Preselected Properties Research Articles

Graph signatures: Identification and optimization

We introduce a new graph-theoretic paradigm called a graph signature that describes persistent patterns in a sequence of graphs. This framework is motivated by the need to detect subgraphs of significance in temporal networks, e.g., social and biological networks that evolve over time. Because the subgraphs of interest may not all “look alike” in the snapshots of the temporal network, the framework deems a subgraph to be persistent if it satisfies one of several preselected properties in each snapshot of a consecutive subsequence. The persistency requirement is parameterized by the length of this subsequence. This discrete mathematical framework can be viewed more broadly as a way to generalize classical graph properties and invariants associated with a single graph to a sequence of graphs.In this introductory article, we formulate the graph signature identification problem as a mixed-integer program and propose an algorithmic framework based on dynamic programming. This methodology is applicable to any collection of mixed-integer representable graph properties. We also demonstrate how this framework can be tailored to exploit property-specific decomposition and scale reduction techniques through three different computational case-studies. Our experiments show that the dynamic programming algorithm solves this problem across most instances in our test bed to optimality. Moreover, for the instances in our test bed, the optimal signature sizes are comparable to those of their static counterparts, suggesting that our new framework can identify subgraphs of significance in complex dynamic networks.

Calculation of thermal conductivity coefficient of thermal insulation mixtures

The majority of prospective deposits of oil and natural gas in the Russian Federation are located in the zones of permanently frozen rocks - the permafrost. This region is characterized not only by harsh climatic conditions, causing difficulty in development of the deposits, but also by negative cryogenic processes impacting the reliability of construction and use of various engineering structures. It is necessary to know the regularities of and to be able to forecast the thermal regime of the soils and rocks in order to forecast the degree of influence of cryogenic processes on the engineering structures. In particular, the depth of thawing and freezing of soils in the locations of underground and surface structures, such as pipelines, is of importance. The depth of thawing of soil is an important indicator for the choice of the method of construction on the frozen surfaces. Control of the thawing/freezing depth can be ensured with the use of thermal insulation as well as replacement of the soil itself with an artificial soil with preselected properties. Transportation of oil and natural gas is realized using pipelines laid through frozen rocks. In order to decrease cryogenic impact on the pipes, special thermal insulation beddings replacing a section of soil are used. To determine the thermal insulation properties of beddings made out of polystyrene, variant calculations of thermal conductivity coefficient have been done according to the Odelevski and Schwerdtfeger formulas. Calculations were done for beddings in thawed and frozen state with different polystyrene content concentration. The conclusion is that both formulas can be used for theoretical determination of thermal conductivity coefficient. Absolute and relative errors do not exceed those permissible in engineering calculations for a wide range of conditions.

Evolution of Statistical Properties of Hybrid System Starting from Binary Field States Constructed in Experiments

In quantum optics, researchers usually study evolution of states starting from traditional ones: coherent, squeezed, Fock, and their superpositions. In a recent work (Ferreira et al. Int. J. Mod. Phys. B, 1850222, 2018), we discussed an example of ex- periment involving “atom”-field interaction allowing us to construct a list of field states inside a high-Q microwave cavity. The procedure employed a dispersive Hamiltonian ensuring both sub-systems to remain with only two Fock state components for all times of their evolution. The aim was to use this sequence of states having pre-selected properties as initial states in other investigations. Here, we use an updated platform and a variety of states at our disposal in the mentioned list to study the evolution of a hybrid system under the action of the Jaynes-Cummings Hamiltonian. Interesting results are obtai- ned, e.g., when we examine how the “atomic” population inversion and field statistics evolve in time from initial field states with different degrees of super- and sub-Poissonian effects. The experimental feasibility of the proposal was also discussed.

Atom-field interaction in optical cavities: Calibration of the atomic velocities to obtain a list of field states with preselected properties

We investigate statistical properties of a single mode field that interacts with a two-level atom inside an optical cavity. The whole system is described by dispersive Jaynes–Cummings Hamiltonian, both subsystems starting from superpositions of two states. We consider properties of the field states only at the moment each atom is detected in the ground state immediately after it has crossed the cavity. This allows us to get a list of atomic velocities corresponding to field states with preselected properties. The scheme is exemplified for excitation inversion and sub-Poissonian statistics.

Multifunctional Hydrogels with Reversible 3D Ordered Macroporous Structures.

Three-dimensionally ordered macroporous (3DOM) hydrogels prepared by colloidal crystals templating display highly reversible shape memory properties, as confirmed by indirect electron microscopy imaging of their inverse replicas and direct nanoscale resolution X-ray microscopy imaging of the hydrated hydrogels. Modifications of functional groups in the 3DOM hydrogels result in various materials with programmed properties for a wide range of applications.

Functional properties of metallomesogens modulated by molecular and supramolecular exotic arrangements.

New concepts for the synthesis of metallomesogens have been recently developed in order to use the metal centre as a scaffold for grafting different functionalities and inducing non-conventional shapes and properties in the resulting complexes. Our strategy was based on the synthesis of mesogenic coordination complexes whose molecular architectures are controlled by the modulation of different and tunable molecular motifs: the nature of the metal ion and the surrounding ligands as central unit, the number of flexible chains at the periphery, and the nature of counter-ions in ionic complexes. The appropriate choice of molecular construction motifs allows control at global architectures and induces pre-selected properties from the level of single molecule to supramolecular network, confirming that metal coordination provides a helpful tool for obtaining multifunctional soft materials.

Study on the influence of attached mortar content on the properties of recycled concrete aggregate

Recycled concrete aggregates mainly differ from natural aggregates in that they are composed of two different materials: natural aggregate and cement mortar attached. It is well known that cement mortar content affects other properties of recycled aggregates: absorption is higher, Los Angeles abrasion coefficient is lower, etc., but the available data that support this statement are scattered, as they were obtained in many individual studies. There is no a general study about the quantitative influence of mortar content on other properties of the recycled aggregate. The objective of this study has been to obtain experimental relationships between the attached mortar content and other recycled aggregate properties, covering a wide range of different aggregates qualities. The interest of these general relationships is diverse: • They can be used to establish the mortar content that adversely affects other important properties of the aggregate for different applications. For example, in this research it has been concluded that only recycled aggregates with mortar content under 44% could be used of structural concrete. With this criterion, aggregates with bulk specific density higher than 2160 kg/m 3, water absorption lower than 8% and Los Angeles abrasion loss under 40%, are obtained. • The results can also be useful for recycling plants as they can adjust the production processes using the relationships to obtain an aggregate with pre-selected properties reducing mortar content, for example, by means of several crushing processes. This research has analyzed data from experimental works carried out in CEDEX and also from literature review. The results show that the main properties unfavourably affected by the attached mortar content are density, absorption and Los Angeles abrasion, and correlations between them and attached mortar content have been obtained and discussed in detail.

5306640 Method for determining preselected properties of a crude oil

5306640 Method for determining preselected properties of a crude oil