Complex Systems and Its Applications

A special issue of Symmetry (ISSN 2073-8994). This special issue belongs to the section "Mathematics".

Deadline for manuscript submissions: closed (15 December 2021) | Viewed by 21625

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Guest Editor
LABSS (Laboratory of Agent Based Social Simulation), Institute of Cognitive Science and Technology, National Research Council (CNR), Via Palestro 32, 00185 Rome, ItalyGrupo Interdisciplinar de Sistemas Complejos (GISC), Departamento de Matemáticas, Universidad Carlos III de Madrid, 28911 Leganés, Spain
Interests: physics of complex systems (particular in social and biological systems); game theory; interdisciplinary physics; evolutionary dynamics; biophysics and experimental psychology
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Special Issue Information

Dear colleagues,

Symmetry has been found ubiquitously in nature. Symmetric features of mathematical and physical systems are of great importance for the understanding of the behaviour of the systems themselves. The role of symmetry has also been proven fundamental in other different disciplines, such as biology, chemistry, and psychology. More in general, in complex systems, symmetric properties assume even more relevance due to the difficulty, not to say impossibility, in getting a complete, mathematical description of the phenomena involved. 

For this Special issue, we invite authors to submit their works in which symmetry is an essential factor for the description, study and analysis of complex systems in general or for a specific instance. Works from every field are welcome, with special attention to biological, social and psychological applications. In particular, the following keywords should be considered:

Symmetry and complex systems;

Symmetries in biological systems;

Symmetries in society;

Symmetries in human behaviour;

Symmetry, complexity and criticality.

Dr. Daniele Vilone
Guest Editor

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Published Papers (7 papers)

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Research

34 pages, 4649 KiB  
Article
Semi-Adaptive Evolution with Spontaneous Modularity of Half-Chaotic Randomly Growing Autonomous and Open Networks
by Andrzej Gecow and Laszlo Barna Iantovics
Symmetry 2022, 14(1), 92; https://doi.org/10.3390/sym14010092 - 6 Jan 2022
Cited by 1 | Viewed by 1363
Abstract
Up until now, studies of Kauffman network stability have focused on the conditions resulting from the structure of the network. Negative feedbacks have been modeled as ice (nodes that do not change their state) in an ordered phase but this blocks the possibility [...] Read more.
Up until now, studies of Kauffman network stability have focused on the conditions resulting from the structure of the network. Negative feedbacks have been modeled as ice (nodes that do not change their state) in an ordered phase but this blocks the possibility of breaking out of the range of correct operation. This first, very simplified approximation leads to some incorrect conclusions, e.g., that life is on the edge of chaos. We develop a second approximation, which discovers half-chaos and shows its properties. In previous works, half-chaos has been confirmed in autonomous networks, but only using node function disturbance, which does not change the network structure. Now we examine half-chaos during network growth by adding and removing nodes as a disturbance in autonomous and open networks. In such evolutions controlled by a ‘small change’ of functioning after disturbance, the half-chaos is kept but spontaneous modularity emerges and blurs the picture. Half-chaos is a state to be expected in most of the real systems studied, therefore the determinants of the variability that maintains the half-chaos are particularly important in the application of complex network knowledge. Full article
(This article belongs to the Special Issue Complex Systems and Its Applications)
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17 pages, 885 KiB  
Article
On the Controllability of a System Modeling Cell Dynamics Related to Leukemia
by Ioan Ştefan Haplea, Lorand Gabriel Parajdi and Radu Precup
Symmetry 2021, 13(10), 1867; https://doi.org/10.3390/sym13101867 - 3 Oct 2021
Cited by 8 | Viewed by 2179
Abstract
In this paper, two control problems for a symmetric model of cell dynamics related to leukemia are considered. The first one, in connection with classical chemotherapy, is that the evolution of the disease under treatment should follow a prescribed trajectory assuming that the [...] Read more.
In this paper, two control problems for a symmetric model of cell dynamics related to leukemia are considered. The first one, in connection with classical chemotherapy, is that the evolution of the disease under treatment should follow a prescribed trajectory assuming that the drug works by increasing the cell death rates of both malignant and normal cells. In the case of the second control problem, as for targeted therapies, the drug is assumed to work by decreasing the multiplication rate of leukemic cells only, and the control objective is that the disease state reaches a desired endpoint. The solvability of the two problems as well as their stability are proved by using a general method of analysis. Some numerical simulations are included to illustrate the theoretical results and prove their applicability. The results can possibly be used to design therapeutic scenarios such that an expected clinical evolution can be achieved. Full article
(This article belongs to the Special Issue Complex Systems and Its Applications)
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20 pages, 1477 KiB  
Article
Bateson and Wright on Number and Quantity: How to Not Separate Thinking from Its Relational Context
by William P. Fisher, Jr.
Symmetry 2021, 13(8), 1415; https://doi.org/10.3390/sym13081415 - 3 Aug 2021
Cited by 2 | Viewed by 2713
Abstract
As part of his explication of the epistemological error made in separating thinking from its ecological context, Bateson distinguished counts from measurements. With no reference to Bateson, the measurement theory and practice of Benjamin Wright also recognizes that number and quantity are different [...] Read more.
As part of his explication of the epistemological error made in separating thinking from its ecological context, Bateson distinguished counts from measurements. With no reference to Bateson, the measurement theory and practice of Benjamin Wright also recognizes that number and quantity are different logical types. Describing the confusion of counts and measures as schizophrenic, like Bateson, Wright, a physicist and certified psychoanalyst, showed mathematically that convergent stochastic processes informing counts are predictable in ways that facilitate methodical measurements. Wright’s methods experimentally evaluate the complex symmetries of nonlinear and stochastic numeric patterns as a basis for estimating interval quantities. These methods also retain connections with locally situated concrete expressions, mediating the data display by contextualizing it in relation to the abstractly communicable and navigable quantitative unit and its uncertainty. Decades of successful use of Wright’s methods in research and practice are augmented in recent collaborations of metrology engineers and psychometricians who are systematically distinguishing numeric counts from measured quantities in new classes of knowledge infrastructure. Situating Wright’s work in the context of Bateson’s ideas may be useful for infrastructuring new political, economic, and scientific outcomes. Full article
(This article belongs to the Special Issue Complex Systems and Its Applications)
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15 pages, 1791 KiB  
Article
Feature Ranking and Differential Evolution for Feature Selection in Brushless DC Motor Fault Diagnosis
by Chun-Yao Lee and Chen-Hsu Hung
Symmetry 2021, 13(7), 1291; https://doi.org/10.3390/sym13071291 - 18 Jul 2021
Cited by 12 | Viewed by 3035
Abstract
A fault diagnosis system with the ability to recognize many different faults obviously has a certain complexity. Therefore, improving the performance of similar systems has attracted much research interest. This article proposes a system of feature ranking and differential evolution for feature selection [...] Read more.
A fault diagnosis system with the ability to recognize many different faults obviously has a certain complexity. Therefore, improving the performance of similar systems has attracted much research interest. This article proposes a system of feature ranking and differential evolution for feature selection in BLDC fault diagnosis. First, this study used the Hilbert–Huang transform (HHT) to extract the features of four different types of brushless DC motor Hall signal. When there is a fault, the symmetry of the Hall signal will be influenced. Second, we used feature selection based on a distance discriminant (FSDD) to calculate the feature factors which base on the category separability of features to select the features which have a positive correlation with the types. The features were entered sequentially into the two supervised classifiers: backpropagation neural network (BPNN) and linear discriminant analysis (LDA), and the identification results were then evaluated. The feature input for the classifier was derived from the FSDD, and then we optimized the feature rank using differential evolution (DE). Finally, the results were verified from the BLDC motor’s operating environment simulation with the same features by adding appropriate signal-to-noise ratio magnitudes. The identification system obtained an accuracy rate of 96% when there were 14 features. Additionally, the experimental results show that the proposed system has a robust anti-noise ability, and the accuracy rate is 92.04%, even when 20 dB of white Gaussian noise is added to the signal. Moreover, compared with the systems established from the discrete wavelet transform (DWT) and a variety of classifiers, our proposed system has a higher accuracy with fewer features. Full article
(This article belongs to the Special Issue Complex Systems and Its Applications)
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15 pages, 21758 KiB  
Article
The Use of a Game Theory Model to Explore the Emergence of Core/Periphery Structure in Networks and Its Symmetry
by Ladislav Beranek and Radim Remes
Symmetry 2021, 13(7), 1214; https://doi.org/10.3390/sym13071214 - 6 Jul 2021
Cited by 3 | Viewed by 2485
Abstract
In network systems characterized by complex interactions of various types, core-periphery structures can be found. In this paper, we deal with such questions as what processes can lead to the emergence of core-periphery formation, whether this structure is symmetric, and to what extent. [...] Read more.
In network systems characterized by complex interactions of various types, core-periphery structures can be found. In this paper, we deal with such questions as what processes can lead to the emergence of core-periphery formation, whether this structure is symmetric, and to what extent. Namely, the question of symmetry in a complex network is still the subject of intense research interest. Symmetry can relate to network topology, network relationships, and other processes on networks. To answer these questions, we modified the model of the classic social dilemma called the repeated prisoner’s dilemma (or repeated PD game) by adding the cost of maintaining relationships between the pairs of players (partners) and especially by adding the possibility of ending some relationships. We present the results of simulations that suggest that the players’ network strategy (i.e., partner selection or termination of relationships with some partners) is the driving force behind the emergence of a core-periphery structure in networks rather than the player’s strategy in PD. Our results also suggest that the formed core is symmetric, and this symmetry is a result of the symmetric interactions of core players. Our outcomes can help understand various economic or social questions related to creating centers or peripheries, including their symmetry in different network systems. Full article
(This article belongs to the Special Issue Complex Systems and Its Applications)
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13 pages, 921 KiB  
Article
Asymmetry of Authority or Information Underlying Insufficient Communication Associated with a Risk of Crashes or Incidents in Passenger Railway Transportation
by Atsuo Murata and Waldemar Karwowski
Symmetry 2021, 13(5), 803; https://doi.org/10.3390/sym13050803 - 5 May 2021
Cited by 3 | Viewed by 2735
Abstract
Similar crashes or incidents may recur as a result of insufficient communication in uncertain and risky situations that potentially threaten safety. The common root causes of insufficient communication across a series of incidents and crashes must be explored in detail to prevent a [...] Read more.
Similar crashes or incidents may recur as a result of insufficient communication in uncertain and risky situations that potentially threaten safety. The common root causes of insufficient communication across a series of incidents and crashes must be explored in detail to prevent a vicious circle of similar incidents or crashes from occurring. This study summarizes a series of incidents and crashes (derailment due to excessive train speed) at JR West at the West Japan Railway Company (JR West) that are considered to have arisen from insufficient communication. The incidents included (i) resuming train service without confirming the number of passengers on board and leaving passengers behind the station at Higashi-Hiroshima station, (ii) continuing train service in spite of an apparent risk of a crash detected at Okayama station, and (iii) leaving the crack of the train hood as it was at Kokura station. We discuss the causes of insufficient communication (particularly in relation to the sharing of information) among the three branches of staff—the station staff, the conductor and train driver, and the train operation management center—that led to the incidents or crashes. Two factors contributed to the insufficient communication in the series of incidents and crashes: (a) Asymmetry of authority, which hinders the discussion of issues openly and equally among the branches concerned. (b) An unacceptable level of knowledge or information for all branches concerned. Full article
(This article belongs to the Special Issue Complex Systems and Its Applications)
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12 pages, 948 KiB  
Article
On the Root Causes of the Fukushima Daiichi Disaster from the Perspective of High Complexity and Tight Coupling in Large-Scale Systems
by Atsuo Murata and Waldemar Karwowski
Symmetry 2021, 13(3), 414; https://doi.org/10.3390/sym13030414 - 4 Mar 2021
Cited by 5 | Viewed by 5470
Abstract
This study explores the root causes of the Fukushima Daiichi disaster and discusses how the complexity and tight coupling in large-scale systems should be reduced under emergencies such as station blackout (SBO) to prevent future disasters. First, on the basis of a summary [...] Read more.
This study explores the root causes of the Fukushima Daiichi disaster and discusses how the complexity and tight coupling in large-scale systems should be reduced under emergencies such as station blackout (SBO) to prevent future disasters. First, on the basis of a summary of the published literature on the Fukushima Daiichi disaster, we found that the direct causes (i.e., malfunctions and problems) included overlooking the loss of coolant and the nuclear reactor’s failure to cool down. Second, we verified that two characteristics proposed in “normal accident” theory—high complexity and tight coupling—underlay each of the direct causes. These two characteristics were found to have made emergency management more challenging. We discuss how such disasters in large-scale systems with high complexity and tight coupling could be prevented through an organizational and managerial approach that can remove asymmetry of authority and information and foster a climate of openly discussing critical safety issues in nuclear power plants. Full article
(This article belongs to the Special Issue Complex Systems and Its Applications)
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