Graph Theory Methods Research Articles

Lean facility layout selection in a post service to enhance operational performance: a graph theory model

PurposeThis study attempts to analyze the overall effectiveness of Lean System (LS)-based India post facility layout design (FLD) selection.Design/methodology/approachWe have grouped all Lean Six Sigma elements into three different categories: Lean Technical Practices, Lean Workplace Environment Practices, and Lean Ergonomics Practices based on literature support and field surveys in the Indian postal service. Further, it employs a mathematical model known as the graph theory (GT) method. From the GT approach, interactions were identified through LS tools represented through the digraph, matrix model approach. This study was directed at the National Sorting Hub in Mysuru, Karnataka, in the southern part of India. A number of insights were given in the GT area where FLD is possible to evaluate.FindingsThe results showed that Layout five has the highest value, followed by Layout one from the GT approach. The relative relevance and effect values are given as inputs to the permanent function in the digraph technique, and an evaluation index is obtained as an output.Research limitations/implicationsWhen solving any optimization issue with a high number of attributes, the digraph and matrix technique is successful. The layouts that have been identified have yielded valuable insights into how to enhance critical decision-making processes, which are necessary to accomplish company strategic objectives like growing postal business services.Originality/valueThe process operations carried out in India post service as well as its heterogeneity of articles and the intangible measures of production are the significant challenges to keenly analyze the layout design through lean service principles.

How Can Graph Theory Inform the Dual-stream Model of Speech Processing? A Resting-state Functional Magnetic Resonance Imaging Study of Stroke and Aphasia Symptomology.

The dual-stream model of speech processing describes a cortical network involved in speech processing. However, it is not yet known if the dual-stream model represents actual intrinsic functional brain networks. Furthermore, it is unclear how disruptions after a stroke to the functional connectivity of the dual-stream model's regions are related to speech production and comprehension impairments seen in aphasia. To address these questions, in the present study, we examined two independent resting-state fMRI data sets: (1) 28 neurotypical matched controls and (2) 28 chronic left-hemisphere stroke survivors collected at another site. We successfully identified an intrinsic functional network among the dual-stream model's regions in the control group using functional connectivity. We then used both standard functional connectivity analyses and graph theory approaches to determine how this connectivity may predict performance on clinical aphasia assessments. Our findings provide evidence that the dual-stream model of speech processing is an intrinsic network as measured via resting-state MRI and that functional connectivity of the hub nodes of the dual-stream network defined by graph theory methods, but not overall average network connectivity, is weaker in the stroke group than in the control participants. In addition, the functional connectivity of the hub nodes predicted linguistic impairments on clinical assessments. In particular, the relative strength of connectivity of the right hemisphere's homologues of the left dorsal stream hubs to the left dorsal hubs, versus to the right ventral stream hubs, is a particularly strong predictor of poststroke aphasia severity and symptomology.

Анализ транспортной доступности населенных пунктов Республики Мордовия с использованием геоинформационных технологий

The study is devoted to the analysis of transport accessibility of the settlements in the Republic of Mordovia, which is proposed by the authors as one of the indicators for assessing the level of the transport system development. Methods of spatial analysis and graph theory are used to create a transport network model. The selection of graph elements includes settlements in Mordovia with a population of 2 000 people or more, as well as all sections of highways that provide the shortest paths between them. The measure of distance is used as impedance. The article discusses the usability of geographic and potential accessibility, as well as the detour index to detect problematic elements of the transport network, and compares the indicators using the ranking and classification methods. Using web mapping services and network analysis tools in GIS, the selected indicators were calculated and a series of maps were created to display them, using natural breaks classification method and graduated symbols as a method of cartographic representation. During the study, it was found that some of the shortest paths between the considered settlements of the Republic of Mordovia pass through the Nizhny Novgorod Oblast, which indicates that the regional transport network goes beyond the borders of the federal subject. The problem of artificial barriers within one country at the level of municipal districts and federal subjects has been identified. The possibility of creating a project to improve transport accessibility of the region is being considered, and arguments in favor of the construction of missing direct connections between settlements of the Republic of Mordovia are given. The target indicators and limiting factors for improving the transport accessibility of settlements in the region are identified. The possibilities of further research using the obtained results for a comprehensive analysis of the regional transport system are considered.

σ Interference: Through-Space and Through-Bond Dichotomy.

Dividing orbital interactions into through-space (TS) and through-bond (TB) modes is valuable for understanding various molecular properties. In this paper, we elucidate how the quantum interference phenomenon known as σ interference in electron transport through σ systems arises from TS and TB interactions. We performed electron transport calculations using a combination of density functional theory and nonequilibrium Green's function methods, focusing on ethylenediamine, a classical molecule that effectively highlights the contrast between TS and TB interactions. Our results confirm that destructive σ interference occurs in the syn and gauche conformers of this molecule. To further investigate both TS and TB interactions, we employed two analytical methods: the fragment molecular orbital (FMO) method, which captures the effects of both TS and TB interactions, and the chemical graph theory method, which specializes in TB interactions. The FMO analysis demonstrated that TB interactions lead to the characteristic distribution and energy level alignment of the frontier orbitals. Additionally, it was clarified that a change in TS interaction, due to a variation in the dihedral angle of the molecule, alters the energy gap between these orbitals, resulting in the manifestation of σ interference in the syn and gauche conformers, but not in the trans conformer. The chemical graph theory analysis based on the ladder C model, aimed at exploring the topological origin of σ interference from the network of TB interactions, revealed that σ interference is caused by the cancellation between the walk associated with geminal interactions (σ-conjugation) and the one related to vicinal interaction (σ-hyperconjugation). Notably, it was found that the vicinal interaction, which changes sign with the dihedral angle, has a decisive influence on whether this cancellation occurs. These findings clarify that σ interference arises from the interplay between TS and TB interactions. This insight will be valuable for designing molecular systems that utilize σ interference.

Modeling multiple-pipe failures in stormwater networks using graph theory

ABSTRACT One way to enhance the resilience of urban stormwater networks is to identify critical components of the network for targeted management and maintenance strategies. However, tackling multiple-pipe failures poses a significant hurdle due to the computational burden of conventional methods, making it impractical to analyze all potential combinations of pipe failures. To address this research gap, this study proposes a novel method based on complex network analysis to determine critical pipe failure combinations. The method incorporates network topology and estimates flooding impacts based on graph measures instead of solving complex hydraulic equations. The method is tested on two case studies with varying loop degrees and for different failure levels and compared with the state-of-the-art hydrodynamic modeling method (HMM) in terms of accuracy and computational time. Results show that the proposed graph theory method (GTM) can be used to identify the most critical pipe failure combinations. However, the accuracy of the GTM decreases slightly with increasing failure level and with increasing loop degree of the network. A hybrid graph-hydrodynamic model (GHM) is also developed as part of the study which combines advantages from both GTM and HMM.

Analytical railway line capacity methods from graph-theoretical and polyhedral perspectives

ABSTRACT This paper rigorously addresses the consumed capacity underestimation caused by division-based methods in graph theory and polyhedral geometry. Graph-theoretically, such underestimation occurs because subgraphs in shorter sections approximate their combined graph. Our polyhedral study suggests that the capacity analysis is computationally ‘easy’ because its linear programme in the complete section has an orthogonal projection on the Euclidean plane containing five proper faces, one being the objective-defined one-dimensional optimal facet. Geometrically, we conclude that the polyhedra of the linear programmes in shorter and complete sections have parallel facets, with the former nested within the latter. Consequently, the optimal values of the former cannot exceed those of the latter. With these theoretical insights, we derive a train operation labelling algorithm that takes proven linear time. Beyond enabling faster capacity computation, the findings deepen our understanding of the connection between infrastructure capacity utilisation and timetable structure, ultimately leading to more efficient railway optimisation.

Synchronization of Euler-Lagrangian networks: a periodic intermittent dynamic event-triggered control strategy

In this paper, the synchronization problem of Euler–Lagrange networks is studied by designing periodic intermittent dynamic event-triggered control strategy. The synchronization of all agents is successfully realized by injecting negative comments into the discontinuous interval of the agents described by the Euler–Lagrange systems. Different from the traditional intermittent event-triggered control strategy, the control strategy proposed in this study introduces internal dynamic variables to expand the sampling interval of the event-triggered mechanism, thereby improving resource utilization efficiency. In addition, the event trigger instants of each agent are asynchronous. By using graph theory and Lyapunov method, the synchronization criteria of Euler–Lagrange networks are derived. The effectiveness of the proposed control scheme is verified by simulations for the Euler-Lagrangian network composed of six two-link rotating manipulators.

Erratum to “Kinematic analysis of adjusting mechanism of bamboo and wood-based special-shaped panels sucker based on graph theory and closed-loop vector method”

Erratum to “Kinematic analysis of adjusting mechanism of bamboo and wood-based special-shaped panels sucker based on graph theory and closed-loop vector method”

Aging-aware co-optimization of topology, parameter and control for multi-mode input- and output-split hybrid electric powertrains

Existing research has focused on battery intrinsic optimization, Hybrid Energy Storage System (HESS), and powertrain control perspectives to enhance battery life. However, the impact of powertrain physical architecture -control multi-layer co-optimization on battery life has been neglected. Therefore, this study innovatively proposes a multi-mode dedicated hybrid transmission (DHT)—from the perspective of powertrain architecture—to reduce battery life degradation by switching between input split (IS) and output split (OS) modes. In order to fully optimize the battery degradation potential, a topology-parameter-control multi-layer co-optimization (TPCMC) method is proposed in this paper. In the topology layer, graph theory method is used for automatic generation, screening and modeling. In the parameter and control layer, a novel near-optimal energy management strategy, Rapid Dynamic Programming+ (Rapid-DP+), is proposed by introducing Pareto optimization, slope filtering, and Battery Life Aging Optimization (BLAO) methods, which improves the computational efficiency by 3500 times with 9.09–21.1 % battery life optimization. The results show that, relative to the Toyota Prius, the optimized powertrain improves the acceleration by 41.3 %, fuel economy by 6.08 %–8.1 %, and battery life degradation by 9.9 %–22.5 % under different driving cycles. This paper contributes to battery life degradation in the electrified transportation through an advanced TPCMC approach.

Interdisciplinary aspect in the organization of research and project activities of students of a technical university: on the example of the "Graph theory" discipline

The article considers the possibilities of using educational and professional humanitarian-oriented research tasks in the educational process of the university as a means of forming and developing research skills of students of technical specialties. The process of solving educational and professional tasks is considered by the example of constructing an optimal route using graph theory methods.

Графовые алгоритмы для расчёта распределения следов амурского тигра на территории Приморского края

The paper analyzes the distribution of the Amur tiger (Panthera tigris altaica) tracks in the Primorsky Krai municipalities according to observations obtained during the one-time winter count organized by the Pacific Institute of Geography of the Far Eastern Branch of the Russian Academy of Sciences in 2005. This task is related to the need to calculate the number of animals based on the tracks of their vital activity. Based on the initial data we form a sample to analyze a set of tracks to identify intersection areas of various tiger habitats in Primorsky Krai. The map of Primorsky Krai municipalities was presented in the form of a planar graph to identify their intersections. A recurrent algorithm for identifying tiger clusters was developed using graph theory methods. According to them, the territory of Primorsky Krai is divided into northern, central, southern and southwestern zones with intersections. The districts of Primorsky Krai included in the designated zones are listed. The total number of tracks in intersecting adjacent zones was counted to identify possible tiger migrations in Primorsky Krai. A quantitative assessment of the degree of intersection of the selected zones by the number of tiger tracks is given. The proposed calculation scheme can be used to clarify and verify the results of modeling the spatial distribution and total population size of the Amur tiger.

Web search results processing in an information support system for decision-making processes

Objectives. The problem of the web search results processing in an information support system for decision[1]making is solved in order to create and correct a meaningful description of a problem situation. An approach to solving this problem is proposed based on the use of thematic text corpora (collections of texts on a specific topic) as knowledge about the subject area, as well as a knowledge representation model based on verbal associations. When solving problems of the web search results processing in a decision-making information support system, five main goals are pursued: the formation of an extended description of a problem situation, the synthesis of a search prescription, an Internet search for information about decisions made, the synthesis of a retelling of the information found, and an assessment of the quality of the found analogues of the decisions made.Methods. Methods of set theory, graph theory and mathematical linguistics are used.Results. A mathematical model has been developed for the web search results processing in an information support system for decision making. The concepts of verbal association of words and texts, as well as pragmatically complete lexical structure, are formalized. The proven properties of such structures provide algorithmization of information processes in the model under consideration.Conclusion. The approach to modeling is based on the formalization of the concepts of the informativeness of words, sentences, texts and the informativeness of verbal associations between them. As an implementation of the model proposed in the article, algorithms have been developed for creating a dictionary of pragmatically complete lexical structures, creating structural-lexical templates for sentences, texts and subject areas, synthesizing a brief retelling of the information found, and assessing the quality of the found analogues of the decisions made.

Model and Methods of Traffic Routing in a Communication Network Using UAVs

Relevance. The development of 5G networks and subsequent generations is accompanied by the development of new services, in particular, virtual, augmented reality services, as well as telepresence, as well as radio access networks. In particular, there is an increase in operating frequencies, which poses additional challenges for organizing a network that can meet the requirements for the quality of traffic service from new services and ensure the availability of communication to users. These problems can be solved by various methods of placing access points, including using UAVs. This approach ensures the efficiency of construction and flexibility of the access network structure, but also requires the use of methods for placing access points in relation to users and other elements of the communication network. Problem statement: development of methods for placing routers in a UAV swarm and selecting traffic routes when organizing an access network, in order to improve the efficiency of the communication network. Purpose of the work: improving the efficiency of building an access network using UAVs through the development of clustering methods and distributing routers in a UAV swarm. Methods. The studies were carried out using the provisions of information theory, mathematical optimization methods, graph theory methods and clustering methods. The numerical results were obtained using the numerical simulation method in Python. Result. The developed model and methods allow for the distribution of network routers (access points) located on UAVs taking into account the quality of service and ensuring the construction of a connected mesh network and its connection with the mobile network, which can be used in both modern and future communication networks. Novelty: a modeling and methodological apparatus has been developed that allows for increasing the efficiency of building wireless access networks using UAVs, in particular, allowing for selecting the placement positions of routers in a UAV swarm and the logical structure of the network. The developed modeling and methodological apparatus solves the problem of traffic routing taking into account the quality of its service. Practical significance: the proposed model and methods can be used to organize service in 5G networks and subsequent generations. In particular, they allow for ensuring the availability of communication and the efficiency of network organization in cases of insufficient coverage, as well as in cases of failure of individual network elements. The ability to unload traffic to a local network allows for improving the quality of traffic service in the operator's network.

Kinematic analysis of adjusting mechanism of bamboo and wood-based special-shaped panels sucker based on graph theory and closed-loop vector method

Kinematic analysis of adjusting mechanism of bamboo and wood-based special-shaped panels sucker based on graph theory and closed-loop vector method

Graph Theory Applications in Optimizing Emergency Response Logistics

This study explores the utilization of graph theory and optimization methods to improve the effectiveness of emergency response logistics. The study devises and evaluates multiple algorithms with the objective of enhancing the efficiency of emergency routes and resource distributions, showcasing advancements compared to conventional approaches. The findings demonstrate substantial decreases in response times, operational expenses, and improvements in resource utilization rates. This study provides reliable and powerful resources for emergency managers to enhance their ability to strategize and carry out response operations with more efficiency. Furthermore, the models introduced in this work are versatile and may be utilized in different emergency situations to guarantee the most efficient allocation of resources and response times. The results emphasize the practical significance of graph theory in emergency logistics, establishing a solid basis for additional advancement and practical implementation.

The Impact of Sparse Datasets When Harmonizing Data from Studies with Different Measures of the Same Construct.

Prevention science has increasingly turned to integrative data analysis (IDA) to combine individual participant-level data from multiple studies of the same topic, allowing us to evaluate overall effect size, test and model heterogeneity, and examine mediation. Studies included in IDA often use different measures for the same construct, leading to sparse datasets. We introduce a graph theory method for summarizing patterns of sparseness and use simulations to explore the impact of different patterns on measurement bias within three different measurement models: a single common factor, a hierarchical model, and a bifactor model. We simulated 1000 datasets with varying levels of sparseness and used Bayesian methods to estimate model parameters and evaluate bias. Results clarified that bias due to sparseness will depend on the strength of the general factor, the measurement model employed, and the level of indirect linkage among measures. We provide an example using a synthesis dataset that combined data on youth depression from 4146 youth who participated in 16 randomized field trials of prevention programs. Given that different synthesis datasets will embody different patterns of sparseness, we conclude by recommending that investigators use simulation methods to explore the potential for bias given the sparseness patterns they encounter.

Mathematical models and algorithms for designing main pipeline for transporting georesources

Relevance. The practical importance of the tasks of utility networks design, namely, the problems of optimizing the structure of the main pipeline according to given criteria, such as efficiency, reliability etc., under conditions of limitations, for example, the compatibility of various types of utilities. Since the main pipeline is laid on the ground with various physical and geological factors, natural and situational conditions, it is advisable to take the reliability of its operation as a global criterion. The task of network optimization is proposed in the form of displaying the main pipeline along the selected routes in three-dimensional space, which considers various existing communications and objects, as well as elevation marks of the area. The paper presents the problems of optimizing networks, both in the continuous case and in the discrete case, and also studies various indicators of the reliability of the operation of the main pipeline. Aim. To develop a model for laying the main pipeline in three-dimensional space, considering the reliability of the pipeline transport; to conduct a comparative analysis for various reliability indicators and topologies of the main pipeline. Objects. Utility communications and networks laid in three-dimensional space. Methods. Calculus of variations, discrete optimization methods, graph theory and hypernet theory methods, network reliability analysis methods. Results. The task of optimizing the main pipeline transport is given taking into account its nesting along the route in three-dimensional space with the choice of an optimization criterion (economic efficiency, reliability, etc.). The problem is presented in the form of continuous and discrete formulations, which is important for its development both within the theory of the calculus of variations and discrete optimization. In this work, the problem was studied within the framework of the theory of graphs and hypernets, which allow, firstly, taking into account the nesting of one structure (main pipeline) into another (a discrete analogue of three-dimensional space) and, secondly, clearly illustrating the results of numerical experiments. It is shown that under the conditions of a given variants for laying a secondary network along the primary channels, various optimal structures are obtained when considering various reliability indicators as a criterion, which can be used to implement a design solution for the construction and operation of pipeline transport for various purposes.

Fuzzy logic in the problems of determining the economic parameters of project implementation

The goal of this work is to forecast project execution terms and its main economic parameters using graph theory and fuzzy logic methods. The subject of research in the article is the method of calculating the main properties or parameters of the project, forecasting the terms of its implementation and the possibility of taking into account force majeure situations. The article discusses the task of finding the optimal plan for the project of creating an e-commerce site and calculating its main economic parameters. The work uses methods of the theory of network planning and management. Fuzzy logic methods are used to solve the fuzzy optimization problem. Graph theory methods, namely the CPM critical path method, are used to forecast project deadlines. The following results were obtained: the main economic parameters were calculated for two versions of the project to create an e-commerce site – sequential, when the team does not have many developers to implement it (or enough resources), and parallel execution of work, which allows you to optimize the execution time by involving additional workers. The cost of both projects was also calculated, which in the future can help managers draw conclusions regarding the implementation of one or another planning option for this type of project. For the first project, the project work plan will be completed in a time not exceeding 230 days, with a reliability of 30%. Or does not exceed 295 days with a reliability of 80% percent. For the second project, the project work plan will be completed in a time not exceeding 230 days, with a reliability of 30%. Or does not exceed 278 days with a reliability of 70% percent. Conclusions: the paper proposes a fuzzy mathematical model for finding the optimal plan and calculating the main economic parameters of the project of creating an e-commerce site with a fuzzy set of plans and a vaguely defined goal. The work also presents a method for solving this problem. The obtained results of the research are of great value for planning the project, for solving the question of the feasibility of its initiation, for forecasting the resources that will be needed for its implementation. These indicators are essential for improving processes and correct allocation of work, which can help strengthen competitiveness and increase project profits.

Response inhibition in premotor cortex corresponds to a complex reshuffle of the mesoscopic information network.

Recent studies have explored functional and effective neural networks in animal models; however, the dynamics of information propagation among functional modules under cognitive control remain largely unknown. Here, we addressed the issue using transfer entropy and graph theory methods on mesoscopic neural activities recorded in the dorsal premotor cortex of rhesus monkeys. We focused our study on the decision time of a Stop-signal task, looking for patterns in the network configuration that could influence motor plan maturation when the Stop signal is provided. When comparing trials with successful inhibition to those with generated movement, the nodes of the network resulted organized into four clusters, hierarchically arranged, and distinctly involved in information transfer. Interestingly, the hierarchies and the strength of information transmission between clusters varied throughout the task, distinguishing between generated movements and canceled ones and corresponding to measurable levels of network complexity. Our results suggest a putative mechanism for motor inhibition in premotor cortex: a topological reshuffle of the information exchanged among ensembles of neurons.

Efektivitas Algoritma Kruskal dalam Mengoptimalkan Jalur Terpendek pada Jaringan Intranet

This research takes a case study at the Communication and Information Service, Bondowoso Regency, which is one of the media for conveying information and connecting interactive communication between the government and the community. In the process of conveying information to the public, they utilize information technology, the Intranet Network. The problem found was that there were obstacles in ineffective cable installation. This relates to non-optimality in determining the shortest path between two points in an intranet network, and how to determine the correct wiring position, so that the amount used is minimal but can still function optimally and be connected to all computers. To overcome the problems above, in this research the Kruskal Algorithm will be applied which is one of the network optimization methods in Graph Theory. Graph Theory is one of fields in Mathematics that studies the relationships between objects and how these objects interact with each other. Meanwhile, the Kruskal algorithm is an algorithm used to find the shortest path between two points in a graph. It is hoped that this research can optimize the amount of cabling used in designing intranet network topologies so that we can design optimal intranet routes with minimal costs.