scholarly journals A decomposition algorithm of Petri net utilizing index function

Filomat ◽  
2020 ◽  
Vol 34 (15) ◽  
pp. 5085-5094
Author(s):  
Kai-Qing Zhou ◽  
Li-Ping Mo ◽  
Chang-Feng Chen ◽  
Wei Jiang
Keyword(s):  
Petri Net ◽  
Large Scale ◽  
Dynamic Properties ◽  
Decomposition Algorithm ◽  
State Explosion ◽  
Decomposition Approach ◽  
Index Function ◽  
Knowledge Based ◽  
And Control

Recently, it is difficult to simulate, analyze and control a real knowledge-based system using the correspondence Petri net (PN) when there exist many current states. To overcome the state explosion problem of PN, an efficient decomposition algorithm is presented to divide a large-scale PN into a series of corresponding sub-PNs by keeping the consistency of dynamic properties. In this novel decomposition approach, an index function is defined to judge the subnet needs to be decomposed or not. Furthermore, an exhaustive analysis on the consistency of related dynamic properties is also discussed between the original PN and the corresponding sub-PNs. Finally, a case study is carried out to illustrate the feasibility and validity of the proposed approach.

The Star Degree Centrality Problem: A Decomposition Approach

2021 ◽  
Author(s):  
Mustafa C. Camur ◽  
Thomas Sharkey ◽  
Chrysafis Vogiatzis
Keyword(s):  
Integer Programming ◽  
Large Scale ◽  
Benders Decomposition ◽  
Open Neighborhood ◽  
Decomposition Algorithm ◽  
Solution Time ◽  
Set Cover ◽  
Degree Centrality ◽  
Decomposition Approach ◽  
Acceleration Techniques

We consider the problem of identifying the induced star with the largest cardinality open neighborhood in a graph. This problem, also known as the star degree centrality (SDC) problem, is shown to be [Formula: see text]-complete. In this work, we first propose a new integer programming (IP) formulation, which has a smaller number of constraints and nonzero coefficients in them than the existing formulation in the literature. We present classes of networks in which the problem is solvable in polynomial time and offer a new proof of [Formula: see text]-completeness that shows the problem remains [Formula: see text]-complete for both bipartite and split graphs. In addition, we propose a decomposition framework that is suitable for both the existing and our formulations. We implement several acceleration techniques in this framework, motivated by techniques used in Benders decomposition. We test our approaches on networks generated based on the Barabási–Albert, Erdös–Rényi, and Watts–Strogatz models. Our decomposition approach outperforms solving the IP formulations in most of the instances in terms of both solution time and quality; this is especially true for larger and denser graphs. We then test the decomposition algorithm on large-scale protein–protein interaction networks, for which SDC is shown to be an important centrality metric. Summary of Contribution: In this study, we first introduce a new integer programming (NIP) formulation for the star degree centrality (SDC) problem in which the goal is to identify the induced star with the largest open neighborhood. We then show that, although the SDC can be efficiently solved in tree graphs, it remains [Formula: see text]-complete in both split and bipartite graphs via a reduction performed from the set cover problem. In addition, we implement a decomposition algorithm motivated by Benders decomposition together with several acceleration techniques to both the NIP formulation and the existing formulation in the literature. Our experimental results indicate that the decomposition implementation on the NIP is the best solution method in terms of both solution time and quality.

The Big-headed Ant Pheidole megacephala: a new threat to monsoonal northwestern Australia

1998 ◽  
Vol 4 (3) ◽  
pp. 250 ◽  
Author(s):  
Benjamin D. Hoffmann
Keyword(s):  
Agricultural Production ◽  
Large Scale ◽  
Foraging Ecology ◽  
Potential Threat ◽  
Pheidole Megacephala ◽  
Realistic Option ◽  
Northwestern Australia ◽  
Nature Park ◽  
And Control

The Big-headed Ant Pheidole megacephala is a major threat to native invertebrate assemblages and to agricultural production world-wide. This paper reviews its known biology including its foraging ecology, colony founding and dispersal behaviour. A case study is presented to illustrate its potential conservation significance for northern Australia. At Howard Springs Nature Park in the Darwin region of the Northern Territory, an infestation of P. megacephala was found to cover 25 ha and is continuing to spread, with its distribution centred on a rainforest patch. The abundance of P. megacephala within the rainforest was 37?110 times that of total native ant abundance at uninfested sites. Only two individuals of a single native ant species were found in the highest abundance of P. megacephala and abundance of other invertebrates was only 15% of natural levels. Pheidole megacephala is a serious potential threat to native biodiversity in monsoonal Australia. Successful eradication on a large scale is a realistic option and control methods are discussed, including chemicals and fire.

scholarly journals Thermofluid Modelling of Large-Scale Orchards for Optimal Design and Control of Active Frost Prevention Systems

Energies ◽  
2020 ◽  
Vol 13 (2) ◽  
pp. 378
Author(s):  
Ercan Atam ◽  
Se-Woon Hong ◽  
Alessia Arteconi
Keyword(s):  
Optimal Design ◽  
Control Systems ◽  
Large Scale ◽  
Initial Conditions ◽  
Minimum Energy ◽  
Prunus Armeniaca ◽  
Thermal Dynamics ◽  
Heating Systems ◽  
And Control

Accurate modelling and simulation of temperature dynamics in large-scale orchards is important in many aspects, including: (i) for the calculation of minimum energy required to be used in optimal design of active frost prevention energy systems (fully renewable or partially renewable) to prevent freezing of fruit flowers, buds, or leaves; (ii) for testing frost prevention control systems before real-implementation which regulate active heating systems inside orchards targeted to prevent frost. To that end, in this study, first, a novel and sophisticated parametric computational thermofluid dynamics (CTFD) model for orchard air thermal dynamics for different orchard parameters (such as fruit type, climate, number of trees, their sizes, and distance between them) and boundary/initial conditions was developed and validated with field data from the literature. Next, the use of the developed parametric CTFD model was demonstrated through a case study to calculate the minimal thermal energy required to prevent frost under different frost levels in a test Prunus armeniaca orchard located in Malatya, Turkey, which is the world capital for dry apricot production.

scholarly journals Coordinating Knowledge Work in Multiteam Programs

2018 ◽  
Vol 49 (6) ◽  
pp. 64-77 ◽  
Author(s):  
Torgeir Dingsøyr ◽  
Nils Brede Moe ◽  
Eva Amdahl Seim
Keyword(s):  
Software Development ◽  
Large Scale ◽  
Development Program ◽  
Knowledge Work ◽  
Agile Development ◽  
Development Projects ◽  
Development Programs ◽  
Knowledge Based ◽  
Over Time

Software development projects have undergone remarkable changes with the arrival of agile development approaches. Although intended for small, self-managing teams, these approaches are used today for large development programs. A major challenge of such programs is coordinating many teams. This case study describes the coordination of knowledge work in a large-scale agile development program with 12 teams. The findings highlight coordination modes based on feedback, the use of a number of mechanisms, and how coordination practices change over time. The findings can improve the outcomes of large knowledge-based development programs by tailoring coordination practices to needs over time.

Reactive tracers reveal hydraulic and control instabilities in full-scale activated sludge plant

2008 ◽  
Vol 57 (7) ◽  
pp. 1001-1007 ◽  
Author(s):  
D. Braun ◽  
W. Gujer
Keyword(s):  
Large Scale ◽  
Oxygen Sensor ◽  
Electrochemical Sensors ◽  
Aeration Tank ◽  
Control Loop ◽  
Reactive Tracers ◽  
And Control ◽  
Present Case Study ◽  
Aeration Control

The hydraulic characteristics of aeration tanks in WWTPs have a major impact on the degradation of pollutants, as well as on the control of the aeration. In particular in long reactors, which are not separated by baffles, hydraulic shortcuts or large scale recirculation can lead to a loss of performance. This work demonstrates that reactive tracers such as ammonium and oxygen can be used to investigate the hydraulics of aeration tanks in detail. With the use of electrochemical sensors it is possible to investigate effects in a broad range of time scales. In the present case study a slow oscillation of the aeration control loop was investigated. Large scale recirculation in the aeration tank and fast fluctuations of the ammonium concentrations close to the oxygen sensor were identified as the cause of these oscillations. Both, the recirculation as well as the fluctuation of the ammonium have a substantial influence on the performance of the aeration tank and the aeration control loop.

scholarly journals Power monitoring and control for large scale projects: SKA, a case study

2016 ◽  
Author(s):  
Domingos Barbosa ◽  
João Paulo Barraca ◽  
Dalmiro Maia ◽  
Bruno Carvalho ◽  
Jorge Vieira ◽  
...  
Keyword(s):  
Large Scale ◽  
Monitoring And Control ◽  
Power Monitoring ◽  
And Control

scholarly journals Into the thirteenth Month: A Case Study on the Outbreak Analytics and Modeling the spread of SARS-CoV-2 Infection in Pune City, India

2021 ◽  
Author(s):  
Joy Monteiro ◽  
Bhalchandra Pujari ◽  
Sarika Maitra Bhattacharrya ◽  
Anu Raghunathan ◽  
Ashwini Keskar ◽  
...  
Keyword(s):  
Real Time ◽  
Large Scale ◽  
Information Dissemination ◽  
Public Access ◽  
Accurate Information ◽  
Time Data ◽  
Outbreak Response ◽  
First Case ◽  
And Control

With more than 140 million people infected globally and 3 million deaths, the COVID 19 pandemic has left a lasting impact. A modern response to a pandemic of such proportions needs to focus on exploiting all available data to inform the response in real-time and allow evidence-based decision-making. The intermittent lockdowns in the last 13 months have created economic adversity to prevent anticipated large-scale mortality and relax the lockdowns have been an attempt at recovering and balancing economic needs and public health realities. This article is a comprehensive case study of the outbreak in the city limits of Pune, Maharashtra, India, to understand the evolution of the disease and transmission dynamics starting from the first case on March 9, 2020. A unique collaborative effort between the Pune Municipal Corporation (PMC), a government entity, and the Pune knowledge Cluster (PKC) allowed us to layout a context for outbreak response and intervention. We report here how access to granular data for a metropolitan city with pockets of very high-density populations will help analyze, in real-time, the dynamics of the pandemic and forecasts for better management and control of SARS-CoV-2. Outbreak data analytics resulted in a real-time data visualization dashboard for accurate information dissemination for public access on the epidemic's progress. As government agencies craft testing and vaccination policies and implement intervention strategies to mitigate a second wave, our case study underscores the criticality of data quality and analytics to decode community transmission of COVID-19.

A Rule Level Knowledge Management System for Knowledge Based Engineering Applications

2002 ◽  
Author(s):  
I.-S. Fan ◽  
G. Li ◽  
M. Lagos-Hernandez ◽  
P. Bermell-Garci´a ◽  
M. Twelves
Keyword(s):  
Large Scale ◽  
Additional Data ◽  
Product Knowledge ◽  
Maintenance System ◽  
Knowledge Based ◽  
Microsoft Access ◽  
Knowledge Based Engineering ◽  
Generic Representation ◽  
And Control ◽  
Rules Maintenance

This paper reports on a system that has been developed to facilitate the structure and reuse of engineering rules (ERs) in Knowledge-Based Engineering (KBE) systems. The proposed structure for rule elements supports the traceability of knowledge sources as well as where the knowledge elements are used in KBE applications. This forms the infrastructure to systematically manage the use and reuse of knowledge and control the version and update of the rules when new knowledge is gained. Representing product knowledge in rules is a way to capture the know-why of the design by modelling the decisions involved in the design process. KBE has been used as the mechanism to deploy this knowledge. Although the KBE technology can support the management of this knowledge, the maintenance of the knowledge is often a neglected task. This leads to a number of practical difficulties in the large scale rollout of KBE applications. To design an improved KBE rules maintenance system, the research team developed a generic representation to unify the off-line storage of the IF, COND and CASE statements used in the ICAD Design Language. Additional data fields are defined to maintain the traceability of the origin and use of rules. This is implemented in a Microsoft Access database. The integration of this off-line rule repository with the ICAD KBE system is achieved and validated in an industrial application. The data structure defined and the implementation system is detailed in this paper.

scholarly journals An Automatic Algorithm to Generate a Reachability Tree for Large-Scale Fuzzy Petri Net by And/Or Graph

Symmetry ◽  
2018 ◽  
Vol 10 (10) ◽  
pp. 454 ◽  
Author(s):  
Kai-Qing Zhou ◽  
Li-Ping Mo ◽  
Lei Ding ◽  
Wei-Hua Gui
Keyword(s):  
Petri Net ◽  
Large Scale ◽  
Production Rules ◽  
Knowledge Based ◽  
Three Phase ◽  
Fuzzy Petri Net ◽  
Fuzzy Production Rules ◽  
Relationship Of ◽  
Reachability Tree ◽  
Automatic Algorithm

Fuzzy Petri net (FPN) is widely used to repre sent, model and analyse knowledge-based systems (KBSs). Meanwhile, a reachability tree is an important tool to fully represent the flow relationship of FPN and is widely applied to implement inference in industrial areas. However, the traditional reachability ignores recording the dependence relationships (‘and/or’ relationship) among the places in the neighbouring layers. This paper develops a modified reachability tree based on an and/or graph and presents a three-phase generation algorithm to model the reachability tree for the corresponding FPN automatically via fuzzy production rules (FPRs). Four cases are used to verify the correctness and feasibility of the proposed algorithm from different viewpoints, such as general FPRs, FPRs with a condition-sharing situation, FPRs with a conclusion-sharing situation, and FPRs with multi-conclusions. Simulation results reveal that the proposed approach has the ability to automatically generate the reachability tree for the corresponding FPN correctly.

scholarly journals Managing Recurrent Congestion of Subway Network in Peak Hours with Station Inflow Control

2018 ◽  
Vol 2018 ◽  
pp. 1-16 ◽  
Author(s):  
Qingru Zou ◽  
Xiangming Yao ◽  
Peng Zhao ◽  
Fei Dou ◽  
Taoyuan Yang
Keyword(s):  
Large Scale ◽  
Practical Applications ◽  
C Programming Language ◽  
Passenger Flow ◽  
Assignment Model ◽  
C Programming ◽  
Subway System ◽  
And Control ◽  
Internal Relationship

Station inflow control (SIC) is an important and effective method for reducing recurrent congestion during peak hours in the Beijing, Shanghai, and Guangzhou subway systems. This work proposes a practical and efficient method for establishing a static SIC scheme in normal weekdays for large-scale subway networks. First, a traffic assignment model without capacity constraint is utilized to determine passenger flow distributions on the network. An internal relationship between station inflows and section flows is then constructed. Second, capacity bottlenecks are identified by considering the transport capacity of each section. Then, a feedback-based bottleneck elimination strategy is established to search target control stations and determine their control time and control strength. To validate the effectiveness of the proposed approach, a decision support system coded in the C# programming language was developed, and the Beijing subway was used as a case study. The results indicate that the proposed method and tool are capable of practical applications, and the generated SIC plan has better performance over the existing SIC plan. This study provides a practical and useful method for operation agencies to construct SIC schemes in the subway system.

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