Добірка наукової літератури з теми "Irvine cables"

Cables are typically used in engineering applications as tensile members. Relevant examples are the main cables of suspension bridges, the stays of cable-stayed bridges, the load-bearing and stabilizing cables of tensile structures, the anchor cables of floating mooring structures, the guy-ropes for ship masts, towers, and wind turbines, the copper cables of electrical power lines. Since cables are characterized by non-linear behavior, analysis of cable structures often requires advanced techniques, like non-linear FEM, able to consider geometric non-linearity. Nevertheless, a traditional simplified approach consists in replacing the cable with an equivalent tie rod, characterized by a suitable non-linear constitutive law. Currently used equivalent constitutive laws have been derived by Dischinger, Ernst and Irvine. Since the equivalence is restricted to taut cables, characterized by small sag to chord ratios, these traditional formulae are not appropriate for uniformly loaded sagging cables: the main cables of suspension bridges are a particularly emblematic case. Despite some recent attempts to find more refined solutions, the problem is still open, since closed form solutions of general validity are not available. In the paper, general analytical formulae of the non-linear constitutive law of the equivalent tie rod are proposed, distinguishing two relevant cases, according as the length of the cable can vary or not. The expressions, derived by applying the general form of the theorem of virtual work, can be applied independently on the material, on the sag to chord ratio, on the load intensity and on the stress level, so allowing the replacement of the whole cable with a single equivalent tie rod. The expressions are critically discussed referring to a wide parametric study also in comparison with the existing formulae, stressing the influence of the most relevant parameters.

The paper reports an investigation on a continuous model for dynamics of cables, taking bending stiffness and sag extensibility into account. The new approach involves the use of derived sensitivity coefficients associated with various cable parameters of interest, and use these coefficients to achieve optimal cable performance. The fatigue damage is calculated in the time domain through an adequate cycles counting method. A discussion of the influence of the Irvine parameter on the total fatigue damage is then performed. A Monte Carlo parametric analysis on a case-study,representative of a suspended cable typical of overhead power-line applications, especially in cyclic exposure, exceeds the present chromate-based systems.introduces a discussion on the convergence of the modal expansions and highlights the respective importance of the different classes of non-linear terms included in the model.

Submerged tensioned anchor cables (STACs) are pivotal components utilized extensively for anchoring and supporting offshore floating structures. Unlike tensioned cables in air, STACs exhibit distinctive nonlinear damping characteristics. Although existing studies on the free vibration response and tension identification of STACs often employ conventional Galerkin and average methods, the effect of the quadratic damping coefficient (QDC) on the vibration frequency remains unquantified. This paper re-examines the effect of bending stiffness on the static equilibrium configuration of STACs, and establishes the in-plane transverse free motion equations considering bending stiffness, sag, and hydrodynamic force. By introducing the bending stiffness influence coefficient and the Irvine parameter, the exact analytical solutions of symmetric and antisymmetric frequencies and modal shapes of STACs are derived. An improved Galerkin method is proposed to discretize the nonlinear free motion equations ensuring the accuracy and applicability of the analytical results. Additionally, this paper presents an analytical solution for the nonlinear free vibration response of the STACs using the improved averaging method, along with improved frequency formulas and tension identification methods considering the QDC. Through a case study, it is demonstrated that the improved methods introduced in this paper offer higher accuracy and wider applicability compared to the conventional approaches. These findings provide theoretical guidance and reference for the precise dynamic analysis, monitoring, and evaluation of marine anchor cable structures.

A mechanical model describing finite motions of nonshallow cables around the initial catenary configurations is proposed. An exact kinematic formulation accounting for finite displacements is adopted, whereas the material is assumed to be linearly elastic. The nondimensional mechanical parameters governing the motions of nonshallow cables are obtained via a suitable nondimensionalization, and the regions of their physically plausible values are portrayed. The spectral properties of linear unforced undamped vibrations around the initial static configurations are investigated via a Galerkin-Ritz discretization. A classification of the modes is obtained on the basis of their associated energy content, leading to geometric modes, elastostatic modes (with prevalent transverse motions and appreciable stretching), and elastodynamic modes (with prevalent longitudinal motion). Moreover, an extension of Irvine’s model to moderately nonshallow cables is proposed to determine the frequencies and mode shapes in closed form.

An improved mathematical model used to study the coupling characteristic of the multi-span transmission lines is developed. Based on the solution method for single-span cable, an expression for the dynamic stiffness of two-span transmission lines with an arbitrary inclination angle is formulated. The continuity of displacements and forces at a suspension point is used to derive the dynamic stiffness. Interactions between insulator strings and adjacent spans are accommodated. Considering the infinite dynamic stiffness corresponds to the natural frequencies of the transmission lines, the finite-element method (FEM) is employed to assess the validity of the dynamic stiffness. In the numerical investigation, attention is focused on the effect of the inclination angles, Irvine parameter, insulator string length and damping parameter. In addition, the modal function corresponding to the natural frequencies is derived. Then, the results of comprehensive parametric studies are presented and discussed. Special attention is paid to the effect of the Irvine parameter and damping parameter on the in-plane modal shapes. Finally, according to the theoretical model of two-span transmission lines, the generalized dynamic stiffness of transmission lines with an arbitrary number of spans and inclination angles is derived. The method can be used as the basis of the vibration analysis on a wide variety of multi-span transmission lines.

Cable-based technologies have been a backbone for harvesting on steep slopes. Computing the layout of a single cable road requires considering the standards of structural design, aiming to (1) guarantee structural safety, and (2) provide the required serviceability. Currently applied analysis methods, such as the Pestal method, are unprecise. Alternatively, methods based on the catenary, such as Zweifel or Irvine, are better suited to analyze and predict load path and occurring forces for skylines anchored fix on both ends. However, studies that validate those catenary analyses (concurrently load path and forces) are rare and were not carried out under realistic heavy load conditions. Therefore, the aim of the project was to validate the catenary analyses under realistic, heavy load conditions for cable roads with multiple spans. In two case studies in Switzerland, the deflection in every span as well as the skyline tensile force at the anchor were measured for different load configurations and compared with theoretical computations of Zweifel and Pestal. The approach of Zweifel maps the mechanical properties realistic. However, as proven by our measurements, it slightly overestimated the deflection and the skyline tensile forces because the friction on the supports was neglected (between skyline and saddle). The deflections calculated with the Pestal formulas were significantly larger than the measured values, in particular with heavy load and in large spans. Our measurement studies confirmed that the mechanical properties of a cable road can be described adequately with the algorithm by Zweifel. However, it should be further developed with the inclusion of effects like the friction to improve the efficiency, safety and cost-performance ratio in cable road planning.

BackgroundBecause conventional single-cell strategies rely on dissociating tissues into suspensions that lose spatial context,1 we developed Slide-TCR-seq to sequence both whole transcriptomes and TCRs with 10µm-spatial resolution, & applied it to renal cell carcinoma (ccRCC) treated with immune checkpoint inhibitors (ICI).MethodsSlide-TCR-seq combines Slide-seqV22 3—a 10µm-resolution spatial approach utilizing mRNA capture and DNA-barcoded beads—with sensitive targeted capture of TCR sequences (rhTCRseq,4 previously developed by our group), thereby enabling amplification of segments extending from upstream of CDR3 to the 3’-end of the TCR transcript (figure 1A). We tested Slide-TCR-seq first on OT-I murine spleen and then applied this methodology to 3 patients‘ pre-αPD-1 ccRCC samples5 and a post-αPD-1 metastasis to investigate the spatial, functional, and clonotypic organization of T cells in relationship to tumor using RCTD,6 spatial enrichment, and spatial expression analyses.ResultsUsing Slide-TCR-seq, we first recapitulated native spatial structure of OT-I mouse spleen (figure 1B-G). TCRα/β CDR3 sequences were detected on 37.1% of beads with Trac/Trbc2 constant sequences—comparable to other scTCRseq methods. Because the clonal and spatial context of TILs have been increasingly implicated in immunotherapy resistance, we used Slide-TCR-seq to analyze a lung ccRCC metastasis following αPD-1 therapy. We employed unsupervised clustering to delineate the tumor, intervening boundary, and lung compartments, and RCTD analyses to spatially map individual cell types; together recapitulating the architecture observed in corresponding histology (figure 2). We identified 1,132 unique clonotypes, with distinct spatial distributions spanning the tissue compartments. Eight clonotypes were significantly enriched in tumor, whereas 5 were depleted (all p<0.05) (figure 3). We then analyzed the relationships between the T cells’ clonotype, gene expression, and tumor infiltration depth among clonotypes. Using a T-cell geneset associated with poor response to ICI,7 we dichotomized T-clonotype beads by geneset expression, and found spatial segregation of this geneset’s expression both within and across clonotypes (figure 4). TCR-4—the most significantly tumor-enriched clonotype—and TCR-2 displayed high expression of the poor ICI response geneset near the tumor’s edge, but low expression deeper in the tumor compartment; indicating that there are transcriptionally distinct subpopulations of these clonotypes, which depended on the extent of their tumor infiltration.Abstract 76 Figure 1Slide-TCR-seq spatially localizes T cell receptors and transcriptome information. a. Schematic of Slide-TCR-seq, in which tissue is placed onto an in situ barcoded bead array. cDNA libraries prepared with Slide-seqV2 are split prior to fragmentation with one portion used for targeted amplification via rhTCRseq optimized for use with Slide-seq libraries. Slide-TCR-seq provides gene expression, cell type, and clonotype information in space. b. Serial sections of the OT-1 mouse spleen with hematoxylin and eosin stain show characteristic architecture of red pulp and white pulp separation. c. Spatial reconstruction of Slide-TCR-seq array for a corresponding section of OT-I mouse spleen, with RCTD immune cell type assignment. NK = natural killer. d. Gene expression gaussian-filtered heatmap for visualizing the spatial distribution of gene markers for marginal zone (Marco), red blood cells (RBCs; Gypa), and CD8 T cells (Cd8a). e and f. Comparing the spatial distribution of constant (left) and variable (right) sequences for TCRα (e) and TCRβ (f), with superimposed density plot. g. The fraction of beads that capture CDR3 variable sequences (y-axis) when constant UMIs are captured (x-axis) for TCRα (left, light blue) and TCRβ (right, dark blue), with the number of corresponding beads along the top axis. All scale bars: 500 µm.Abstract 76 Figure 2Slide-TCR-seq identifies spatial differences between T cell clonotypes in renal cell carcinoma. (a) H&E stain of a ccRCC metastasis to the lung following PD-1 blockade therapy. (b) The compartment assignment of lung (green), immune cell boundary (orange), and tumor (blue) by applying K-nearest neighbors to cell types determined by unsupervised clustering from Slide-TCR-seq of a sequential tissue section. (c) Spatial reconstruction of cell type identifies using RCTD anaysis of the Slide-TCR-seq data. (d) Spatial localization of T cell clonotypes (n=447 clonotypes, colored by clonotype) from the the Slide-TCR-seq data.Abstract 76 Figure 3Top: y-axis Significance of clonotype spatial distributions compared against all other clonotypes with at least ten beads per array from the ccRCC lung metastasis plotted against an x-axis of magnitude of tumor enrichment or depletion (data from n=3 replicate arrays, two one-tailed K-S tests). Bottom: Visualization of selected significant clonotypes, ordered by tumor enrichment, in tissue compartments for a single array (T cells within the tumor compartment are displayed as opaque, T cells within other compartments are displayed as translucent).Abstract 76 Figure 4Spatial and molecular heterogeneity in clonotype gene expression and tumor infiltration. a. The three axes — spatial localization, gene expression, and T cell clonotype — that Slide-TCR-seq can relate. b. Top: distribution of poor response to immune checkpoint inhibitor treatment (’PRI’) geneset7 expression across all clonotypes in the tumor region of the same post-PD1 inhibitor RCC lung metastasis from figures 2–3 (from a single replicate) with kernel density estimation. Yellow = clonotypes with lower than median PRI expression; purple = clonotypes with PRI expression greater than or equal to the median value. Bottom: localization of low (yellow) and high (purple) PRI geneset expression clonotypes within the tumor region (light blue) from the Slide-TCR-seq array shows their distinct spatial separation (light blue = tumor region, orange = boundary region, green = lung region). Scale bar: 500 µm. c. Smoothed histograms comparing the distance infiltrated into tumor by two-tailed K-S test comparing low (yellow) and high (purple) expression clonotypes, as dichotomized by median expression of PRI. d. Comparing distance infiltrated into tumor by two-tailed K-S test between low and high PRI expression T cells across those clonotypes with at least 20 beads (n=7 clonotypes).ConclusionsSlide-TCR-seq effectively integrates spatial transcriptomics with TCR detection at 10µm resolution, thereby relating T cells’ clonality and gene expression to their spatial organization in tumors. Our findings suggest that a clonotype’s T cells may exhibit mixed responses to ICI depending on their spatial localization. The heterogeneity among clonotypes, in both gene expression and organization, underscores the importance of studying the TCR repertoire with spatial resolution.AcknowledgementsWe are grateful to Irving A. Barrera-Lopez, Zoe N. Garcia, and Aziz Al’Khafaji for technical assistance.ReferencesGohil S, Iorgulescu JB, Braun D, Keskin D, Livak K. Applying high-dimensional single-cell technologies to the analysis of cancer immunotherapy. Nat Rev Clin Oncol 2021; 18:244–256.Stickels RR, Murray E, Kumar P, Li J, Marshall JL, Di Bella DJ, Arlotta P, Macosko EZ, Chen F. Highly sensitive spatial transcriptomics at near-cellular resolution with Slide-seqV2. Nat Biotechnol 2021 Mar;39(3):313–319.Rodriques SG, Stickels RR, Goeva A, Martin CA, Murray E, Vanderburg CR, Welch J, Chen LM, Chen F, Macosko EZ. Slide-seq: A scalable technology for measuring genome-wide expression at high spatial resolution. Science 2019 Mar 29;363(6434):1463–1467.Li S, Sun J, Allesøe R, Datta K, Bao Y, Oliveira G, Forman J, Jin R, Olsen LR, Keskin DB, Shukla SA, Wu CJ, Livak KJ. RNase H-dependent PCR-enabled T-cell receptor sequencing for highly specific and efficient targeted sequencing of T-cell receptor mRNA for single-cell and repertoire analysis. Nat Protoc 2019 Aug;14(8):2571–2594.Braun DA, Street K, Burke KP, Cookmeyer DL, Denize T, Pedersen CB, Gohil SH, Schindler N, Pomerance L, Hirsch L, Bakouny Z, Hou Y, Forman J, Huang T, Li S, Cui A, Keskin DB, Steinharter J, Bouchard G, Sun M, Pimenta EM, Xu W, Mahoney KM, McGregor BA, Hirsch MS, Chang SL, Livak KJ, McDermott DF, Shukla SA, Olsen LR, Signoretti S, Sharpe AH, Irizarry RA, Choueiri TK, Wu CJ. Progressive immune dysfunction with advancing disease stage in renal cell carcinoma. Cancer Cell 2021 May 10;39(5):632–648.Cable DM, Murray E, Zou LS, Goeva A, Macosko EZ, Chen F, Irizarry RA. Robust decomposition of cell type mixtures in spatial transcriptomics. Nat Biotechnol 2021 Feb 18. doi: 10.1038/s41587-021-00830-w. Epub ahead of print. PMID: 33603203.Sade-Feldman M, Yizhak K, Bjorgaard SL, Ray JP, de Boer CG, Jenkins RW, Lieb DJ, Chen JH, Frederick DT, Barzily-Rokni M, Freeman SS, Reuben A, Hoover PJ, Villani AC, Ivanova E, Portell A, Lizotte PH, Aref AR, Eliane JP, Hammond MR, Vitzthum H, Blackmon SM, Li B, Gopalakrishnan V, Reddy SM, Cooper ZA, Paweletz CP, Barbie DA, Stemmer-Rachamimov A, Flaherty KT, Wargo JA, Boland GM, Sullivan RJ, Getz G, Hacohen N. Defining T Cell States Associated with Response to Checkpoint Immunotherapy in Melanoma. Cell 2018 Nov 1;175(4):998–1013Ethics ApprovalThis study was approved by MGB/DFCI/Broad institution’s Ethics Board; approval number 2019P000017.

Les robots parallèles à câbles (CDPR) se présentent comme une nouvelle classe de robots parallèles. Ces robots utilisent des câbles enroulés pour leurs jambes plutôt que les chaînes d'éléments rigides comme les robots parallèles classiques. Cette technologie est dépendante des câbles, donc sujette à l'unilatéralité des efforts exercés par les câbles sur la plate-forme, à l'élasticité des câbles, et à leur affaissement dû à leur masse propre. Dans un premier temps, nous présentons la modélisation de ce type de robot, en particulier avec le comportement des câbles dits d'Irvine, pour son caractère plus réaliste par rapport à d'autres modélisations. Dans un second temps, nous traitons de l'utilisation des réseaux de neurones (NN) pour la résolution du modèle géométrique direct (MGD), et ceci tout en ayant présenté les performances des autres moyens de résolution auparavant pour comparaison. Si les NN présentent des qualités intéressantes pour la résolution de problèmes dans de nombreux domaines, ils nécessiteront néanmoins d'être grandement adaptés au problème du MGD en commençant par pouvoir déterminer plusieurs solutions exactes tout en minimisant leur temps de calcul. Enfin, nous aborderons le problème de la calibration des modules de Young E des matériaux des câbles, qui a pour objectif d'identifier l'élasticité de chaque câble à partir de mesures réalisées sur le CDPR. La calibration vise à répondre à un besoin crucial de sécurité dans le cadre de l'assistance à la mobilité pour personnes fragiles et peut être utilisée pour la maintenance et l'amélioration des performances. Nous montrons en simulation la faisabilité d'une telle calibration en utilisant deux méthodes : la descente de gradient et l'utilisation des NN tout en montrant leurs limites en l'état
Cable-driven parallel robots (CDPR) represent a new class of parallel robots. These robots use wound cables for their legs instead of the rigid link chains used in traditional parallel robots. This technology is cable-dependent and therefore subject to the unilateral forces exerted by the cables on the platform, the cables' elasticity, and sagging due to their own weight. Initially, we present the modeling of this type of robot, particularly focusing on the behavior of so-called Irvine cables, as this offers a more realistic approach compared to other models. Next, we address the use of neural networks (NN) for solving the direct kinametic model (DK), after having previously presented the performance of other solving methods for comparison. NNs exhibit interesting qualities for problem-solving in various fields; however, they will need to be significantly adapted to the DK problem, starting with the ability to determine multiple exact solutions while minimizing computation time, which is a critical challenge in this context. Finally, we will address the problem of calibrating the Young's modulus E of the cable materials, with the goal of identifying the elasticity of each cable based on measurements taken from the CDPR. The calibration aims to meet a crucial safety need in the context of mobility assistance for vulnerable individuals and can be used for maintenance and performance improvement. We demonstrate the feasibility of such calibration through simulation, using two methods: gradient descent and the use of NNs, while also highlighting their current limitations. These limitations indicate that further research and development are necessary to refine these methods for practical use, especially in real-world applications where accuracy and speed are of paramount importance

Abstract Traveling cables or threadlines appear in a number of technical applications such as textile machinery, V-belts, ski lifts, funiculars and also in simple models of traveling webs in paper machinery. The mechanical models used so far, most often neglect the effect of sag due to the weight of the cable, although it is well known that in some cases it may be quite important. In this paper, the authors develop a particularly simple model for translating cables using the assumption that the longitudinal inertia forces are negligible in comparison to the transversal inertia forces if the sag of the cable is sufficiently small. This assumption has already been made in a study of linear vibrations of stationary cables in 1970 by Irvine & Caughey. This lead to surprising results which have also been verified experimentally in the laboratory. The extended model presented in this paper includes gyroscopic and nonlinear terms in the equations of motion, related to the cable transport velocity and geometric nonlinearities. As a particular case (zero longitudinal speed and linear theory) the model of Irvine & Caughey is again contained in the present analysis. The linear and non-linear vibrations about a steady state solution are studied. The results show some interesting features which may also be relevant to technical systems if the transport speed is sufficiently high.

This paper deals with experimental study and with understanding via a finite number of degrees of freedom model of the vibrations of an inclined cable linked to a continuous beam. This is a simplified version of deck and cable of a bridge. External excitation is exerted on the beam. The cable attached to the end of the beam is submitted to a vertical sinusoidal solicitation due to the response of the finite stiffness beam. The excitation of the cable though it is more complex looks similar to the excitation used in previous works. A guided device located at the end of the beam ensures the excitation with a variation of the horizontal component of the cable tension that introduces a new parametric excitation. Analysis of preliminary experimental results for main and secondary resonances permits us to consider simple modeling with one degree of freedom systems obtained by projection of the continuous three-dimensional model of the cable on adapted Irvine mode. Analytical treatment of these models involving data from the experimental devices shows a correct qualitative agreement between preliminary experiments and theoretical. Continuation technique are used to highlight the influence of physical parameters.

Ocean energy developments are appearing around the world including Scotland, Ireland, Wales, England, Australia, New Zealand, Japan, Korea, Norway, France Portugal, Spain, India, the United States, Canada and others. North America’s first tidal energy demonstration facility is in the Minas Passage of the Bay of Fundy, near Parrsboro, Nova Scotia, Canada. The Fundy Ocean Research Center for Energy (FORCE) is a non-profit institute that owns and operates the facility that offers developers, regulators, scientists and academics the opportunity to study the performance and interaction of instream tidal energy converters (usually referred to as TISECs but called “turbines” in this paper.) with one of the world’s most aggressive tidal regimes. FORCE provides a shared observation facility, submarine cables, grid connection, and environmental monitoring at its pre-approved test site. The site is well suited to testing, with water depths up to 45 meters at low tide, a sediment -free bedrock sea floor, straight flowing currents, and water speeds up to 5 meters per second (approximately 10 knots). FORCE will install 10.896km of double armored, 34.5kV submarine cable — one for each of its four berths. Electricity from the berths will be conditioned at FORCE’s own substation and delivered to the Provincial power grid by a 10 km overhead transmission line. There are four berth holders at present: Alstom Hydro Canada using Clean Current Power Systems Technology (Canada); Minas Basin Pulp and Power Co. Ltd. with technology partner Marine Current Turbines (UK); Nova Scotia Power Inc. with technology partner OpenHydro (Ireland) and Atlantis Resources Corporation, in partnership with Lockheed Martin and Irving Shipbuilding. In November 2009, NSPI with technology partner OpenHydro deployed the first commercial scale turbine at the FORCE site. The 1MW rated turbine was secured by a 400-tonne subsea gravity base fabricated in Nova Scotia. The intent of this paper is to provide an overview of FORCE to the international marine energy community during OMAE 2011 taking place in Rotterdam, Netherlands.