Network structure optimization for social networks by minimizing the average path length

Network structure plays an important role in the natural and social sciences. Optimization of network structure in achieving specified goals has been a major research focus. In this paper, we propose a definition of structural optimization in terms of minimizing the network’s average path length (APL) by adding edges. We suggest a memetic algorithm to find the minimum-APL solution by adding edges. Experiments show that the proposed algorithm can solve this problem efficiently. Further, we find that APL will ultimately decrease linearly in the process of adding edges, which is affected by the network diameter.

APPLICATION OF PNEUMATIC FORMWORK FOR REPAIR AND RESTORATION OF SEWER PIPELINES USING CLINKER BRICK AND POLYMER CONCRETE

Raising of problem. A significant part of wastewater in Ukrainian cities is discharged using sewer collectors with a diameter of 300 to 1 400 mm, the depth of which is within 3…8 m. A significant part of them is destroyed due to corrosion processes that take place in the surface space. Today, the problem of repair and restoration of sewerage networks is becoming especially relevant in connection with the increased requirements for environmental protection. Failure in sewer lines usually results in wastewater infiltration into groundwater and soil. During the repair and restoration of sewage collectors, open and closed methods of work are used. Taking into account that a significant part of sewage collectors passes through areas where there are no transport arteries, through agricultural land and have an insignificant depth of occurrence, and also the fact that their trough part, as a rule, cannot be destroyed due to corrosion, it is advisable to carry out repair and restoration work on them in an open way. Analysis of accidents on sewage collectors, which took place in different cities of Ukraine, showed that, as a rule, due to corrosion, intensive destruction of the roof of the collectors occurs. At the same time, the trough part of the collectors remains intact due to the fact that it is constantly filled with waste water. When repairing such sections of sewerage networks in recent years, operating organizations have been using polyethylene and fiberglass pipes. These smaller pipes are installed in the retained trough part, thus reducing the network diameter. The cost of new pipes is quite high, which in turn increases operating costs. The use of pneumatic formwork allows you to create a new collector, and as the main bearing element, you can use the saved tray part. Purpose. Evaluation of the possibility of using known materials for the manufacture of pneumatic formwork, which will make it possible to carry out repair work to create a new vault using the trough part of the sewer collector as a supporting structure, which will significantly reduce repair costs compared to using pipes made of polymer materials. Conclusion. The investigated samples of materials – fabric Mare 1400 and Hypolon (ORCA 828) – can be used for the manufacture of pneumatic formwork, since laboratory tests made it possible to conclude that there was no adhesion between concrete and material samples.

Low-diameter topic-based pub/sub overlay network construction with minimum–maximum node degree

In the construction of effective and scalable overlay networks, publish/subscribe (pub/sub) network designers prefer to keep the diameter and maximum node degree of the network low. However, existing algorithms are not capable of simultaneously decreasing the maximum node degree and the network diameter. To address this issue in an overlay network with various topics, we present herein a heuristic algorithm, called the constant-diameter minimum–maximum degree (CD-MAX), which decreases the maximum node degree and maintains the diameter of the overlay network at two as the highest. The proposed algorithm based on the greedy merge algorithm selects the node with the minimum number of neighbors. The output of the CD-MAX algorithm is enhanced by applying a refinement stage through the CD-MAX-Ref algorithm, which further improves the maximum node degrees. The numerical results of the algorithm simulation indicate that the CD-MAX and CD-MAX-Ref algorithms improve the maximum node-degree by up to 64% and run up to four times faster than similar algorithms.

k-Anonymous Query Scheme on the Internet of Things: a Zero Trust Architecture

The paper investigates query-anonymity in Internet of things (IoT) formed by a sensor cloud, where the sensor nodes provide services of sensing and are subject to user queries of sensing data. Due to the heterogeneity and multi-carrier natures of the sensor cloud, user privacy could be impaired when the queries have to go through nodes of a third party. Thus, the paper firstly introduces a novel query k-anonymity scheme that countermeasures such a privacy threat. Based on the proposed k-anonymity scheme, the trade-offs between the achieved query-anonymity and various performance measures including, communication-cost, return-on-investment metric, path-length, and location anonymity metrics, are analyzed. By adopting a hybrid approach that takes into account the average and worst-case analysis, our evaluation results show that most of the obtained bounds on various performance anonymity trade-offs can be expressed precisely in terms of the offered level-of-anonymity k and network diameter d.

Approaching textual coherence of machine translation with complex network

This study analyzes topological properties of complex networks of textual coherence, and investigates the textual coherence of machine translation by contrasting these properties in machine-translated texts with those in a human-translated text. The complex networks of textual coherence are built by drawing on the knowledge from Systemic Functional Linguistics, with Themes and Rhemes denoted as vertices and the semantic connections between them as edges. It is found that the coherence networks are small-world, assortatively mixed, scale-free with an exponential cut-off, and hub-dependent. The basic building blocks consist of fully-connected triads and fully-connected squares, with the latter playing a more significant role in the network construction. Compared with the complex network of human translation, the networks of machine translations have fewer vertices and edges, lower average degree, smaller network diameter, shorter average path length, larger cluster coefficient, bigger assortativeness coefficient and more types of motifs. Thus, we suggest that the machine-translated texts are sparsely, locally, unevenly and monotonously connected, which may account for why and how machine translation is weak in coherence. This study is the first effort ever to employ complex networks to explore textual coherence of machine translations. It may hopefully promote the cross-disciplinary interaction between linguistics, computer science and network science.

PROPERTIES OF AUTOSEMANTIC WORD NETWORKS IN UKRAINIAN TEXTS

We present results of network analysis of Ukrainian texts. Autosemantic (meaningful) words are considered as network vertices connected with links when belonging to one sentence. Subnetworks corresponding to specific parts of speech (verbs, nouns, adjectives, etc.) are also built. The obtained networks are small-world and scale-free. To make comparisons, random texts with parameters corresponding to real texts are generated using several approaches. Various parameters of networks are calculated, including transitivity, betweenness, degree centralization, mean distance, network diameter, exponents of degree distribution, etc. Comparison of network parameters of real and generated texts shows that borders between them are quite fuzzy.