Bar State Research Articles

An Enhanced Path Finder Algorithm for the estimation of the stator current envelope to detect rotor bar breakage in an induction motor

The Enhanced Path Finder Algorithm (EPFA) is used in this research to present an innovative approach for examining the state of the rotor bars in an induction motor, employing a hybrid metaheuristic algorithm. Compared to current optimization techniques, the suggested approach permits more balanced exploration and exploitation. The method addresses the drawbacks of traditional analysis of fault related frequencies, such as short data length, spectrum leakages, and inadequate sampling frequency. The primary goal of this research is to identify the twice-slip frequency component and its harmonics in the current envelope that correlates with the fault. The A signal model of the stator current envelope and the residual error function have been used to define a nonlinear least-squares problem. An induction machine model has been developed in 2D ANSYS Maxwell software where faults have been implemented and studied. Finally, the efficiency of the fault detection scheme has been verified with a practical data set.

Theoretical and Experimental Analysis of a 44 Recongurable MZI-Based Linear Optical Processor

A 4 4 reconfigurable Mach-Zehnder interferometer (MZI)-based linear optical processor is investigated through its theoretical analyses and characterized experimentally. The linear transformation matrix of the structure is theoretically determined using its building block, which is a 2 2 reconfigurable MZI. To program the device, the linear transformation matrix of a given application is decomposed into that of the constituent MZIs of the structure. Thus, the required phase shifts for implementing the transformation matrix of the application by means of the optical processor are determined theoretically. Due to random phase offsets in the MZIs resulting from fabrication process variations, they are initially configured through an experimental protocol. The presented calibration scheme allows to straightforwardly characterize the MZIs to mitigate the possible input phase errors and determine the bar and cross states of each MZI for tuning it at the required sate before programming the device. After the configuration process, the device can be programmed to construct the linear transformation matrix of the application. In this regard, using the required bias voltages, the phase shifts obtained from the decomposition process are applied to the phase shifters of the MZIs in the device.

Dynamic bond stress-slip relationship of steel reinforcing bars in concrete based on XGBoost algorithm

The bond stress-slip relationship between a deformed steel bar and concrete under various loading rates is required to appropriately simulate the ultimate conditions of concrete structures under dynamic loading. Furthermore, the corresponding key bond parameters are crucial to ensure the accuracy of the bond-slip model. This study analyzed the effect of concrete strength, geometric profile of steel bar, concrete cover, and stress state around the bond region on the dynamic bond parameters and bond-slip curves. For this purpose, a database containing 1056 pullout specimens was established, which was used to train three ensemble learning models, including Extreme Gradient Boosting Decision Tree (XGBoost), Gradient Boosting Regression Tree, and Random Forest, thereby predicting the bond parameters. The ensemble learning models exhibited higher accuracy than existing empirical models, with the XGBoost algorithm attaining the highest accuracy. Furthermore, the predicted bond parameters were found to express the bond response of the steel bar under different loading rates and lateral confinements with good accuracy. The model proposed in this study provides a new approach for determining the bond parameters and improves the accuracy of bond stress-slip model.

The dynamical state of bars in cluster dwarf galaxies: the cases of NGC 4483 and NGC 4516

ABSTRACT Dwarf barred galaxies are the perfect candidates for hosting slowly rotating bars. They are common in dense environments and have a relatively shallow potential well, making them prone to heating by interactions. When an interaction induces bar formation, the bar should rotate slowly. They reside in massive and centrally concentrated dark matter haloes, which slow down the bar rotation through dynamical friction. While predictions suggest that slow bars should be common, measurements of bar pattern speed, using the Tremaine–Weinberg method, show that bars are mostly fast in the local Universe. We present a photometric and kinematic characterization of bars hosted by two dwarf galaxies in the Virgo Cluster, NGC 4483, and NGC 4516. We derive the bar length and strength using the Next Generation Virgo Survey imaging and the circular velocity, bar pattern speed, and rotation rate using spectroscopy from the Multi-Unit Spectroscopic Explorer. Including the previously studied galaxy IC 3167, we compare the bar properties of the three dwarf galaxies with those of their massive counterparts from literature. Bars in the dwarf galaxies are shorter and weaker, and rotate slightly slower with respect to those in massive galaxies. This could be due to a different bar formation mechanism and/or to a large dark matter fraction in the centre of dwarf galaxies. We show that it is possible to push the application of the Tremaine–Weinberg method to the galaxy low-mass regime.

Mode thermo-optic coefficient engineering of sub-wavelength gratings and its application for a mode-insensitive switch.

It is shown that the thermo-optic (TO) coefficients of various waveguide modes of a sub-wavelength grating (SWG)-assisted strip waveguide is closely dependent on the various waveguide parameters with different dependencies, including the SWG width, strip waveguide width, duty cycle, and pitch. This offers what we believe to be new degrees of freedom in the design of TO coefficients for integrated-optic waveguides, opening the door to engineering the TO coefficients of individual spatial modes or polarization states using sub-wavelength structures. Such a capability is expected to offer new design possibilities for a variety of integrated photonic, thermo-optic devices. To demonstrate the application of the concept, a mode-insensitive switch on silicon-on-insulator using a TO coefficient-engineered SWG as a mode-independent, thermo-optic phase shifter is designed and experimentally demonstrated. The experimental results show that the switching powers of the TE0-TE2 modes are only ∼29 mW, and the maximum extinction ratios for the cross (bar) states are 38.2 dB (31 dB), 37.9 dB (37 dB), and 31.9 dB (20.5 dB) for the TE0-TE2 modes, respectively, at the wavelength of 1550 nm.

Spatiotemporal dynamics and present perception of gravel bars in natural and regulated environments

Gravel bars represent unique habitats in gravel bed rivers. These formations are endangered by river management affecting the channel natural behavior and flow conditions. This could result in the initial loss of gravel bar dynamic, leading to overgrowth of vegetation and degradation. The main aim of this study is to analyze spatiotemporal changes and public perception of gravel bars and their vegetation in regulated and natural river environments. We combine sociological and geomorphological research to better understand the current state of gravel bar dynamics and the public view of them, which is beneficial information for any future management of gravel bar habitat. We examined the 77 km-long fluvial corridor of the Odra River (Czechia) between 1937 and 2020 using aerial images for mapping gravel bars and assessment of morphodynamics. For the public perception, we conducted an online survey with photosimulations of different gravel bar environments and states of vegetation.Gravel bars were most frequent in natural reaches associated with intensive morphodynamics in wide channel segments and meanders of high amplitude. The length of the regulated river channel increased during the studied period and gravel bars were reduced. In 2000–2020, the trend was toward overly vegetated and stable gravel bars. The public perception data indicated a high preference for fully vegetated gravel bars in terms of naturalness, aesthetics, and vegetation cover in both natural and regulated environments. This emphasizes a misleading public view regarding unvegetated gravel bars as an unpopular feature that should be vegetated or removed for it to be perceived as natural or aesthetic. These findings should encourage better gravel bar management and change in the public's negative perception of unvegetated gravel bars.

Structure and strain state of aluminum bars at the initial phase of extrusion

The structure of insufficiently deformed areas at the non-steady phase of extrusion was studied. The tests at Kamensk Uralsky Metallurgical Works using a 120 MN press and 800 mm dia. container, in order to extrude a 355.6 mm dia. Bar was performed. The bar material is the Al–Mg–Si AD33 aluminum alloy (GOST 4784), similar to ASTM 6061. The percentage reduction was 80 %, and the reduction ratio was 5.06. After that, the macrostructure, microstructure, and average grain size along the radius, mechanical properties at room and elevated temperatures were investigated. It was found that the extruded bar macrostructure is fine-grained, homogeneous, and dense, with no nonmetallic or intermetallic inclusions. The cross-section contained several structures. The central part is weakly deformed preserving the dendritic cell structure inherited from the casting. At the circumference, a streaked structure is formed. Its components are crushed and uniformly distributed. We measured the strength at elevated temperatures and compared the results to the data available in the literature. The tested material strength almost doubled, thus indicating its incomplete softening. The ductility was also performed. The DEFORM-2D software, in order to simulate the low reduction of extrusion was used. The metal at the circumference is exposed to a greater strain from the extrusion beginning. A step-by-step analysis indicated that at the first step, the strain is localized near the die hole. In the second step, a rigid area is formed in the vicinity of the die/container liner interface. The circumference layer of metal with a 1.75–2.00 reduction of area is formed. At the bar center, this range is 0.75–1.00 (half of the circumference value). In the third step, the circumference layer with an elevated strain has a wedge-like shape. In the fourth step, the circumference layer (with elevated strain) has an equal thickness along the extrusion axis. This indicates the steady phase. The plastic strain at the bar front end is higher at the circumference than in the center. This confirms the structural analysis results. They show that the central part of the bar may retain its cast structure, while the circumference is deformed. If the bar central part is required to have some specific properties, the bar has to undergo another manufacturing operation to increase the accumulated strain. Re-extrusion processes the areas insufficiently deformed during the first extrusion.

Shape memory alloy reinforcement for strengthening of RCC structures—A critical review

Significant performance and safety issues can arise from the deterioration of reinforced concrete (RC) structural components brought on by ageing processes and high stress occurrences. Shape memory alloys (SMAs), one of the options for restoring such components, have special qualities including recovering inelastic strain when unloaded (super elasticity) or heated (shape memory effect, SME). To lessen permanent deformations into RC constructions, super elasticity and SME of SMA bars can be used. The stiffness and strength of RC structures can also be improved by the addition of SMAs, allowing them to withstand loads of high intensities with minimal damage. Despite the wide range of studies done on the applications of SMAs in structures, a comprehensive analysis of the present state, key results, potential drawbacks, and future contemplation of SMA bars for the reinforcement of RC structures lacking in the literature. Additionally, detailed instructions for choosing the types and traits of SMAs best suited for a certain strengthening application are lacking. We conducted an extensive examination of the applications of SMA bars in RC beams, in order to fill the basic and practical gaps that were observed. The implementations were investigated from the viewpoints of crack recovery, strength augmentation, confinement, and shear strengthening of new and existing RC structures. The benefits and drawbacks of strengthening with SMAs are then discussed critically, particularly in light of other strengthening techniques and materials. The end of this review highlights the challenges of using SMAs as well as potential future opportunities that might arise from their effective use of RCC.

Design and analyses of BER performance in a tri-directional optical transmission system

The aim of the paper is to verify the stability of the tri-directional fiber transmission system. The design of transmission methods is different wavelengths modulated in the electrical signal of 10 Gbit/s and 2.5 Gbit/s based on the corresponding architectures. The goals are to measure the influence of the signal with the same and adjacent channel interference. The experimental architecture is designed in parallel. We chose the wavelength of 1552.5 nm as the receiving signal to keep the scheme working in the same conditions for comparison. In addition, we insert an additional 25 km and 50 km single-mode fiber (SMF). The result shows that power penalty can be improved within a range of 2–3 dB if a bandpass filter (BPF) is inserted before the measurement equipment. The standard in the experiment requires a wavelength spacing of 0.8 nm between each channel. The result shows that in transmission methods with different wavelengths and distances, the power penalties are 0.304 dB, 0.595 dB, and 1.173 dB, respectively. As the transmission speed decreases with different distances of 0 km, 25 km, and 50 km, the power penalties are 0.101 dB, 0.385 dB, and 0.538 dB, respectively. With the hybrid speed under different distances, the power penalties are 0.278 dB, 0.404 dB, and 0.551 dB. The tri-directional transmission can be divided into with or without an optical switch connection, while the function of the optical switch is to divide the system into the cross and parallel switching modes. According to experimental results, the power loss is in a range of 2–4 dB, and the power reimbursement is slightly increased by 0.1–0.2 dB. To compare the results with the worst condition, the power penalties for no optical switch (OSW), OSW in bar state, and OSW in cross state are 0.756 dB, 0.317 dB, and 0.329 dB, respectively.

High accurate self-calibration of photonic integrated circuit using lossless thermo-optic phase shifters.

The accurate calibration of large-scale switch networks is critical for integrated photonics, in which the integrated optical true time delay chip is typical. In this work, a novel self-calibration method without extra testing ports is proposed by introducing lossless thermo-optic phase shifters instead to calibrate the network. As a demonstration, a 5-bit delay line based on silicon nitride is fabricated and calibrated. The extinction ratio of all the switches is greater than 30.9 dB at the cross and bar states. Using this method, the 5-bit optical delay line which can be tuned in a range of 118.53 ps and reach a low delay time deviation less than ±0.4 ps.

Generalized formula for estimating the oscillation frequency response of a cantilever bar with point masses

This paper presents a study of natural oscillations of a cantilever bar with five point masses with variable geometric and stiffness parameters (distances between locations of the masses, coefficients of variability of the bending stiffness of the bar sections). Using the exact method of forces based on the Mohr formula, there have been obtained expressions in general form for calculating the main unit coefficients of the secular equation, which makes it possible to perform calculations and to determine the oscillation frequency response of natural oscillations with a wide range of changes in the initial parameters of the physical and geometric state of cantilever bars. A numerical example has been given to illustrate the proposed theoretical approaches. The results have been compared with the results based on calculating a similar can tilever bar with one( reduced by masses) degree of freedom. A graphical dependence of the oscillation frequency response value on changing the value of the bending stiffness along the length of the cantilever bar gas been obtained. The theoretical provisions and applied results presented in the work will be widely used both in the practical design of bar systems and in scientific research in the field of mechanics of a deformable solid body.

Photonic Crystal Based All-Optical Switch Using a Ring Resonator and Kerr Effect

ABSTRACT This paper proposes an all-optical switch using Kerr-type nonlinearity based on a photonic crystal ring resonator (PCRR). For the first time, the bar state and cross-state operation with 2 × 2 elements of an optical switch is implemented using a nonlinear ring resonator. Chalcogenide glass rods are used in the air background to simulate the proposed structure. The operating wavelength for this structure is calculated to be 1551 nm using the finite element method. The functional parameters such as the extinction ratio, response time, bit rate, crosstalk, and insertion loss values are studied using the finite-difference time-domain (FDTD) method. The presented structure design has a fast data rate of 0.46 Tbps, a low crosstalk value of −17.14 dB, and a fast response time of 2.16 ps. The proposed optical switch has a total footprint of about 398.56 μm2. The device’s performance makes it suitable for switching applications and integration in all-optical circuits.

Study on electrochemical characteristics of reinforced concrete corrosion under the action of carbonation and chloride

Considering parameters of corrosion area ratio and mass loss degree, the half-cell potential method and linear polarization method were applied to study the corrosion state of steel bars under the influence of carbonation, chloride salt and compound environmental action. X-ray photoelectron spectroscopy (XPS) was used to measure steel corrosion under coupling action and the effect of sodium nitrite rust inhibitor in the compound environment was studied. The results show that the corrosion rate of steel under carbonation, chloride salt and compound environment increases in the beginning and then decreases. In the chloride environment, sufficient moisture inside the concrete at the initial stage of curing induces a faster corroding. With the destruction of the passive film on the surface of the steel bars together with the balance of internal and external humidity, the corrosion rate tends to stabilize. At the following curing stage, the corrosion rate decreases as the degree of steel corrosion increases and the corrosion layer is formed. Carbonation reduces the alkalinity around the passive film and damages the passive film, which accelerates the corrosion happening. The following development of the corrosion layer of steel bars limits the corrosion rate. The corrosion degree in the compound environment is more serious than that under the condition of single factor action. Under electrochemical action, the order of product components resulting from steel corrosion are Fe2O3, Fe3+-Ca2SiO4 and FeO from high to low. Nitrite oxidizes the unstable Fe2+ into stable Fe3+ and precipitates on the surface of the steel to form a passivation film, which has a good anti-rust effect.

Cryogenic electro-optic modulation in titanium in-diffused lithium niobate waveguides

Lithium niobate is a promising platform for integrated quantum optics. In this platform, we aim to efficiently manipulate and detect quantum states by combining superconducting single photon detectors and modulators. The cryogenic operation of a superconducting single photon detector dictates the optimisation of the electro-optic modulators under the same operating conditions. To that end, we characterise a phase modulator, directional coupler, and polarisation converter at both ambient and cryogenic temperatures. The operation voltage of these modulators increases, due to the decrease in the electro-optic effect, by 74% for the phase modulator, 84% for the directional coupler and 35% for the polarisation converter below 8.5. The phase modulator preserves its broadband nature and modulates light in the characterised wavelength range. The unbiased bar state of the directional coupler changed by a wavelength shift of 85 while cooling the device down to 5. The polarisation converter uses periodic poling to phasematch the two orthogonal polarisations. The phasematched wavelength of the utilised poling changes by 112 when cooling to 5.

Detection of Jacket Offshore Wind Turbine Structural Damage using an 1D-Convolutional Neural Network with a Support Vector Machine Layer

Because offshore wind turbines, particularly their foundations, operate in hostile environments, implementing a structural health monitoring system is one of the best ways to monitor their condition, schedule maintenance, and predict possible fatal failures at lower costs. A novel strategy for detecting damage in offshore wind turbine jacket foundations is developed in this work, based on a vibration monitoring methodology that reshapes the data into a multichannel array, with as many channels as correlated sensors with the predicted variable, a 1-D deep convolutional neural network to extract temporal features from the monitored data, and a support vector machine as a final classification layer. The obtained model allows the detection of three types of bar states: healthy bar, cracked bar, and bar with an unlocked bolt.

Design method of serviceability limit states of BFRP bar reinforced ecological high ductility concrete beam: Experimental and theoretical analysis

Ecological high ductility concrete (Eco-HDC) has a larger tensile deformation than normal concrete, and Eco-HDC can be used to cast bridge deck link slab in negative moment zone. To acquire the flexural design method of bridge deck link slab made by BFRP (basalt fiber reinforced polymer) bar reinforced Eco-HDC, serviceability limit states of beam containing crack width and deflection are studied through the experimental and theoretical analysis. Test variables are diameter of BFRP bar, cover thickness and loading regime. Increasing the BFRP bar diameter or decreasing the cover thickness is an efficient method to decrease the maximum crack width. Cyclic loading type is also beneficial to reduce the maximum crack width. Besides, as the diameter increases, the peak deflection increases within a diameter of 8 mm ∼ 12 mm, and then decreases. Beam with a larger cover thickness has a lower peak deflection. Peak deflection is independent on the loading regime. Formulas in design codes are adopted to predict the maximum crack width and peak deflection, and the formulas are proposed to evaluate the test results. In addition, maximum crack width limit, maximum limit of stress and strain in Eco-HDC and BFRP bar are the governing parameters to compute the reinforcement ratio of BFRP bar in the design of bridge deck link slab.

Lost in Translation

As a reciprocal contract, Islamic marriage (nikāḥ) furnishes rights and obligations for both spouses. Usually split into two portions, the deferred part of the bridal dower (mahr muʾakhkhar)—a one-time financial liability that both spouses agree on during the wedding proceedings—is customarily received by the Muslim wife where her husband seeks to divorce her unilaterally (ṭalāq). However, US courts faced with construing mahr-agreements have been reluctant to enforce the financial promises stipulated in such agreements. Based on evidence gathered from case law, this article argues that a combination of several factors, most importantly, the judicial anxiety to get involved in religious doctrinal interpretation, as well as the misinformed analogizing of bridal dowers to prenuptial agreements, adversely affects Muslim women as courts increasingly adhere to the presumption that mahr-agreements are non-enforceable, squarely placing the burden of proof to the contrary on women. Moreover, women's financial hardship is often the immediate result of the court's refusal to uphold a husband's commitment to pay dower. As a critical feature of Islamic marriage, the agreed-on dower payment assures financial stability after divorce, predictability, and women's bargaining power throughout a marital relationship. Since 2013, state legislators' partially successful endeavors to bar state courts from applying Islamic law under comity function as a compounding factor that has created dire prospects for the future of mahr-agreements in the US, posing a substantial risk not only to the institution of Islamic marriage, but also the parties’ freedom of contract.

Diagnosis of Broken Rotor Bars during the Startup of Inverter-Fed Induction Motors Using the Dragon Transform and Functional ANOVA

A proper diagnosis of the state of an induction motor is of great interest to industry given the great importance of the extended use of this motor. Presently, the use of this motor driven by a frequency converter is very widespread. However, operation by means of an inverter introduces certain difficulties for a correct diagnosis, which results in a signal with higher harmonic content and noise level, which makes it difficult to perform a correct diagnosis. To solve these problems, this article proposes the use of a time-frequency technique known as Dragon Transform together with the functional ANOVA statistical technique to carry out a proper diagnosis of the state of the motor by working directly with the curves obtained from the application of the transform. A case study is presented showing the good results obtained by applying the methodology in which the state of the rotor bars of an inverter-fed motor is diagnosed considering three failure states and operating at different load levels.

Resonant bistable 2 × 2 crossbar switches using dual nanobeams clad with phase-change material

We present the first bistable 2 × 2 crossbar switches using dual suspended nanobeams with phase changing Ge2Sb2Se4Te1 (GSST) cladding material. The dual suspended nanobeam configuration gives a higher-temperature pulse that will efficiently change the phase of a nanoscale GSST cladding on each nanobeam cavity region. The compact resonant 2 × 2 Mach–Zehnder switch has stable cross and bar states corresponding to the amorphous and crystalline phases of the GSST, respectively. We have optimized the nanobeam design using 3D FDTD and have made detailed numerical simulations that predict low insertion loss and low crosstalk with ∼100 GHz bandwidth. Finally, the application of this device to N x N x Mλ wavelength cross-connect switching is presented. The unique integration of switch design elements presented in this paper enables, for the first time, the combination of nonvolatile resonant behavior, low switching power, low insertion loss and crosstalk, wide bandwidth, and fast switching times, for WDM switching applications.

Prediction of fatigue damage in ribbed steel bars under cyclic loading with a magneto-mechanical coupling model

As a ferromagnetic material, the magnetization of ribbed steel bars will change with the development of fatigue damage under cyclic loading, which can be used to evaluate the fatigue damage state of steel bars. However, the quantitative relationship between fatigue damage and the variation in magnetization is still unclear, and the existing magneto-mechanical model cannot be applied to ribbed steel bars directly. To accurately predict the magnetization and the fatigue damage state during fatigue, it is also necessary to consider the influence of stress concentration caused by ribs on stress and fatigue life. This paper proposes a magneto-mechanical model suitable for ribbed steel bars, which use the Neuber law and Coffin-Manson relationship to determine the stress range and fatigue life under stress concentration. Additionally, the magnetic induction intensity of the HRB400 ribbed steel bar in the tensile fatigue test was measured to verify the proposed model, and the mechanism of the magnetization change trend during fatigue was analyzed in detail. Through the fatigue damage formula based on the magnetic indicator, the simulation and experimental comparison results show that the proposed model can effectively describe the fatigue damage state of ribbed steel bars in the fatigue.