Special Gauge Research Articles

Methodology for Studying the Wear of Drill Pipe Threads during Repeated Making up and Holding under Load

Purpose of reseach is to develop a methodology for studying the wear of drill pipe threads during repeated making up and holding under load. Methods. For the research, stand “IRS-1” was used. This stand is a device for creating a torque of up to 80 kNm and transferring it to a made-up pipe. It is equipped with a make-up torque sensor and a control system that performs make-up until the specified tightening torque is achieved or periodically applies the torque to the made-up thread pair. The test procedure for IRS-1 stand consists of the following sequence of actions: before starting the tests, the threaded protectors are removed; the threads on the nipple and sleeve are cleaned of the preservative grease and traces of corrosion by dry wiping and subsequent degreasing; the thread on the nipple is measured according to the measurement chart using a gauge. The gauge is made on the basis of the threaded surface impression and is a plate with cutouts in the form of a cross-section of four threads. The gap between the gauge and the thread is measured using a set of probes from 0.01 to 0.09 mm in increments of 0.01 mm, over 0.1 mm to 0.45 mm in increments of 0.05 mm, over 0.5 mm to 1 mm in increments of 0.1 mm. Results. A new tribotechnical stand of IRS-1 model was designed and created, which allows implementing various techniques for studying the wear of drill pipe threads during repeated making-up and holding under load. An important feature of the designed stand is a make-up torque sensor and a control system that perform make-up until the specified tightening torque is achieved or periodically applies the torque to the made-up threaded pair. The maximum torque generated by the stand is 80 kNm. A particular technique was developed. The technique includes the requirements of the API 7G-2 standard and has shown its effectiveness in the study of thread wear of steel drill pipes. To implement the technique, a special gauge was developed on the basis of the threaded surface impression and is a plate with cutouts in the form of a cross-section of four threads. Within this technique, a measurement chart with two selected measurement areas was developed. An algorithm for making up a pipe at a uniform speed was created. The algorithm includes three stages. There was developed an algorithm of measurements using reference marks, providing measurements at four points in each selected area. Conclusion. The results obtained can be used to create resource-saving technologies for processing ingot, powder, and nanocomposite materials with different dispersion of phase and structural components that are operated under extreme conditions and states.

A string theory realization of special unitary quivers in 3 dimensions

We propose a string theory realization of three-dimensional mathcal{N} = 4 quiver gauge theories with special unitary gauge groups. This is most easily understood in type IIA string theory with D4-branes wrapped on holomorphic curves in local K3’s, by invoking the Stückelberg mechanism. From the type IIB perspective, this is understood as simply compactifying the familiar Hanany-Witten (HW) constructions on a T3. The mirror symmetry duals are easily derived. We illustrate this with various examples of mirror pairs.

The role of U(1)\u2019s in 5d theories, Higgs branches, and geometry

We explore the Higgs branches of five-dimensional mathcal{N} = 1 quiver gauge theories at finite coupling from the paradigm of M-theory on local Calabi-Yau threefolds described as ℂ∗-fibrations over local K3’s. By properly counting local deformations of singularities, we find results compatible with unitary as opposed to special unitary gauge groups. We interpret these results by dualizing to both IIA on local K3’s with D6-branes, and to IIB with 5-branes. Finally, we find that, by compactifying the ℂ∗-fibers to tori, a well-known Stückelberg mechanism eliminates Abelian factors, and provides missing Higgs branch moduli in a very interesting way. This is also explained from the dual IIA and IIB viewpoints.

Performance assessment of railway track under the impact of longitudinal forces during the implementation of maximum traction modes when using electric locomotives with an asynchronous traction drive

Strategic task of increasing carrying capacity of railways requires a constant increase in the mass of trains due to the passage of heavy and coupled trains. Development of heavy haul traffic is one of the most significant technological solutions aimed at increasing efficiency of using the infrastructure's capacity. In this case, capabilities of the track infrastructure become decisive. The article presents the results of experimental studies of the performance of a continuous welded track under the influence of longitudinal forces arising from the motion of modern locomotives with an asynchronous traction drive in the modes of maximum traction and electrodynamic braking. It is shown that it is necessary to take these forces into account when calculating continuous welded track for strength and stability. The object of testing was a railway track under the influence of increased longitudinal forces during the motion of the 2EV120 electric locomotive with the implementation of various traction modes and electrodynamic braking. Tests were carried out on three sections of the Test Center's track of the JSC VNIIZhT, the experimental joint was equipped with special strain gauge pads designed to measure longitudinal forces. According to the research results, it can be noted that the longitudinal forces in the rails caused by the implementation of the maximum traction forces and electrodynamic braking can reach up to 25 % of the maximum temperature forces. The real forces of resistance to the longitudinal displacement of rails in the nodes of intermediate fasteners when tightened with the force provided by the standards are about 3-4 kN, which is significantly lower than the standard values of 14-16 kN, and may be a consequence of the wear of the elements of intermediate fasteners and the state of friction surfaces. These phenomena can cause longitudinal displacement of both individual rail lines and the grid as a whole. The development of a set of measures to prevent this phenomenon requires a wide range of studies in real operating conditions, including optimization of traction and braking modes of driving heavy haul trains.

3d mirrors of the circle reduction of twisted A2N theories of class S

Mirror symmetry has proven to be a powerful tool to study several properties of higher dimensional superconformal field theories upon compactification to three dimensions. We propose a quiver description for the mirror theories of the circle reduction of twisted A2N theories of class S in four dimensions. Although these quivers bear a resemblance to the star-shaped quivers previously studied in the literature, they contain unitary, symplectic and special orthogonal gauge groups, along with hypermultiplets in the fundamental representation. The vacuum moduli spaces of these quiver theories are studied in detail. The Coulomb branch Hilbert series of the mirror theory can be matched with that of the Higgs branch of the corresponding four dimensional theory, providing a non-trivial check of our proposal. Moreover various deformations by mass and Fayet-Iliopoulos terms of such quiver theories are investigated. The fact that several of them flow to expected theories also gives another strong support for the proposal. Utilising the mirror quiver description, we discover a new supersymmetry enhancement renormalisation group flow.

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.

A validated high-performance thin-layer chromatography method for quantification of bavachin, bakuchiol, and psoralen from Psoralea corylifolia seeds

A sensitive and reliable high-performance thin-layer chromatography method has been developed for the simultaneous estimation of bavachin, bakuchiol, and psoralen in Psoralea corylifolia seeds. The methanolic extract of the seeds was applied on a silica gel G 60 F254 plate. The plate was developed using toluene–ether, 1:1, saturated with 10% acetic acid (v/v) as the mobile phase and detection and quantification were performed by densitometric scanning at 254 nm. The correlation coefficients were found to be 0.999, 0.999, and 0.999 for bavachin, bakuchiol, and psoralen, respectively, in the developed method. The accuracy of the method was confirmed by conducting recovery studies at different levels using the standard addition method. The average recovery of bavachin, bakuchiol, and psoralen was found to be close to 98% confirming the accurateness of the method. The proposed method offers a new, sensitive, specific, and precise gauge for quantification of bavachin, bakuchiol, and psoralen representing all the categories of bioactive constituents in P. corylifolia.

Enhancement of Withstand Voltage in Silicon Strain Gauges Using a Thin Alkali-Free Glass.

We present a cost-effective approach to produce silicon strain gauges that can withstand very high voltage without using any complex package design and without sacrificing any sensor performance. This is achieved by a special silicon strain gauge structure created on an alkali-free glass substrate that has a high breakdown voltage. A half-bridge silicon strain gauge is designed, fabricated, and then tested to measure its output characteristics. The device has a glass layer that is only 25–55 µm thick; it shows it is able to withstand a voltage of over 2000 V while maintaining a high degree of linearity with correlation coefficients higher than 0.9990 and an average sensitivity of 104.13. Due to their unique electrical properties, silicon strain gauges-on-glass chips hold much promise for use in advanced force and pressure sensors.

Real-time error correction of two-dimensional flood-inundation simulations during rainstorm events

This study develops a real-time error correction model named RTEC_2DIS for two-dimensional (2D) flood-inundation simulations. Inundation depth and flooding area provided by a 2D numerical hydraulic modeling (SOBEK model) are corrected in accordance with real-time observations at specific road-based water-level gauges. The proposed RTEC-2DIS method can estimate the forecast error of inundation depths for various lead times at both gauged grids and ungauged grids within the watershed/basin. By doing so, the real-time correction of the resulting inundation area composed of corrected water-depth forecast at all concerned grids can be achieved by adding the water-depth forecasts to the corresponding forecast errors. In this study, the demonstration of the model is made in the Tainan district in Southern Taiwan under the consideration of the design rainstorm events of specific return periods with a central-peak storm pattern and a real rainstorm event from Typhoon Megi in 2016. The results from the numerical demonstration indicate that the RTEC-2DIS method can effectively reduce the uncertainty in the estimating inundation depth at gauged grids to enhance its correction performance with the percentage of error reduction of 42% in the case of the real rainstorm event. Furthermore, regarding the design events, through the proposed RTEC-2DIS method, the accuracy of the simulated inundation area can be improved by 55%. In summary, the proposed RTEC-2DIS method not only can correct forecasted inundation depths at gauged grids, but also facilitate the accuracy and reliability of the resulting inundation area in accordance with real-time observations recorded at road-based water-level gauges.

Energy and helicity fluxes in line-tied eruptive simulations

Context.Conservation properties of magnetic helicity and energy in the quasi-ideal and low-βsolar corona make these two quantities relevant for the study of solar active regions and eruptions.Aims.Based on a decomposition of the magnetic field into potential and nonpotential components, magnetic energy and relative helicity can both also be decomposed into two quantities: potential and free energies, and volume-threading and current-carrying helicities. In this study, we perform a coupled analysis of their behaviors in a set of parametric 3D magnetohydrodynamic (MHD) simulations of solar-like eruptions.Methods.We present the general formulations for the time-varying components of energy and helicity in resistive MHD. We calculated them numerically with a specific gauge, and compared their behaviors in the numerical simulations, which differ from one another by their imposed boundary-driving motions. Thus, we investigated the impact of different active regions surface flows on the development of the energy and helicity-related quantities.Results.Despite general similarities in their overall behaviors, helicities and energies display different evolutions that cannot be explained in a unique framework. While the energy fluxes are similar in all simulations, the physical mechanisms that govern the evolution of the helicities are markedly distinct from one simulation to another: the evolution of volume-threading helicity can be governed by boundary fluxes or helicity transfer, depending on the simulation.Conclusions.The eruption takes place for the same value of the ratio of the current-carrying helicity to the total helicity in all simulations. However, our study highlights that this threshold can be reached in different ways, with different helicity-related processes dominating for different photospheric flows. This means that the details of the pre-eruptive dynamics do not influence the eruption-onset helicity-related threshold. Nevertheless, the helicity-flux dynamics may be more or less efficient in changing the time required to reach the onset of the eruption.

Unitary quantization of a scalar charged field and Schwinger effect

Quantum field theory in curved spacetimes suffers in general from an infinite ambiguity in the choice of Fock representation and associated vacuum. In cosmological backgrounds, the requirement of a unitary implementation of the field dynamics in the physical Hilbert space of the theory is a good criterion to ameliorate such ambiguity. In- deed, this criterion, together with a unitary implementation of the symmetries of the equations of motion, leads to an equivalence class of unitarily equivalent quantizations that, even though it is still formed by an infinite number of Fock representations, is unique. In this work, we apply the procedure developed for fields in cosmological settings to analyze the quantization of a scalar field in the presence of an external electromagnetic classical field in a flat background. We find a natural Fock representation that admits a unitary implementation of the quantum field dynamics. It automatically allows to define a particle number density at all times in the evolution with the correct asymptotic behavior, when the electric field vanishes. Moreover we show the unitary equivalence of all the quantizations that fulfill our criteria, so that they form a unique equivalence class. Although we perform the field quantization in a specific gauge, we also show the equivalence between the procedures taken in different gauges.

Gluon radiation from a classical point particle. II. Dense gluon fields

The goal of this paper is to extend the results of Ref. [1], where formulae were derived for gluonic radiation for a high energy nucleus colliding with a classical colored particle. In Ref. [1], we computed the amplitudes for radiation in the fragmentation region of the particle for a dilute gluonic field. In this paper, we compute the radiation by solving the fluctuation equations of the dense background field in a specific gauge which makes it simple to solve the asymptotic radiation from an initial condition immediately after the passage of the nucleus. We identify and compute two components of gluon radiation, a bulk component which extends to the central region and bremsstrahlung, which may give rise to an experimentally observable intensity peak in the target fragmentation region.

Scalar-field dark energy nonminimally and kinetically coupled to dark matter

We provide a general framework for studying the dark energy cosmology in which a scalar field $\phi$ is nonminimally and kinetically coupled to Cold Dark Matter (CDM). The scalar-graviton sector is described by the action of Horndeski theories with the speed of gravitational waves equivalent to that of light, whereas CDM is treated as a perfect fluid given by a Schutz-Sorkin action. We consider two interacting Lagrangians of the forms $f_1(\phi,X)\rho_c (n_c)$ and $f_2 (n_c, \phi,X) J_c^{\mu} \partial_{\mu}\phi$, where $X=-\partial^{\mu} \phi \partial_{\mu} \phi/2$, $\rho_c$ and $n_c$ are the energy density and number density of CDM respectively, and $J_c^{\mu}$ is a vector field related to the CDM four velocity. We derive the scalar perturbation equations of motion without choosing any special gauges and identify conditions for the absence of ghosts and Laplacian instabilities on scales deep inside the sound horizon. Applying a quasi-static approximation in a gauge-invariant manner, we also obtain the effective gravitational couplings felt by CDM and baryons for the modes relevant to the linear growth of large-scale structures. In particular, the $n_c$ dependence in the coupling $f_2$ gives rise to an interesting possibility for realizing the gravitational coupling with CDM weaker than the Newton gravitational constant $G$.

On constant solutions of SU(2) Yang-Mills equations with arbitrary current in Euclidean space ℝn

In this paper, we present all constant solutions of the Yang-Mills equations with SU(2) gauge symmetry for an arbitrary constant non-Abelian current in Euclidean space ℝn of arbitrary finite dimension n. Using the invariance of the Yang-Mills equations under the orthogonal transformations of coordinates and gauge invariance, we choose a specific system of coordinates and a specific gauge fixing for each constant current and obtain all constant solutions of the Yang-Mills equations in this system of coordinates with this gauge fixing, and then in the original system of coordinates with the original gauge fixing. We use the singular value decomposition method and the method of two-sheeted covering of orthogonal group by spin group to do this. We prove that the number (0, 1, or 2) of constant solutions of the Yang-Mills equations in terms of the strength of the Yang-Mills field depends on the singular values of the matrix of current. The explicit form of all solutions and the invariant F2 can always be written using singular values of this matrix. The relevance of the study is explained by the fact that the Yang-Mills equations describe electroweak interactions in the case of the Lie group SU(2). Non-constant solutions of the Yang-Mills equations can be considered in the form of series of perturbation theory. The results of this paper are new and can be used to solve some problems in particle physics, in particular, to describe physical vacuum and to fully understand a quantum gauge theory.

A 2D Real-Time Flood Forecast Framework Based on a Hybrid Historical and Synthetic Runoff Database

Operational real-time flood forecast is often done on the prediction of discharges at specific gauges using hydrological models. Hydrodynamic models, which can produce inundation maps, are computationally demanding and often cannot be used directly for that purpose. The FloodEvac framework has been developed in order to enable 2D flood inundations map to be forecasted at real-time. The framework is based on a database of pre-recorded synthetic events. In this paper, the framework is improved by generating a database based on rescaled historical river discharge events. This historical database includes a wider variety of runoff curves, including non-Gaussian and multi-peak shapes that better reflect the characteristics and the behavior of the natural streams. Hence, a hybrid approach is proposed by joining the historical and the existing synthetic database. The increased number of scenarios in the hybrid database allows reliable predictions, thus improving the robustness and applicability of real-time flood forecasts.

A User-Printable Three-Rate Rain Gauge Calibration System

Our objective was to develop and validate a freely downloadable, open-source, 3D printed rain gauge calibrator that can be adjusted for a wide range of gauges. The calibrator applies constant low, medium, and high-intensity water delivery rate, and allows the user to modify the design to conform to their system based on parametric design. The design may be modified and printed using freely available computer-aided design (CAD) software. Currently available devices for calibration tend to be designed for specific rain gauges, are expensive, employ low-precision water reservoirs, are not field portable, and do not offer the flexibility needed to test the ever more popular small-aperture rain gauges (smaller surface area to catch precipitation than the classical 200mm standard). To overcome the fact that different 3D printers yield different print qualities, we devised a simple post-printing step that controls critical dimensions to assure robust performance. Specifically, orifices of the calibrator are drilled to reach the target flow rates. Laboratory tests showed that flow rates of 25, 50, and 83 ml/min were consistent between prints (coefficient of variation of 3.9, 2.2, and 1.8, % respectively), and between trials of each part, while the total applied water was precisely controlled (0.1%) by the use of a volumetric flask as the reservoir. The entire system costs under US$10.

Fakeons, unitarity, massive gravitons, and the cosmological constant

We give a simple proof of perturbative unitarity in gauge theories and quantum gravity using a special gauge that allows us to separate the physical poles of the free propagators, which are quantized by means of the Feynman prescription, from the poles that belong to the gauge-trivial sector, which are quantized by means of the fakeon prescription. The proof applies to renormalizable theories, including the ultraviolet complete theory of quantum gravity with fakeons formulated recently, as well as low-energy (nonrenormalizable) theories. We clarify a number of subtleties related to the study of scattering processes in the presence of a cosmological constant Λ. The scattering ampli- tudes, defined by expanding the metric around flat space, obey the optical theorem up to corrections due to Λ, which are negligible for all practical purposes. Problems of interpretation would arise if such corrections became important. In passing, we obtain local, unitary (and “almost” renormalizable) theories of massive gravitons and gauge fields, which violate gauge invariance and general covariance explicitly.

Landau-like quantized levels of neutral atom induced by a dark-soliton shaped electric field**Project supported by China Scholarship Council, Shanxi Province Natural Science Foundation, China (Grant No. 201601D011009), the Enterprise Project (Grant No. 01110116100051), Shanxi 1331KSC and 111 Project (Grant No. D18001), and the National Natural Science Foundation of China (Grant Nos. 11404415 and 61873154).

Motivated by the fascinating progresses in the cold atom experiments and theories, especially the artificial gauge field induced spin–orbit coupling of neutral atoms, we present a novel dispersion of neutral atoms carrying a non-vanishing magnetic moment in a special gauge field, an external electric field of dark-soliton shaped profile. By means of WKB approximation, we obtain discrete quantized landau-like energy levels, which is instructive for the quantum Hall effect of neutral particles. The observability of the results is also discussed.

Soldering spin-3 opposite helicities in D=2+1

Here we present the `soldering' of opposite helicity states of a spin-3 particle, in $D=2+1$, into one parity doublet. The starting points may be either the sixth- or the fifth-order (in derivatives) spin-3 self-dual models of opposite helicities. The high number of derivatives avoids the use of auxiliary fields which has been so far an obstacle for a successful soldering procedure. The resulting doublet model is a new Lagrangian with six orders in derivatives and no auxiliary field. It may be regarded as a spin-3 analogue of the linearized `New Massive Gravity'. We check its particle content via a gauge invariant and Lorentz covariant analysis of the analytic structure of the two-point amplitude with the help of spin-3 analogues of the Barnes and Rivers projection operators. The particle content is alternatively confirmed in a specific non-covariant gauge by a decomposition in helicity variables. The soldered model is ghost free and contains two physical states as expected for a parity doublet.

Electrodynamics in the 't Hooft gauge, a covariant operator approach

This article is devoted to describe the 't Hooft gauge electrodynamics by means of non-perturbative methods together with Heisenberg perturbation theory insights. The point is that this specific gauge choice introduces a non-linear photon field self interaction. So, this model is analyzed in a BRST framework in analogy to the non-Abelian cases. Finally, we show that the asymptotic transverse photon modes are the same as that of the linear gauge well known case while just the non-physical longitudinal sector get renormalized by such gauge self interaction. Then the physical gauge independence is explicitly verified.