General Network System Research Articles

Optimal inspection of binary systems via Value of Information analysis

We develop computable metrics to assign priorities for information collection on binary systems composed of binary components. Components are worth inspecting because their condition states are uncertain, and system functioning depends on them. The Value of Information (VoI) enables assessment of the impact of information in decision making under uncertainty, including the component’s reliability and role in the system, the precision of the observation, the available maintenance actions and the expected economic loss. We introduce the VoI-based metrics for system-level (“global”) and component-level (“local”) maintenance actions, analyze the properties of these metrics, and apply them to series and parallel systems. We discuss their computational complexity in applications to general network systems and, to tame the complexity for the local metric assessment, we present a heuristic and assess its performance on some case studies.

Almost sure exponential synchronization of network systems under a new intermittent noise-diffusion layer

In this paper, a novel intermittent noise-diffusion layer is proposed to synchronize a network system. Different from most of the traditional noise-induced synchronization or noise stabilization (noise exists in nodes of the network), we give an intermittent noise-diffusion layer (the noise exists in the edges of the network) to study the almost sure exponential synchronization. The theoretical results show that the general network system can be synchronized in the almost sure sense as long as the topological structure of the network in the intermittent noise-diffusion layer is an undirected connected graph. Two examples are proposed to illustrate the theory obtained.

Reciprocally convex approach for cooperative tracking control of general network systems with fixed/switching topologies

AbstractThe cooperative tracking problem of general network systems with fixed/switching topology having a directed spanning tree is investigated in this paper. A distributed sampled‐data controller is preferentially designed for each follower to track the independent leader. By using tools from input‐delay and a reciprocally convex approach, some sufficient conditions ensuring the purpose of tracking are derived. Theoretical analysis is then extended to the case that the topologies of network systems are time‐varying. It is demonstrated that the cooperative tracking problem for network systems can be solved under some sufficient conditions. Through the above investigation, the cooperative tracking problem of general network systems with fixed/switching topology is solved. The capabilities of the proposed control algorithm are finally verified on our experimental platform.

Efficiency measurement for general network systems: a slacks-based measure model

Traditional radial DEA models treat DMUs as black boxes, whose internal structures are ignored, and measure input and output changes proportionally. On the other hand, network DEA models consider the internal structure of a DMU as a network system where sub-processes are connected by intermediate products aside from consuming main inputs and producing final outputs. The interest in network DEA has increased over the years producing different types of formulations including the network slacks-based measure DEA (NSBM). NSBM is a non-radial network approach suitable for measuring efficiencies when inputs and outputs may change non-proportionally. However, NSBM models and some of its recent developments failed to adhere to three important efficiency measurement issues: (a) able to properly define overall and divisional efficiencies, (b) able to identify Pareto-Koopmans efficiency status, and (c) able to show equivalence of primal (multiplier) and dual (envelopment) forms of the network DEA model. This study addressed these issues based on the NSBM approach and compared the results of the proposed network SBM model with other existing models in the literature. A numerical study on 10 electric power companies further illustrated the use and significance of the proposed network SBM model in efficiency measurement.

Finding continuity and discontinuity in fish schools via integrated information theory.

Collective behaviours are known to be the result of diverse dynamics and are sometimes likened to living systems. Although many studies have revealed the dynamics of various collective behaviours, their main focus has been on the information processing performed by the collective, not on interactions within the collective. For example, the qualitative difference between three and four elements in a system has rarely been investigated. Tononi et al. proposed integrated information theory (IIT) to measure the degree of consciousness Φ. IIT postulates that the amount of information loss caused by the minimum information partition is equivalent to the degree of information integration in the system. This measure is not only useful for estimating the degree of consciousness but can also be applied to more general network systems. Here, we obtained two main results from the application of IIT (in particular, IIT 3.0) to the analysis of real fish schools (Plecoglossus altivelis). First, we observed that the discontinuity on 〈Φ(N)〉 distributions emerges for a school of four or more fish. This transition was not observed by measuring the mutual information or the sum of the transfer entropy. We also analysed the IIT on Boids simulations with respect to different coupling strengths; however, the results of the Boids model were found to be quite different from those of real fish. Second, we found a correlation between this discontinuity and the emergence of leadership. We discriminate leadership in this paper from its traditional meaning (e.g. defined by transfer entropy) because IIT-induced leadership refers not to group behaviour, as in other methods, but the degree of autonomy (i.e. group integrity). These results suggest that integrated information Φ can reveal the emergence of a new type of leadership which cannot be observed using other measures.

On network two stages variable returns to scale Dea models

Multiplicative decomposition of stages indices is shown to be consistent with Vrs network technologies. It is also shown why the primal dual correspondence breaks for serial network Vrs models. Different Vrs models can be associated with alternative transfer pricing systems, within the network. Multiplicative decomposition implies marginal cost pricing across stages. While other pricing systems (full cost) correspond to some of the known non-multiplicatively decomposable Vrs models, proposed in the literature. Stages indices, therefore, respond not only to efficiency, but also to the network’s distributive criteria across stages. The distributive contents of stage indices provide the key element for a solution to the problem of measuring scale efficiency in network systems. Multiplicative decomposable Vrs models can be extended to more general network systems, containing both parallel and in series structures. The cost of this generalisation is that efficiency indices are referred to modified stages, that is to stages that include dummy processes. In perspective, these results contribute to show how organisational aspects, such as transfer pricing systems, could be modelled once network technologies are approached from the multiplier (ratio) side.

Vibrational Analysis of Li1+xAlx Ti2-x(PO4)3 (0.0 < x < 0.5) Glass Ceramic Electrolytes Prepared by Acetic Acid­ Assisted Sol-Gel Method

In this study, Li1+xAlxTi2-x(PO4)3 (0.0 < x < 0.5) was prepared by acetic acid­assisted sol-gel method. The structural properties of NASICON phosphates material with chemical formula LiTi2 (PO4)3 were observed using the Fourier transform infrared spectroscopy. NASICON is a family of crystalline phosphate with a general network system consisting of PO4 tetrahedra, thus bands were assigned by vibrations contributed by basic phosphates, in the wavenumber region between 1300 cm-1 and 600 cm-1. Experimental spectra indicated that all Li1+xAlxTi2-x(PO4)3 (0.0 < x < 0.5), heat treated at 600°C and 700°C for 3 hours in air, samples showed the presence of phosphate peaks with shift in frequency as Al3+ is substituted into the structure, and with increasing temperatures. Some bands broadened and overlapped causing it hard to analyze the arising bands. It however determined the existence of NASICON structure in all of the samples under study.

Vibrational Analysis of Li1+xAlxTi2-x(PO4)3(0.0 < x < 0.5) Glass Ceramic Electrolytes Prepared by Acetic Acid­ Assisted Sol-Gel Method

In this study, Li1+xAlxTi2-x(PO4)3(0.0 < x < 0.5) was prepared by acetic acid­assisted sol-gel method. The structural properties of NASICON phosphates material with chemical formula LiTi2 (PO4)3 were observed using the Fourier transform infrared spectroscopy. NASICON is a family of crystalline phosphate with a general network system consisting of PO4 tetrahedra, thus bands were assigned by vibrations contributed by basic phosphates, in the wavenumber region between 1300 cm-1 and 600 cm-1. Experimental spectra indicated that all Li1+xAlxTi2-x(PO4)3(0.0 < x < 0.5), heat treated at 600°C and 700°C for 3 hours in air, samples showed the presence of phosphate peaks with shift in frequency as Al3+ is substituted into the structure, and with increasing temperatures. Some bands broadened and overlapped causing it hard to analyze the arising bands. It however determined the existence of NASICON structure in all of the samples under study.

A unified network-DEA model for performance measurement of production systems

Traditional DEA methods treat a production unit as a black box without any consideration to the internal relations of its sub-processes. In recent DEA literature, there are many researches about production systems with network structure, in which outputs of some stages could be considered as the inputs of some other stages in producing final outputs. In most of these works, network systems assume to have special parallel or series structures. Although in real world applications, production processes are often complex and there is no complete and unified model available for performance evaluation of these general network systems. This paper introduces a unified general model for efficiency evaluation of network production systems when arbitrary relations between individual sub-processes are allowed. The new general network DEA model is then illustrated by some numerical examples.

An intelligent modeling system for generalized network flow problems: With application to planning for multinational firms

This paper presents a discussion of the Generalized Network System (GNS), a system that captures knowledge about generalized network flow problems, in order to help users formulate, solve and interpret generalized network flow problems. Although previous researchers have built intelligent systems that incorporate knowledge about linear programming, this system includes more specific knowledge about generalized network flow problems. GNS is illustrated using it in a setting that requires international financial and replan rapidly. In addition, they need to be able to model complex events and organization GNS is illustrated using it in a setting that requires international financial and replan rapidly. In addition, they need to be able to model complex events and organization structures. For example, multinational planners need to be able to plan for production in multiple countries and repatriatization of funds. GNS allows users to meet these needs.

Seismic Risk Analysis of Buried Pipelines

A method is proposed for the seismic risk anlysis of buried pipelines, in which an analytical procedure is developed to estimate the annual probability of occurrence of different damage states (damage indexes) in a component segment (including pipe intersection) of the general network system for pipelines considering earthquake motions as stationary random processes. In the analysis described, the power spectral density functions (PSDFs) of ground accelerations characterizing the earthquake motions are related to the earthquake intensity measured in Modified Mercalli Intensity (MMI) scale. The expected peak values of stress developed at various sections are determined for each earthquake intensity. The annual probability of occurrence of different damage states is obtained by combining a damage probability matrix with the annual probability of occurrence of different levels of earthquake intensity. The proposed method is used to conduct a numerical study to show the effect of types of soil, the pipe end conditions, the types of intersections, the pipe radius, and the angle of incidence of earthquake wave with respect to the global coordinates of the pipeline system on the damage probability of the component pipe segment.