Round Cores Research Articles

Experimental study on slender buckling-restrained knee braces with round steel bar cores

Experimental study on slender buckling-restrained knee braces with round steel bar cores

Measurements of Coupling Time Constants and Geometry Factors of Coupling Losses in Spiral Copper-Plated Multifilament Coated Conductors

Spiral geometry is effective to reduce coupling time constants of copper-plated multifilament coated conductors. We wound copper-plated multifilament coated conductors with various specifications spirally on round cores, and measured their magnetization losses in a wide range of frequency to determine their coupling time constants as well as the geometry factors of coupling losses. The core diameter was decreased down to 2.5 mm in order to show the feasibility of such conductors with reasonably high overall current density. The influence of various conductor parameters such as copper thickness, conductor width, and number of striations (filament width) as well as core diameter on coupling time constants and geometry factors were studied. By using the obtained coupling time constants and geometry factors, we calculated coupling losses of various conductors, whereas we calculated their hysteresis losses by using Brandt and Indenbom's formulae. These calculated hysteresis losses and coupling losses were compared with measured magnetization losses for various conductors.

НАУКОВИЙ СУПРОВІД РЕМОНТУ МОСТА НА КМ 159 + 267 ПРИ РЕКОНСТРУКЦІЇ АВТОМОБІЛЬНОЇ ДОРОГИ Н-31 ДНІПРО – ЦАРИЧАНКА – КОБЕЛЯКИ – РЕШЕТИЛІВКА

Abstract Introduction. Bridges are one of the most important components of transport infrastructure. And transport structures are built of complex structures, and the cost of their operation is high. In the last period, the traffic intensity and weight of vehicles on the roads of Ukraine have significantly increased. Ensuring reliable and trouble-free operation is a priority, complex and responsible task. Problem statement. After the installation of a cement-concrete surface on the bridge on KM 159+267 of the H – 31 Dnipro – Tsarichanka – Kobelaki-Reshetilovka road, cracks were found on the cement-concrete surface across the entire passage after some time. Oblique and transverse cracks soon appeared in the surface on both adjacent bridges (separate bridges for different directions of movement). The opening of cracks reached 1 mm. Materials and methods. On the bridge at Km 159+267, an experimental design was applied – a cement-concrete coating made of concrete of class B40. It provides for the device of dense waterproof concrete of the roadway slab, 110 mm thick, made of monolithic concrete of Class B40 F300 W12 (C32/40, XF4, C1 0,20 according to DSTU b v. 2.7-176:2008, crushed stone fraction 5-10 mm), after the device of a monolithic slab with a thickness of 200 mm, combining the beams of the superstructure. To study damaged structures, methods for measuring the opening of cracks using probes and tape measures were used. To determine the adhesion of the coating to a monolithic slab, samples were taken – round cores using a core collector. The strength of the concrete was measured with a sclerometer. Results. As a result of the conducted research, the lack of adhesion of the cement-concrete coating to the monolithic slab of the bridge was revealed. To achieve high performance, it is necessary to disassemble the damaged cement-concrete surface and install a new coating to eliminate defects in the bridge surface on km 159 + 267 of the H-31 highway. Conclusions. Studies have shown that more and more new cracks appear in the cement-concrete coating, and the opening of old ones increases. The cause of cracks is shrinkage of concrete. Since concrete shrinkage can last up to 1.5 years, even more cracks should have been expected to appear. It also turned out that the cement-concrete coating does not adhere to the monolithic slab of the superstructure. Given the above reasons, it is impractical to repair individual cracks. To achieve high performance, it is necessary to disassemble the damaged cement-concrete coating and install a new one. Taking into account the capabilities of the contractor, the construction of the bridge bed and asphalt concrete pavement was developed. Keywords: bridge, highway, cement-concrete pavement, asphalt concrete.

Buckling-restrained steel bar damper for spine frame system

This paper presents an experimental investigation on buckling-restrained steel bar dampers used at the lower sides of a spine frame. The dampers are mainly composed of round steel bar cores restrained by round steel tubes, and additional components called supporters that provide the lateral support against flexural buckling of the round steel tube. One characteristic of the proposed damper is that its buckling length can be controlled by using supporters. Cyclic loading tests were conducted on 10 scaled specimens to assess the functionality and energy dissipation performance of the proposed damper. The test specimens differed mainly with regard to the number of supporters, number of contraction allowance zones, type of connection to the base beam, and damper length. The performance of the damper was extensively discussed base on the cyclic behavior of the different specimen configurations and the mechanical performance of the different damper components. Furthermore, the supporter connection was assessed via collapse mechanism analysis to determine strength requirements. The test results revealed the optimal configurations, the functionality, and the plastic deformation capacity of the proposed system.

Buckling-restrained brace using round steel bar cores restrained by inner round steel tubes and outer square steel tube

This study proposes a buckling-restrained brace (BRB) which is composed of round steel bar cores restrained by inner round steel tubes and an outer square steel tube. One advantage of using the round steel bar cores against the steel plates and tubes is that the bar-ends can be connected to the structural members using screw-joints. The cyclic loading tests were conducted on two test specimens to examine the hysteretic performance of the proposed BRBs. Test results revealed the applicability, restraining capacity, and end-coupler performance of the proposed brace. With an increase in the number of contraction allowance zones, efficacy and performance of the brace became more satisfactory. Furthermore, a theoretical method for designing the proposed BRB in a simplified and optimal way is discussed. For the creation of the design guideline, the braces were analyzed comparatively over a wide range of sections, lengths, and different load conditions, which are most suitable for low to mid-rise buildings. It was found that the design is governed by the heaviest components of the brace, and that the pin connection to the frame was a key component for optimal design.

Особенности исследования характеристик ленточных высокочастотных проводов, использующих трехпроводную схему передачи сигналов

The characteristics of tape conductors using the three-wire signal transmission arrangement are considered. The theoretical and experimental studies of tape conductor circuits are based on an analysis of multiwire planar communication lines. At the first stage of studies the cable article circuits modeling method is used. An example of the electromagnetic field model in the three-wire line of a tape conductor with insulation of limited thickness is given. It is pointed out that the electromagnetic field is concentrated not only in the tape conductor’s plane, but partly spreads into the surrounding space. The modeling is based on the analogy existing between the electrostatic field in the conductor insulation and the stationary electric field of the model. Its complexity is main difficulty in implementing the method. An electric field model developed using the oblique squares method is presented, the use of which makes it possible to determine the tape conductor capacitance and the extent to which the conductor circuits are immune to mutual influence. The electrodes in the model are arranged taking into account the relative permittivity of individual insulation layers. For theoretical calculations both the elegiac magnetic field structure in the insulation and the electric field structure in the three-wire line conductors have been studied. The current density profiles in the conductor cross sections determined taking the skin effect into account are presented. Formulas for calculating the attenuation ratio for the single three-wire circuit of a high-frequency tape conductor are given along with formulas for calculating the electrical resistance taking into account the skin effect and the proximity effect for round and rectangular cores of tape conductors, and for calculating electrical capacitance at certain ratio of tape conductor thicknesses. The frequency dependence of an attenuation ratio for a three-wire cable circuit is given. The obtained study results show that, all other factors being identical, tape conductors with rectangular-shaped cores have a lower attenuation ratio. This is attributed to the influence of the skin effect and proximity effect on losses in the cores, which is also confirmed from an analysis of the tape conductor circuit electromagnetic field patterns obtained by simulation.

Expansion of a superconducting vortex core into a diffusive metal

Vortices in quantum condensates exist owing to a macroscopic phase coherence. Here we show, both experimentally and theoretically, that a quantum vortex with a well-defined core can exist in a rather thick normal metal, proximized with a superconductor. Using scanning tunneling spectroscopy we reveal a proximity vortex lattice at the surface of 50 nm—thick Cu-layer deposited on Nb. We demonstrate that these vortices have regular round cores in the centers of which the proximity minigap vanishes. The cores are found to be significantly larger than the Abrikosov vortex cores in Nb, which is related to the effective coherence length in the proximity region. We develop a theoretical approach that provides a fully self-consistent picture of the evolution of the vortex with the distance from Cu/Nb interface, the interface impedance, applied magnetic field, and temperature. Our work opens a way for the accurate tuning of the superconducting properties of quantum hybrids.

Comparison of Warner-Bratzler shear force values between round and square cross-section cores for assessment of beef Longissimus tenderness

The objective of this experiment was to determine whether there is a difference between Warner-Blatzler shear force values of round (WBSF) and square (WBsSF) cross-section cores for assessment of beef tenderness. To compare the effect of core sampling, Longissimus thoracis muscles were obtained from 43 beef carcasses at 1, 14, and 28days postmortem. For each sample, tenderness was assessed by a trained sensory panel and by WBSF and WBsSF techniques. There was a strong and linear relationship (R2=0.77) between WBSF and WBsSF, but the average shear force of square cores were (P<0.05) greater than those of round cores. The WBsSF had greater repeatability (R=0.85 vs 0.81) and explained slightly more of the variation in sensory panel perception of beef tenderness (76% vs 74%) than WBSF. The results indicate that WBsSF seems to be a more precise method of measuring shear force, being little more sensitive for detecting tenderness differences than WBSF.

Comparison of Warner–Bratzler shear force values between round and square cross-section cores from cooked beef and pork Longissimus muscle

This study was conducted to investigate the effect of core sampling on Warner–Bratzler shear force evaluations of beef and pork loins (Longissimus thoracis et lumborum muscles) and to determine the relationship between them. Steaks of 2.54cm from beef and pork loins were cooked and five round cross-section cores and five square cross-section cores of each steak were taken for shear force evaluation. Core sampling influenced both beef and pork shear force values with higher (P<0.05) average values and standard deviations for square cross-section cores. There was a strong and linear relationship (P<0.01) between round and square cross-section cores for beef (R2=0.78), pork (R2=0.70) and for beef+pork (R2=0.82) samples. These results indicate that it is feasible to use square cross-section cores in Warner–Bratzler shear force protocol as an alternative and potential method to standardize sampling for shear force measurements.

Proteomic and Electron Microscopy Study of Bacteriophages From Bartonella Henselae And Bartonella Grahamii

Bacteriophages are one of the key factors playing an important role in exchange of genetic information between different bacterial species leading towards bacterial evolution. Their study becomes especially significant if bacteriophages contribute to the development of new human pathogens. In the present study we have investigated the occurence of bacteriophages in Bartonella, a genus of Gram-negative bacteria representing facultative intracellular parasites causing strong infections mainly in immune-compromised patients. Proteomic and morphologic characterization of bacteriophage preparations from B. henselae and B. grahamii bacteriophages indicated the presence of three different types of bacteriophages. Bacteriophage-like particles with diameter 42 nm, non-enveloped tailed bacteriophages and large enveloped phages with icosahedral to round cores were identified. Most of the results of our observations suggests, that B. henselae is the host of tailed dsDNA bacte- riophages belonging to order Caudovirales and family Myoviridae (similar to bacteriophage P2), and enveloped bacteriophages similar to dsRNA viruses from family Cystoviridae. Small size bacteriophage-like particles could correspond to defective or satellite phages. Similar conclusions might be drawn for B. grahamii, though less experimental evidences are available.

The first microbiological contamination assessment by deep-sea drilling and coring by the D/V Chikyu at the Iheya North hydrothermal field in the Mid-Okinawa Trough (IODP Expedition 331)

During the Integrated Ocean Drilling Program (IODP) Expedition 331 at the Iheya North hydrothermal system in the Mid-Okinawa Trough by the D/V Chikyu, we conducted microbiological contamination tests of the drilling and coring operations. The contamination from the drilling mud fluids was assessed using both perfluorocarbon tracers (PFT) and fluorescent microsphere beads. PFT infiltration was detected from the periphery of almost all whole round cores (WRCs). By contrast, fluorescent microspheres were not detected in hydrothermally active core samples, possibly due to thermal decomposition of the microspheres under high-temperature conditions. Microbial contamination from drilling mud fluids to the core interior subsamples was further characterized by molecular-based evaluation. The microbial 16S rRNA gene phylotype compositions in the drilling mud fluids were mainly composed of sequences of Beta- and Gammaproteobacteria, and Bacteroidetes and not archaeal sequences. The phylotypes that displayed more than 97% similarity to the sequences obtained from the drilling mud fluids were defined as possible contaminants in this study and were detected as minor components of the bacterial phylotype compositions in 13 of 37 core samples. The degree of microbiological contamination was consistent with that determined by the PFT and/or microsphere assessments. This study suggests a constructive approach for evaluation and eliminating microbial contamination during riser-less drilling and coring operations by the D/V Chikyu.

BEHAVIOR CHARACTERISTICS OF BUCKLING-RESTRAINED BRACES USING ROUND STEEL BAR CORES AND DOUBLE STEEL TUBES

In the previous research by the authors, the buckling restrained braces (BRBs) using round steel bar cores and double steel tubes were developed and some loading tests revealed that the BRBs have sufficient capability as hysteretic dampers. However the test specimens were relatively small and limited to the rigid connection type. The present paper firstly presents evaluation of the rotation characteristics of the outer tube end and loading tests using the element specimens. Then some full-scale tests are conducted using rather large test specimens in which the pin connection type BRBs are employed in addition to the rigid connection type ones. The test results reveal the behavior of the inner tubes, influence of the number of contraction allowance parts, energy dissipation capacity and behavior characteristics of the pin connection type BRBs. Finally, the design conditions of the outer tubes are discussed considering the evaluation results of the rotation characteristics of the outer tube end.

Dynamic Modulus Testing of Thin Pavement Cores

Abstract A novel method of testing thin surface cores using the dynamic (complex) modulus test is proposed that utilizes composite mechanics theory. Rectangular specimens are sawed from the round surface layer cores, and the sawed blocks are simply stacked horizontally without bonding. Two hydrostone caps are made to provide flat and smooth loading ends, as well as to restrain the blocks from moving during loading. Two Linear Vertical Differential Transformers are attached 180° apart to the flat uniform side of the horizontally stacked cores to obtain the strain response without measuring over the joint of the cores. The advantage of this approach over the diametral loading mode, used for resilient modulus testing, is that it provides homogenous testing conditions, which gives direct access to stress and strain and, therefore, constitutive equations.

Core–clad silver halide fibers with few modes and a broad transmission in the mid-infrared

There is interest in single-mode fibers that are highly transparent in the mid-infrared. Such fibers would be valuable for spectroscopy, interferometry, and heterodyne detection. We have developed core-clad fibers made of crystalline silver halides with an external diameter of 900 microm and core diameters as small as 60 microm. These fibers exhibit homogeneous core and cladding regions, round cores, and smooth core-cladding interfaces. The 60 microm fibers support roughly 70 modes and have low losses over a broad spectral range in the mid-infrared. This will pave the road for the development of single-mode mid-infrared fibers. ie ty of America

Compressive fracture characteristics of a Zr-based bulk metallic glass at high test temperatures

This paper presents the fracture characteristics of Zr41.25Ti13.75Ni10Cu12.5Be22.5 bulk metallic glass (BMG) subjected to compression tests at the calorimetric glass transition temperature and in the supercooled liquid region. Under compressive load, the catastrophic fracture is not a pure shear process and the normal stress played a critical role. Based on the Mohr–Coulomb criterion, it was found that the increase in cohesive strength due to the increase of strain rates leads to the change of fracture angles from 40° to 56°. At the calorimetric glass transition temperature, the fracture characteristics are similar to those observed at room temperature, while at higher test temperatures, different fracture features including the flow layer and round cores that are regarded as the unique features for tensile fractures of BMGs, were observed.

Fatigue and fracture behavior of bulk metallic glass

Tensile, compressive, cyclic tension-tension, and cyclic compression-compression tests at room temperature were systematically applied to a Zr52.5CU17.9Al10Ni14.6Ti5 bulk metallic glass for comprehensive understanding of its damage and fracture mechanisms. Under tensile loading, the metallic glass only displays elastic deformation followed by brittle shear fracture. Under compressive loading, after elastic deformadon, obvious plasticity (0.5 to 0.8 pct) can be observed before the final shear fracture. The fracture strength under compression is slightly higher than that under tension. The shear fracture under compression and tension does not occur along the maximum shear stress plane. This indicates that the fracture behavior of the metallic glass does not follow the Tresca criterion. The fracture surfaces show remarkably different features, i.e., a uniform vein structure (compressive fracture) and round cores coexisting with the radiating veins (tensile fracture). Under cyclic tension-tension loading, fatigue cracks are first initiated along localized shear bands on the specimen surface, then propagated along a plane basically perpendicular to the stress axis. A surface damage layer exists under cyclic compression-compression loading. However, the final failure also exhibits a pure shear fracture feature as under uniaxial compression. The cyclic compression-compression fatigue life of the metallic glass is about a factor of 10 higher than the cyclic tension-tension fatigue life at the same stress ratio. Based on these results, the damage and fracture mechanisms of the metallic glass induced by uniaxial and cyclic loading are elucidated.

A novel ryanodine receptor gene mutation causing both cores and rods in congenital myopathy.

Central core disease (CCD) and nemaline rod myopathy are generally considered two genetically and histologically distinct disorders. CCD is defined by the presence of well-demarcated round cores within most myofibers. Nemaline rod myopathy is distinguished by the presence of characteristic nemaline bodies within myofibers. The simultaneous occurrence of both cores and rods in the same muscle biopsy has been described, but no gene mutations have been reported yet for this condition. To describe a family containing 16 affected individuals in six generations with an autosomal dominant congenital myopathy that shows clinical and histologic features of both CCD and nemaline myopathy, and to determine the genetic etiology and protein composition of the cores/rods in this family. The results of linkage analyses excluded involvement of the two autosomal dominant nemaline myopathy loci on chromosome 1, but were consistent with a localization of the disease gene at the CCD locus on chromosome 19q13.1 (ryanodine receptor). SSCP analysis and DNA sequencing identified a novel Thr4637Ala mutation in the transmembrane region of the ryanodine receptor protein. Immunofluorescence studies of patient muscle biopsies showed the central cores to stain for ryanodine receptor. These data suggest that the occurrence of nemaline bodies can be a secondary feature of CCD, and that genetic studies on previously reported core/rod families should be targeted to the ryanodine receptor locus. The results of the immunofluorescence studies suggest that the cores contain excess abnormal ryanodine receptor protein.

Age and zircon inheritance of eastern Blue Ridge plutons, southwestern North Carolina and northeastern Georgia, with implications for magma history and evolution of the Southern Appalachian Orogen

High-resolution ion microprobe analysis of zircon has provided ages for previously undated plutons of the high-grade eastern Blue Ridge of northeastern Georgia and southwestern North Carolina. These data, together with backscattered electron imaging, reveal the presence of nearly ubiquitous inherited cores of highly variable age and magmatic rims that have experienced variable Pb loss, thus making interpretation of conventional U-Pb analyses very difficult. Ion probe rim analyses indicate that the plutons were emplaced during both the mid-Ordovician (Taconian orogeny; Whiteside pluton, 465 Ma; Persim- mon Creek Gneiss, 480 Ma) and mid-Devonian (Acadian orogeny; Rabun pluton, 375 Ma; Pink Beds pluton, 390 Ma; Looking Glass pluton, 380 Ma). A large trondhjemite dike north of Asheville is less confidently assigned an age of 415 Ma. Zircons from all intrusions have predominantly 1.0 to 1.25 Ga cores (Grenvillian). In addition, both Devonian and Ordovician plutons have smaller populations of Late Proterozoic-early Paleozoic (0.5-0.75 Ga), Middle Proterozoic (1.4 Ga), and Late Archean (2.6-2.9 Ga) cores. The ubiquitous, round cores and thick magmatic rims suggest significant resorption and then protracted growth within the melts. Zircon saturation tem- peratures based on whole-rock (melt) Zr concentrations are lower than ex- pected for magma generation (710°-760°C). Zirconium concentrations may not reflect saturation at maximum temperature, if melting was very rapid (10 5 yrs), or if zircon cores represent grains that were shielded from melt inside host grains for much of the magmatic history. The Late Proterozoic-early Paleozoic and Grenvillian inheritance is similar to documented ages of basement exposed in the eastern Blue Ridge. No expo- sures of 1.4 Ga rocks are known in the southern Appalachians, but detrital and inherited zircons of this age have been reported, and 1.4 Ga granites are widespread in the craton to the northwest. However, the combination of absence of Early Proterozoic zircon and presence of Late Archean zircon is inconsistent with the known distribution of basement rocks in southeastern North America. No Archean rocks or inherited zircons have been reported from the southern and central Appalachians; the nearest Archean exposures are 1000 km north, across a dominantly Early Proterozoic terrane. This suggests either that the Laurentian configuration of Archean basement was very complex or that the crust that underlay the plutons at the time of their emplacement included a far-travelled terrane (emplaced during Grenvillian or early Paleozoic orogeny?). Ages of magmatic and inherited zones of zircon from the plutons demon- strate that similar crust underlay the eastern Blue Ridge during both Taconian and Acadian orogenies, that there was no single episode of voluminous magma- tism, and that metamorphism and deformation began before 470 Ma and contin- ued after 370 Ma. These plutons do not constitute a significant convergence- related arc, though it is possible that they represent a displaced part of an arc that lies primarily to the east (in the Inner Piedmont?). Previous geochemical studies have demonstrated that the eastern Blue Ridge intrusions include both a very primitive component, either mafic magma or relatively young mafic source rock, and a component derived from more mature

Theory of the circular harmonics expansion method for multiple-optical-fiber system

The circular harmonics expansion method that has been applied to solve the modal characteristics of multiple-core fiber structure is given a formal derivation. The validity of the field expansion expression in the method is rigorously proved by expanding the Green's function for the scalar wave equation in a surface integral equation into circular harmonics. It is found that for coupled round cores only the modified Bessel functions of the second kind are needed in the expansion, and that the modified Bessel functions of the first kind do not appear in the expansion.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Effect of Salinity on the Measurement of Moisture in Sandstone Cores usingX-Band Microwaves

Measurements have been made to determine the effect of salinity of water on the accuracy of moisture measurement in round berea sandstone cores using X-band microwaves. The results demonstrate that for precise determination of water content, the value of salinity should be known.