Plate Segments Research Articles

Steel slit shear walls with an efficient geometry

This paper presents the results of a study to improve the seismic behavior of steel shear walls with vertical slits. In this system, the steel plate segments between the slits behave as a series of flexural links, which provide a fairly ductile response without the need for heavy stiffening. An efficient slit geometry is proposed, which assures simultaneous yielding of the plate along the vertical links and prevents strain localization. Experimental study and finite element modeling are used to verify the proposed steel slit shear wall and to study its nonlinear behavior under monotonic and cyclic loading. Out-of-plane buckling of the wall and the effects of buckling restraining clamps on this phenomenon is also studied. The results show satisfactory performance of this system, when used as a seismic force resisting system. The important geometric parameters that result in the desired behavior of the wall, including appropriate stiffness and strength, as well as stable hysteresis curve, are determined and evaluated.

Use of q-plate as a coupler.

A coupler is a device that allows interconversion of angular momentum of the optical beam among spin and orbital parts, without absorbing any angular momentum. In this paper, we demonstrate that a q-plate with q=1 can act as a coupler for any of the polarization distribution that can be represented by a point on a Poincare sphere (PS), or on a higher-order PS, or on a hybrid-order PS. A q-plate with any q-value can act as a coupler for polarization distribution that can be represented by an equatorial point on any of these spheres. It is also possible to find a q-plate with an appropriate q-value that can act as a creation or annihilation operator that raises or lowers the polarization singularity index. The q-plate being a coupler and made of half-wave plate segments, the singularity index change is concomitant with the helicity inversion of C-points. Interconversion of bright and dark C-points is possible by using a q-plate.

Treatment Outcomes for Periprosthetic Femoral Fractures in Cementless Press-Fit Total Hip Replacement.

The aim of this study was to report outcomes in dogs with periprosthetic femoral fractures associated with a press-fit cementless femoral total hip replacement implant. Electronic medical records and digital radiographs were used to identify dogs with periprosthetic femoral fractures associated with press-fit cementless total hip replacement. Data collected included signalment, weight, time of fracture, cause of fracture, presence of intra-operative fissure, fracture type, repair technique, and clinical and radiographic outcomes. Long-term patient outcome was assessed by communication with owners or referring veterinarians. Twenty-eight dogs with femoral fracture repair associated with cementless press-fit total hip replacement were identified. Eight of the fractures occurred intraoperatively and 20 occurred at a median of 2 days postoperatively. An oblique or spiral configuration was noted in 19 cases and 15 occurred at the distal end of the femoral stem (type B), with thirteen type B1, one type B2 and one type B3 fractures. Fractures were repaired with non-locking (18/28) or locking-plate fixation (10/28). Cerclage wire was applied around the plate and proximal bone segment in 17/28 dogs. Major complications occurred in 7/28 cases (five deep infection, two mechanical failures). Bone healing was noted in 21/23 cases, for which follow-up radiographic interpretation was available. Return to function was complete in 17 cases, acceptable in 8 cases and unacceptable in 3 cases. While cementless total hip replacement periprosthetic femoral fractures can be successfully repaired with lateral plate fixation, the risk of infection appears to be high.

A unified modeling method for dynamic analysis of GPL-reinforced FGP plate resting on Winkler-Pasternak foundation with elastic boundary conditions

In this paper, dynamic analysis of functionally graded porous (FGP) plate with reinforcement of graphene platelets (GPLs) resting on elastic foundation and restrained by elastic boundary condition is investigated. Four types of porous materials reinforced with four types of graphene platelets varying along the thickness direction are considered. The analytical model of the GPLs-FGP plate is formulated by the first-order shear deformation theory and the multi-segment partition technique. For each plate segment, the displacement component of translation and revolution is implemented by Jacobi polynomials. Ultimately, the dynamics of the GPLs-FGP plate analysis model is solved by the Rayleigh-Ritz method. Aimed at validating the accuracy of the present method, the analytical results are compared with the results of finite element simulations after the convergence test is completed. Based on the above investigation, series of parametric studies with regard to the free, forced vibration and transient analysis are conducted, which provide reference data for future research.

Test and numerical investigations on the spatial mechanics characteristics of extra-wide concrete self-anchored suspension bridge during construction

This work is aimed at studying the mechanics characteristics of the self-anchored suspension bridge with extra-wide concrete girder during girder erection and system transformation. First, the determination and implementation processes of reasonable completion state were introduced briefly, taking the Hunan Road Bridge as the background project, which is the widest concrete self-anchored suspension bridge in China currently. Then, the ANSYS beam-type finite element model and field monitoring data were integrated to investigate the cable system evolutions during system transformation. Finally, the global refined finite element model was established using solid element to consider the shear lag effects in extra-wide girder. The measured data show that the cable displacements in tensioned domains were characterized by weak coherence and contraflexure characteristics. The longitudinal and transverse stresses of extra-wide girder distributed unevenly along transverse direction. The maximum shear lag coefficients of girder at completion state reached to 1.3. Moreover, small transverse compressive stress, or even the transverse tensile stress reaching to 1.80 MPa, appeared in the top plate segments. The measures including the arrangement optimization of transverse prestressed tendons and monitoring point redistribution were given. The research can provide references for the structural designing and safety control of the similar bridges.

A unified formulation for free vibration of laminated plate through Jacobi-Ritz method

Abstract In this research, an analytical Jacobi-Ritz method for the free vibration analysis of composite laminated rectangular plate subject to arbitrary boundary conditions is proposed. The theoretical model is constructed in the framework of the first-order shear deformation theory (FSDT), and the multi-segment partitioning strategy is introduced. The boundary condition as well as the interface continuity condition is dealt with through the artificial spring technique. The displacement functions for every separated plate segment are expanded in the way of Jacobi polynomials along both the length and width orientations. And all the undetermined coefficients are decided through the Ritz method. The solution exhibits excellent convergence performance and shows stable features. The reliability and precision of the proposed methodology are validated by comparison with results from literature, where general boundary conditions are taken into account. Furthermore, parameterized study of the composite laminated rectangular plate is conducted, the results of which can be benchmark results for the future study.

Thermal-hydraulic Performance Analysis of Corrugated Plate Heat Exchanger

Plate heat exchangers (PHEs) have been getting popularity in industries due to their low cost, high heat transfer efficiency and operational flexibility. Heat transfer enhancement could be achieved by using the PHE with corrugated plate configuration, which provides additional heat transfer area and increased turbulence in fluid flow. This work explored how complex corrugated plates with different chevron angles, channel depth and pitch in multi-segmented configuration could further improve thermal-hydraulic performance of the PHE. Water was used as the heat transfer fluid. Key geometrical parameters were first identified as different chevron angles (βhigh and βlow), corrugation aspect ratio (γ) and number of plate segments (NS). Then, thermal-hydraulic models for the PHE with a wide range of corrugation geometries have been proposed and validated. These models could accurately estimate heat transfer and flow friction loss of the PHE with different plate corrugation structures and provide deep insight into the influence of the corrugation geometries. They could be applied as a guide in PHE design, operational optimization and heat transfer network retrofit in industries.

Bi-directional functionally graded thin-walled non-prismatic Euler beams of generic open/closed cross section Part I: Theoretical formulations

This paper presents a detailed treatment of the formulation for buckling and free vibration analysis of Bi-Directional Functionally Graded (BDFG) Thin-Walled non-prismatic beams of generic open/closed cross section. The theory developed is limited to small strains, moderate deflections and small rotations. It is based on the assumption that the shear strain on the mid-surface contour of the cross section of the member is neglected. Using the membrane theory of shells rigorous expressions for strains are obtained by which the effect of nonlinear tapering is considered. The material properties are assumed to be graded both in the longitudinal and depth-wise directions of the plate segment of the thin-walled beams. The governing equations are developed defining the displacements with reference to any arbitrary point (say geometric centre) and get away with the usual shear centre and centroid. For computer solutions for classical buckling and vibration analyses, the Finite Element Method is used. Simpson’s rule of numerical integration is adopted for the computation of axial, coupled and bending rigidities as well as inertial properties of the plate segment and the Gaussian Quadrature of numerical integration is used for the computation of flexural stiffness, geometric stiffness and mass matrices of an element over the length of the beam. Critical buckling loads and the natural frequencies and their corresponding buckled and mode shapes for various examples are obtained by solving as an eigen-value problem and compared with the published results in the companion paper.

Stress Analysis of Pelton Turbine Distributor Using UG-NX Software

The main objective of this paper is analysis of stress in the distributor to find out optimum thickness for safe and satisfactory working at different load condition. To describe how different plate segments required fabricating wyes branches to ensure greater reliability. The distributor of Pelton turbine consists of pipe segments and wyes branches which are then connected to nozzle. A wyes branch, where the distributor bifurcates has a very complex shape and is very difficult to design. A practical case of distributor of 6 jets vertical Pelton turbine of 43 MW power has been carried but using UG-NX software.

Stress Analysis of Pelton Turbine Distributor Using UG-NX Software

The main objective of this paper is analysis of stress in the distributor to find out optimum thickness for safe and satisfactory working at different load condition. To describe how different plate segments required fabricating wyes branches to ensure greater reliability. The distributor of Pelton turbine consists of pipe segments and wyes branches which are then connected to nozzle. A wyes branch, where the distributor bifurcates has a very complex shape and is very difficult to design. A practical case of distributor of 6 jets vertical Pelton turbine of 43 MW power has been carried but using UG-NX software.

Opposite Subduction Polarity in Adjacent Plate Segments

AbstractActive and fossil subduction systems consisting of two adjacent plates with opposite retreating directions occur in several areas on Earth, as the Mediterranean or Western Pacific. The goal of this work is to better understand the first‐order plate dynamics of these systems using the results of experimental models. The laboratory model is composed of two separate plates made of silicon putty representing the lithosphere, on top of a tank filled with glucose syrup representing the mantle. The set of experiments is designed to test the influence of the width of plates and the initial separation between them on the resulting trench velocities, deformation of plates, and mantle flow. Results show that the mantle flow induced by both plates is asymmetric relative to the axis of each plate causing a progressive merging of the toroidal cells that prevents a steady state phase of the subduction process and generates a net outward drag perpendicular to the plates. Trench velocities increase when trenches approach each other and decrease when they separate after their intersection. The trench curvature of both plates increases linearly with time during the entire evolution of the process regardless their width and initial separation. The interaction between the return flows associated with each retreating plate, particularly in the interplate region, is stronger for near plate configurations and correlates with variations of rollback velocities. We propose that the inferred first‐order dynamics of the presented analog models can provide relevant clues to understand natural complex subduction systems.

The Field of Attraction of a Polyhedron and Polygonal Plate with Linear Density

New representations of the elements of the fields of attraction (potential and its first derivatives) are presented for the important approximating models such as polyhedron and polygonal plates with the density varying by the linear law. It is shown that these elements are determined through the elements of the fields from the models with the known analytical representations (polyhedron, polygonal plate, and material segment with constant densities) and the additional integrals for which the explicit analytical expressions exist.

Characterizing Afterslip and Ground Displacement Rate Increase Following the 2014 Iquique‐Pisagua Mw 8.1 Earthquake, Northern Chile

AbstractThe 2014 Iquique‐Pisagua Mw 8.1 earthquake ruptured only parts of the 1877 Northern Chile‐Southern Peru seismic gap. Here we present a comprehensive analysis of 152 continuous and campaign Global Positioning System time series that captured more than a decade of interseismic loading prior to the event and 2 years of afterslip. In high spatiotemporal resolution, our data document upper plate response not only at the coseismically affected latitudes but also at the adjacent Loa plate segment to the south. Using a combination of elastic and viscoelastic half‐space models of different stages of the seismic cycle, we found that the highly coupled, former seismic gap contains a narrow low coupling zone at 21°S latitude. Just after the 2014 earthquake, this zone acts as a barrier impeding afterslip to continue southward. Possible reasons for this impediment could involve crustal heterogeneities or coupling discontinuities at the plate interface. After 2 years, afterslip cumulates to a maximum of ~89 cm and becomes negligible. Global Positioning System observations south of the inferred seismotectonic barrier reveal a deformation rate increase in the second year after the event. Our slip models suggest that this could be caused by a downdip coupling increase, perhaps bringing the highly coupled southern Loa segment closer to failure. Taken together, our results reveal (1) the interaction between different areas undergoing stress release and stress buildup in a major seismic gap, (2) constraints for the temporal variation of coupling degree in different stages of the seismic cycle, and (3) the influence of large earthquakes at adjacent segments.

Heat transfer enhancement of flow insulator by combined stainless steel fibrous and wire net porous materials

The present research article aims to propose the heat transfer enhancement of the flow insulator using combined fibrous and wire net stainless steel porous material. The stainless fibrous plate with porosity of 0.9292 was combined to the stainless steel wire net having pore per inch (PPI) of 16 and total thickness of 30 mm. Two models of the arranging porous plates were prepared, which were model BA and model AB. Each porous plate segment had the same thickness. The examined porous plate model have porosities of 0.8452. The porous plate was placed normal to the flow direction. The air was used as working fluid heated by 5 kW electric heater, which was controlled by the automatic temperature control. Type-K thermocouples were employed to measure the air temperatures. The temperature at front of the porous plate was varied to be 350, 450, and 550°C. The air flow rate was varied in the range of 4-12 m3/hr. The experimental result showed that the temperature drop across the porous plate and the thermal efficiency increase with the inlet temperature. The air velocity slightly affects the temperature profile inside the test section at the upstream side of the porous plate but greatly affects temperature inside the porous plate. In consideration of the arranging porous plate, placing of the stainless steel wire net at the upstream side and placing the stainless steel fibrous at downstream side (model BA) results in the highest temperature drop and the highest thermal efficiency. At Re 733 and inlet temperature 550°C for model BA at 30 mm thickness, the thermal efficiency was 50%. It was shown that the combined stainless steel fibrous and stainless steel wire net porous material could be a good flow insulator.

Seismicity in the Vicinity of the Tristan Da Cunha Hot Spot: Particular Plate Tectonics and Mantle Plume Presence

AbstractEarthquake locations along the southern Mid‐Atlantic Ridge have large uncertainties due to the sparse distribution of permanent seismological stations in and around the South Atlantic Ocean. Most of the earthquakes are associated with plate tectonic processes related to the formation of new oceanic lithosphere, as they are located close to the ridge axis or in the immediate vicinity of transform faults. A local seismological network of ocean‐bottom seismometers and land stations on and around the archipelago of Tristan da Cunha allowed for the first time a local earthquake survey for 1 year. We relate intraplate seismicity within the African oceanic plate segment north of the island partly to extensional stresses induced by a bordering large transform fault and to the existence of the Tristan mantle plume. The temporal propagation of earthquakes within the segment reflects the prevailing stress field. The strong extensional stresses in addition with the plume weaken the lithosphere and might hint at an incipient ridge jump. An apparently aseismic zone coincides with the proposed location of the Tristan conduit in the upper mantle southwest of the islands. The margins of this zone describe the transition between the ductile and the surrounding brittle regime. Moreover, we observe seismicity close to the islands of Tristan da Cunha and nearby seamounts, which we relate to ongoing tectono‐magmatic activity.

РАЗРАБОТКА И ОБОСНОВАНИЕ ПАРАМЕТОВ СВЧ УСТАНОВКИ СО СФЕРИЧЕСКИМ РЕЗОНАТОРОМ ДЛЯ ТЕРМООБРАБОТКИ БОЕНСКИХ ОТХОДОВ

The improvement of microwave technology and the design of installations, that ensure the matching of the processes of dehydration, grinding and heat treatment of non-food animal slaughter waste is an urgent task. The purpose of the work is the development and justification of the effective parameters of the operation of a microwave plant for heat treatment of non-food waste of animal origin of high humidity in a continuous mode, which ensures the improvement of the quality of the feed product with the least operating costs. In the work we used statistical processing of the results of the research, using computer programs Microsoft Excel 10.0, Statistic 5.0, 3D modeling of the design of microwave installations in the Compass-3D V15 program. The developed microwave device with a spherical perforated resonator provides for combining the processes of dewatering, grinding and heat treatment of raw materials in a continuous mode. It contains a rotating spherical resonator in a spherical shielding body, with a receiving and unloading nozzles. A dielectric shaft is rotated along the vertical axis of the resonator, rotating from the electric motor. The upper parts of the spherical shielding unit and the spherical resonator, whose diameter is matched to the wavelength, are as close as possible to each other, and have coaxial holes for fixing the receiving branch pipe and the dielectric shaft. On the outside of the shielding case, a chopper and microwave generators are installed, so that the emitters are directed into the rotating spherical resonator uniformly along the perimeter of the dielectric plate segment. The spherical resonator is perforated, the dimensions of the holes are coordinated with the particle sizes of the finished products. An operating-technological scheme for the operation of a device with a spherical diffraction cavity for heat treatment of raw materials in a continuous mode is developed. The microbiological indices of the non-food waste of animals slaughter after exposure of electromagnetic fields and ultrahigh frequencies were estimated. As a result of the research, a microwave technology was developed for heat treatment of non-food waste of slaughter animals with high humidity for the production line of protein feed, using a spherical perforated resonator. A positive evaluation of the microbiological indices of a product, treated in an electromagnetic field of an ultrahigh frequency, was carried out.

Magnetic light cloaking control in the marine planktonic copepod Sapphirina

We investigated the light cloaking behavior of the marine planktonic copepod Sapphirina under a magnetic field. Optical interferences in the multi-laminated guanine crystal layer beneath the dorsal body surface create a brilliant structural color, which can be almost entirely removed by changing the light reflection. In the investigation, we immersed segments of Sapphirina in seawater contained in an optical chamber. When the derived Sapphirina segments were attached to the container surface, they were inert to magnetic fields up to 300 mT. However, when the back plate segments were attached to the substrate at a point, with most of the plate floating in the seawater, the plate rotated oppositely to the applied magnetic field. In addition, the brilliant parts of the Sapphirina back plate rotated backward and forward by changing the magnetic field directions. Our experiment suggests a new model of an optical micro-electro-mechanical system that is controllable by magnetic fields.

Late Stage Interseismic Strain Interval, Cascadia Subduction Zone Margin, USA and Canada

Modern horizontal strain (2006-2016) measured along 56 new and 108 previously published GPS station baselines are used to establish the length (800 km) and width (300 - 400 km) of the central Cascadia convergent margin seismogenic structure. Across-margin (west-east) annual rates of shortening range from 10﹣9 a﹣1 at the eastern (landward) limit of the central Cascadia seismogenic structure to 10﹣7 a﹣1 along the western onshore portion of the interplate zone. Relatively high shortening strain rates (10﹣8 a﹣1 to 10﹣7 a﹣1) are also measured in western transects from the northern (Explorer plate) and southern (Gorda plate) segments of the convergent margin, demonstrating that the full length of the margin (1300 km length) is currently capable of sustaining and/or initiating a major great earthquake. Vertical GPS velocities are averaged over the last decade at 321 stations to map patterns of uplift (0 - 5 mm yr﹣1) and subsidence (0 - 9 mm yr﹣1) relative to the study area mean. Along-margin belts of relative uplift and subsidence, respectively, are approximately associated with Coast Ranges and the Cascade volcanic arc. However, the vertical velocity data are locally heterogeneous, demonstrating patchy “anomalies” within the larger along-margin belts. A large coastal subsidence anomaly occurs in southwest Washington where the modern short-term trend is reversed from the long-term (~200 yr) tidal marsh record of coastal uplift since the last co-seismic subsidence event (AD1700). The modern vertical displacements represent a late stage of the current inter-seismic interval. If the horizontal strain is considered largely or fully elastic, extrapolating the modern strain rates over the last 100 years show the accumulated strains would be similar in magnitude to the observed co-seismic strains resulting from the Tōhoku, Japan, Mw 9.0 earthquake in 2011. We believe that the central Cascadia seismogenic structure has accumulated sufficient elastic strain energy, during the last 300 years, to yield a Mw 9.0 earthquake from a rupture of at least one-half (400 km) of its length.

Analyzing 2D segment by Multiphysics in heat transfer and solid mechanics, pondering variables by Design of Experiment (DOE)

The application of reinforcements on plates is very important to increase products strengths and sometimes applied to promote higher heat dissipation efficiency. The understanding of the design of simple plates regarding thermal and mechanical characteristics, visualizing future utilization, favors the development of optimized and robust products. This paper aims to present a simplified plate segments (2D) in order to understand and ponder mathematically, by novelty Multiphysics (FEM) and statistically (DOE), its design possibilities under external variables. The identification of main effects and interaction between such variables (design, pressure and temperature) can significantly contribute to improve the design of real products.

Subduction initiation from a stagnant lid and global overturn: new insights from numerical models with a free surface

Subduction initiation is a key in understanding the dynamic evolution of the Earth and its fundamental difference to all other rocky planetary bodies in our solar system. Despite recent progress, the question about how a stiff, mostly stagnant planetary lid can break and become part in the global overturn of the mantle is still unresolved. Many mechanisms, externally or internally driven, are proposed in previous studies. Here, we present the results on subduction initiation obtained by dynamically self-consistent, time-dependent numerical modelling of mantle convection. We show that the stress distribution and resulting deformation of the lithosphere are strongly controlled by the top boundary formulation: A free surface enables surface topography and plate bending, increases gravitational sliding of the plates and leads to more realistic, lithosphere-scale shear zones. As a consequence, subduction initiation induced by regional mantle flow is demonstrably favoured by a free surface compared to the commonly applied, vertically fixed (i.e. free-slip) surface. In addition, we present global, three-dimensional mantle convection experiments that employ basal heating that leads to narrow mantle plumes. Narrow mantle plumes impinging on the base of the plate cause locally weak plate segments and a large topography at the lithosphere-asthenosphere boundary. Both are shown to be key to induce subduction initiation. Finally, our model self-consistently reproduces an episodic lid with a fast global overturn due to the hotter mantle developed below a former stagnant lid. We conclude that once in a stagnant-lid mode, a planet (like Venus) might preferentially evolve by temporally discrete, global overturn events rather than by a continuous recycling of lid and that this is something worth testing more rigorously in future studies.