Transverse Configuration Research Articles

Toric configuration spaces: the bipermutahedron and beyond

We establish faithful tropicalisation for point configurations on algebraic tori. Building on ideas from enumerative geometry, we introduce tropical scaffolds and use them to construct a system of modular fan structures on the tropical configuration spaces. The corresponding toric varieties provide modular compactifications of the algebraic configuration spaces, with boundary parametrising transverse configurations on tropical expansions. The rubber torus, used to identify equivalent configurations, plays a key role. As an application, we obtain a modular interpretation for the bipermutahedral variety.

Design and development of a flexible-rigid Triglide sorting manipulator

Flexible manipulators have been widely applied in various tasks involving grasping and manipulation, and their unique characteristics in terms of lightweight design and adaptability make them particularly suitable for tackling complex spatial pick-and-place operations. In this work, a Triglide flexible manipulator is presented and developed, based on the parallel Biglide mechanism and dual leaf springs in parallelogram structure, which features adjustable stiffness by changing the transverse configuration of the leaf springs. To analyze the deflections of the leaf springs efficiently, a segmented approach is deployed, to calculate large deflection within the plane of the leaf-springs parallelogram structure. The adopted approach uses classical bending deformation formulas from mechanics of materials. Consequently, the static models of the manipulator are derived for analyzing bending deformation and workspace by means of numerical calculations. Finite element analysis is adopted to investigate the mechanical characteristics of the manipulator. A prototype of the variable stiffness manipulator is built, and an experimental setup is established for static testing. The obtained results align with the previously observed mechanical characteristics. The main advantages of the flexible robotic manipulator lie in its simple structure, small footprint, and simple kinematic model for control.

Depinning of domain walls in a notched ferromagnetic nanostrip: role of inertial and nonlinear damping effects

Abstract In this work, we investigate theoretically the static and kinetic depinning field of a domain wall in a notched magnetic nanostrip under the generalized framework of the Landau–Lifshitz-Gilbert equation, which combines inertial and nonlinear viscous-dry friction damping effects. We assume a head-to-head transverse domain wall configuration and analyzed its motion subject to a time-varying external magnetic field. To deduce the equation ruling the spatio-temporal evoution of the magnetic domain wall, we adopt the Schryer and Walker trial function approach. The results show that static and kinetic depinning fields increase as the dry friction dissipation increases. Moreover, viscous dissipation exhibits a weak dependence on the kinetic depinning field and saturated domain wall velocity, while inertial damping due to the relaxation time of angular momentum significantly impacts the kinetic depinning field, depinning time, and breakdown velocity. Our numerical results are in good qualitative agreement with the recent observations reported in the literature.

Mitigation of the microbunching instability through transverse Landau damping

The microbunching instability has been a long-standing issue for high-brightness free-electron lasers (FELs) and is a significant showstopper to achieve full longitudinal coherence in the x-ray regime. This paper reports the first experimental demonstration of microbunching instability mitigation through transverse Landau damping, based on linear optics control in a dispersive region. Analytical predictions for the microbunching content are supported by numerical calculations of the instability gain. The effect is confirmed through the experimental characterization of the spectral brightness of the FERMI FEL under different transverse optics configurations of the transfer line between the linear accelerator and the FEL. Published by the American Physical Society 2024

Experimental study on the behavior of small-scaled circular and square RC columns under various loading conditions and corrosion effect

Reinforced concrete columns are vital load-bearing elements, responsible for transferring vertical loads and resisting lateral forces. While numerous factors govern column performance, this study pinpoints cross-sectional shape, transverse reinforcement configuration, and the corrosive threat as its primary areas of investigation. Thus, 20 small-scaled (1/8th scale) RC columns (square and circular, with ties or spirals) were tested under various loading conditions. Columns were divided into five groups. A preliminary test was conducted to determine individual axial load capacity through failure under axial compressive loading. The main test then explored their behavior under combined axial load and variable lateral drift compared to their behavior at two corrosion levels 15% and 25%. While corrosion levels were roughly achieved, uneven distribution due to the accelerated process concentrated pitting near construction joints, impacting reinforcement more than rebar. Results confirmed the efficacy of spirals in enhancing capacity, particularly for circular columns where they also increased lateral load capacity. However, spirals also amplified corrosion vulnerability in circular columns, suggesting a steeper decline in performance at higher corrosion levels. Two key models were derived from analyzing the recorded data: normalized total dissipated energy and normalized absolute peak load. Future research should prioritize exploring column behavior under a wider range of combined loads and corrosion levels to refine and validate these models.

Resonance behaviour of magnetoelectric (PSLZT multilayer - NZFO) layered composites: A comprehensive theory – Experimental perspective

In recent years, compact antenna and miniaturized power transfer devices are among the interesting applications of magnetoelectric (ME) composites in low frequency (LF) / very low frequency (VLF) range. Here we elucidate, in general, analytical calculations used to understand, the vibrational modes and resonance frequencies of the layered ME composite and; Finite Element Analyses (FEM) with isotropic and anisotropic properties to accurately predict the resonance frequencies pertaining to the axisymmetric and asymmetric mode of vibrations with respect to significant ME response. Further, ME coefficient of the composite with Longitudinal - Transverse (L-T) configuration based on the interface coupling model were utilized to completely study the ME composites. The configuration optimized through the design was in particular corroborated experimentally with a representative PSLZT multilayer on NZFO based ME layered composite system. The PSLZT multilayer on NZFO based ME composite was fabricated by tape casting the constituent thick films and co-sintering process which are further analysed for their ME responses at their resonance frequencies. ME voltage spectrum showed a maximum of 7.74 V/cm.Oe at its axisymmetric resonance mode at 30.6 kHz. Various peaks at different resonance frequencies with respect to axisymmetric and asymmetric modes of vibrations agree well and validates the above modeling studies. Overall, the complete study provides a systematic design guideline for optimizing the ME composite configuration suitable for specific application with required resonance frequency.

Enhanced microfluidic multi-target separation by positive and negative magnetophoresis

We introduce magnetophoresis-based microfluidics for sorting biological targets using positive Magnetophoresis (pM) for magnetically labeled particles and negative Magnetophoresis (nM) for label-free particles. A single, externally magnetized ferromagnetic wire induces repulsive forces and is positioned across the focused sample flow near the main channel's closed end. We analyze magnetic attributes and separation performance under two transverse dual-mode magnetic configurations, examining magnetic fields, hydrodynamics, and forces on microparticles of varying sizes and properties. In pM, the dual-magnet arrangement (DMA) for sorting three distinct particles shows higher magnetic gradient generation and throughput than the single-magnet arrangement (SMA). In nM, the numerical results for SMA sorting of red blood cells (RBCs), white blood cells (WBCs), and prostate cancer cells (PC3-9) demonstrate superior magnetic properties and throughput compared to DMA. Magnetized wire linear movement is a key design parameter, allowing device customization. An automated device for handling more targets can be created by manipulating magnetophoretic repulsion forces. The transverse wire and magnet arrangement accommodate increased channel depth without sacrificing efficiency, yielding higher throughput than other devices. Experimental validation using soft lithography and 3D printing confirms successful sorting and separation, aligning well with numerical results. This demonstrates the successful sorting and separating of injected particles within a hydrodynamically focused sample in all systems. Both numerical and experimental findings indicate a separation accuracy of 100% across various Reynolds numbers. The primary channel dimensions measure 100 µm in height and 200 µm in width. N52 permanent magnets were employed in both numerical simulations and experiments. For numerical simulations, a remanent flux density of 1.48 T was utilized. In the experimental setup, magnets measuring 0.5 × 0.5 × 0.125 inches and 0.5 × 0.5 × 1 inch were employed. The experimental data confirm the device's capability to achieve 100% separation accuracy at a Reynolds number of 3. However, this study did not explore the potential impact of increased flow rates on separation accuracy.

Evolution of flow structure and heat transfer enhancement mechanism in impinging jets excited by piezoelectric fan

While jet impingement is recognized for significantly enhancing local convective heat transfer, there remains a considerable challenge in further improving its heat transfer performance and uniformity to meet the growing demand for efficient heat transfer. To address this challenge, this study proposes a method that integrates a piezoelectric fan into a continuous jet, taking advantage of the piezoelectric fan's vibration to deliver pulsating excitation to jet impingement while preserving its continuity. An experimental study is performed to identify the roles of piezo-fan integration on improving convective heat transfer from a continuous circular jet onto a flat target surface. The tests are performed under Rej=2,500∼7,500 (circular jet), s/d = 2∼28 (non-dimensional fan-to-jet distance) and L/d = 2∼8 (non-dimensional jet-to-target distance). In addition, few numerical simulations regarding the flow fields are also made to illustrate the mutual interaction mechanism between piezo-fan and continuous jet. The findings reveal that, in the longitudinal configuration, the average values of heat transfer enhancement factor (χ) and heat transfer uniformity factor (ξ) are approximately 13% and 0.5% higher, respectively, compared to the transverse configuration. In the longitudinal arrangement, the significance of the piezoelectric fan amplifies as the circular nozzle gradually distances itself from the target surface. This fan assumes a pivotal role in augmenting both the uniformity and efficiency of heat transfer associated with the circular jet. Conversely, when the piezoelectric fan moves beyond a specific s/d value (s/d = 10), the interaction between intermittent flow and the wall-jet experiences complete cessation. Despite the existence of a fountain effect resulting from the interaction between the piezoelectric fan and the circular jet in the longitudinal configuration, its discernible impact on overall heat transfer attenuation is minimal. The insights gained from this study will be valuable in improving active strategies for jet impingement and promoting the development of piezoelectric functional devices.

Structural Behavior of Circular Concrete Columns Reinforced with Longitudinal GFRP Rebars under Axial Load

This paper presents experimental and theoretical assessments of the structural behavior of circular steel fiber-reinforced concrete (SFRC) columns reinforced with glass fiber-reinforced polymer (GFRP) bars subjected to a concentric axial compressive load. Laboratory experiments were planned to evaluate and compare the effect of different design parameters on the structural behavior of column specimens based on experiments and finite element (FE) analysis. The experimental variables were (i) concrete types, i.e., conventional concrete (CC) and fiber-reinforced concrete (FC), (ii) longitudinal reinforcement types, i.e., steel and GFRP bars, and (iii) transverse rebar configurations, i.e., tied and spiral with different pitches. Sixteen column specimens were fabricated and categorized into four groups with respect to rebar configurations and concrete types. The results showed that the failure modes and cracking patterns of those four column groups were comparable, particularly in the pre-peak branches of load-deflection curves. Even though the average ultimate load of the columns with longitudinal GFRP bars was 17.9% less than that with longitudinal steel bars, the ductility index (DI) was 10.2% greater than their counterpart on average. The addition of steel fibers (SF) to concrete increased the axial peak load by up to 3.1% and the DI by up to 6.6% compared to their counterpart CC columns without SFs. The DI of specimens was increased by higher volumetric ratios (up to 12%) and spiral types (up to 5.5%). The concrete damage plastic (CDP) model for FC columns was updated in the finite element software ABAQUS 6.14. Finally, a new simple equation was theoretically proposed to predict the axial capacity of specimens by considering the inclusion of longitudinal GFRP rebars, volumetric ratio, and steel spiral/hoop ties. Good agreement between the proposed model predictions and the experimental/numerical results was observed.

Dual-Channel Transverse Fields Radiofrequency Coils for 1.5 T Magnetic Resonance Imaging.

This theoretical study presents the design and analytical/numerical optimization of novel dual-channel transverse fields radiofrequency (RF) surface coils for 1.5 T Magnetic Resonance Imaging (MRI). The research explores a planar setup with two channels on a row with aligned spatial orientation of the RF coils, aiming to solve a common design drawback of single-channel transverse field RF coils: the reduced Field Of View (FOV) along the direction of the RF field. A significant challenge in this design is the efficient decoupling of two sets of transverse field RF coils to prevent mutual interference. Our modeling approach integrates thin wire theoretical modeling, magnetostatic computation for strip conductor coils, and their full-wave electromagnetic simulation. Key findings at 64 MHz demonstrate that strategic geometric placement among the two-channel RF coil and the introduction of geometrical asymmetry in the design of the individual RF coils does minimize the mutual inductance, paving the way for effective dual-channel MRI applications. This decoupling approach allows to enhance the FOV, providing a theoretical framework for the development of optimized dual-channel transverse field RF coil configurations. The current design was validated with full-wave numerical study at 64 MHz (1H, 1.5 T), has the potential to be extended at lower or higher frequencies, and the presence of lossy samples needs to be considered in the latter case.

Prediction model and sensitivity analysis of ultimate drift ratio for rectangular reinforced concrete columns failed in flexural-shear based on BP-Garson algorithm

Considering that the deformation capacity of reinforced concrete (RC) columns is crucial in performance-based seismic design, the ultimate drift ratio of RC columns failed in flexural-shear are studied using BP neural network and Garson (BP-Garson) algorithm. Firstly, this study employed data onto tests conducted on 35 rectangular RC columns with flexural-shear failure. Nine influencing factors including axial load ratio, shear span ratio, longitudinal reinforcement configuration, transverse reinforcement configuration, and material strength were selected as variables, a BP neural network was used to establish the relationship between the ultimate drift ratio and these variables. Accordingly, a predictive model for the ultimate drift ratio of RC rectangular columns failed in flexural-shear was constructed. Then, the Garson algorithm for local sensitivity analysis was applied to determine the sensitivity of each influence of the ultimate drift ratio of RC rectangular columns failed in flexural-shear. The results showed that the BP neural network could accurately predict the ultimate drift ratio of RC rectangular columns with flexural-shear failure, of which the primary influencing factors are shear span ratio, axial load ratio, volume transverse reinforcement ratio and longitudinal reinforcement ratio. The BP-Garson algorithm integrates model development with influence analysis, which could improve computational efficiency and serves as a reference for evaluating the sensitivity of seismic performance and its influencing factors in other structural components.

A case series of retrosigmoid craniectomies and an emergent grading system for the transverse, sigmoid and superior petrosal sinus configuration.

A case series of retrosigmoid craniectomies and an emergent grading system for the transverse, sigmoid and superior petrosal sinus configuration.

Horizontal magnetic tweezers and its applications in single molecule micromanipulation experiments.

Magnetic tweezers (MTs) have become indispensable tools for gaining mechanistic insights into the behavior of DNA-processing enzymes and acquiring detailed, high-resolution data on the mechanical properties of DNA. Currently, MTs have two distinct designs: vertical and horizontal (or transverse) configurations. While the vertical design and its applications have been extensively documented, there is a noticeable gap in comprehensive information pertaining to the design details, experimental procedures, and types of studies conducted with horizontal MTs. This article aims to address this gap by providing a concise overview of the fundamental principles underlying transverse MTs. It will explore the multifaceted applications of this technique as an exceptional instrument for scrutinizing DNA and its interactions with DNA-binding proteins at the single-molecule level.

High-Mobility Topological Semimetals as Novel Materials for Huge Magnetoresistance Effect and New Type of Quantum Hall Effect.

The quantitative description of electrical and magnetotransport properties of solid-state materials has been a remarkable challenge in materials science over recent decades. Recently, the discovery of a novel class of materials-the topological semimetals-has led to a growing interest in the full understanding of their magnetotransport properties. In this review, the strong interplay among topology, band structure, and carrier mobility in recently discovered high carrier mobility topological semimetals is discussed and their effect on their magnetotransport properties is outlined. Their large magnetoresistance effect, especially in the Hall transverse configuration, and a new version of a three-dimensional quantum Hall effect observed in high-mobility Weyl and Dirac semimetals are reviewed. The possibility of designing novel quantum sensors and devices based on solid-state semimetals is also examined.

A Diamond Terahertz Large Aperture Photoconductive Antenna Biased by a Longitudinal Field

The novel design of a terahertz large aperture photoconductive antenna (LAPCA) is reported. It features a longitudinal orientation of the bias electric field within the photoconductive substrate, and has the advantage of a small interelectrode gap, resulting in a higher field for the same applied voltage. The proposed LAPCA configuration has been tested with a nitrogen-doped (∼10 ppm) synthetic monocrystalline diamond, which is a promising material for high-intensity and high-power terahertz sources. Two antennas with different high-voltage electrode realizations were assembled, pumped by a 400 nm femtosecond laser, and tested for THz emitter function. The experimental data are found to be in good correlation with the numerical simulation results. The performance of antennas with the conventional transverse E-field configuration and the novel longitudinal configuration is compared and discussed.

Assessment of plastic hinge length in reinforced concrete columns

Plastic hinge properties are crucial parameters in predicting the nonlinear response of structural elements. Because of the intricate material nonlinearity, precise determination of the plastic hinge length (PHL) has encountered several obstacles. Over the last few decades, there have been various definitions and models put forth to forecast this length, nevertheless, the outcomes displayed significant disparities. Therefore, the paper introduces a comprehensive method for determining PHL using certain criteria, including rebar strain profiles, concrete cover and core peak strains, curvature profiles, and damage observations. Furthermore, a set of four full-scale reinforced concrete (RC) columns measuring 400 mm × 400mm × 3000mm and featuring varying transverse reinforcement configurations were constructed and subjected to testing under a high axial load ratio (ALR). The tested results implied that it is necessary to separate the PHLs based on different criteria. The high axial compression load led to enhancing the PHLs, which were based on rebar compressive yield strains, curvature profiles, concrete cover and core peak strains. In contrast, it has a minor effect on PHL based on tensile yield strains. In addition, the amount of transverse reinforcement had an insignificant effect on all PHLs for tested columns. Hence, a revised equation was proposed to estimate the equivalent PHLs of rectangular RC columns based on tested results and a 114-column database. The proposed equation had better accuracy compared with some other model results in the literature.

Acute human defibrillation performance of a subcutaneous implantable cardioverter-defibrillator with an additional coil electrode

The subcutaneous implantable cardioverter-defibrillator (S-ICD) delivers 80 J shocks from an 8 cm left-parasternal coil to a 59 cm3 left lateral pulse generator (PG). A system that defibrillates with lower energy could significantly reduce PG size. Computer modeling and animal studies suggested that a second shock coil either parallel to the left-parasternal coil or transverse from the xiphoid to the PG pocket would significantly reduce the defibrillation threshold. The purpose of this study was to acutely assess the defibrillation efficacy of parallel and transverse configurations in patients receiving an S-ICD. Testing was performed in patients receiving a conventional S-ICD system. Success at 65 J was required before investigational testing. A second electrode was temporarily inserted from the xiphoid incision connected to the PG with an investigational Y-adapter. Phase 1 (n = 11) tested the parallel configuration. Phase 2 (n = 21) tested both parallel and transverse configurations in random order. This study enrolled 35 patients (28 males (80%); mean age 51 ± 17 years; left ventricular ejection fraction 40% ± 15%; body mass index 26 ± 4 kg/m2; prior myocardial infarction 46%; congestive heart failure 49%; cardiomyopathy 63%). Compared to the conventional S-ICD system, mean shock impedance decreased for both parallel (69 ± 15 Ω vs 86 ± 20 Ω; n = 33; P < .001) and transverse (56 ± 14 Ω vs 81 ± 21 Ω; n = 20; P < .001) configurations. Shock success rates at 20, 30, and 40 J were 55%, 79%, 97%, and 25%, 70%, 90% for parallel and transverse configurations, respectively. Defibrillation threshold testing was well tolerated with no serious adverse events. Adding a second shock coil, particularly in the parallel configuration, significantly reduced the impedance and had a high likelihood of defibrillation success at energies ≤40 J. This may enable the development of a smaller S-ICD.

Experimental investigation of assembly-oriented steel column-beam connection with transverse reverse channels for prefabricated structures

The purpose of this study is to experimentally investigate the mechanical behaviour of the innovative steel column-beam connection involving transverse reverse channels in prefabricated structures with the aim of improving the assemblability during the construction processes. A series of experiments were performed on steel square hollow section (SHS) column and H-section beam connection involving three different transverse reverse channel configurations, i.e., unstiffened transverse reverse channel (UTC), between-channel stiffened (BCS) transverse reverse channel, and in-channel stiffened transverse reverse channel (ICS). The traditional connection involving vertical reverse channel (VRC) was also tested as the control to evaluate the mechanical performance of the new column-beam design, such as flexural resistance, strain distribution and failure modes. The experimental results demonstrate that stiffening the transverse reverse channels internally (ICS) could significantly strengthen the flexural resistance of the connection and the out-of-plane rigidity of the channel web. For example, the flexural resistance of ICS connection is more than 50% and 100% higher than that of the VRC and UTC connection, respectively. However, stiffening between the two transverse reverse channels externally (BCS) has little influence in the flexural resistance of the connection. The failure of the ICS connection is mainly due to the buckling of the beam, while UTC and BCS connections fail because of excessive deformation of the transverse reverse channels. Theoretical formulas can conservatively estimate the bending bearing capacity of those connections.

LED-pumped Er:Cr:YSGG light sources.

For, what we believe is, the first time, an Er:Cr:YSGG crystal is pumped by LEDs through a Ce:YAG luminescent concentrator. We demonstrate both laser emission at 2.79 µm and strong spontaneous emission at 1.6 µm. The luminescent concentrator delivers 1.5 ms pulses at 10 Hz in the visible (550-650 nm) to the Er:Cr:YSGG crystal, in a transverse pumping configuration. The Er:Cr:YSGG laser produces up to 6.8 mJ at 2.79 µm in a biconcave cavity. The Er:Cr:YSGG also stands out as a bright broadband incoherent source around 1.6 µm with a unique combination of peak power (351 mW) and brightness (1.4 W/sr/cm2).

Design and Hydrodynamic Performance Analysis of Offshore Multi-Module Floating Docks

This study presents a design scheme for a multi-module connected floating dock, comprising two configurations for the lower floating body: transverse and longitudinal floats. An articulated connection between the modules is also included. The hydrodynamic performance of the floating dock with these two configurations is compared and analyzed by taking the South China Sea as an example. Frequency and time-domain analysis methods are employed, considering the coupling between the mooring and the multi-module floating dock. The results indicate that, under the condition of both cross waves and oblique waves, the transverse float configuration exhibits superior motion response performance in all degrees of freedom compared to the longitudinal float configuration, particularly in terms of roll performance. Furthermore, the maximum mooring tension and connection structure load for the transverse float configuration are lower than those for the longitudinal float configuration, resulting in superior overall hydrodynamic performance.