems, consisting of cylindrical cups with an aspect ratio of height/radius close to unity. Both bilayer structures, with the SC cup placed inside the FM one, and multilayer structures, made up of two SC and two FM alternating cups, have been considered. Induction magnetic field values have been calculated by means of a finite element model based on the vector potential formulation, simultaneously taking into account the non-linear properties of both the SC and FM materials. The analysis highlights that at low applied fields, the presence of a height difference between the edges of the SC/FM cups, as well as a suitable choice of the lateral gap between the cups, is a key factor in obtaining hybrid structures with a shielding potential comparable to, or even higher than, that of the single SC cup. In contrast, at high applied fields, all the hybrid arrangements investigated always provide much greater shielding factors than the SC cup alone. The computation results show that at both low and high applied fields, the multilayer solutions are the hybrid shields with the highest efficiency.

Improvement of Lubrication Performance in External Gear Machines through Micro-surface Wedged Gears

ABSTRACTThis article demonstrates how a properly designed micro-surface linear wedge added to the lateral surfaces of the gear teeth can improve the lubricating ability of external gear machines (EGMs), resulting in lower power losses and chance of wear during their operation. The approach of study is based on the use of a fluid structure interaction (FSI) model for the analysis of the lateral lubricating gaps developed in the authors' research team. Such a model is used to determine the best design of the wedged gear by considering the overall axial balance problem of pressure compensated EGMs for high-pressure applications. The article shows the numerical predictions along with the experimental verifications of the advantages offered by the proposed solution in terms of torque loss reduction for a particular reference pump.

A new lattice hydrodynamic model considering the effects of bilateral gaps on vehicular traffic flow

This study proposes a new lattice hydrodynamic model considering the effects of bilateral gaps on a road without lane discipline. In particular, a lattice hydrodynamic model is proposed to capture the impacts from the lateral gaps of the right-side and left-side sites of the considered lattice sites. Linear stability analysis of the proposed model is performed using the perturbation method to obtain the stability condition. Nonlinear analysis of the proposed model is performed using the reductive perturbation method to derive the modified Korteweg–de Vries (mKdV) equation to characterize the density wave propagation. Results from numerical experiments illustrate that the smoothness and stability of the proposed model are improved compared with the model that considers the effect of unilateral gap. Also, the proposed model is able to more quickly dissipate the effect of perturbation occurring in the vehicular traffic flow.

Influence of Lateral-Impact Force on Electropermanent Magnet Suspension Conveyor With Inherent Guidance Force

This paper addresses the influence of lateral external force effects on the non-guidance force control of a hybrid-type electropermanent magnet suspension (EPMS) magnetic levitation (maglev) conveyor. The benefits of this maglev system are good ride comfort and frictionless and abrasion-free operation. However, it is possible for an unintended lateral force to generate lateral oscillation, and lateral displacement affects the levitation and guidance forces. These forces were calculated using a 3-D finite-element model, using the current, levitation air gap, and lateral displacement as inputs of the EPMS. To determine the influence of the lateral force effect, an experiment was conducted using an impact hammer to apply an impulse force at two points on the maglev. In one case, a lateral force was applied to the center of one side of a maglev conveyor. In this case, the external force affected the front and rear EPMSs equally. In the second case, a lateral force was applied to a corner of the maglev. In this case, the unbalanced external force affected the EPMSs unequally. The experimental results illustrate the effects of balanced and unbalanced external lateral forces on the lateral vibration, air gap, and input current.

Study of traffic flow characteristics using different vehicle-following models under mixed traffic conditions

To understand the congestion problem and the occurrence of bottlenecks and to formulate solutions for it, a thorough study of vehicle-to-vehicle interactions is necessary. Car-following models replicate the behavior of a driver following another vehicle. These models are widely used in the development of traffic simulation models, and in analysis of safety and capacity. In India, traffic on roads is mixed in nature with wide variations in physical dimensions and other vehicular and traffic characteristics with loose lane discipline. In mixed traffic conditions, leader-follower vehicle types are not only car–car cases but also there are different combinations of vehicles (e.g. car-two wheeler, two wheeler-auto rickshaw, and heavy vehicle-two wheeler). The present study focuses on evaluation of different vehicle-following models under mixed traffic conditions. The car-following models such as Gipps, Intelligent Driver Model (IDM), Krauss Model and Das and Asundi were selected for this study. These models were implemented in a microscopic traffic simulation model for a mid-block section. The performance of different vehicle-following models was evaluated based on different Measure of Effectiveness (MoE) using field data collected from a four-lane divided urban arterial road in Chennai city. Speed-concentration and flow-concentration relationships for different vehicle-following models were developed and analyzed for different compositions. Capacity is higher when the proportion of smaller size vehicles is higher, since these vehicles use longitudinal and lateral gaps effectively. The simulation model was also applied to evaluate a range of traffic control measures based on vehicle type and lane (Ex: exclusion of auto-rickshaws, heavy vehicles, auto-rickshaws + heavy vehicles, etc.). The results showed the promise of some measures based on vehicle class, namely, the exclusion of auto rickshaws or auto rickshaws and heavy vehicles. The findings have interesting implications for capacity and PCU estimation and Level of Service (LoS) Analysis.

A Unified Epi-Seal Process for Fabrication of High-Stability Microelectromechanical Devices

This paper presents a thin-film wafer-level encapsulation process based on an epitaxial deposition seal that incorporates both narrow and wide lateral transduction gaps (0.7–50 $\mu \text{m}$ ), both in-plane and out-of-plane electrodes, and does not require release etch-holes in the device layer. Resonant structures fabricated in this process demonstrate high-quality factors ( $f\times Q$ products of up to $2.27e+13$ Hz) and exceptional stability (±18 ppb over one month) with no obvious aging trends. Studies on cavity pressure indicate that vacuum levels better than 0.1 Pa can be achieved after final encapsulation, thus reducing gas damping for high surface-to-volume devices. The vast diversity of functioning devices built in this process demonstrates the potential for combinations of high-performance MEMS devices in a single process and/or single chip. [2015-0278]

Giant photoluminescence enhancement in tungsten-diselenide-gold plasmonic hybrid structures.

Impressive properties arise from the atomically thin nature of transition metal dichalcogenide two-dimensional materials. However, being atomically thin limits their optical absorption or emission. Hence, enhancing their photoluminescence by plasmonic nanostructures is critical for integrating these materials in optoelectronic and photonic devices. Typical photoluminescence enhancement from transition metal dichalcogenides is 100-fold, with recent enhancement of 1,000-fold achieved by simultaneously enhancing absorption, emission and directionality of the system. By suspending WSe2 flakes onto sub-20-nm-wide trenches in gold substrate, we report a giant photoluminescence enhancement of ∼20,000-fold. It is attributed to an enhanced absorption of the pump laser due to the lateral gap plasmons confined in the trenches and the enhanced Purcell factor by the plasmonic nanostructure. This work demonstrates the feasibility of giant photoluminescence enhancement in WSe2 with judiciously designed plasmonic nanostructures and paves a way towards the implementation of plasmon-enhanced transition metal dichalcogenide photodetectors, sensors and emitters.

Do Well-Balanced Primary TKA Patients Achieve Better Outcomes Within the First Year After Surgery?

Some surgically modifiable factors are related to soft tissue balance. With computer-assisted surgery, it is possible to access these variables quantitatively. The aim of this analysis was to study the influence of gap balance on clinical outcomes within the first year after computer-navigated total knee arthroplasty (TKA). Based on navigation data, 3 independent variables reflecting gap balance were used to split the patients in 2 groups. The Knee Society Scores (Function [KSS-F] and Knee [KSS-K]) and the maximal knee flexion (MKF) measured preoperatively and at 3, 6 and 12 months were compared using analyses of variance (2×4 design) for repeated measures. Higher flexion-extension gap equality led to statistically higher KSS-F and KSS-K scores at 1 year (P=.02). Higher medial-lateral flexion gap equality led to superior mean MKF at all measurement points; however the differences were statistically only significant at 3 months (P=.01). The coefficients of variation of the variables used to select the patients were overall very low. With computer-assisted navigation, it is possible to access quantitatively the size of the medial and lateral flexion and extension gaps. Higher flexion-extension gap equality values led to statistically significant better KSS-F and KSS-K scores at 1 year. Higher medial-lateral flexion gap equality values led to better MKF values; however the differences were only statistically significant at 3 months. [Orthopedics. 2016; 39(3):S6-S12.].

자기부상열차의 부상안정성을 고려한 3방향 분기기의 설계 파라미터 연구

분기기 거더 경량화는 제작비 감소 및 제작의 용이함을 위해 필수적이다. 자기부상열차용 3방향 분기기 경량화를 위한 설계변수는 부상안정성과 관련 있기 때문에 신중히 결정되어야 한다. 도시형 자기부상열차는 대차가 레일을 감싸는 구조로 되어 있기 때문에 거더 높이 변경을 통해서 경량화가 가능하다. 실제 테스트베드에서 반복 주행시험을 통해 안정성을 확보해야 하지만 공간적, 비용적 제한에 의해 여러 거더 높이의 테스트베드 제작은 불가능하며 이를 보완하기 위한 설계 파라미터 연구는 필수적이다. 본 논문에서는 자기부상열차 주행 시 3방향 분기기 경량화에 따른 부상안정성을 고려한 설계 파라미터 연구에 그 목적이 있다. 이를 위해 분기기 거더 높이 변경을 통해 경량화하였고 모달 중첩법을 이용하여 유연체로 모델링 하였다. 유연체 분기기와 자기부상열차 동역학 모델과의 연동해석을 통해 차량의 통과속도, 횡 공극, 부상 공극을 비교하고 부상안정성에 미치는 영향을 분석하였다. 이를 통해 거더높이와 부상안정성과의 상관관계에 대해 분석하였다. 본 논문의 연구 결과는 자기부상열차용 분기기 설계에 활용 가능할 것이다. It is essential to lighten the weight of switch girders in order to reduce their costs of manufacturing and make it easier to use them in construction. Lightening the weight of switch is also important to the Maglev 3-way switches system, however, the design variables should be considered very carefully if lightening is to be applied to the system, because these variables are vitally related to the levitation stability. Because Urban Maglev trains have a structure in which train bogie wraps around the guiderail, the adjustment of a girder's height is a possible way to reduce the weight. The safety of the application of this concept is ensured by repeated experiments in a test bed, however, due to a lack of space and budget limits, the design parametric study for the system model can substitute for actual application. The purpose of this paper is to study the design parameters that are concerned with levitation stability while a Maglev train is running on the Maglev 3-way system depending on the weight of the switch girders. In this study, switch girder weight is reduced by adjustment of girder height and girders are and modeled as a flexible body. The effect of the adjustment of girder height on the levitation stability can be analyzed by comparing the velocity of the train when it passes the switch girders, with the lateral gap, and the levitation gap which are obtained from the co-simulation of the Maglev train's dynamics model and flexible switching system. The results of this research will be used to design a Maglev switch.

Non-lane-discipline-based car-following model considering the effect of visual angle

This study proposes a new car-following (CF) model considering the effect of visual angle under the non-lane-discipline environment. In particular, a car-following model is proposed to capture the impacts from the visual angle of the driver between the following vehicle and the preceding vehicle as well as its change rate on a road without lane discipline. Stability analysis of the proposed CF model is performed using the perturbation method to obtain the stability condition. Numerical experiments analyze three scenarios: start process, stop process, and evolution process for lane-discipline-based FVD model, non-lane-discipline-based CF model with lateral gap, and the proposed model, respectively. Results from numerical experiments illustrate that the proposed CF model that considers the effects of both lateral gap and visual angle has larger stable region compared with FVD model and the NLBCF model. Also, the responsiveness and smoothness of the proposed CF model is improved with respect to the velocity, and acceleration or deceleration profiles.

Effect of wall proximity of two staggered triangular cylinders on the transport process in a channel

A numerical investigation has been carried out to analyze the heat transfer and the flow field around two isothermal triangular cylinders of equal size placed staggered in a horizontal plane channel with adiabatic walls. Computations have been carried out for Reynolds numbers (based on triangle width) 100, 250, and 350, lateral gap ratios (d/B) 0, 0.5, and 1, and longitudinal gap ratios (S/B) 1, 2, 3 and 4. The effect of longitudinal and lateral gap between obstacles and proximity of channel walls is investigated. Results show that when obstacles are placed in close vicinity of the channel's wall (d/B = 1), vortex shedding disappears at the downstream of triangles at Re = 100 and 250 at all S/B, but for Re = 350 creating and disappearing of the vortex shedding depend on the longitudinal gap ratio (S/B). Proximity of obstacles has more effect on the second triangle than the first triangle especially from longitudinal gap ratio equals 2, so that with approaching the channel wall, the Nusselt number for the first triangle decreases, while for the second triangle a different behavior is seen. Staggered arrangement causes the Nusselt number of the second triangle to become greater than the first triangle.

Asymmetrical Deterministic Lateral Displacement Gaps for Dual Functions of Enhanced Separation and Throughput of Red Blood Cells

Deterministic lateral displacement (DLD) method for particle separation in microfluidic devices has been extensively used for particle separation in recent years due to its high resolution and robust separation. DLD has shown versatility for a wide spectrum of applications for sorting of micro particles such as parasites, blood cells to bacteria and DNA. DLD model is designed for spherical particles and efficient separation of blood cells is challenging due to non-uniform shape and size. Moreover, separation in sub-micron regime requires the gap size of DLD systems to be reduced which exponentially increases the device resistance, resulting in greatly reduced throughput. This paper shows how simple application of asymmetrical DLD gap-size by changing the ratio of lateral-gap (GL) to downstream-gap (GD) enables efficient separation of RBCs without greatly restricting throughput. This method reduces the need for challenging fabrication of DLD pillars and provides new insight to the current DLD model. The separation shows an increase in DLD critical diameter resolution (separate smaller particles) and increase selectivity for non-spherical RBCs. The RBCs separate better as compared to standard DLD model with symmetrical gap sizes. This method can be applied to separate non-spherical bacteria or sub-micron particles to enhance throughput and DLD resolution.

Superconducting and hybrid systems for magnetic field shielding

In this paper we investigate and compare the shielding properties of superconducting and hybrid superconducting/ferromagnetic systems, consisting of cylindrical cups with an aspect ratio of height/radius close to unity. First, we reproduced, by finite-element calculations, the induction magnetic field values measured along the symmetry axis in a superconducting (MgB2) and in a hybrid configuration (MgB2/Fe) as a function of the applied magnetic field and of the position. The calculations are carried out using the vector potential formalism, taking into account simultaneously the non-linear properties of both the superconducting and the ferromagnetic material. On the basis of the good agreement between the experimental and the computed data we apply the same model to study the influence of the geometric parameters of the ferromagnetic cup as well as of the thickness of the lateral gap between the two cups on the shielding properties of the superconducting cup. The results show that in the considered non-ideal geometry, where the edge effect in the flux penetration cannot be disregarded, the superconducting shield is always the most efficient solution at low magnetic fields. However, a partial recovery of the shielding capability of the hybrid configuration occurs if a mismatch in the open edges of the two cups is considered. In contrast, at high magnetic fields the hybrid configurations are always the most effective. In particular, the highest shielding factor was found for solutions with the ferromagnetic cup protruding over the superconducting one.

Evaluating the performance of vehicular platoon control under different network topologies of initial states

This study proposes a feedback-based platoon control protocol for connected autonomous vehicles (CAVs) under different network topologies of initial states. In particularly, algebraic graph theory is used to describe the network topology. Then, the leader–follower approach is used to model the interactions between CAVs. In addition, feedback-based protocol is designed to control the platoon considering the longitudinal and lateral gaps simultaneously as well as different network topologies. The stability and consensus of the vehicular platoon is analyzed using the Lyapunov technique. Effects of different network topologies of initial states on convergence time and robustness of platoon control are investigated. Results from numerical experiments demonstrate the effectiveness of the proposed protocol with respect to the position and velocity consensus in terms of the convergence time and robustness. Also, the findings of this study illustrate the convergence time of the control protocol is associated with the initial states, while the robustness is not affected by the initial states significantly.

Lateralization of the Pharyngeal Flap for Treatment of Lateral Velopharyngeal Gap.

Pharyngeal flap is usually used for treatment of velopharyngeal insufficiency (VPI); it is bridged between the posterior pharyngeal wall and the soft palate traversing the central part of the velopharyngeal port. The aim of this study was to assess the efficacy of lateralization of the pharyngeal flap for treatment of VPI in patients with lateral velopharyngeal gap. Fifteen patients with VPI due to lateral velopharyngeal gap were subjected to closure of the gap by pharyngeal flap that was lateralized to fill the gap. Preoperative and postoperative assessment of velopharyngeal functions including flexible nasopharyngoscopy, auditory perceptual assessment (APA), and nasometric assessment were performed. Postoperatively, flexible nasopharyngoscopy showed complete velopharyngeal closure in all the patients, with significant improvement of speech parameters as measured by APA. Also, nasalance score showed significant improvement for oral and nasal sentences that was measured by nasometry. Lateralization of the pharyngeal flap for treatment of VPI in patients with lateral velopharyngeal gap is an effective method; it improves the velopharyngeal closure and the speech of the patients.

Quantification of the Effect of Vertical Bone Resection of the Medial Proximal Tibia for Achieving Soft Tissue Balancing in Total Knee Arthroplasty.

BackgroundDegenerative osteoarthritis of the knee usually shows arthritic change in the medial tibiofemoral joint with severe varus deformity. In total knee arthroplasty (TKA), the medial release technique is often used for achieving mediolateral balancing. But, in a more severe varus knee, there are more difficult technical problems. Bony resection of the medial proximal tibia (MPT) as an alternative technique for achieving soft tissue balancing was assessed in terms of its effectiveness and possibility of quantification.MethodsTKAs were performed in 78 knees (60 patients) with vertical bone resection of the MPT for soft tissue balancing from September 2011 to March 2013. During operation, the medial and lateral gaps were measured before and after the bony resection technique. First, the correlation between the measured thickness of the resected bone and the change in medial and lateral gaps was analyzed. Second, the possibility of quantification of each parameter was evaluated by linear regression and the coefficient ratio was obtained.ResultsA significant correlation was identified between alteration in the medial gap change in extension and the measured thickness of the vertically resected MPT (r = 0.695, p = 0.000). In the medial gap change in flexion, there was no statistical significance (r = 0.214, p = 0.059). When the MPT was resected at an average thickness of 8.25 ± 1.92 mm, the medial gap in extension was increased by 2.94 ± 0.87 mm. In simple linear regression, it was predictable that MPT resection at a thickness of 2.80 mm was required to increase the medial gap by 1.00 mm in knee extension.ConclusionsThe method of bone resection of the MPT can be considered effective with a predictable result for achieving soft tissue balancing in terms of quantification during TKA.

Analysis of the Effect of Variable Lateral Gap Maintaining Behavior of Vehicles on Traffic Flow Modeling

Vehicular interaction between different types of vehicles, in both the lateral and longitudinal directions, significantly affects the heterogeneous traffic flow modeling. From the field data it has been observed that the drivers vary gaps based on the changing traffic conditions. This variable gap maintaining behavior has been characterized using macroscopic traffic characteristic called area occupancy. Variable gaps are explained through effective vehicle width and it is found to be influenced by various factors. In this study, variable gap maintaining behavior is modeled using the concept of cellular automata (CA), with the help of a modified cell structure. Cell width in the modified cell structure has been varied corresponding to the observed variation in the effective vehicle width. It was found that the results obtained from the model incorporated with the variable gap maintaining behavior are significantly different from that of the uniform-cell-width based CA model. The effect is more significant for urban traffic conditions due to the presence of two-wheelers and three-wheelers.

Review of parameters influencing the structural response of a submerged body under cavitation conditions

Submerged structures that operate under extreme flows are prone to suffer large scale cavitation attached to their surfaces. Under such conditions the added mass effects differ from the expected ones in pure liquids. Moreover, the existence of small gaps between the structure and surrounding bodies filled with fluid also influence the dynamic response. A series of experiments and numerical simulations have been carried out with a truncated NACA0009 hydrofoil mounted as a cantilever beam at the LMH-EPFL cavitation tunnel. The three first modes of vibration have been determined and analysed under various hydrodynamic conditions ranging from air and still water to partial cavitation and supercavitation. A remote nonintrusive excitation system with piezoelectric patches has been used for the experiments. The effects of the cavity properties and the lateral gap size on the natural frequencies and mode shapes have been determined. As a result, the significance of several parameters in the design of such structures is discussed.

Postoperative Knee Flexion Angle Is Affected by Lateral Laxity in Cruciate-Retaining Total Knee Arthroplasty

BackgroundAlthough many studies have reported that postoperative knee flexion is influenced by preoperative conditions, the factors which affect postoperative knee flexion have not been fully elucidated. We tried to investigate the influence of intraoperative soft tissue balance on postoperative knee flexion angle after cruciate-retaining (CR) total knee arthroplasty (TKA) using a navigation and an offset-type tensor. MethodsWe retrospectively analyzed 55 patients with osteoarthritis who underwent TKA using e.motion-CR (B. Braun Aesculap, Germany) whose knee flexion angle could be measured at 2 years after operation. The exclusion criteria included valgus deformity, severe bony defect, infection, and bilateral TKA. Intraoperative varus ligament balance and joint component gap were measured with the navigation (Orthopilot 4.2; B. Braun Aesculap) while applying 40-lb joint distraction force at 0° to 120° of knee flexion using an offset-type tensor. Correlations between the soft tissue parameters and postoperative knee flexion angle were analyzed using simple linear regression models. ResultsVarus ligament balance at 90° of flexion (R = 0.56; P < .001) and lateral compartment gap at 90° of flexion (R = 0.51; P < .001) were positively correlated with postoperative knee flexion angle. In addition, as with past studies, joint component gap at 90° of flexion (R = 0.30; P < .05) and preoperative knee flexion angle (R = 0.63; P < .001) were correlated with postoperative knee flexion angle. ConclusionLateral laxity as well as joint component gap at 90° of flexion is one of the most important factors affecting postoperative knee flexion angle in CR-TKA.

Patient-related factors influence stiffness of the soft tissue complex during intraoperative gap balancing in cruciate-retaining total knee arthroplasty.

How much force is needed to pre-tension the ligaments during total knee arthroplasty? The goal of this study was to determine this force for extension and flexion, and for both compartments, and to identify predicting patient-related factors. Eighty patients [55 females, mean age 71 (SD 9.7)] were recruited and had a navigated cruciate-retaining total knee arthroplasty. Distraction of the medial and lateral compartments of the extension and flexion gap (90°) with an instrumented bi-compartmental double-spring tensioner took place after finishing the bone cuts. Applied forces and resulting gap distances were recorded by the navigation system, resulting in a force-elongation curve. Lines were fitted with the intersection defined as the stiffness transition point. The slopes (N/mm) represented the stiffness of the ligamentous complex. Linear multiple regression analysis was performed to identify predicting factors. The amount of force at the stiffness transition point was on average 52.3 (CI95 50.7-53.9), 54.5 (CI95 52.7-56.3), 48.3 (CI95 46.2-50.2), and 59.3 (CI95 57.0-61.6)N for the medial and lateral extension and flexion gap, respectively, and varied considerably between patients. The force at the stiffness transition point was significantly different between extension and flexion and both compartments (P<0.05). Stiffness of the ligaments statistically significantly helped to predict the amount of force at the stiffness transition point, as well as body mass index, gender, and varus-valgus alignment. The amount of force at the stiffness transition point varies between 48 and 59N, depending on flexion/extension and compartment. Patient-related factors influence the stiffness transition point and can help predict the stiffness transition point. When forces higher than 60N are used for gap distraction, the ligamentous sleeve of the knee might be over-tensioned. Prognostic study, Level I-high-quality prospective cohort study with >80% follow-up, and all patients enrolled at same time point in disease.