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Copyright of Archives of Civil Engineering (Polish Academy of Sciences) is the property of Polish Academy of Sciences and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Investigation on the behaviour of hybrid beams is presented. Hybrid beam stands for an element with hybrid cross sections. This means sections that consist of steel and concrete parts, connected together with composite dowels, and both are considered for shear flow analysis. In practice, a more general solution may be used for bridges in the form of a beam in which the span sections are hybrid and the support sections are concrete. For the first time in the world, it was decided to introduce a girder in bridge construction, in which a concrete web with a thickness of only 20 cm was formed, directly connected to the steel web, so that a hybrid cross-section is created in accordance with the new European design regulations currently being developed (1994-1-102). The solution is new itself and requires also a new approach for internal forces determination. In this paper a parametric analysis of different hybrid beams with span range from 20 to 40 m and with different reinforcment ratio is performed to get knowledge on the influence of (1) concrete cracking and (2) rheology of concrete on the redistribution of internal forces. Results are analysed and conclusions are presented. As a final step, a general method for computer aided modelling of hybrid beams (hybrid beam concept) is proposed, which is based on the uncracked analysis. Such an analysis is designer-friendly and while appropriate benchmarked (as in this paper) can spare a lot of time needed for detailed iterative cracked analysis. [ABSTRACT FROM AUTHOR]

While the effects of axial compression on beams have long been known, the effect of tensile axial loads on one-sided transversely cracked beams is less known. The crack namely shifts the position of the resultant of the axial normal stresses deeper into the uncracked part of the cross-section, and the crack tends to open, causing a transverse displacement. Therefore, this paper focuses on empirical modeling of the considered phenomenon for slender prismatic beams in order to establish a suitable 1D computational model based on detailed 3D FE mesh results. This goal can be achieved through the already established simplified model, where the crack is represented by an internal hinge endowed with a rotational spring. Several analyses of various beams differing in geometry, crack locations, and boundary conditions were executed by implementing 3D FE meshes to establish the appropriate model's bending governing differential equation. After that, the corresponding parameter definitions were calibrated from the database of 3D FE models. By redefining the model's input parameters, a suitable solution is achieved, offering a good balance between the results' accuracy and the required computational effort. The functionality of the newly obtained solutions was verified through some comparative case studies that supplement the derivations. [ABSTRACT FROM AUTHOR]

This paper studies the chatter stability of composite cutter bar milling system in rotating coordinate frame. The main contribution of this paper is establishing a continuous distributed chatter analysis model for a composite cutter bar milling system in rotating coordinate frame. The stability of the milling system with a rotary symmetric dynamic cutter bar is predicted using the semi‐discrete time domain method. The effects such as internal damping, external damping, and symmetrical and asymmetric laminates on the stability of the milling system were analysed, and the results were compared between rotating and fixed coordinate frames. The results are consistent for symmetrical cutter bars in both the rotating and fixed coordinate frames. A new chatter instability zone appears at high rotating speeds due to the material internal damping of the rotating composite cutter bar. [ABSTRACT FROM AUTHOR]

In this paper, we investigate the transient response of Lorentz force at finite magnetic Reynolds numbers Rm on an electrically conducting rectangular bar that is strongly accelerated in the presence of a localized magnetic field. This is done through numerical simulations utilizing a coupled finite-difference boundary element approach. The results show good qualitative agreement with existing experiments with a circular cylinder. The Lorentz force rise time is seen to be a linear function of Rm . The linear dependence of Lorentz force on Rm is found to be valid only for low values of Rm , after which the slope decays leading to an apparent saturation in the Lorentz force at sufficiently large values of Rm . Our results provide important information for the development of Lorentz force flow meters for transient flow applications. [ABSTRACT FROM PUBLISHER]

In this paper, a new possibility of fabricating a metal lattice structure with a continuous rod is demonstrated. A multi-layer, periodic, and aperiodic lattice structure can be manufactured with a continuous thin rod by bending it with a repetitive pattern. However, joining their nodes are challenging and an important problem to solve. This paper is investigating the joining of nodes in a loose lattice structure by delivering materials through the dipping process. Both liquid state (epoxy) and solid-state (inorganic particles) joining agents are considered for polymer–metal and metal–metal bonding, respectively. Liquid Carrier Systems (LCS) are designed considering their rheological behavior. We found 40% solid loading with the liquid carrier system provides sufficient solid particles transfer at dipping and join the lattice node using transient liquid phase bonding (TLP). 3D metal lattice structures are constructed, and their mechanical properties are investigated. The lattice structure shows comparable strength even with smaller relative density (< 10%). The strength and elastic modulus of all the fabricated samples decreases with the increase in cell size, which is consistent with the traditional wisdom. [ABSTRACT FROM AUTHOR]

Thin sheets assembled into three dimensional folding origami can have various applications from reconfigurable architectural structures to metamaterials with tunable properties. Simulating the elastic stiffness and estimating deformed shapes of these systems is important for conceptualizing and designing practical engineering structures. In this paper, we improve, verify, and test a simplified bar and hinge model that can simulate essential behaviors of origami. The model simulates three distinct behaviors: stretching and shearing of thin sheet panels; bending of the initially flat panels; and bending along prescribed fold lines. The model is simple and efficient, yet it can provide realistic representation of stiffness characteristics and deformed shapes of origami structures. The simplicity of this model makes it well suited for the origami engineering community, and its efficiency makes it suitable for design problems such as optimization and parameterization of geometric origami variations. [ABSTRACT FROM AUTHOR]

This paper presents a 2-D static analytical method in the frequency domain for the calculation of magnetic field distribution, eddy-currents, circuit model parameters, and steady-state performances in multiphase/multipole cage rotor induction motors with integer and fractional stator winding. The complex model allows to study the healthy, defective, and broken bars conditions in these electrical machines. The proposed static analytical model considers stator and rotor slotting with tooth-tips. The method is based on the resolution of Poisson’s, Laplace’s, and Helmholtz’s equations in stator slots, air-gap, and rotor bars regions, respectively. The electromagnetic torque is obtained from both the electrical equivalent circuit and Maxwell stress tensor that is given by the magnetic field calculation. The analytical results are validated by those issued from time harmonic finite-element method. [ABSTRACT FROM PUBLISHER]

It is necessary to generate the yield position away from the column face to minimize damage to the beam-column joint during a large earthquake in a reinforced concrete building. The same efficacy can be realized using partially high strengthened rebar. The number of longitudinal bars can be calculated for a bending moment smaller than the column face, reducing their number compared to the conventional bar-arrangement method. This paper describes reinforced concrete an interior beamcolumn subassemblage tests using this rebar as the longitudinal bars of beams and a column. The beam yield hinge was formed at a position apart from the column face, and the damage to the beam-column joint was less than the conventional bar-arrangement method. Additionally, the good performance was obtained if the bending strength of the column was large, even if the shear capacity margin of the beam-column joint was small. The column-beam flexural strength ratio and shear capacity margin at the beam-column joint need to be set with consideration of their relationship. [ABSTRACT FROM AUTHOR]

The compression load of straight bars, for which the cross-sections are smaller compared to their length, causes a phenomenon of bending along the longitudinal axis. Upon reaching a certain level, called the critical level of the stresses, the bending deformations begin to increase beyond the bearing limit of the bar. It yields instantly, due to an unstable elastic deformation state, although the material's resistance limit has not been exceeded. The irreversibility of the phenomenon is dangerous especially for the railway tracks and is not fully mastered by calculation methods. They can eventually establish the level of the critical demand, which has values specific to each rail configuration. It is accepted that for loads lower than this level, buckling of the respective rail does not occur. The longitudinal tension in the railway tracks occurs due to the expansion caused by their heating under the action of the sun's rays, but also due to the friction between the rails and the train wheels. This paper proposes the realization of a study model of the buckling of the railway tracks. This model is represented by an assembly, built in the SOLIDWORKS application for which a Buckling simulation was made. The imposition of two distinct temperatures on the rails and crossties is the source of the model's request. The increase in the temperature of the component parts of the assembly causes their expansion, so implicitly the appearance of some longitudinal deforming forces, specific to the buckling phenomenon. [ABSTRACT FROM AUTHOR]

The planar mechanisms with articulated bars and gears (which we will simply note MeBaRd) are part of the general planar mechanics category. Although structural structural studies have been carried out [7], the structural synthesis of bars and wheels can be approached as a distinct problem. Some papers refer directly to a certain class of mechanisms, such as planetary mechanisms [1], [2], others stop on subsystems with zero mobility, called structural groups with toothed elements [6], [8]. In this paper, developing some ideas presented in [3], [5], a general algorithm for unitary structural synthesis of MeBaRd was developed and developed, having the input parameters: M - the degree of mobility and N - the number of contours. [ABSTRACT FROM AUTHOR]

Copyright of Technical Transactions / Czasopismo Techniczne is the property of Sciendo and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The benefits and drawbacks of a 5-hp reconfigurable induction motor, which was designed for experimental emulation of stator winding interturn and broken rotor bar faults, are presented in this paper. It was perceived that this motor had the potential of quick and easy reconfiguration to produce the desired stator and rotor faults in a variety of different fault combinations. Hence, this motor was anticipated to make a useful test bed for evaluation of the efficacy of existing and new motor fault diagnostics techniques and not the study of insulation failure mechanisms. Accordingly, it was anticipated that this reconfigurable motor would eliminate the need to permanently destroy machine components such as stator windings or rotor bars when acquiring data from a faulty machine for fault diagnostic purposes. Experimental results under healthy and various faulty conditions are presented in this paper, including issues associated with rotor bar-end ring contact resistances that showed the drawbacks of this motor in so far as emulation of rotor bar breakages. However, emulation of stator-turn fault scenarios was successfully accomplished. [ABSTRACT FROM AUTHOR]

This paper treats an exact elastica solution for a clamped-hinged beam, and its applications to a carbon nanotube. Although the elastica has a long history, and the exact post-buckling solution for the Euler buckling problem has been known for at least 150 years, it seems that the elastica solution for a post-buckled clamped-hinged beam has never been obtained. Therefore, the exact solution obtained in this paper constitutes an addition to the existing family of elastica solutions. As an application of the results, a post-buckling analysis of a single wall carbon nanotube is studied. Also, a potential use of the post-buckling analysis of the carbon nanotube for the determination of its Young's modulus has been indicated. [ABSTRACT FROM AUTHOR]

Abstract: This paper presents a flexural analysis of I-shaped laminated composite beams. A general analytical model applicable to thin-walled I-section composite beams subjected to vertical load is developed. This model is based on the shear-deformable beam theory, and accounts for the flexural response of the thin-walled composites for arbitrary laminate stacking sequence configuration, i.e. unsymmetric as well as symmetric. Governing equations are derived from the principle of the stationary value of total potential energy. Numerical results are obtained for thin-walled composites under vertical loading, addressing the effects of fiber angle and span-to-height ratio of the composite beam. [Copyright &y& Elsevier]

This paper deals with the modelling of a plastic beam experiencing softening. This kind of behaviour is observed in steel or reinforced concrete structural members undergoing large rotation amplitudes, which may occur typically for civil engineering structures in the seismic area. The homogeneous cantilever beam loaded by a concentrated force at its extremity is considered. This simple structural problem with gradient bending moment allows an analytical treatment of the evolution problem. It is shown that a local plastic softening model makes the evolution problem ill-posed. Moreover, if we require the plastic curvature to be a continuous variable of the spatial coordinate, Wood’s paradox is encountered. A non-local gradient plastic model is developed in order to overcome this paradox. However classical gradient plastic models may not eliminate the ill-posedness since the beam response may not be continuous with respect to the loading parameter. The new gradient plastic model, presented in this paper, is similar to previous classical gradient models. The main difference is the yield moment considered as a non-local material parameter. This permits to ensure continuity between the elastic and the plastic regions during the loading process. These solutions are controlled by the ratio between the material length and the geometrical length of the beam. The new evolution problem may remain ill-posed as it possesses a finite number of solutions (which can be unique). Closed-form solutions of the unknown deflection are given. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Engineering Sciences is the property of Faculty of Engineering - Assiut University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The objective of this paper is to use µ-X-ray fluorescence (XRF) analysis to evaluate the fineness and components of European Medieval Silver Bars samples. Conductivity measurements were used to assess the fineness and localization of the faults found in the samples. Because unevenness causes a change in conductivity, the tests were performed on the flattest areas of the Bars. Some rods, such as B3 and B9, have greater conductivity than others. All bars were subjected to the segregation test. In the instance of certain bars, it was not always practicable to categorically state that segregation had happened. There is no diminishing conductivity curve as one moves away from the zero height, as there is for bars B1, B8, and B9. As a result, there may be no solidification on these bars from Obverse to Reverse. A scanning electron microscope was used to record the following bars at various positions on the bars, and quantitative determinations were achieved using energy-dispersed XRF analysis through intensity measurements of the element-specific wavelength. [ABSTRACT FROM AUTHOR]

The phenomenon of the lateral instability of the vehicle when the steering is one of the extremely serious and dangerous problems. To improve safety and stability, vehicles often are equipped with stabilizer bars at the front and rear axles. However, the passive stabilizer bar cannot guarantee safe and stable performance in dangerous cases. Therefore, the active stabilizer bar is used to replace the passive stabilizer bar. The active stabilizer can automatically generate an anti-roll moment depending on the condition of the vehicle at each time. In dangerous cases, the anti-roll moment of the active stabilizer bar is much greater than the passive stabilizer bar. This research focused on the problem of establishing a spatial dynamics model in combination with a nonlinear double-track dynamic model to describe the state of oscillation of the vehicle when steering. The PID control method is used to control the hydraulic stabilizer bar. The results of the research indicated that when the vehicle was equipped with the hydraulic stabilizer bar, the values of the roll angle, the displacement of the un-sprung mass, the vertical force at the wheel, ... were significantly reduced. [ABSTRACT FROM AUTHOR]

Detection and evaluation of corrosion in reinforcing steel bars (rebars) commonly used in cement-based structures is an important ongoing concern. Embedded sensor technologies hold promise for this purpose. In recent years, modulated scatterer technique (MST) has shown great potential as an embedded sensor technology. The first step in evaluating the potential of embedded MST for rebar corrosion detection is to evaluate its potential for detecting the presence of subtle corrosion in a rebar. This short paper investigates the measurement potential for a dual-loaded differential MST approach for detecting relatively subtle corrosion in a steel rebar. [ABSTRACT FROM AUTHOR]

A model for fiber reinforced composites that takes into account the fiber slipping is presented in this paper and applied to the analysis of reinforced concrete elements. The model is formulated within the framework of the plasticity theory and the mixtures theory, considering two phases corresponding to the matrix (concrete) and the fibers (reinforcing bars) and modifying the behavior of the last to take into account the relative displacement between the two phases. An elasto-plastic interface model developed by other writers is used to describe the bond–slip mechanism. The resulting model is attractive for the analysis of reinforced concrete problems at the macrostructural level since the explicit discretization of reinforcing bars and interface is not required, with the consequent computational cost reduction. The paper concludes with application examples and comparisons with experimental results of reinforced concrete elements that show the capacity of the model developed. [ABSTRACT FROM AUTHOR]

This paper presents new finite element methods for the analysis of localized failures in plastic beams and frames in the form of plastic hinges. The hinges are modeled as discontinuities of the generalized displacements of the underlying Timoshenko beam/rod theory. Hinges accounting for a discontinuity in the transversal and longitudinal displacements and the rotation field are developed in this context. A multi-scale framework is considered in the incorporation of the dissipative effects of these discontinuities in the large-scale problem of a beam and a general frame. A localized softening cohesive law relating these generalized displacements with the stress resultants acting at the level of the cross section is effectively introduced in the frame response. The resulting models, referred to as localized models, are then able to capture the localized dissipation observed in the localized failures of these structural members, avoiding altogether the inconsistencies observed for classical models in the stress resultants with strain softening. The constructive approach followed in the development of these models leads naturally to the formulation of enhanced strain finite elements for their numerical approximation. In this context, we develop new finite elements incorporating the singular strains associated to the plastic hinges at the element level. A careful analysis is presented so the resulting finite elements avoid the phenomenon of stress locking, that is, an overstiff response in the softening of the hinge, not allowing for the full release of the stress. The accurate approximation of the kinematics of the hinges requires a strain enhancement linking the jumps in the deflection and the rotation fields, given the coupled definition of the transverse shear strain in these two fields. Different enhanced strain elements, involving different base finite elements and different enhancement strategies, are considered and analyzed in detail. Their performance are then compared in several representative numerical simulations. These analyses identify optimally enhanced finite elements for the accurate modeling the localized failures observed in common framed structures. [ABSTRACT FROM AUTHOR]

This paper investigates the behavior of composite steel girder bridges by means of sophisticated three-dimensional nonlinear finite-element (FE) analyses. The bridge model is such that the deck is represented by shear flexible shell elements and the structural steel girder is idealized by Timoshenko beam elements. The full composite action between slab and girder is guaranteed by multipoint constraints. Both the bridge deck and steel girder are divided into a number of layers to account for the cracking and yielding through their depth. This paper also presents a reinforced concrete material model, which utilizes a strain decomposition approach. The strain decomposition technique enables the explicit inclusion of physical behavior across the cracked concrete surface, such as aggregate interlock and dowel action, rather than intuitively defining the shear retention factor. The proposed material model is integrated into the commercial FE software ABAQUS shell elements through a user-supplied material subroutine. The FE results have been compared to experimental results reported by other researchers. The proposed bridge FE model is capable of predicting the initial cracking load level, the ultimate load capacity, and the crack pattern with good accuracy. [ABSTRACT FROM AUTHOR]

New systems of pretwisted bars are suggested, and their stability under a conservative load is investigated. In this paper, closed‐form relationships are obtained for the direct evaluation of critical loads of pretwisted cross bracings with different end connections and an arbitrary ratio of the dimensionless parameters of tension and compression elements. The equation for the critical loads is derived for tension and compression braces with different section properties, lengths, and axial loading. It is found that the critical load of a twisted brace is higher than that of a nontwisted brace. Parametric solutions are graphically displayed to clarify the distinct behavior, including the boundary separating symmetric and antisymmetric modes of buckling. [ABSTRACT FROM AUTHOR]

Conventional reinforced concrete shear walls are vulnerable to strong earthquakes with significant residual deformations, which substantially affect structural service and can even lead to structural collapse. Superelastic shape memory alloys (SMAs) are advanced materials that can realize strain recovery upon unloading. If SMAs can be used as reinforcing bars in structures, they can undergo large deformation without permanent deformation. This study presents a complementary and synergistic material system that integrates SMA with damage-tolerant engineered cementitious composites (ECCs) to minimize residual displacement and mitigate concrete damage. This study explored the seismic performance of shear walls using SMA and ECC in the plastic hinge region. Reverse cyclic loading tests were performed on four specimens to demonstrate the feasibility of this method. The specimens included a conventional steel-reinforced concrete shear wall (SW-R-C), steel-reinforced ECC shear wall (SW-R-ECC), SMA-reinforced concrete shear wall (SW-SMA-C), and SMA-reinforced ECC shear wall (SW-SMA-ECC). The results show that the SW-SMA-C specimen exhibited remarkable self-centering capability of more than 85% even after a large deformation, compared to SW-R-C. Furthermore, reduced damage and better ductility were observed in the SW-SMA-ECC specimen in addition to reduced residual displacement. The proposed approach indicated that SMA combined with ECC is more effective in mitigating plastic hinge damage and minimizing residual displacements, which could improve the seismic performance of shear walls. [ABSTRACT FROM AUTHOR]

Recently, a new numerical approach for core loss evaluation in media exhibiting hysteresis has been proposed for relatively long conductive rods, subject to surface excitation along their azimuthal direction. In this approach, the Crank-Nicolson finite-difference technique is used, while enact media properties are taken into account by utilizing Preisach-type models of hysteresis. The purpose of this paper is to provide some experimental verification of the aforementioned approach. Accuracy of this approach has been assessed for a 2 cm diameter, 25 cm long iron alloy rod. Voltage wave-forms and core losses corresponding to some controlled applied field frequencies and amplitudes were experimentally deduced. For every experimentally considered excitation amplitude and frequency, computations were performed rising the developed approach. Comparisons have demonstrated good quantitative agreements between the experimentally measured computed results. Sample comparison results are given in the paper. [ABSTRACT FROM PUBLISHER]

Abstract The use of glass fibre reinforced polymer (GFRP) bars as internal reinforcement of concrete structures has been growing, mainly due to the advantages they present over steel reinforcement, namely their low weight, high strength and corrosion resistance. However, at moderately elevated temperatures, especially when approaching the glass transition temperature (T g) of the polymeric matrix (usually between 65 and 150 °C), the stiffness, strength and bond properties of these rebars are known to be significantly degraded. The first part of this paper presents an experimental investigation comprising tensile and pull-out tests on sand coated GFRP rebars at elevated temperatures under steady-state conditions; the tensile tests were carried out up to 300 °C, whereas the pull-out tests were performed up to 140 °C (measured at the GFRP-concrete interface); two embedment lengths of the rebars were considered. The obtained results confirmed that the stiffness and strength of the GFRP-concrete interface are significantly reduced with temperature increase, especially when the T g of the GFRP rebars is approached and exceeded. In the second part of the paper, analytical bond vs. slip relations for the GFRP-concrete interface are proposed for each of the tested temperatures; the defining parameters of these local laws were calibrated with the experimental data from the pull-out tests. Moreover, the accuracy of two empirical (relaxation) models in predicting the GFRP-concrete bond strength reduction with temperature was also assessed. [ABSTRACT FROM AUTHOR]

The present paper provides a collision model for Cosserat rods, able to represent a very general collision response, including frictional effects as well as multiple simultaneous collisions of a large number of rods. The proposed collision model falls into the category of constraint-based collision models. This concept is extended to a general class of objects sharing properties of rigid and deformable bodies, here undertaken for viscoelastic Cosserat rods. The collision constraints are imposed by collision impulses added to the external loads of the equations of motion of the colliding objects. No iterations between the equations of motion and the collision model are required. Both parts are executed in a staggered manner, so that the collision model is well separated from the equations of motion. Hence, existing solvers for Cosserat rods or similar objects can easily be extended, so that the range of application is significantly enlarged to the collisional regime. Extensive validations are presented using various test cases, ranging from a collision of a single rod with a wall to more realistic configurations with multiple simultaneous collisions of numerous rods. [ABSTRACT FROM AUTHOR]

In this paper an analytical, exact procedure for the reconstruction of simply supported bending vibrating beams having given values of the first N natural frequencies is presented. The results hold for beams in which the product between the bending stiffness and the linear mass density is constant. The analysis is based on the fact that this class of beams is spectrally equivalent to a family of strings fixed at the ends, and uses recent results on the exact construction of second-order Sturm–Liouville operators with prescribed natural frequencies. The analysis can be adapted to beams with pinned–sliding and sliding–sliding ends. [ABSTRACT FROM PUBLISHER]

Copyright of Technical Transactions / Czasopismo Techniczne is the property of Sciendo and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Technical Transactions / Czasopismo Techniczne is the property of Sciendo and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The paper proposes an implementation of creep analysis of reinforced concrete structures which utilizes the B3 model and the direct stiffness method for reinforced concrete frames. The analysis is based on a numerical integration and it is implemented in an algorithmic programming language. There is presented a solution with the mentioned approaches which is compared with solution based on the EN 1992-1-1 technical standard. [ABSTRACT FROM AUTHOR]

The conventional capacitance-type liquid level sensor consists of an insulated solid metallic rod electrode immersed in the liquid contained in a metallic storage tank, or two such identical electrodes in a nonmetallic storage tank. Such metallic rods may suffer from the self-inductance effect which varies nonlinearly with the level. In this paper, we present a modified capacitance-type level sensor in which effect of self-inductance of the metallic rod has been eliminated. The theoretical equations describing the operation of the sensor are derived. The sensor is designed and tested experimentally and is found to follow the theoretical equations. The experimental results are also presented. A very good linearity of the sensor is observed. [ABSTRACT FROM PUBLISHER]

A vision-based inspection system has been investigated in order to improve the quality of products and processes found in various industries. In this paper, we propose a new defect detection algorithm for steel wire rods produced by the hot rolling process. Because the steel wire rods are long cylinder rods with a circular cross section, the brightness at the sides and center is inconsistent. Moreover, the various types of steel wire rods and the presence of scales affect the reflection properties of the rod surface. In order to resolve the abovementioned difficulties, the use of dynamic programming and a discrete wavelet transform are proposed. An adaptive local binarization method is used to further reduce the effects of scale. The effectiveness of the proposed method is shown by means of experiments conducted on images of steel wire rods that were obtained from an actual steel production line. [ABSTRACT FROM AUTHOR]

To overcome the influence of the skewed rotor bars on the operating performance of the cage induction motors, this paper presents a design method for non-skewed small and medium cage induction motor based on the time-stepping finite element method, in which the approaches of asymmetrical rotor slots, closed slots, reasonable slot combination, and air-gap length are adopted and studied systematically. With this method, the cage induction motors with non-skewed rotor bars can be realized. Simultaneously, the slot harmonic, which is caused by slot opening, can be eliminated effectively and the starting performance can also be improved. The design example on a 5.5 kW cage induction motor is presented and the experimental validation is also performed. [ABSTRACT FROM AUTHOR]

In precise cropping of the metal bars with different geometrical parameters, it is very important to obtain the reasonable initial external forces required by the bars rapidly and accurately. Stress concentration factor and stress intensity factor are proposed to calculate the initial external force accurately in this paper according to geometrical sizes of metal bars. By means of numerical simulation and linear fitting method, the correctional expressions of stress concentration factor and stress intensity factor of V-shaped notch tip, which include the geometric parameters of the bar, are obtained respectively and the error analyses are also performed. The ratio of the depth of V-shaped notch to the diameter of the bar is presented to be a condition parameter. The numerical analytical results show that the method of stress concentration factor can be used to calculate the initial external force accurately when the ratio of the depth of V-shaped notch to the diameter of the bar is more than 0.05, and the method of the stress intensity factor can be used when the ratio is less than 0.05. The calculating formulas of reasonable initial external forces for the bars with different geometrical parameters are also given. The cropping experimental results have confirmed that it is feasible that the reasonable initial external forces required by the bars with different geometrical parameters are calculated effectively by using the stress concentration factor or the stress intensity factor in precision cropping. [ABSTRACT FROM AUTHOR]

Glass fiber-reinforced polymer (GFRP) concrete reinforcement exhibits high strength, is lightweight, can decrease time of construction, and is corrosion resistant. However, research has shown that chemical reactions deteriorate the GFRP reinforcing bars over time, resulting in a reduced tensile capacity. This paper develops a time-variant probabilistic model to predict the tensile capacity of GFRP bars embedded in concrete. The developed model is probabilistic to properly account for the relevant sources of uncertainties, including the statistical uncertainty in the estimation of the unknown model parameters (because of the finite sample size), the model error associated with the inexact model form (e.g., a linear expression is used when the actual and unknown relations are nonlinear), and missing variables (i.e., the model only includes a subset of the variables that influence the quantity of interest.) The proposed model is based on a general diffusion model, in which water or ions penetrate the GFRP bar matrix and degrade the glass fiber-resin interface. The model indicates that GFRP reinforcement bars with larger diameters exhibit lower rates of capacity loss. The proposed probabilistic model is used to assess the probability of not meeting the tensile strength requirement based on specifications over time and can be used to assess the safety and performance of GFRP reinforced systems. Sensitivity and importance analyses are carried out to explore the effect of the parameters and random variables on the probability estimates. [ABSTRACT FROM AUTHOR]

The article offers the author's insights on the study regarding the applicability of standard penetration test (SPT) in measuring the shear strength properties of soils. The author says that the writers of the study assumed that energy losses are negligible based from the belief that rod weight can balance the lost wave energy. He mentions a principle evaluated by a numerical analysis which shows the inability of rod potential energy to compensate the energy losses from wave propagation.

The spin transfer modified Landau-Lifshitz-Gilbert equation is used to model a permalloy bar with configurations for current, transverse field, and magnetizations resembling those of a read head. The trends of noise power and noise peak frequency against sensing currents and transverse fields with different polarities are calculated and analyzed by symmetry and asymmetry properties, by magnetization dynamics, and by extended linear stability analysis that is applicable to shape anisotropy. With the linear stability analysis, it is found that smaller track width (with aspect ratio fixed) has larger field stability and larger current-density stability. This paper presents a theoretical study of nonlinear transition shift (NLTS) in perpendicular recording process. The study is carried out using numerical simulations, and an analytical method is introduced in this paper. In analyses of the effect of recorded transitions, the demagnetization field due to written patterns on the recording medium is taken into consideration in the field solution for a write head with shield poles. The influence of the gap length between the shield and the pole-tip is also studied using the new analytical model. [ABSTRACT FROM AUTHOR]

Abstract This paper presents a new approach to detect the location of multiple broken rotor bars (MBRBs) in induction motor (IM) drive, running under no load and full load conditions using direct in and variable frequency drives. This technique is based on earlier work of location detection of one broken rotor bar. The techniques are tested for various fault severity levels so the detection of the exact location of the fault at early stage helps to reach sufficient time maintenance. In this paper, the authors used Hilbert Transform to extract the fault signature from the stator current envelope which is the low frequency component. Then statistical analysis is applied which produce a formula that is used to get the exact location of the fault in IM rotor. Highlights • Novel approach for detecting the location of multiple broken bar in a three-phase induction motor squirrel cage rotor. • Hilbert transform is applied to obtain the envelope of the signal. • Statistical analysis is used in extracting the fault location by analyzing the envelope of the signal. • The proposed technique offers fast computational and accurate location diagnostic process. • The diagnostic technique is considered for detecting two and three broken rotor bars. [ABSTRACT FROM AUTHOR]

In deep hole boring process, long and flexible boring bars are often used. Due to the large length-to-diameter ratio, the stiffness of the boring bars is inevitably reduced, where the boring bars’ vibration effects will occur. The influences of vibration will significantly degrade the accuracy and the surface quality, or even lead failure of the production. Therefore, it is of significant importance to develop techniques to reduce vibration in deep hole boring. In this paper, a new boring bar with a variable stiffness dynamic vibration absorber (VSDVA) is presented, where the basic parameters of the proposed boring bar are measured. Based on the proposed dynamic model, the vibration characteristics of the proposed boring bar are analyzed, and the change laws of the vibration reduction performance are obtained under different excitation frequencies. A new vibration reduction method is proposed, where best vibration reduction performance can be achieved by adjusting the stiffness of the VSDVA. Finally, the vibration reduction performance of the proposed boring bar is validated and evaluated by boring experiments. These works could provide guidance for designing new types of boring bars, selecting cutting parameters, and adjusting the vibration reduction performance of the proposed boring bar, and as a result, it provides a new design idea for the design of boring bar. [ABSTRACT FROM AUTHOR]

In this paper, the design and application of permanent mold casting technology reserving a significant place in the light alloy casting technology was conducted due to its convenience for mass production and industrial need. The metal tensile bar mold design, mold preheat temperature (100°C-150°C-200°C), thermal stress, fatigue and damage analyses were examined to be used in the casting experiments by using the finite element analysis. As well as the casting temperature and solidification time, the material flow analyses were conducted by using a computer- aided program. By producing the mold following the modeling and analyses studies, AA7075 aluminum alloy was melted at 800°C and casted in the permanent mold. Following the casting procedure, the tensile bars of aluminum alloys were prepared in conformity with the standards and their tensile and hardness tests were conducted. The general and fracture surface microstructure differences of experiment specimens were examined. As a result of modeling and analysis studies made in the computer environment, the surface stresses of specimen and runner regions which were significant in the mold design were calculated at 100, 150 and 200°C preheating temperatures. The most convenient mold lifetime was calculated by making fatigue calculations for permanent mold at 800°C. [ABSTRACT FROM AUTHOR]

In this paper, a diagnosis method based on Hilbert and discrete wavelet transform (DWT) for broken rotor bars in induction machine has been proposed. The method is based from using Hilbert transform (HT) to obtain the envelope for the stator current and processed via DWT. The main advantage of HT is the removal of the fundamental component to allow a clearer vision of the fault frequencies. The result by HDWT (HT and DWT) is more suitable for emergency signal analysis. This technique is effective for the stationary signal as well as non-stationary signal processing. The HDWT analysis was introduced to overcome the shortcomings of Fourier analysis. The performance of this approach is evaluated in simulation and experimental results. [ABSTRACT FROM AUTHOR]

This paper presents a study on the bond characteristics of glass fiber reinforced polymer (GFRP) bars in engineered cementitious composite (ECC). Ninety beam specimens having variable parameters namely bar diameter, GFRP bar types (standard low modulus 'LM' and high modulus 'HM'), two concrete types (ECC and normal concrete 'NC') and embedded length (5, 7 and 10 times bar diameter) were tested as per RILEM specifications. Bond stress-slip characteristics and failure modes of specimens as well as influence of variable parameters on bond strength are described. The performance of various Codes and other existing equations in predicting bond strength of both low/high modulus GFRP bars embedded in ECC compared to NC is described based on experimental results. The bond strength decreased with the increase of embedment length--maximum bond strength reduction of 36% was observed. For both ECC and NC, bond strength reduced with the increase of bar size and ECC produced maximum 1.6 times higher bond strength compared to NC. Code based and other existing equations were found conservative in predicting bond strength of GFRP bars embedded in ECC. [ABSTRACT FROM AUTHOR]

Toward improving conventional beam elements in order to include distortional effects in their analysis, in this paper, independent parameters have been taken into account. Beam's behavior becomes more complex, especially for eccentric loading, due to the coupling between warping and distortion. Thus, the importance of including higher-order phenomena in the analysis arises in order to derive accurate results. Due to the fact that more degrees of freedom are employed, the computational cost of the problem is significantly increased. Isogeometric tools (B-splines and NURBS), either integrated in the finite element method or in a boundary element-based method called analog equation method, are employed in this contribution for the static analysis of beams of open or closed (box-shaped) cross sections toward improving computational effort. Responses of the stresses, stress resultants and displacements to static loading have been studied. [ABSTRACT FROM AUTHOR]

The object of this paper is the uniform torsion of inhomogeneous, isotropic, linearly elastic cylindrical bar. The aim is to give lower and upper bounds for the torsional rigidity of the bar with doubly connected cross section. The outer and inner boundary curves of cross section are similar curves. The level lines of the function which gives the change of the shear rigidity on the cross section are also similar curves to the boundary curves. The application of derived bounding formulae is illustrated by examples. An approximated formula to determine the shear stresses is also presented. [ABSTRACT FROM AUTHOR]

In this paper, a new analytical methodology is proposed to estimate core losses in line-start and inverter-fed induction motors under rotor broken bars. This methodology can be utilized for different supply and load conditions. Core losses are precisely calculated taking into account the effects of nonsinusoidal distribution of the magnetic flux density due to bars breakage. Furthermore, increase of the stator current side-band components magnitude is considered to estimate Ohmic losses accurately. In order to calculate the above-mentioned losses, distribution of the magnetic flux density and stator currents of the induction motor is simulated using modified winding function method. In this modification, influence of nonlinear characteristics of the core materials is taken into account. Moreover, impacts of the spatial distribution of the stator windings, stator and rotor slots are considered. Two well known CV/F and direct torque control techniques are applied to the modeled motor and the aforementioned losses are calculated in the line-start, and inverter-fed modes. The simulation results are verified by the experimental results. [ABSTRACT FROM AUTHOR]