Nodal Points Research Articles

Global vibration control of offshore wind turbines with a flexible monopile foundation using a pendulum-tuned mass damper: Risk mitigation and performance incrementation

This study investigates an optimized design approach for a passive-adaptive pendulum-tuned mass damper (PTMD). The PTMD is used to mitigate structural vibrations in offshore wind turbines (OWTs) with flexible monopile foundations considering Pile-Soil Interaction (PSI). The model OWT is based on the 5-MW design proposed by the National Renewable Energy Laboratory (NREL). The PSI incorporates a pile that is modeled as beam–column elements supported by nonlinear springs and accounts for lateral loads (p-y curves) and axial loads (t-z and Q-z curves) at nodal points. Wind and wave spectra estimation, as well as hydrodynamic and aerodynamic load analysis, are performed using a bespoke MATLAB® program operated in conjunction with an ANSYS® 3-D finite element global model. The resultant peak response at the OWT hub was evaluated through power spectral density (PSD) analysis. Optimal design choices for PTMD parameters are obtained via parametric analysis, which assesses the dynamic response in the along and across directions at the hub and stress at the tower base. A systematic representation considers the uncertainties stemming from the geometric and mechanical properties of the tower, environmental loads, and rotating blade dynamics. To address these uncertainties, a Monte Carlo simulation is employed to assess the structural risk via the Performance-Based Wind Engineering (PBWE) framework. Consequently, the probabilistic evaluation of structural response, foundation stresses, and power production assists in the optimal design process of PTMDs that mitigate the global structural vibrations of OWTs.

Software implementation of the algorithm for automatic detection of lineaments and their properties on open-pit dumps

The paper presents an algorithm and a description of its software implementation for detecting lineaments (ground erosions or cracks) in aerial photography images of open-pits. The proposed approach is based on the apparatus of convolutional neural networks based on the semantic classification of binarized images of objects (lineaments), as well as graph theory for determining the geometric location of linearized objects, followed by determining their lengths and areas. Three-channel RGB images of high-resolution aerial photography (pixel 10x10 cm) were used as initial data. The software unit of the model is logically divided into three layers: pre-processing, detection and post-processing. The first level includes preprocessing of input data to form a training sample based on successive transformations of an RGB image into a binary one using the OpenCV library. A neural network of the U-Net type, which includes blocks of the convolutional (Encoder) and scanning parts (Decoder), represents the second level of the information model. At this level, automatic lineament detection (washouts) is implemented. The third level of the model is responsible for calculating the areas and lengths of lineaments. The result of the work of the convolutional neural network is transferred to the input. Lineament area is calculated by summing the total number of points multiplied by the pixel size. The length of the lineaments is computed by linearizing a plane object into a line segmental object with nodal points and then calculating the lengths between them, also relying on the resolution of the original image. The software module can work with input images, with their subsequent resulting merging to the size of the original image.

An innovative simulation algorithm for optimising the cost of communal water supply systems using EPANET

In this work, the EPANET software is used to parametrize the design, simulate and optimise the overall cost of building and running a reliable, sustainable and efficient communal Water Supply System. Considering a model community of forty houses with an average of six occupants per home, the developed optimization algorithm using the simulated annealing heuristics approach minimizes the total cost of continuous water distribution to the community through a system of pipe network in a way that satisfies the critical hydraulic rules and constraints for efficient water distribution. Thus, the controlled variables of the simulated system include volumetric flow, velocity and head loss. To realize the desired goal, the prototyped communal water distribution system was first simulated by water free fall i.e., only gravity feed under a peak demand flow condition. This facilitated the identification and localization of head-loss zones. Subsequently, virtual pump stations of various capacities were optimally introduced as boosters at identified nodal points to overcome critical head losses. The response of the system to varying capacities of the booster pumps was then used to analyse and determine the optimum capacity of the pump. Simulation outcome showed that the optimum least cost design for a sixtyyear system’s life cycle is achieved by using a combination of gravity and 5 hp (3.73 kW) pump with optimum pipe diameter ranging from 60 - 150mm.

‘Hypocrite!’ Affective and argumentative engagement on Twitter, following the Christchurch terrorist attack

This article intervenes in debates about whether public-facing social media enable the rapid spread of hate speech, or whether these platforms can offer valuable opportunities to contest it. Advancing scholarship on ‘networked counter-publics’ and research emphasising the affective dimensions of digital media, we identify three different modes of counter-public contestation that coalesced on Twitter in the immediate aftermath of the Christchurch terrorist attack. Using a combined keyword and hashtag search, our research project sampled 3,099,138 tweets posted on/about the Christchurch attack and its repercussions, between 15 March 2019 and 15 April 2019. First, we examine two hashtags that trended, approaching these as nodal points for the construction of different affective responses to the terrorist attack. Second, we analyse instances where users quote-tweeted the condolences of politicians, rejecting their sentiments, arguing that the sincerity conditions of the Speech Act (condolence) were not met. Here, we focus on the ways that people invoke a discourse of indignation at either the past actions or current character of the politician, to justify rejecting their statements. Our findings illustrate a need to depart from broad narratives about how the affordances of particular social media platforms lend themselves to the circulation or contestation of hate. Instead, we argue, it is important to develop more situated empirical and conceptual approaches to interrogate how specific relationships between affective publics and structures of feeling enable or constrain political possibilities.

Monthly engagement with EIP keyworkers was associated with a five-fold increase in the odds of engagement with psychosocial interventions.

Early intervention in psychosis (EIP) supports people who are experiencing their first episode of psychosis (FEP). A new Model of Care (MoC) for EIP services was launched in Ireland in 2019. Three EIP demonstration sites were chosen to test this MoC through a 'hub and spoke' approach. These services were a new way of organising care for people experiencing FEP, based upon a recovery model of care, and which sought to standardise care, improve access by clinically led multidisciplinary teams. This included newly created EIP keyworker roles whereby keyworkers assumed responsibilities regarding assessment, comprehensive individual care planning and coordination of care. A mixed methods design utilising the UK Medical Research Council's process evaluation framework. Purposive sampling techniques were utilised. Descriptive analyses and logistic regression were performed to examine how increased keyworker engagement influenced the use of other psychosocial interventions within the EIP demonstration sites. Thematic analyses was used for qualitative data. There was a strong positive relationship between keyworker contacts and psychosocial interventions offered. Specifically, the odds of achieving at least monthly engagement with cognitive behavioural therapy for psychosis (CBTp; (5.76 (2.43-13.64), p < 0.001), and behavioural family therapy (BFT; (5.52(1.63-18.69, p < 0.006)) increased by fivefold with each additional monthly keyworker contact. For individual placement support (IPS) each additional monthly keyworker contact was associated with a three-fold increase in the odds of achieving monthly attendance with IPS (3.73 (1.64-8.48), p < 0.002). Qualitative results found that the EIP keyworker role as viewed by both service users and staff as a valuable nodal point, with a particular emphasis on care coordination and effective communication. This study advances the understanding of keyworker effects through qualitative evidence of keyworkers functioning as a "linchpin" to the service, while the positive response association between keyworker contacts and engagement with other services provides quantitative support for keyworkers reducing the organisational or structural barriers to service access. Given the importance of these positions, health systems should ensure that EIP programmes identify qualified and experienced staff to fill these roles, as well as allocate the appropriate funding and protected time to support keyworker engagement and impact.

On convergence of a three‐layer semi‐discrete scheme for the non‐linear dynamic string equation of Kirchhoff‐type with time‐dependent coefficients

AbstractThis paper considers the Cauchy problem for the non‐linear dynamic string equation of Kirchhoff‐type with time‐varying coefficients. The objective of this work is to develop a time‐domain discretization algorithm capable of approximating a solution to this initial‐boundary value problem. To this end, a symmetric three‐layer semi‐discrete scheme is employed with respect to the temporal variable, wherein the value of a non‐linear term is evaluated at the middle node point. This approach enables the numerical solutions per temporal step to be obtained by inverting the linear operators, yielding a system of second‐order linear ordinary differential equations. Local convergence of the proposed scheme is established, and it achieves quadratic convergence regarding the step size of the discretization of time on the local temporal interval. We have conducted several numerical experiments using the proposed algorithm for various test problems to validate its performance. It can be said that the obtained numerical results are in accordance with the theoretical findings.

Analysis of Optimization Waena Terminal Infrastructure, Jayapura City

A terminal is a part of land transportation which is the node point for various land transportation facilities (modes). The Waena Terminal has been equipped with terminal facilities and complementary buildings, but has not been used optimally, and even looks dirty and unkempt. This research aims to analyze the condition of the infrastructure, utilization and maintenance of the Waena Terminal. This research was conducted in Jayapura City, precisely at the Waena Public Transport Terminal which is administratively part of the Jayapura Municipal government area. Data analysis was carried out qualitatively. The research results show that the physical infrastructure at Waena Terminal is very complete when viewed against the standards set by the government. However, in terms of soft infrastructure, the Waena terminal has not been fulfilled, namely there is no terminal management by the related parties. The use and maintenance of the Waena Terminal has not gone well because it appears there is no terminal management.

Improved analytical model for calculating mesh stiffness and transmission error of helical gears considering root curve: Theoretical analysis and experiments

A modified algorithm is proposed in this study to correct time-varying mesh stiffness (TVMS) and transmission error (TE) in helical gears considering tooth root transition curve. The parametric model of helical gear is established by using the meshing principle of helical gear and hob in order to obtain the accurate tooth root transition curve. Moreover, a TE test rig is set up to compare the theoretical and experimental results. The results of the improved algorithm are very similar to the experimental results compared to the traditional model, and the relative error of TE is also small. In this study, the effect of multi-parameters (e.g. pressure angle, meshing position, transverse contact ratio, and overlap ratio) on TE are investigated by comparing theory with experimental analysis. Through the analysis of parameters, it has been established that an elevation in pressure angle leads to a decrease in TE, followed by an increase. In the event that the meshing position is situated closer to the nodal point, the TE slightly decreases. Moreover, as the transverse contact ratio and overlap ratio increase, the TVMS increases, while the TE decreases. When the overlap ratio approaches an odd multiple of 0.5, the TE displays a significant peak.

Electric and thermoelectric response for Weyl and multi-Weyl semimetals in planar Hall configurations including the effects of strain

We investigate the response tensors in planar Hall (thermal Hall) configurations such that a three-dimensional Weyl or multi-Weyl semimetal is subjected to the influence of an electric field E (temperature gradient ∇rT) and an effective magnetic field Btot oriented at a generic angle with respect to each other. The effective magnetic field consists of two parts — (a) an actual/physical magnetic field B, and (b) an emergent magnetic field B5 which quantifies the elastic deformations of the sample. B5 is an axial pseudomagnetic field because it couples to conjugate nodal points with opposite chiralities with opposite signs. We study the interplay of the orientations of these two components of Btot with respect to the direction of the electric field (temperature gradient) and elucidate how it affects the characteristics involving the chirality of the node. Additionally, we show that the magnitude and sharpness of the conductivity tensor profiles strongly depend on the value of the topological charge at the node in question.

Damageability of Metals under Impulse Loading

Impulse loading of a sample of limited dimensions (at least two free surfaces) leads to the oscillation of the sample in the standing wave mode as a consequence of wave reflection from the faces and their interaction with each other. Localized strain bands originate and evolve at the standing wave nodes (wave interference zone), where the deformation of the material occurs in the compression-tension mode and the stress in the wave interference zone does not exceed the spall strength of the material. (Excessive stress leads to the formation of spall cracks and sample destruction). As a result of the absence of energy transfer through the nodal points,which is typical of standing waves, the deformation of the sample can last for a long time after passing a shock wave until dissipative processes would bring about oscillatory process damping. Another characteristic feature of standing waves is the formation of new harmonics with their own wavelengths and vibration eigen frequencies with new spall damage occurring at each node.

Symmetry-enforced fourfold degenerate phonons in noncentrosymmetric space groups

Multifold degenerate phonons have received much attention due to their nontrivial monopole topological charge and fascinating boundary states. Although Yu et al recently provides a comprehensive list of all potential nodal points for systems with specific space groups (SGs) (2022 Sci. Bull. 67 375). However, our understanding of the fundamental mechanisms that give rise to the formation of fourfold-degenerate (FD) phonons is still limited. In this paper, we have directed our research towards investigating the generation mechanism of these FD phonons in noncentrosymmetric SGs. Using symmetry arguments and k⋅p model analysis, we have classified them into two categories: the first origins from the commutation/anticommutation relation of the little cogroup operations, and the second associates to the combination of threefold rotation, mirror and time-reversal symmetries. Moreover, the band dispersions of the FD phonons in the first group are required to be linear, whereas the band dispersions of the FD phonons in the second category may be quadratic. On the basis of first-principles calculations, we propose that K 2 Mg2O3 and Na 4 SnSe4 are representative candidates for the two categories, respectively. Furthermore, for each SG with fourfold degenerate phonons, we propose corresponding materials that must host the FD points. Our work not only deepens our understanding of the mechanisms underlying the formation of these FD phonons, but it also proposes practical materials for observing FD phonons in crystalline systems without inversion symmetry.

Construction and optimization of ecological security patterns in the songnen plain

To address the ecological security issues in the Songnen Plain, this study constructs the ecological security pattern by using the Multi-Criteria Evaluation Method, Minimum Cumulative Resistance (MCR) model, and Circuit Connectivity Model. Results show that: 1) The ecological source areas were 66, 52, and 56 blocks in 2000, 2010, and 2020 respectively, which are composed mainly of forests, water bodies, and wetlands. The distribution of resistance values of the ecological resistance surface shows a gradually increases trend from the source areas to the outward surrounding regions. The high and low value areas are more dispersed, consisting with the overall spatial distribution; 2) The numbers of ecological corridors show a temporal declining trend from 178 in 2000 to 159 in 2020 with a reduction of 645.46 km in total length. Node areas are mainly distributed in the southwestern and central-eastern regions and its number decreased from 232 in 2000 to 229 in 2020. The sizes of obstacle areas are 74029.52 km2, 70203.72 km2, and 75529.72 km2 in the three periods; 3) The size of important ecological source areas has decreased by 5779.16 km2, the area of medium ecological source areas has increased by 11466.44 km2, and the area of general ecological source areas has increased by 9509.16 km2. The areas being classified as ecological conservation, ecological enhancement, ecological restoration, and ecological control are 30346.68 km2, 8480.56 km2, 51473.92 km2, and 122047.48 km2, respectively. The multiple spatial pattern optimization strategies are proposed based on the identified ecological source areas, corridors, node points, and other comprehensive ecological security patterns. It not only provides practical reference for the ecological restoration and ecological protection in the Songnen Plain, but also can be used for the ecological security pattern investigations in other study regions in the world.

Diverse degeneracy types in topological phonons: A perspective

The study of novel topological quantum states is gaining significant attention. Recently, the concept of topology has expanded from fermions to bosons, leading to the new era of topological phonons. In crystals, distinctive symmetry constraints lead to diverse excitations among quasiparticles. This makes different patterns of phonon degeneracy in the spectrum. In this perspective, we review recent advances in various types of degeneracies found in topological phonons, including nodal points, nodal lines or rings, and unconventional nodal points with higher Chern numbers. We conclude by looking ahead at exciting possibilities in topological phonons.

Analisis kontribusi konsep matematis pada sawah lodok khas kearifan lokal masyarakat manggarai

This study aims to find out the contribution of mathematical concepts to lodok rice fields (ricefield spider net) in Manggarai Regency. The main instrument is the researcher himself, and the supporting instruments are observation and interview guidelines. Data was collected by means of field observations and interviews with manggarai traditional leaders, where the selection of traditional leaders used a purposive sampling technique. To obtain valid and reliable data, the researchers used technique triangulation and source triangulation. Data analysis used is reducing data, presenting data, and drawing conclusions or verification. The results of the study found that the shape of lodok rice fields in Manggarai Regency was made by applying the concept of ''Circle Center Point'' at the meeting point (node point) of the land of all residents, which is referred to as Lodok and the concept of ''Juring Circle'' on the shape and size of the land area of each resident as well as a barrier to land ownership rights between one resident and another, known as Langang or Lance.

SPECTRAL PROPERTIES AND INVERSE NODAL PROBLEMS FOR SINGULAR DIFFUSION EQUATION

In this study, some properties for the pencils of singular Sturm-Liouville operators are investigated. Firstly, the behaviors of eigenvalues were learned, then the solutions of the inverse problem were given to determine the potential function and parameters of the boundary condition with the help of a dense set of nodal points and lastly we obtain a constructive solution to the inverse problems of this class.

Curve Trajectory Model for Human Preferred Path Planning of Automated Vehicles

Automated driving systems are often used for lane keeping tasks. By these systems, a local path is planned ahead of the vehicle. However, these paths are often found unnatural by human drivers. In response to this, this paper proposes a linear driver model, which can calculate node points reflective of human driver preferences and based on these node points a human driver preferred motion path can be designed for autonomous driving. The model input is the road curvature, effectively harnessed through a self-developed Euler-curve-based curve fitting algorithm. A comprehensive case study is undertaken to empirically validate the efficacy of the proposed model, demonstrating its capacity to emulate the average behavioral patterns observed in human curve path selection. Statistical analyses further underscore the model's robustness, affirming the authenticity of the established relationships. This paradigm shift in trajectory planning holds promising implications for the seamless integration of autonomous driving systems with human driving preferences.

Visually-shaped comfort of perceiving the architectural environment in conditions of artificial lighting (using the example of Chelyabinsk)

The study, conducted at the facilities of Chelyabinsk, aims to identify the essence of the comfort visually-shaped perception of the artificial architectural and light environment. This is achieved by an integrated approach, which involves the analysis of scientific and information resources, including regulatory and legal documents, field observations and surveys, graphical analysis of architectural and light environmental fragments under artificial lighting. An analysis of the regulatory framework on the lighting of architectural objects and urban space demonstrated the technical regulations of this sphere clearly articulating the visual comfort concept and its parameters only in relation to the interior space and the road transport system. The study clarified the concept and conditions of creating a shaping aspect in the visual perception of the urban artificial architectural and light environment. Mostly in terms of comfort for this process, the Chelyabinsk areas of the architectural and light environment in artificial lighting conditions were studied. Based on the results of the study, it can be concluded that the process of forming an artificial architectural and light environment of the city should be based on a visuallyshaped comfort, proceeding in a certain sequence and associated with the emergence of new factors of innovative urban environmental development. The relationship between the visually-shaped comfort of perceiving the artificial architectural and light environment, as well as the basics of the functional safety of subjects at the nodal points of the city were established. According to the experience of a typical domestic metropolis of Chelyabinsk, theoretical and research materials, presented in the article, can serve as the basis for the further interdisciplinary development of a visually comfortable and safe artificial architectural and light environment of cities.

Analysis of autogenic bifurcation processes resulting in river avulsion

Abstract. River bifurcations are constituent components of multi-thread fluvial systems, playing a crucial role in their morphodynamic evolution and the partitioning of water and sediment. Although many studies have been directed at exploring bifurcation dynamics, the conditions under which avulsions occur, resulting in the complete abandonment of one branch, are still not well understood. To address this knowledge gap, we develop a novel 1D numerical model based on existing nodal point relations for sediment partitioning, which allows for the simulation of the morphodynamic evolution of a free bifurcation. Model results show that when the discharge asymmetry is so high that the shoaling branch does not transport sediments (partial avulsion conditions) the dominant branch undergoes significant degradation, leading to a higher inlet step between the bifurcates and further amplifying the discharge asymmetry. The degree of asymmetry is found to increase with the length of the downstream channels to the point that when they are sufficiently long, the shoaling branch is completely abandoned (full avulsion conditions). To complement our numerical findings, we also formulate a new analytical model that is able to reproduce the essential characteristics of the partial avulsion equilibrium, which enables us to identify the key parameters that control the transition between different configurations. In summary, this research sheds light on the fundamental processes that drive avulsion through the abandonment of river bifurcations. The insights gained from this study provide a foundation for further investigations and may offer valuable information for the design of sustainable river restoration projects.

Emergence of nodal Bogoliubov quasiparticles across the transition from the pseudogap metal to the d-wave superconductor

We model the pseudogap state of the hole- and electron-doped cuprates as a metal with hole and/or electron pocket Fermi surfaces. In the absence of long-range antiferromagnetism, such Fermi surfaces violate the Luttinger requirement of enclosing the same area as free electrons at the same density. Using the Ancilla theory of such a pseudogap state, we describe the onset of conventional d-wave superconductivity by the condensation of a charge e Higgs boson transforming as a fundamental under the emergent SU(2) gauge symmetry of a background π-flux spin liquid. In all cases, we find that the d-wave superconductor has gapless Bogoliubov quasiparticles at 4 nodal points on the Brillouin zone diagonals with significant velocity anisotropy, just as in the BCS state. This includes the case of the electron-doped pseudogap metal with only electron pockets centered at wavevectors (π, 0), (0, π), and an electronic gap along the zone diagonals. Remarkably, in this case, too, gapless nodal Bogoliubov quasiparticles emerge within the gap at 4 points along the zone diagonals upon the onset of superconductivity.

The Practices of Historicism in Metamodern Condition

The paper answers the question, if metamodern, which replaced the postmodern discourse, is conceptually viable. The discussion is focused on a particular case of rethinking the Historicist views that are increasingly arising in connection with the task of creative justification of the theory of history. This problem is supposed to be solved, first, by showing that metamodern practices actualize a special type of subject that can be demanded in the context of creative attitude to history, and second, by analyzing what the strategies of constructing a newly emerging historicist narrative will be after the critique of the projects of ‘big stories’ put forward by postmodernity. By doing so, we aim to analyze the epistemological and aesthetic aspects of historicism in the metamodern condition. The return to the principles of Historicism on the grounds constructed by contemporary authors (B. Latour, G. Harman, D. Haraway, etc.) appears to be debatable, so the article pays special attention to the criticism of the conceptual issues and aspects associated with them. As a result of the study, we come to the following conclusions: metamodern requires the revival of a special subject, and the revival itself is by default connected with the aesthetic rethinking of the subject formed by the modern era and neutralized by postmodern relativism. Further, the metamodern subject can be described as ‘flickering’ in the sense that it is not a ready-made construct, but is in constant formation, passing through such ‘nodal points’ in which its conditioning by the totality of circumstances of the present is manifested. Finally, the aesthetic instruments that contribute to the formation of the metamodern subject also make it possible to form post-historical narratives, in which the principle of eventuality restores the unity of time and space of interaction between different actors.