Nodal Connections Research Articles

Aberrant brain topological organization and granger causality connectivity in Parkinson's disease with impulse control disorders.

Impulse control disorders (ICDs) refer to the common neuropsychiatric complication of Parkinson's disease (PD). The white matter (WM) topological organization and its impact on brain networks remain to be established. A total of 17 PD patients with ICD (PD-ICD), 17 without ICD (PD-NICD), and 18 healthy controls (HCs) were recruited. Graph theoretic analyses and Granger causality analyses were combined to investigate WM topological organization and the directional connection patterns of key regions. Compared to PD-NICD, ICD patients showed abnormal global properties, including decreased shortest path length (Lp) and increased global efficiency (Eg). Locally, the ICD group manifested abnormal nodal topological parameters predominantly in the left middle cingulate gyrus (MCG) and left superior cerebellum. Decreased directional connectivity from the left MCG to the right medial superior frontal gyrus was observed in the PD-ICD group. ICD severity was significantly correlated with Lp and Eg. Our findings reflected that ICD patients had excessively optimized WM topological organization, abnormally strengthened nodal structure connections within the reward network, and aberrant causal connectivity in specific cortical- limbic circuits. We hypothesized that the aberrant reward and motor inhibition circuit could play a crucial role in the emergence of ICDs.

Modeling and simulation for prediction of multiple sclerosis progression

In light of extensive work that has created a wide range of techniques for predicting the course of multiple sclerosis (MS) disease, this paper attempts to provide an overview of these approaches and put forth an alternative way to predict the disease progression. For this purpose, the existing methods for estimating and predicting the course of the disease have been categorized into clinical, radiological, biological, and computational or artificial intelligence-based markers. Weighing the weaknesses and strengths of these prognostic groups is a profound method that is yet in need and works directly at the level of diseased connectivity. Therefore, we propose using the computational models in combination with established connectomes as a predictive tool for MS disease trajectories. The fundamental conduction-based Hodgkin-Huxley model emerged as promising from examining these studies. The advantage of the Hodgkin-Huxley model is that certain properties of connectomes, such as neuronal connection weights, spatial distances, and adjustments of signal transmission rates, can be taken into account. It is precisely these properties that are particularly altered in MS and that have strong implications for processing, transmission, and interactions of neuronal signaling patterns.The Hodgkin-Huxley (HH) equations as a point-neuron model are used for signal propagation inside a small network. The objective is to change the conduction parameter of the neuron model, replicate the changes in myelin properties in MS and observe the dynamics of the signal propagation across the network. The model is initially validated for different lengths, conduction values, and connection weights through three nodal connections. Later, these individual factors are incorporated into a small network and simulated to mimic the condition of MS. The signal propagation pattern is observed after inducing changes in conduction parameters at certain nodes in the network and compared against a control model pattern obtained before the changes are applied to the network. The signal propagation pattern varies as expected by adapting to the input conditions. Similarly, when the model is applied to a connectome, the pattern changes could give an insight into disease progression. This approach has opened up a new path to explore the progression of the disease in MS. The work is in its preliminary state, but with a future vision to apply this method in a connectome, providing a better clinical tool.

Considerations for Space Grid Structures: Comprehensive Review of Key Design Aspects and Developing Trends

The investigation aimed to identify key directions for advancing space grid structures. It involved a comprehensive survey of existing structural solutions, nodal connections, and design features specific to spatial rod structures. The analysis included theoretical, numerical, and experimental studies on the stress-strain state, factors influencing it, geometric optimization, and design principles. The focus was on space grid structures, particularly structural plates and their prevalent nodal connections. The investigation revealed that scientific and technological progress, such as improvements in material properties, calculation methods, and software simulations, significantly contributed to the advancement of structural designs by enhancing accuracy and reducing complexity. Geometric dimensions of modular elements and the height-to-span ratio were identified as key parameters affecting structural efficiency. The study also examined global experiences in nodal connection development and provided a general classification of such connections. By identifying advantages and disadvantages of existing space grid structures, potential pathways for further improvement were illuminated. The findings underscored the importance of developing innovative nodal connections as a primary avenue for enhancing space grid structures.

МОДЕЛИРОВАНИЕ ПЯТИЯРУСНЫХ КОНСТРУКЦИЙ В ВИДЕ ГИПЕРБОЛОИДОВ ВРАЩЕНИЯ И ПРОВЕДЕНИЕ ЛАБОРАТОРНЫХ ИСПЫТАНИЙ ПО ИЗУЧЕНИЮ ИЗМЕНЕНИЙ НАГРУЗОК НА УЗЛОВЫЕ КРЕПЛЕНИЯ

This article studies hyperboloids of rotation (such as the Shukhov tower) made of polymer structures. Laboratory studies were conducted to model the deformations of this type of structures; to study physical loads on polymer elements, depending on the number of mesh shell elements in the diameter of the hyperboloid rotation tier; and to study the deformation of the material of the mesh shell joints. The data show the physical features of such structures and possible changes in the loads in structures made of polymer materials. The article presents the results of studies on the change of loads on nodal fasteners depending on the number of elements forming the tier and the resulting deformations in the lower, middle, and upper nodal joints of the tier elements. It shows the deformation and the resistance of structural elements and other processes with changes in loads. It studies the distribution of loads along the nodal connection of the hyperboloid of rotation, improving these nodal connections and studies changes in loads on joints depending on the number of elements of the tier, their position and the possibility of replacing metal elements with polymer ones.

Multi-Scale FC-Based Multi-Order GCN: A Novel Model for Predicting Individual Behavior From fMRI.

Predicting individual behavior from brain imaging data using machine learning is a rapidly growing field in neuroscience. Functional connectivity (FC), which captures interactions between different brain regions, contains valuable information about the organization of the brain and is considered a crucial feature for modeling human behavior. Graph convolutional networks (GCN) have proven to be a powerful tool for extracting graph structure features and have shown promising results in various FC-based classification tasks, such as disease classification and prognosis prediction. Despite this success, few behavior prediction models currently exist based on GCN, and their performance is not satisfactory. To address this gap, a new model called the Multi-Scale FC-based Multi-Order GCN (MSFC-MO-GCN) was proposed in this paper. The model considers the hierarchical structure of the brain system and utilizes FCs inferred from multiple spatial scales as input to comprehensively characterize individual brain organization. To enhance the feature learning ability of GCN, a multi-order graph convolutional layer is incorporated, which uses multi-order neighbors to guide message passing and learns high-order graph information of nodal connections. Additionally, an inter-subject contrast constraint is designed to control the potential information redundancy of FCs among different spatial scales during the feature learning process. Experimental evaluation were conducted on the publicly available dataset from human connectome project. A total of 805 healthy subjects were included and 5 representative behavior metrics were used. The experimental results show that our proposed method outperforms the existing behavior prediction models in all behavior prediction tasks.

FEATURES OF BEHAVIOR AND CALCULATION OF DOWEL TIMBER JOINTS WITH SLOTTED-IN PLATES ACCORDING TO EC5

The paper presents an overview of theoretical and experimental studies of connections of timber structures with steel dowel with steel slitted-in plates. The correct choice of the type of connections allows you to significantly influence the total cost of the structure due to the formation of thestructural and assembly scheme of the structure (minimization of the number of nodal and assembly connections), optimal unification of connections isan additional argument for creating an economical and competitive solution. For the analysis of the dowel connection, it is taken into account that theforce is transmitted due to the bending and shear resistance of the fastening element, as well as crumpling in the connected timber elements. The limitstates of the dowel joint are considered loss of strength due to crumpling and splitting of the wood of the hole wall, as well as due to bending of the nailin the nail socket. The works considered in the review provide extensive factual material on the strength of connections depending on the geometricand physical parameters of its components, as well as the stiffness of the connection, which is currently the subject of active attention of researchers. Attention is paid to the need to study the operation of nodes under the action of a moment during group operation of the connection. The analysis of numerous experiments makes it possible to check the reliability of the current design rules and norms of EC5 and the design norms of DBN В.2.6-161:2017 implemented to them, and also revealed the shortcomings and limits of the application of the design rules for this type. connections The results of numerical and experimental studies are the basis for improvingthe structural solutions of the joints of wooden elements and allowed to accumulate significant factual material for the verification of numerical simulation models.

ҒИМАРАТТАРДЫҢ ҚОРШАУ ҚҰРЫЛЫМДАРЫ АРҚЫЛЫ ЖЫЛУ ШЫҒЫНЫН АЗАЙТУДЫ ЗЕРТТЕУ

One of the most important ways to save fuel and energy resources is to reduce heat losses through the building envelope. The use of high-performance heat-insulating, refractory materials makes it possible to create lightweight building envelopes that meet modern architectural requirements, allowing to reduce the operating costs of buildings by reducing heat loss. The purpose of this work is to study the causes of defects in operating buildings with enclosing structures made of sandwich panels to identify heat loss in the interface zones. The article addresses the issues of improving the nodal connections of enclosing structures made of sandwich panels, which is of great interest to designers in the construction of low-rise prefabricated buildings.

On the Issue of Determining the Modulus of Elasticity of Bamboo Moso Under Tension

Introduction. A large number of works devoted to the research of physical and mechanical properties of bamboos, methods of nodal connections of bamboo rods are indicated. The main "bamboo" countries in which bamboo is gaining popularity as a structural material in the modern construction industry are listed. With the development of modern processing technologies, bamboo is widely used in the construction industry, including in the manufacture of slabs and boards, as well as in the decoration and interior decoration of rooms in Oriental style. The results of studies of the physical and mechanical properties of various types of bamboos conducted by scientists from different countries are currently combined into three ISO editions concerning building codes and rules for the use of bamboos in construction.Materials and Methods. Consideration of the macrostructure of bamboo allows us to characterize the high mechanical properties inherent in natural and artificial polymers. Such an approach to the consideration of bamboo and wood as natural polymers makes it possible to use methods applied to the testing of wood and structural plastics in determining the mechanical characteristics of bamboo. Two series of samples of five pieces each were made. Tables of geometric characteristics of the cross-section of the samples are compiled. A constructive solution is proposed related to the reinforcement of the sample blades with an epoxy composition in order to increase the reliability of securing the samples in the grips of the test rig.Results. To determine the elastic modulus of bamboo under tension, an experimental setup consisting of two grips in which the test sample is placed has been developed and manufactured. Through the lower gripper, the test load is applied by means of a steel rod with a loading platform on which the calibrated piece loads are stacked. To determine the magnitude of the absolute elongation of the sample base during stretching, contact deflection meters are used, as which watchtype indicators of the Mitutoyo company (Japan) are used.Discussion and Conclusion. The formula for determining the elastic modulus under tension is given. The arithmetic mean of the modulus of elasticity of the tested samples and the mean square deviation of the results of the modulus of elasticity are taken as the test result. The analysis of the obtained results allows us to conclude that the experimental values of the modulus of elasticity of Moso bamboo under tension reliably coincide with the values known in the technical literature.

Multi-constrained topology optimization of prefabricated joints in large-span latticed structures

In recent years, topology optimization (TO) has shown great potential in the optimal design of engineering structures. In this study, a parameterized level set (PLS) method capable of solving the compliance minimization problem with both stress and volume constraints is proposed to improve the design efficiency of nodal connections in large-span latticed structures. 3D topology optimization of assembled hub (AH) joints is conducted based on the proposed method. The performances of the optimal designs are compared with those of the traditional joints in terms of volume, stress distribution and compliance value. Different connection types and complex loading conditions are considered to satisfy the requirements of engineering practice. It is indicated that the proposed PLS method exhibits good stability and high computing efficiency during the optimization of AH joints. Compared with the study cases with a single volume constraint, the maximum von Mises stress is effectively controlled by simultaneously introducing the stress and volume constraints. In addition, the variation in the volume constraint has much greater influence on the compliance results than the stress constraint. The compliance continuously increases when the volume constraint decreases from 100% to 40%, while the difference in compliance is less than 1.5% with or without stress constraints. It is demonstrated that the performances of AH joints are significantly improved after the TO design. The reduction rates of mass are in the range of 25.2 % to 35.2 %, and the compliance value is reduced by 0.5 % to 7.6 % for all the study cases.

Формообразование зданий на основе стержневых арок с изменяемой геометрией

Introduction. Spatial core structures of coatings are used for more efficient industrial production of building structures, which reduces the costs of their mass production, specialization of production and rationality of design solutions. When designing spatial coverings, unique designs of single execution are used, which help to solve grandiose architectural and functional tasks. But coatings that are based on standard elements that help to create various architectural forms are also in great demand. Materials and methods. The subject of the study is a spatial architectural and structural system that is capable of implementing various design tasks, being fast-built, lightweight and having unified elements that exclude assembly welding. Such arches will find wide application from sports to exhibition complexes, thanks to their quick installation. The arch can take the shape of a circle, an ellipse, a parabola or bending in two directions, the arch can take the form of an arbitrary curve with the conjugation of curves curved in different directions. Results. The spatial arch is assembled according to the principle of a crystallographic triangulation scheme, where the upper and lower belts, braces and rods can be distinguished. A new universal joint connecting element connecting from six to twelve standard rods is proposed, which allows achieving a minimum number of standard sizes and performing ground-based manual assembly of enlarged structural elements, the spatial rigidity of the system is ensured when they are articulated together. Conclusions. The results of the present study allow us to consider such a variant of the rod spatial arch as a promising solution, as a result of the theoretical study, it was found that the main direction of improvement of spatial rod structures is the development of new nodal connections.

Моделирование процессов выборки ловушечных крабовых порядков с больших глубин

A model for calculating the processes of sampling trapping crab orders from great depths is proposed. The sampling process was simulated with a uniform sampling process using nodal connections when connecting traps to the line. Simulation of hauling processes when hauling was stopped and the winch turned on at maximum speed showed a significant load on the main line with a loss of its strength. Loads when hauling from great depths are much more than 10 tons than stipulated by the rules of fishing for winches. Line wear with the calculated loads on the winch turrets are consistent with the factors of line wear in practice and the choice of winches with 20 tons of effort in the field.

Decreased Brain Structural Network Connectivity in Patients with Mild Cognitive Impairment: A Novel Fractal Dimension Analysis.

Mild cognitive impairment (MCI) is widely regarded to be the intermediate stage to Alzheimer's disease. Cerebral morphological alteration in cortical subregions can provide an accurate predictor for early recognition of MCI. Thirty patients with MCI and thirty healthy control subjects participated in this study. The Desikan-Killiany cortical atlas was applied to segment participants' cerebral cortex into 68 subregions. A complexity measure termed fractal dimension (FD) was applied to assess morphological changes in cortical subregions of participants. The MCI group revealed significantly decreased FD values in the bilateral temporal lobes, right parietal lobe including the medial temporal, fusiform, para hippocampal, and also the orbitofrontal lobes. We further proposed a novel FD-based brain structural network to compare network parameters, including intra- and inter-lobular connectivity between groups. The control group had five modules, and the MCI group had six modules in their brain networks. The MCI group demonstrated shrinkage of modular sizes with fewer components integrated, and significantly decreased global modularity in the brain network. The MCI group had lower intra- and inter-lobular connectivity in all lobes. Between cerebral lobes, the MCI patients may maintain nodal connections between both hemispheres to reduce connectivity loss in the lateral hemispheres. The method and results presented in this study could be a suitable tool for early detection of MCI.

Метод n-линейных компонентов для анализа напряженно-деформированного состояния фланцевых соединений стальных строительных конструкций

The article discusses the main problems of the component method implemented in Eurocode 3 and offers approaches aimed at eliminating the existing shortcomings. The authors investigate the possibility of introducing additional n -linear components that sufficiently accurately describe the behavior of the flange joints for various stages of the stress-strain state of the connection. The key aspects and principles of modeling nodal connections using n -linear components, including the structure of components, methods of their modeling, are determined. The analysis of the performance of the new computational model of the system is carried out, theoretical diagrams of «force-displacement» ( F -δ) of n -linear components and diagrams of «flexing moment-angle of rotation» ( M -φ) for a node with n-linear components are constructed. A numerical experiment on modeling a typical node is carried out and the results obtained are compared with theoretical prerequisites.

Применение технологии цифрового двойника для моделирования и автоматизированного изготовления рыбопромысловых узловых соединений

The article is devoted to fishing nodes, in particular, to the problems of creating their three–dimensional models, as well as digital counterparts based on them, and automation tools that allow servicing and producing nodal connections.

PARALLEL SOLUTION OF THERMOMECHANICAL INVERSE PROBLEMS FOR LASER DIELESS DRAWING OF ULTRA-THIN WIRE

The paper discusses the solving of inverse thermomechanical problems requiring a large number of FEM tasks with various boundary conditions. The study examined the case when all tasks have the same number of nodes, finite elements, and nodal connections. In this study, the speedup of the solution of the inverse problem is achieved in two ways: 1. The solution of all FEM tasks in parallel mode. 2. The use by all FEM tasks a common matrix with addresses of nonzero elements in the stiffness matrices. These algorithms are implemented in the own FEM code, designed to solve inverse problems of the hot metal forming. The calculations showed that developed code in parallel mode is effective for the number of tasks late than 0,7-0,9 of the number of available processors. Thus, at some point, it becomes effective to use a sequential solution to all tasks and to use a common matrix of addresses of nonzero elements in the stiffness matrix. The achieved acceleration at the optimal choice of the algorithm is 2–10 times compared with the classical multivariate calculations in the FEM. The paper provides an example of the practical application of the developed code for calculating the allowable processing maps for laser dieless drawing of ultra-thin wire from copper alloy by solving the thermomechanical inverse problem. The achieved acceleration made it possible to use the developed parallel code in the control software of the laboratory setup for laser dieless drawing.

The evolution of international grain trade pattern based on complex network and entropy

Grain is the most basic material condition for human survival and development, and the structure of grain import and export trade has seriously affected national grain security. In this paper, we quantitatively analyze the evolution of international grain (maize, wheat, rice) trade patterns from 1987 to 2019 based on a complex network and entropy methods, and provide some suggestions and references for relevant countries. We measure the ranking of countries by applying various indicators from complex networks to quantify the importance of nodes in international trade networks. Then, we analyze the evolution of trade scale and community structure in different regions. Finally, we analyze the weight structure of the whole network through entropy, revealing the evolution characteristics and mechanism of the system more comprehensively. The results first show that the international grains trade network (IGTN) satisfies the scale-free properties and that global trade volumes are increasing year by year. The distribution of trade volumes in the IGTN follows the 80/20 rule, with less than 20[Formula: see text] of countries accounting for more than 80[Formula: see text] of global trade volumes. Second, countries in the Asian region have gradually increased their position in the grain trade network, while the position of countries in North and South America has declined. Third, the heterogeneity of the topology and weight structure of the international grain trade network is weakened, and the status of hub countries in the IGTN is reduced. The importance gap of nodal connections is narrowing, showing the trend of multilateralization of global trade. Fourth, the world grain export market is highly concentrated. The USA, Canada, Brazil, Argentina and Russia are the major exporters of grain.

FIRE RESISTANCE DESIGN ANALYSIS FOR STEEL CONNECTIONS USING SPECIALIZED 3D MODELING SOFTWARE

The work presents the design process, analysis and practical evaluation of nodal connections of the beam-column frame of a low-rise building in the BIM design environment for the action of active loads and emergency temperature effects of fire. A study of the use of design tools was conducted. The conduct of such studies is due to the need to increase the reliability of the steel frame in fire conditions and to update the requirements of the normative documents of the Eurocodes regardingthe fire resistance of metal structures. The standard fire mode was considered, the heating parameters ofelements connected in nodes were analyzed. A review of the theoretical foundations of the calculation of steel structures for the high-temperature effect of the working environment showed the feasibility of applying a simplified method of calculation and determination of heating parameters accordingto normative data.Simulated rod diagram of the frame with loads. An analysis of the stress-strain behavior (SSB) ofthe elements under the action of the emergency combination was carried out. 3D modeling of thenode was used for further calculation. The BIM concept is implemented by integrating Robot StructuralAnalysis PC with the IdeaStatica calculation complex. It has been established that the connection ofPC Robot Structural Analysis with the IdeaStatica calculation complex is rational for the design andcalculations of buildings and structures in 3D space and allows using the results of the temperature effect calculation to adjust the structural solution in order to reduce its metal consumption, labor costsand rationalize the reserves of bearing capacity.The presented process of designing frame nodes summarizes approaches to the development of effective structural forms. The use of information models simplified design, optimized work processes, and also made it possible to increase the complexity of nodes both at the level of the designsolution and at the level of the calculation model, taking into account the nonlinear effects of temperature influence.

Design features of modular buildings

The paper is devoted to modular buildings as а current topic of modern construction. A significant number of studies on this topic have appeared both in Russia and abroad in last years. It is necessary to classify modular buildings and highlight their design features to systematize the research. The main distinguishing feature of modular construction is the erection of a structure from volumetric modular blocks manufactured at the factory, each of which must also fully meet the requirements of functional, technical, economic feasibility and architectural expressiveness. Steel or wood is a common materials for modular constructions. Steel modular buildings have become more widespread due to their greater bearing capacity, so the paper provides a classification of modular buildings with a steel structure. Modular buildings are classified according to the following features: structural system of the building (arrangement and load transmission from one module to other); framework of modules (bearing structures of individual modules); nodal connections. There is two types of nodal connections: intermodular (joints of modules to each other) and intramodular (joints of beams and columns inside the module). Based on a review of literature sources and an analysis of advantages and disadvantages, the most common structural solutions for modular buildings in the Russian Federation were identified: buildings from stacked modules with support columns, intermodular joints on welding and welded intramodular joints. However, this provision does not limit research on modular buildings of other design solutions.

Solution of nonlinear contact problems of deformation of nodal connections of steel structures

All mechanisms and structures consist of parts interacting with each other, and the distribution of contact forces between these parts is unknown in advance and can only be found as a result of solving specific problems, called contact problems.Calculation of the stress-strain state under force contact conditions is important because in many cases the contact zone is a probable zone of loss of strength and a zone of structural failure.Data on the stress-strain state of such elements and units can be obtained using a modern apparatus of mathematical modeling - such as the finite element method.
 The paper presents a methodology for modeling nonlinear contact problems in calculations of nodal connections of steel structures. Modeling of contact interaction is performed by the example of a truss support node made of bent-welded profiles in the integrated software system SCAD Office. The developed method is based on the penalty function method, which is based on the concept of contact layer and contact elements with special properties.
 The contact interaction is modeled using one-way connections. The node model is calculated and investigated as geometrically nonlinear based on the method of stepwise analysis.
 The contact forces - stress and contact normal forces - in a steel truss support node have been determined. The obtained data have been analyzed and the deformed models of the nodal connection for the contact and noncontact formulations of the problem have been compared.It is possible to use the results to further investigate the contact stresses arising from the interaction of the elements of the truss support assembly.
 Taking into account the contact interaction of the elements in the calculation of the most important joints of the frame allows you to correctly assess the stress-strain state of the structures and trace the picture of the deformations of the elements, as close to the real.The research results can be used to search for contact stresses arising from the interaction of elements of the frame of civil and industrial buildings.

К ВОПРОСУ ОЦЕНКИ ДЕФОРМАТИВНОСТИ СТЕНКИ ТОНКОСТЕННЫХ ХОЛОДНОГНУТЫХ ПРОФИЛЕЙ С ТРАПЕЦИЕВИДНОЙ ЧАСТЬЮ В БОЛТОВЫХ УЗЛОВЫХ СОЕДИНЕНИЯХ

The article discusses a new nodal connection of thin-walled and cold-formed profiles with a trapezoidal part of the wall using a through stop bushing. The use of this constructive solution allows to place additional bolts in the area of the concave part of the wall of a thin-walled profile, thereby including this area in work. It is noted that the invention in comparison with analogs allows to simplify the assembly process of the node by fixing the position of the sleeve when using a broadened part on one side of the gusset. At the same time, in order to effectively resist the loss of local stability of the wall of a thin-walled and cold-formed profile, it is proposed to arrange adjacent bushings with sides in the opposite direction. Issues of deformability of the wall of a thin-walled and cold-formed profile are studied when additional rows of bolts are installed in the trapezoidal part of the wall due to the developed design solutions: using a through bushing, a through bushing with a stop and in the absence of bolts in the area of the trapezoidal part. The paper presents the results of displacements of the wall under the influence of a compressive load with different variations of bolted nodal joints. A comparative assessment of the efficiency of nodal connections from the point of view of resistance to loss of local stability has been carried out. In result, it is revealed that a bolted nodal connection with the installation of additional bolts in a part of a trapezoidal wall, due to the use of a through bushing, can reduce deformability by 15% and by 33% when using a through bushing with an emphasis in relation to a connection with a two-row bolting