Parallel Strands Research Articles

Short‐circuit current difference of parallel strands in winding turns and its influence on the distribution of electromagnetic force

AbstractTransformer winding turns often consist of multiple parallel strands. The spatial position variation of each strand affects the leakage inductance of each branch, resulting in an uneven distribution of short‐circuit currents within the winding turns. And this unevenness persists even when transposition structures are implemented. Traditional methods in transformer analysis frequently overlooked the distribution characteristics of short‐circuit currents when calculating electromagnetic forces. A frequency‐domain calculation method for analysing the current distribution in winding turns was proposed, with a deviation of less than 3% compared to existing analysis methods. Two typical 110 kV transformer models were utilised to investigate the influence of uneven current distribution on the spatial distribution of electromagnetic forces. The spatial distribution of short‐circuit electromagnetic forces in low‐voltage (LV) windings exhibited significant changes, with maximum change rates of 10% and 61.2% for axial and radial electromagnetic force, respectively, in a LV winding with 4 parallel strands. The research also analysed how strand radial width and axial height affect current distribution unevenness and proposed specific design principles to mitigate these disparities in winding design. The findings offer valuable insights for selecting structural parameters and assessing short‐circuit stability during transformer design.

Spectroscopy evidence of interaction of 1,5 disubstituted piperidino-amido anthraquinone derivative with human telomeric G-quadruplex DNA: Basis of anticancer action

The binding of ligands to G-quadruplex (G4) structures at the ends of human telomeric DNA induces thermal stabilization, which interferes with telomere maintenance by disrupting the association of telomeres with the telomerase enzyme—an important marker for cancer. Understanding the binding mode of the ligand-G quadruplex DNA complex is imperative for evaluating the relative efficacy and specificity of their interaction. We focused on the interaction of 1,5-Bis(3-piperidino propionamido) anthracene-9,10-dione with human telomeric DNA sequences using surface plasmon resonance, absorbance, fluorescence (steady-state and lifetime), and circular dichroism spectroscopy techniques. The ligand binding with HTel22 (Kb = 8.4 × 105 M−1) induced cell toxicity with an IC50 value of ∼ 8.64 µM in MCF-7 cancer cell lines. Significant hypochromism (59 %), fluorescence quenching (97 %), no change in fluorescence lifetime and absence of induced Circular Dichroism (CD) band upon addition of G4 DNA to ligand, suggest a groove/external binding mode. CD spectral changes reflect rearrangement in parallel and antiparallel strands to accommodate the ligand. Docking results reveal specific short contacts of the ligand's side chain, including 9CO, 13N, 14NH, and 11CO, with the grooves of the G4 DNA, without making any contact with the loops, favoring an energetically more favorable conformation. Thermal denaturation profiles, obtained by Differential Scanning Calorimetry and CD, show the stabilization of wHTel26 and HTel22 G4 DNA in K+ and Na+ rich solutions by 21.2 and 17.6 °C, respectively, which may restrict the access of telomerase to telomeres. The findings indicate the potential of modifying anthraquinone substituent groups for therapeutic applications.

Investigation of Surge Voltage Propagation in Inverter-Driven Electric Machine Windings

This paper investigates what parameters affect the voltage propagation pattern in inverter-driven electric machine windings and presents mathematical analysis of this pattern with experiment verification. This work provides a thorough understanding of the behavior of machine windings under surge voltage excitations. First, high-fidelity finite element (FE) models were constructed with various combinations of factors in random-wound stranded machine windings. These factors include various types of parasitic capacitances, parasitic inductances of parallel strands and different wire layouts in slots. The surge voltage distribution along the windings was simulated and compared among different cases to identify the key factors that affect this voltage propagation pattern. Subsequently, machine windings with both single-phase and three-phase structures were analyzed via equivalent circuits that were constructed with those key parameters. Then, the expressions of the coil voltage were derived in the Laplace domain. These expressions explicate the uneven surge voltage propagation pattern at various frequencies. Finally, for verification, both simulations and tests were conducted to analyze the surge voltage propagation in single-phase and three-phase windings.

Experimental study on the combustion properties of four common engineered bamboo and wood composites

AbstractEngineered bamboo and wood composites are increasingly utilized in construction due to their eco‐friendly, low‐carbon footprint, and superior mechanical properties. To investigate the effect of heat flux and grain direction on the combustion properties of parallel strand bamboo (PSB), laminated veneer bamboo (LVB), cross‐laminated timber (CLT), and laminated veneer lumber (LVL), a total of 54 specimens in 3 groups were tested through a cone calorimeter. Parameters including the ignition time, heat release rate, mass loss rate, and smoke production rate were investigated. The analytic hierarchy process method was adopted for a multi‐level, qualitative, and quantitative comprehensive fire risk assessment of the corresponding structural materials. The test results reveal that PSB and LVB demonstrated superior performance to the CLT and LVL through the comparison of four combustion characteristics parameters, despite their drawbacks and virtues. The heat flux increases in inverse proportion to the ignition time. As for the heat release rate, the larger peak value is accompanied by an earlier appearance, along with the greater average mass loss rate and the lower smoke rate of engineered bamboo. The peak heat release rate of engineered bamboo composites parallel to the grain is larger than that perpendicular to the grain, whereas other parameters are not significantly influenced by the grain direction. Compared with engineered wood, engineered bamboo composites have the potential to be a safer and more reliable building material in terms of fire risk assessment.Highlights Cone calorimeter was used to analyze the combustion properties of materials. PSB, LVB, CLT, and LVL were studied considering different grain directions. Analytic hierarchy process method was adopted for a fire risk assessment. Engineered bamboo has the potential to be a reliable building material.

Series or parallel toehold-mediated strand displacement and its application in circular RNA detection and logic gates

Toehold-mediated strand displacement (TMSD) is widely employed in constructing a wide range of chemical reaction networks. In TMSD, single-stranded DNA or RNA can fold back upon itself to form a local short double-strand structure often hindering bimolecular hybridization. Here, based on series and parallel circuits, we introduce two mechanisms: series toehold-mediated strand displacement (STMSD) and parallel toehold-mediated strand displacement (PTMSD). These mechanisms can be highly effective when the target area is blocked by a secondary structure. In addition, these systems allow regulating the reaction rates spanning three to five orders of magnitude by adjusting the length of the two toeholds with the added advantage of multifunctional regulation and selectivity. To demonstrate the impressive function of this approach, a logic operation system based on STMSD was constructed to simulate the signal processing of a half-adder. We believe that the introduction of series and parallel toeholds will provide design flexibility contributing to the development of molecular computers, molecular robotics, and DNA-based biosensors.

Revision of the standard EN 1993‐1‐11 and background information

AbstractWithin the framework of the development of the second generation of Eurocode 3, Part 1‐11, related to the design of steel tension components, was completely revised.This paper introduces the main developments in the prEN 1993‐1‐11:2023 regarding the basis of design for the three groups of tension components: A ‐ Rods, B ‐ Ropes, and C ‐ Parallel strand or wire systems. For each of the three groups, complete information on the “Material”, “Ultimate limit state” (including fatigue) and “Serviceability limit state” requirements are provided. Improved formulas for the design of saddles and clamps are presented, including new saddle solutions for group C. Reference is made to the new group D ‐ Parallel wire tension components for suspended structures, included in new Annex C. Annex A “Product requirements for tension components” was completely revised to reflect modern testing requirements. Informative Annex B has been also updated with new figures that reflect the state of the art in tension elements and terminations.

Modulation of the tetrameric I-motif folding of C-rich Tetrahymena telomeric sequences by hexitol nucleic acid (HNA) modifications

I-motifs are non-canonical DNA structures consisting of two parallel strands held together by hemiprotonated cytosine-cytosine+ base pairs, which intercalate to form a ordered column of stacked base pairs. This unique structure covers potential relevance in various fields, including gene regulation and biotechnological applications. A unique structural feature of I-motifs (iM), is the presence of sugar-sugar interactions through their extremely narrow minor grooves. Consistently, oligonucleotides containing pentose derivatives such as ribose, 2′-deoxyribose, arabinose, and 2′-deoxy-2′-fluoroarabinose highlighted a very different attitude to fold into iM. On the other hand, there is significant attention focused on exploring sugar-modifications that can increase nucleic acids resistance to nuclease degradation, a crucial requirement for therapeutic applications.An interesting example, not addressed in the iM field yet, is represented by hexitol nucleic acid (HNA), a metabolically stable six-membered ring analogue compatible with A-like double helix formation. Herein, we selected two DNA C-rich Tetrahymena telomeric sequences whose tetrameric iMs were already resolved by NMR and we investigated the iM folding of related HNA and RNA oligonucleotides by circular dichroism, differential scanning calorimetry and NMR. The comparison of their behaviours vs the DNA counterparts provided interesting insights into the influence of the sugar on iM folding. In particular, ribose and hexitol prevented iM formation. However, by clustering the hexitol-containing residues at the 3′-end, it was possible to modulate the distribution of the different topological species described for the DNA iMs. These data open new avenues for the exploitation of sugar modifications for I-motif characterization and applications.

A Comprehensive Investigation of Winding Eddy and Circulating Current Losses of Stator Iron Coreless PMBLDC Motors

A method is proposed to comprehensively study the eddy and circulating current losses of stator winding wound by multiple parallel strands, to further improve the power density of stator iron coreless permanent magnet brushless DC (PMBLDC) motors. Analytical models of the eddy and circulating current losses in stator winding are deduced firstly to explicitly express the influencing factors of these two losses. As is shown, these factors are mutually contradicting. While the eddy current loss can be greatly reduced by using multiple parallel conductor strands, the circulating current loss will be extensively increased. The factors influencing these two winding losses, such as the strand diameter, magnetization types, and rotating speed, are investigated. A prototype of stator iron coreless PMBLDC motor without an inner rotor core is manufactured and tested to validate the theory. The experimental results of winding eddy and circulating current losses with different combinations of strand diameters and parallel numbers agree well with the theoretical results.

Elevated temperature creep model of parallel wire strands

Elevated temperature creep model of parallel wire strands

Prestress loss of twisted wire strands and parallel wire strands at elevated temperatures

High-strength prestressing cables exposed to high temperature result in the prestress loss, potentially leading to failure and even collapse of prestressing structures. This paper experimentally investigates thermal expansion of 1860 MPa steel wires and prestress loss of 1860 MPa twisted wire strands and parallel wire strands at elevated temperatures initially. Strands are localised heated in prestress loss tests. Different highest temperatures and initial prestress levels are considered. The test results show that EC2 underestimates the thermal strain of 1860 MPa steel wire at more than 450 °C. Prestress loss of the prestressing strand increases as the temperature increases. Cable types have little influence on the final prestress loss ratio. The strand with higher initial prestress level results in less final prestress loss ratio at less than 400 °C. A series fitting formulas of thermal strain, thermal expansion coefficient and final prestress loss ratio of prestressing strands are proposed. In addition, the finite element model of prestressing strand at elevated temperatures is established and validated. The numerical analysis shows that the temperature of the strand in non-heated region is significant, and the stress of the strand rises and then fall during heating stage, due to the balance between thermal expansion and degradation of mechanical properties. Finally, the analytical model of the prestress loss of the strands at elevated temperatures is proposed. The effect of thermal expansion, degradation of the mechanical properties and high-temperature creep of the strand in the heated region and non-heated region is considered respectively. Simplified method is obtained for more efficient computation. The analytical results have great agreement with the test results. The application of analytical method on practical engineering is discussed, and improved calculation equation is proposed for large span cables exposed to localised fire.

Coarse-Grained Model of Phytic Acid for Predicting the Supramolecular Architecture of Ionically Cross-Linked Chitosan Hydrogels.

Phytic acid is a polyphosphate whose ionized form is used as a cross-linking agent to formulate chitosan-based nanoparticles and hydrogels as carriers with remarkable adhesivity and biocompatibility. To predict the underlying cross-linking pattern responsible for the structural arrangement in the chitosan hydrogels, we put forth coarse-grained parametrization of the phytic acid compatible with the Martini 2.3P force field. The bonded parameters giving the distinctive representation of the phosphate substitutes to the myo-inositol ring of phytic acid are optimized by a structural comparison to the conformation sampled with the GROMOS 56ACARBO force field. The chitosan strand is coarse-grained following a similar approach, and the cross-interaction terms are optimized to reproduce the atomistic features of phytate-mediated cross-linking. The predicted binding motifs of the phytic acid-chitosan complexation enable us to rationalize the structural characteristics of the reticulated chitosan in a semi-dilute solution. The model describes a network topology affected by the phytic acid concentration and a nonmonotonous behavior of the mean pore size caused by a poor predilection for the parallel strand alignment near the charge neutralization of the phytic acid-chitosan complex.

Anisotropy attenuation of reconstituted bamboo lumber by orthogonal layup process

Current reconstituted bamboo lumber materials have significant anisotropy as the strength along the fiber is much stronger than that perpendicular to the fiber, which will bring a lot of mechanical limitations in actual applications. A new kind of cross laminated bamboo (CLB) was designed and four-point bending properties of this CLB were investigated. Flexural mechanical properties of the CLB and traditional parallel bamboo strand lumber (PBSL) were tested both parallel to and perpendicular to the fiber direction to explore the effect of the cross-laminated structure in reducing the anisotropy of bamboo products. The ratio of the parallel strength (0°) to the transverse (90°) is reduced from 8.32 of the PBSL to 1.52 of the CLB in bending. A laminated composite theory with strain failure criterion was developed and consistently predicts the flexural failure of the CLB. With balanced mechanical properties in all directions, the new CLB could be widely applied as plated structures in building engineering.

Numerical Modeling of Litz Wires Based on Discrete Transpositions of Strands and 2-D Finite Element Analysis

A new numerical method is proposed to model the electric behavior of a single bundle litz wire with a large number of strands. The method is first based on a two-dimensional (2D) finite element analysis (FEA) to evaluate the series impedance matrix of a multistrand cable with parallel strands. Then a mathematical algorithm for a discrete transposition of all strands is applied to simulate the bunching and twisting of the strands. The new procedure is very efficient and accurate, as demonstrated by the excellent agreement of the numerical results with those obtained by experiments or with 3D FEA. The error in terms of AC-to-DC resistance ratio is less than 10% in the tested configurations. Furthermore, the computational cost of the proposed method is very low and comparable with a simple 2D FEA.

Toward a Reevaluation of Siegfried Kracauer and the Frankfurt School

This essay reviews the anthology Siegfried Kracauer: Selected Writings on Media, Propaganda, and Political Communication (2022), edited and with translations by Jaeho Kang, Graeme Gilloch, and John Abromeit. The editors describe the volume as "a selection of Kracauer’s diverse materials on propaganda and political communication – texts hitherto unavailable in English or strewn among different […] journals, periodicals, and magazines" (2). Beyond this, Selected Writings presents readers and scholars with an opportunity to re-evaluate the legacy of Siegfried Kracauer, particularly in connection with the strands of mutual influence and parallel thought between his work and the development of early Frankfurt School critical theory. The volume contains remarkable and largely unpublished work on totalitarian propaganda in film; the manipulative devices of the U.S. advertising industry of the 1940s and 50s; and philosophy of science in the area of sociologically informed empirical research.

Real-Time Damage Self-Diagnosis and Self-Localization Brillouin Distributed Optical Fiber–Fiber-Reinforced Polymer Composite Smart Cables

Cables are important components of long-span space structures, cable-supported bridges, slopes, and so on. However, they often suffer from damage such as wire breakage, corrosion, and anchor head loosening, which threatens structural safety seriously. Therefore, it is very important to diagnose and localize their damage. To address this problem, a real-time damage self-diagnosis and self-localization smart cable is proposed. It is made of a polyethylene cover pipe and some parallel intelligent steel strands with the Brillouin distributed monitoring capability. Fiber-reinforced polymer (FRP) and optical fiber are put together in the thermosetting molding process to form the intelligent central wire of each intelligent steel strand. When the side wire of the steel strand reaches the ultimate load, the intelligent central wire only reaches about 50% of its ultimate load, so it can be used in the real-time monitoring of side wires. Numerical models of seven-wire steel strands with different lengths were established, and the broken wire damage was simulated by changing coupling conditions in single and multiple damage cases. To further verify the proposed smart cable, experiments were carried out based on two intelligent steel strands with the length of 34.5 m. Experimental damage cases were simulated by cutting side wires at different positions under different loads. Both numerical and experimental results show that the change in the tension strain of the intelligent central wire can indicate the damaged location of the broken side wire. For a healthy steel strand, the tension strain of the central wire is a constant value; for a damaged steel strand, damage can be localized according to the strain waveform of the intelligent central wire and its ratio of peak strain to stable strain. The proposed smart cable has functions of real-time stress self-sensing, damage self-diagnosis, damage self-localization, damage self-warning of any side wire, and its central wire has excellent corrosion resistance; it can be well used in life-cycle real-time structural health monitoring of cable structures/substructures, which dramatically reduces the probability of cable accidents, and lays a good foundation for smart civil structures.

Multiobjective Design Optimization of a Novel Switched Reluctance Motor With Unequal Alternating Stator Yoke Segments

Switched reluctance motors (SRMs) have attracted considerable attention for energy conversion within industrial applications. To realize the high-quality operation status, optimization for SRMs is one of the most essential steps in the design stage. In this article, a multiobjective design optimization method is proposed for a novel SRM with unequal alternating stator yoke segments. First, the asymmetric flux distribution and the inconsistent current phenomenon of the conventional six-phase SRM are introduced. The unequal yoke SRM (UYSRM) is developed to improve the current profiles and reduce the unnecessary stator mass. Then, an optimization method considering the slot fill factor is proposed and performed on the proposed UYSRM. In the optimization process, the sensitivity analysis is conducted based on the orthogonal array, and the sensitive degrees of different variables are calculated. To take the full advantage of the stator slot area, the number of parallel strands of phase windings is adjusted according to the number of turns and the variables of the stator. The performances of the UYSRM are evaluated to validate the proposed SRM and optimization method. Finally, a prototype motor is manufactured and tested. Both the simulation and test results verify the effectiveness and reasonability of the proposed design optimization method for the UYSRM. In addition, the proposed method offers a new research orientation for electric machines.

Research on Novel Flat Wire Transposed Winding of PMSM for Electric Vehicle

Permanent magnet synchronous motor (PMSM) for electric vehicles is developing higher frequency and speed but triggering a significant increase of eddy current loss. To resolve the eddy current loss issue, a novel flat wire transposed winding composed of double-row multiple parallel strands is proposed. Transposed winding techniques have been proved to be efficient in reducing eddy current loss by preventing the uneven leakage magnetic field induced by high frequency. The proposed transposition further improved this technique in reducing circulating current loss. Taking a 60-kW PMSM as an example, the novel flat wire transposed winding arrangement is carried out. The 3-D field-circuit coupled finite-element models of 360° complete transposed and incomplete transposed winding PMSM are established, and circulating current losses are compared. The analysis results show that incomplete transposed winding has a better performance in reducing the circulating current loss. The transposition method suitable for novel flat wire transposed winding is obtained, and the feasibility of PMSM with novel flat wire transposed winding to reduce winding losses is proven.

Hyperbolic twisted torus links

The twisted torus link T(p, q; r, s) is obtained by twisting r parallel strands of the (p, q)-torus link a total of s full times. In this paper we find all twisted torus links which are hyperbolic for $$\vert s\vert >3$$ .

Unraveling mitotic chromosome structure using optical tweezers.

During mitosis, vertebrate chromosomes compact into X-shapes that are approximately four orders of magnitude shorter than the contour length of the DNA-molecule they consist of. Visualizing the internal structure of these chromosomes is difficult because of their high compaction, though some light has been shed on this problem using (super-resolution) fluorescence microscopy and Hi-C experiments. We developed an optical tweezers method to manipulate mitotic chromosomes and ‘unravel’ them starting from the telomeres, in a way reminiscent of unraveling a woolen sweater by pulling on a thread. The DNA-threads that are pulled from the chromosome are coated by different proteins that are involved in mitotic chromosome architecture (histones, condensins, topoisomerases). Unraveling the chromosome in this way allows us to image its contents without running into problems with the limited resolution of light microscopy, and without resorting to harsh treatments like chromosome fixation. Using immunostaining, we label several different proteins on chromosome threads, and like so, determine their distribution along the chromosomal DNA. While imaging, we measure the force exerted on the chromosome and thread by our optical tweezers. The well-defined overstretching reaction of double-stranded DNA, which occurs at ∼65pN, helps us to determine the number of parallel DNA strands in the unraveled DNA-thread. These DNA-threads show a wide range of thicknesses, with on one end of the spectrum sturdy fiber-like chromatin structures, and on the other end, fragile singular DNA strands. Imaging chromosomal proteins on both these structures will help elucidate the internal structure of mitotic chromosomes. Furthermore, observing the force-extension behavior while unravelling the chromosome gives insight in the folding structure of chromatin in mitotic chromosomes.

Technical Research on Fatigue Resistance and Durability of OVM250 Parallel Strand Cable System

PDF HTML XML Export Cite reminder Technical Research on Fatigue Resistance and Durability of OVM250 Parallel Strand Cable System DOI: 10.59238/j.pt.2023.01.005 Author: Affiliation: (Liuzhou OVM Machinery Co., Ltd., Liuzhou 545005,China) Clc Number: Fund Project: Article | Figures | Metrics | Reference | Related | Cited by | Materials | Comments Abstract:With the development of modern long-span cable-stayed bridges, due to the parallel strand cable (PSC) being assembled on-site strand by strand, which has the advantages such as no need for large-scale equipment for cable-making, delivery, hoisting, traction, tensioning, and the corrosion protection of the cable is excellent, it is more and more favored by designers. As load-bearing components, the stay cables are known as the life cable of the cable-stayed bridge. Its reliability and durability are the key factors that determine the safety and the service life of the cable-stayed bridge. In accordance with the requirements specified in international recommendations, in-depth research has been carried out on cable fatigue, anti-corrosion, and vibration control to optimize OVM250 PSC system. All research results have been successfully applied to cable stayed bridge projects. Reference Related Cited by