Uniform Gauge Research Articles

Design Framework for Polymer Nanocomposite Flexible Strain Sensor Adhesive Tape

In the emerging flexible electronics field, flexible and wearable sensors play a crucial role. Though many reports focused on developing flexible sensors with novel materials, translational research is scarce. The present research focuses on a design framework for flexible strain sensors considering the design scalability, packaging feasibility and end users’ issues along with performance. To be specific, a flexible strain sensor tape framework is designed and developed using poly (vinylidene chloride-co-vinyl chloride) (PVDC-co-VC) and polystyrene sulfonate functionalized carbon nanotube (PSS-CNT) polymer nanocomposite with underneath adhesive coating and a copper contact pad atop the sensor. At the outset, numerical simulation is also carried out to understand the impact of uneven adhesive thickness profile on the sensor performance and emphasis the necessity of uniform adhesive coating underneath the sensor. Further, the PVDC-co-VC/PSS-CNT polymer nanocomposite is systematically optimized to find its percolation threshold to achieve its maximum performance. Later, the scaled-up long flexible strain sensor tape is developed and validated by measuring the gauge factor in multiple positions along the length of the sensor tape; it shows the uniform gauge factor value of 15.2±0.8 which ensures the sensor’s repeatability and reproducibility. As a testimony, the developed flexible strain sensor is demonstrated for wearable electronics applications with an indigenously developed IOT-enabled portable interface device. The present flexible strain sensor tape design framework supports scalability, and packaging feasibility and solves end users’ installation issues.

Thermopower in a boundary-driven bosonic ladder in the presence of a gauge field

We consider a bosonic two-legged ladder whose two-band energy spectrum can be tuned in the presence of a uniform gauge field, to four distinct scenarios: degenerate or non-degenerate ground states with gapped or gapless energy bands. We couple the ladder to two baths at different temperatures and chemical potentials and analyze the efficiency and power generated in the linear as well as nonlinear response regime. Our results, obtained with the Green's function method, show that the maximum performance efficiency and generated power are strongly dependent on the type of the underlying energy spectrum. We also show that the ideal scenario for efficient energy conversion, as well as power generation, corresponds to the case in which the spectrum has a gap between the bands, and the ground state is degenerate.

A miniaturized thin‐plate low cycle fatigue test method at elevated temperature

AbstractThis study aims to develop a high‐temperature low cycle fatigue test method using a nonstandard miniature thin‐plate specimen in order to characterize the cyclic viscoplasticity behavior of a component material. For demonstration, fully reversed strain‐range controlled low cycle fatigue and creep‐fatigue tests at 600°C have been performed for a martensitic steel using standard‐sized full‐scale specimens and miniaturized thin‐plate specimens, respectively. Because the displacement is not directly measured from the uniform gauge section of the miniaturized specimen, a geometry‐dependent scaling factor is obtained and used to convert the uniaxial strain. The results obtained are shown that the miniaturized test method developed in this work has exhibited a clear possibility to produce comparable low cycle fatigue data with those that are normally obtained by conventional standard specimen tests.

Heat, particle, and chiral currents in a boundary driven bosonic ladder in the presence of a gauge field

Quantum systems can undergo phase transitions and show distinct features in different phases. The corresponding transport properties can also vary significantly due to the underlying quantum phase. We investigate the transport behaviour of a two-legged bosonic ladder in a uniform gauge field, which is known to have a Meissner-like phase and a vortex phase in the absence of dissipation. The ladder is coupled to bosonic baths at different temperatures, and we study it using the non-equilibrium Green's function method. In particular, we show the presence of a chiral current and how it is affected by the temperature bias and the dissipation strength. We also demonstrate that the opening of a gap between the lower and upper energy band results in the possibility of tuning heat and particle transport through the ladder. We show that for system parameters for which the ground state is in a vortex phase, the system is more sensitive to external perturbations.

Cruciform Specimen Machining Using EDM and a New Design Verification for Biaxial Testing

Cruciform flat specimen is mostly used to investigate experimentally the in-plane biaxial mechanical behavior of sheet metals. In this study, a modified cruciform specimen design is proposed and validated against the performance of current standard design. The existing standard cruciform specimen prepared through laser cutting for sheet metal can accurately provide biaxial stress–strain curve through biaxial tensile test by ensuring superior homogeneous stress and strain field in gauge section. However, preparation of such specimen using laser cut is cumbersome, expensive and prone to errors. The current standard cruciform specimen design features slotted arm of fixed length and width with specific gauge. Few other designs also feature reduced gauge section to localize failure. Both need high precision of laser cutting and machining to prepare specimens which can achieve biaxial stress–strain curve for more than 4% equivalent plastic strain level. The proposed specimen design features running slits in all four arms of specimen with uniform gauge section machined using electrical discharge machining (EDM) owing to higher accuracy and minimum heat-affected zone (HAZ). This technique also avoids machining effects with an understanding that proposed specimen design is to determine the yield behavior of material only. Also, specimen fabricated from as received sheets and without any thickness reduction in gauge area allows the user to keep full thickness in biaxial condition. The modified design qualifies the commonly accepted performance criteria for cruciform specimen, i.e., stress and strain distribution in the gauge section is found to be homogeneous and the biaxial stress–strain curve can be generated until 4% of equivalent plastic strain. The proposed specimen design is evaluated experimentally by conducting biaxial test at various stress ratios, and it is compared with alike experiments using standard specimen design. One automotive grade material, interstitial-Free high-strength (IFHS) steel sheet of thickness 0.70 mm is tested in this study to validate the specimen design.

Quantale-Valued Uniformizations of Quantale-Valued Generalizations of Approach Groups

We introduce the categories of quantale-valued approach uniform spaces and quantale-valued uniform gauge spaces, and prove that they are topological categories. We first show that the category of quantale-valued uniform gauge spaces is a full bireflective subcategory of the category of quantale-valued approach uniform spaces and; second, we prove that only under strong restrictions on the quantale these two categories are isomorphic. Besides presenting embeddings of the category of quantale-valued metric spaces into the categories of quantale-valued approach uniform spaces as well as quantale-valued uniform gauge spaces, we show that every quantale-valued approach system group and quantale-valued gauge group has a natural underlying quantale-valued approach uniform space, respectively, a quantale-valued uniform gauge space.

On the convergence of almost minimal sets for the Hausdorff and varifold topologies

The geometric properties of (almost) minimal sets, especially the regularity, is an interesting topic in geometric measure theory, which were often studied in the literature, for example [2,4,5,8–10,19,22]. Soap films as well as solutions to Plateau's Problem could be a typical example of such kind of minimal sets. In this paper, we will investigate the convergence of a sequence of such sets, and show that Hausdorff convergence and varifold convergence coincide on the class of almost minimal sets bounded by a uniform gauge function, and we will see that a large amount of sets, including all compact C1,1 submanifolds in Rn, are almost minimal.

Band Gap Closing in a Synthetic Hall Tube of Neutral Fermions.

We report the experimental realization of a synthetic three-leg Hall tube with ultracold fermionic atoms in a one-dimensional optical lattice. The legs of the synthetic tube are composed of three hyperfine spin states of the atoms, and the cyclic interleg links are generated by two-photon Raman transitions between the spin states, resulting in a uniform gauge flux ϕ penetrating each side plaquette of the tube. Using quench dynamics, we investigate the band structure of the Hall tube system for a commensurate flux ϕ=2π/3. Momentum-resolved analysis of the quench dynamics reveals a critical point of band gap closing as one of the interleg coupling strengths is varied, which is consistent with a topological phase transition predicted for the Hall tube system.

Dynamical instability with respect to finite-momentum pairing in quenched BCS superconducting phases

In this work we numerically investigate the fate of the Bardeen-Cooper-Schrieffer (BCS) pairing in the presence of quenched phase under Peierls substitution using time-dependent real space and momentum space Bogoliubov-de Gennes equation methods and Anderson pseudospin representation method. This kind of phase imprint can be realized by modulating electric field in ultracold atoms and illumining of THz optical pump pulse in solids with conventional and unconventional superconductors. In the case of weak phase imprint, the BCS pairing is stable; while in the strong phase imprint, instability towards finite-momentum pairing is allowed, in which the real space and momentum space methods yield different results. In the pulsed gauge potential, we find that this instability will not happen even with much stronger vector potential. We also show that the uniform and staggered gauge potentials yield different behaviors. While the staggered potential induces transition from the BCS pairing to over-damped phase, the uniform gauge may enhance the pairing and will not induce to the over-damped phase. These result may shade light on the realization of finite momentum pairing, such as Fulde-Ferrell-Larkin-Ovchinnikov phase with dynamical modulation.

On pp wave limit for \u03b7 deformed superstrings

In this paper, based on the notion of plane wave string/gauge theory duality, we explore the pp wave limit associated with the bosonic sector of η deformed superstrings propagating in (AdS5 × S5)η . Our analysis reveals that in the presence of NS-NS and RR fluxes, the pp wave limit associated to full ABF background satisfies type IIB equations in its standard form. However, the beta functions as well as the string Hamiltonian start receiving non trivial curvature corrections as one starts probing beyond pp wave limit which thereby takes solutions away from the standard type IIB form. Furthermore, using uniform gauge, we also explore the BMN dynamics associated with short strings and compute the corresponding Hamiltonian density. Finally, we explore the Penrose limit associated with the HT background and compute the corresponding stringy spectrum for the bosonic sector.

Discrete soliton diode induced by synthetic gauge phase

We demonstrate the nonreciprocal dynamics of discrete solitons (DSs) induced by a uniform synthetic gauge phase (SGP) in one-dimensional waveguide array. The SGP is embedded into the coupling constant between the waveguides, which provides a directional momentum to the propagating fields and creates a nonreciprocal for the system. When a kicked Gaussian wave packet propagates through the waveguide arrays, diode effects are formed. Dependence between the diode effect and the SGP is studied. We found that the threshold of the reverse breakdown of this optical diode exhibits a perfect linear dependence against the SGP, and an extremely high diode quality can be achieved when the initial phase tilt exactly compensates the initial momentum provided by the SGP. Moreover, the direction of the diode can be switched by the direction of the SGP, which brings additional freedom to control the one-way propagation of the DSs. Our finding may have potential application to realizing new devices in high-speed all-optical communications.

Fatigue behavior of Ti-6Al-4V ELI including mean stress effects

This paper investigates cyclic deformation, fatigue behavior, and failure mechanisms for Ti-6Al-4V ELI (extra low interstitial) with and without mean strain/stress. This type of titanium alloy is broadly used in the biomedical and aerospace fields, specifically for implants and structural components, respectively. Fatigue properties were obtained using the strain-life approach with the use of smooth uniform gage section specimens under axial fully-reversed loading. The influence of mean stress on fatigue behavior was studied using four different strain ratios, Rε. The generated fatigue data was used to assess some strain-based mean stress fatigue life prediction models, including Morrow, Smith-Watson-Topper, Walker, Kwofie, Ince-Glinka and a modified version of the Smith-Watson-Topper. These models offered acceptable results, specifically the Morrow approach which provided more accurate fatigue life predictions. Fractography analysis was conducted to determine the influence of material defects on fatigue life and no major differences were found for the different strain ratios considered. Overall observations indicate that inclusions found near the surface were of great influence on the fatigue behavior.

A modified energy-based approach for fatigue life prediction of superelastic NiTi in presence of tensile mean strain and stress

Fatigue behavior of superelastic NiTi (i.e. Nitinol) is experimentally investigated and an energy-based fatigue model is proposed to account for the effects of tensile mean strain and stress on fatigue resistance. Several zero and nonzero mean strain tests at various strain amplitudes were conducted on cylindrical fatigue specimens with uniform gage sections. Experimental results revealed significant detrimental effects of the tensile mean stress on the fatigue life of the superelastic NiTi. On the stress plateau, where a change in the mean strain did not significantly influence the stress value, fatigue lives were observed to be similar. A modified energy-based model is proposed to account for the effects of mean stress and strain on the fatigue behavior of superelastic NiTi. Among all the models investigated in this study, the proposed energy approach was able to better correlate the fatigue data with and without mean strains/stresses.

Effect of notches on creep–fatigue behavior of a P/M nickel-based superalloy

A study was performed to determine and model the effect of high temperature dwells on notch low cycle fatigue (NLCF) and notch stress rupture behavior of a fine grain LSHR powder metallurgy (P/M) nickel-based superalloy. It was shown that a 90second (s) dwell applied at the minimum stress (“min dwell”) was considerably more detrimental to the NLCF lives than similar dwell applied at the maximum stress (“max dwell”). The short min dwell NLCF lives were shown to be caused by growth of small oxide blisters which caused preferential cracking when coupled with high concentrated notch root stresses. The cyclic max dwell notch tests failed mostly by creep accumulation, not by fatigue, with the crack origin shifting internally to a substantial distance away from the notch root. The classical von Mises plastic flow model was unable to match the experimental results while the hydrostatic stress profile generated using the Drucker–Prager plasticity flow model was consistent with the experimental findings. The max dwell NLCF and notch stress rupture tests exhibited substantial creep notch strengthening. The triaxial Bridgman effective stress parameter was able to account, with some limitations, for the notch strengthening by collapsing the notch and uniform gage geometry test data into a singular grouping.

Uniform gauge for D1-brane in general background

We construct uniform gauge D1-brane action in general background. We also discuss how this action transforms under double Wick rotation and determine transforma- tion properties of background fields.

Temporal Downscaling of Daily Gauged Precipitation by Application of a Satellite Product for Flood Simulation in a Poorly Gauged Basin and Its Evaluation with Multiple Regression Analysis

Abstract The study demonstrates that the temporal downscaling of rain gauge–measured precipitation with satellite-based precipitation estimates enhances the accuracy of hydrological simulations, especially for flood duration. Multiple regression analysis was examined to predict which hydrometeorological parameters have a significant influence on accuracy. The approach was examined at the Hương River basin in Vietnam (1520 km2), which is a mountainous region subject to heavy rainfall. The multisensor algorithm Global Satellite Mapping of Precipitation, version Moving Vector with Kalman (MVK; GSMaP_MVK; Psat), was employed to downscale the daily gauge precipitation measurements into 6-h time steps. Discharge in the rainy season in 2006–09 was simulated by a distributed hydrological model with 6-h time steps with four precipitation datasets: 6-h gauge (Pcontrol), daily uniform gauge (Puni), Psat, and the downscaled satellite product (Pds). Flood simulation with Pds performed better than that with Puni in 14 out of the 18 flood events, being close to the results with Pcontrol (median Nash–Sutcliffe efficiencies of 0.776, 0.261, and 0.710, respectively). Multiple regression analysis showed that the effectiveness of the downscaling method was significantly related to the bias and random errors of the satellite product. In conclusion, satellite-based precipitation measurements have potential for temporal downscaling of discharge simulations from daily to subdaily resolutions in moderate-sized watersheds that lack subdaily rainfall records, and the degree of simulation improvement can be estimated by statistical analysis. The suggested method can be broadly applied to watersheds where the daily precipitation is measured and when satellite-based precipitation measurements are available.

Integrable theories and generalized graded Maillet algebras

We present a general formalism to investigate the integrable properties of a large class of non-ultralocal models which in principle allows the construction of the corresponding lattice versions. Our main motivation comes from the subsector of the string theory on AdS5 × S5 in the uniform gauge, where such type of non-ultralocality appears in the resulting Alday–Arutyunov–Frolov (AAF) model. We first show how to account for the second derivative of the delta function in the Lax algebra of the AAF model by modifying Maillet’s r- and s-matrices formalism, and derive a well-defined algebra of transition matrices, which allows for the lattice formulation of the theory. We illustrate our formalism on the examples of the bosonic Wadati–Konno–Ichikawa–Shimizu (WKIS) model and the two-dimensional free massive Dirac fermion model, which can be obtained by a consistent reduction of the full AAF model, and give the explicit forms of their corresponding r-matrices.

Synthetic spin-orbit interactions and magnetic fields in ring-cavity QED

The interactions between light and matter are strongly enhanced when atoms are placed in high-finesse quantum cavities, offering tantalizing opportunities for generating exotic new quantum phases. In this work we show that both spin-orbit interactions and strong synthetic magnetic fields result when a neutral atom is confined within a ring cavity, whenever the internal atomic states are coupled to two off-resonant counter-propagating modes. We diagonalize the resulting cavity polariton Hamiltonian and find characteristic spin-orbit dispersion relations for a wide range of parameters. An adjustable uniform gauge potential is also generated, which can be converted into a synthetic magnetic field for neutral atoms by applying an external magnetic field gradient. Very large synthetic magnetic fields are possible as the strength is proportional to the (average) number of photons in each of the cavity modes. The results suggest that strong-coupling cavity quantum electrodynamics can be a useful environment for the formation of topological states in atomic systems.

Analyses of Higher Order Metrics for SPIHT Based Image Compression

The increasing use of digitized images has led to the need to compress such imagery to allow economical storage and fast data transfer. Despite all the advantages of JPEG compression schemes based on DCT namely simplicity, satisfactory performance, and availability of special purpose hardware for implementation; these are not without their shortcomings. The input image needs to be blocked which results in noticeable and annoying blocking artifacts particularly at low bit rates. So over the past several years, the wavelet transform has gained widespread acceptance in signal processing in general and in image compression research in particular. SPIHT codes the individual bits of the image wavelet transform coefficients following a bit-plane sequence. The evaluation of an image compression system is a difficult problem. While mean square error and peak signal to noise ratios are easily and commonly calculated, they are widely recognized to not to be completely satisfactory. The statistical parameters include high order image statistics like skewness and kurtosis which describe the shape and symmetry of the image. The aim of this paper is to provide a uniform gauge of the performance of data compression processes. In addition, it specifies how the performance of different data compression methods should be ranked so that the best compressor for a specific application can be identified. In the present work, three compression algorithms viz. the JPEG coding, the wavelet transform coding and the SPIHT coding have been discussed and compared.

Effect of intrinsic stress gradient on the effective mode-I fracture toughness of amorphous diamond-like carbon films for MEMS

The influence of intrinsic stress gradient on the mode-I fracture of thin films with various thicknesses fabricated for Microelectromechanical Systems (MEMS) was investigated. The material system employed in this study was hydrogen-free tetrahedral amorphous diamond-like carbon (ta-C). Uniform gauge microscale specimens with thicknesses 0.5, 1, 2.2, and 3 μm, containing mathematically sharp edge pre-cracks were tested under mode-I loading in fixed grip configuration. The effective opening mode fracture toughness, as calculated from boundary force measurements, was 4.25±0.7 MPa√m for 0.5-μm thick specimens, 4.4±0.4 MPa√m for 1-μm specimens, 3.74±0.3 MPa√m for 2.2-μm specimens, and 3.06±0.17 MPa√m for 3-μm specimens. Thus, the apparent fracture toughness decreased with increasing film thickness. Local elastic property measurements showed no substantial change as a function of film thickness, which provided evidence for the stability of the sp 2/sp 3 carbon binding stoichiometry in films of different thicknesses. Detailed experiments and finite element analysis pointed out that the dependence of the effective fracture toughness on specimen thickness was due to the intrinsic stress gradient developed during fabrication and post-process annealing. This stress gradient is usually unaccounted for in mode-I fracture experiments with thin films. Thicker films, fabricated from multiple thin layers, underwent annealing for extended times, which resulted in a stress gradient across their thickness. This stress gradient caused an out-of-plane curvature upon film release from its substrate and, thus, combined bending and tensile mode-I loading at the crack tip under in-plane forces. Since the bending component cannot be isolated from the applied boundary force measurements, its contribution, becoming important for thick films, remains unaccounted for in the calculation of the critical stress intensity factor, thus resulting in reduced apparent fracture toughness that varies with film thickness and curvature. It was concluded that in the presence of a stress gradient, accounting only for the average intrinsic stresses could lead in an overestimate of the fracture resistance of a brittle film. Under these considerations the material fracture toughness of ta-C, as determined from specimens with negligible curvature, is K IC=4.4±0.4 MPa√m.