Maximum Degree Research Articles

Pretreatment of alkali activation and carbonation of steel slag for using as binding material

Steel slag (SS) exhibits low hydration activities and expansive phases, which should be pretreated prior to using as binding materials. Thus, these properties of SS were improved through a combined treatment of alkali and then wet carbonation (A_C) in this study. Effect of sodium silicate modulus (M = 1.0–2.5) and carbonation temperature (50–200 °C) on cementitious property of SS was investigated. Results showed that the optimum modulus and temperature were 2.0 and 150 °C under single alkali and single carbonation treatment of SS, respectively. In case of combined treatment, the optimal modulus was 2.0 with an optimum temperature of 100 °C (A2.0_C100°C-SS). The 28 d compressive strength increased by 27.1% and expansion rate decreased by 17.7% of A2.0_C100°C-SS-PC compared to untreated SS-PC. This was attribute to the fact that the newly formed CaCO3 with micro-nano size and high activity existed in A_C-SS can react with Al-containing minerals in OPC to form monocarboaluminate, and Si-gels produced during carbonation can react with CH to form C-S-H phases. The early hydration activity of OPC was more obviously improved by adding A_C-SS compared to adding A_SS or C_SS. This was due to the micro-nano size effect of CaCO3 and Si-gels can provide nucleation sites for C-S-H formation. Alkali pretreatment can improve the SS carbonation, reaching the maximum carbonation degree of 53% at 100 °C compared to carbonation alone (47% at 150 °C). The embodied CO2 index of A2.0_C100-SS-OPC system decreased to 9.843 compared to OPC (10.511), indicating that the A_C treatment for SS was a more sustainable and environmentally friendly method.

Effect of the degree of corrosion damage in reinforcing bars on composite action with concrete

Introduction. The article examines the possibility of using steel reinforcement with instances of corrosion and determines the maximum degree of corrosion damage in reinforcing bars (rebars). Although long-term studies show that corroded reinforcement can be used in the manufacture of reinforced concrete structures, some studies and regulatory documents provide different conditions for the use of such rebars, as well as establishing different corrosion thresholds (thickness of the rust layer on the rebar surface).Aim. To determine the maximum thickness of the rust layer on the surface of corrugated rebars, at which the physicomechanical characteristics of reinforcement are preserved and the capability for composite action with concrete is not hampered; to determine the degree of corrosion damage in rebars at which its use in reinforced concrete is permissible in order to revise the existing regulatory documents on the protection of structures against corrosion.Materials and methods. The experimental studies were conducted on rebar specimens of two classes (A500 and A800) exhibiting different degrees of corrosion damage (rust layer thickness of 0, 150, 250, and 300 μm). In order to determine the composite action with concrete, B15 and B20 concrete was used. The physicomechanical characteristics of rebars with different rust layer thicknesses were determined on rebar specimens having a diameter of 12 mm and length of 400 mm according to the procedure specified in State Standard 12004-81. The reinforcing steel resistance to corrosion cracking was determined on rebar specimens having a diameter of 12 mm and a length of 400 mm as per the procedure given in State Standard 31383-2008. The passivating effect of concrete on steel reinforcement was determined on concrete specimens — 70 × 70 × 140 mm prisms, with rebars having a diameter of 12 mm and a length of 120 mm in the center — according to the procedure given in State Standard 31383-2008. The bond between rebars and concrete was determined on concrete specimens-cubes (150 mm on edge), with rebars having a diameter of 12 mm and a length of 500 mm in the center — using the procedure specified in State Standard 31938-2012.Results. The study yielded experimental data on the physicomechanical characteristics of rebars exhibiting different degrees of corrosion damage; on the resistance of reinforcing steel to corrosion cracking; data on the passivating effect of concrete of two classes on steel rebars exhibiting different degrees of corrosion damage; data on the bond between rebars corroded to various degrees and concrete of two classes.Conclusions. As part of the work, an experimental research program was developed and implemented, which involved the production and testing of rebar specimens of two classes exhibiting four degrees of corrosion damage with the use of concrete of two classes and. The experimental study results were used to determine the effect of corrosion damage of varying degree in rebars on the characteristics of reinforced concrete. The presence of a rust layer on the rebar surface of up to 150 mm in thickness was found not to degrade its physicomechanical characteristics, not to decrease its resistance to corrosion cracking, and not to reduce its composite action with concrete. Any further increase in the thickness of the rust layer on rebar surface reduces these characteristics, except for the bond to concrete. No dependence of rebar-concrete bond stress on the rust layer thickness was observed.

Bounding the distant irregularity strength of graphs via a non-uniformly biased random weight assignment

Given an edge k-weighting ω:E→[k] of a graph G=(V,E), the weighted degree of a vertex v∈V is the sum of its incident weights. The least k for which there exists an edge k-weighting such that the resulting weighted degrees of the vertices at distance at most r in G are distinct is called the r-distant irregularity strength, and denoted sr(G). This concept links the well-known 1–2–3 Conjecture, corresponding to s1(G), with the irregularity strength of graphs, s(G), which coincides with sr(G) for every r at least the diameter of G. It is believed that for every r≥2, sr(G)≤(1+o(1))Δr−1, where Δ is the maximum degree of G, while it is known that sr(G)≤6Δr−1 in general and sr(G)≤(4+o(1))Δr−1 for graphs with minimum degree δ at least log8Δ. We apply the probabilistic method in order to improve these results and show that graphs with δ≫lnΔ satisfy sr(G)≤(e+o(1))Δr−1 as Δ→∞.

ON THE STRUCTURE OF PUNCTUAL LINEAR ORDERS ISOMORPHIC TO THE LEAST LIMIT ORDINAL

The algorithmic complexity of presentations for various structures receives significant attention in modern literature. The main tool for determining such complexities is reducibility. It is a mapping that preserves relations of signature (for example, equivalence relation, orders, and so on). This work is dedicated to the study of punctual representations of the least limit ordinal with respect to primitive recursive reducibility. We denote this structure as PR(ω). In particular, the paper examines the properties of structures Ω, consisting of computable copies of the least limit ordinal with respect to computable reducibility, and Peq, consisting of punctual equivalence relations with respect to primitive recursive reducibility. We say that the linear order L is reducible to the linear order R, if there exists a total function ρ such that (χ, γ) Є L if and only if (ρ(χ), ρ(γ)) Є R. Reducibility is called computable (primitive recursive) if the function that performs the reducibility is computable (primitive recursive). It is shown that the degree of ω is not the least degree in PR(ω), as it was in Ω. The structure PR(ω) does not contain maximal degrees, and this structure is not dense. Also, an example of an incomparable pair that has the least upper bound is given.

Exact Algorithms and Lowerbounds for Multiagent Path Finding: Power of Treelike Topology

In the Multiagent Path Finding (MAPF for short) problem, we focus on efficiently finding non-colliding paths for a set of k agents on a given graph G, where each agent seeks a path from its source vertex to a target. An important measure of the quality of the solution is the length of the proposed schedule l, that is, the length of a longest path (including the waiting time). In this work, we propose a systematic study under the parameterized complexity framework. The hardness results we provide align with many heuristics used for this problem, whose running time could potentially be improved based on our Fixed-Parameter Tractability (FPT) results. We show that MAPF is W[1]-hard with respect to k (even if k is combined with the maximum degree of the input graph). The problem remains NP-hard in planar graphs even if the maximum degree and the makespan l are fixed constants. On the positive side, we show an FPT algorithm for k+l. As we continue, the structure of G comes into play. We give an FPT algorithm for parameter k plus the diameter of the graph G. The MAPF problem is W[1]-hard for cliquewidth of G plus l while it is FPT for treewidth of G plus l.

On the complexity of nucleolus computation for bipartite b-matching games

We explore the complexity of nucleolus computation in b-matching games on bipartite graphs. We show that computing the nucleolus of a simple b-matching game is NP-hard when b≡3 even on bipartite graphs of maximum degree 7. We complement this with partial positive results in the special case where b values are bounded by 2. In particular, we describe an efficient algorithm when a constant number of vertices satisfy bv=2 as well as an efficient algorithm for computing the non-simple b-matching nucleolus when b≡2.

Enhancing Semi-supervised Domain Adaptation via Effective Target Labeling

Existing semi-supervised domain adaptation (SSDA) models have exhibited impressive performance on the target domain by effectively utilizing few labeled target samples per class (e.g., 3 samples per class). To guarantee an equal number of labeled target samples for each class, however, they require domain experts to manually recognize a considerable amount of the unlabeled target data. Moreover, as the target samples are not equally informative for shaping the decision boundaries of the learning models, it is crucial to select the most informative target samples for labeling, which is, however, impossible for human selectors. As a remedy, we propose an EFfective Target Labeling (EFTL) framework that harnesses active learning and pseudo-labeling strategies to automatically select some informative target samples to annotate. Concretely, we introduce a novel sample query strategy, called non-maximal degree node suppression (NDNS), that iteratively performs maximal degree node query and non-maximal degree node removal to select representative and diverse target samples for labeling. To learn target-specific characteristics, we propose a novel pseudo-labeling strategy that attempts to label low-confidence target samples accurately via clustering consistency (CC), and then inject information of the model uncertainty into our query process. CC enhances the utilization of the annotation budget and increases the number of “labeled” target samples while requiring no additional manual effort. Our proposed EFTL framework can be easily coupled with existing SSDA models, showing significant improvements on three benchmarks

Generation and new infinite families of K2-hypohamiltonian graphs

We present an algorithm which can generate all pairwise non-isomorphic K2-hypohamiltonian graphs, i.e. non-hamiltonian graphs in which the removal of any pair of adjacent vertices yields a hamiltonian graph, of a given order. We introduce new bounding criteria specifically designed for K2-hypohamiltonian graphs, allowing us to improve upon earlier computational results. Specifically, we characterise the orders for which K2-hypohamiltonian graphs exist and improve existing lower bounds on the orders of the smallest planar and the smallest bipartite K2-hypohamiltonian graphs. Furthermore, we describe a new operation for creating K2-hypohamiltonian graphs that preserves planarity under certain conditions and use it to prove the existence of a planar K2-hypohamiltonian graph of order n for every integer n≥134. Additionally, motivated by a theorem of Thomassen on hypohamiltonian graphs, we show the existence K2-hypohamiltonian graphs with large maximum degree and size.

სიმაღლეზე მუშაობის შესაძლო საფრთხეების კონტროლი მოაჯირული და საჭერი სისტემების მაგალითით

Thousands of people are employed in the construction field in the countries with both, advanced and developing economies. It is characterized with: constantly changing operations at construction sites; extended chain of contracts, where the relationship between the contractors, sub-contractors and self-employed individuals is hard to ascertain; various jobs concurrently performed by various companies; majority of operations accompanied by high level of risk. Therefore, this is a priority sector for the labour inspectors across the world. Proper and relevant measures are required to prevent any possible risk to the maximum degree when work is performed at height and damage can be caused (e.g.: the use of protective rails). Personal protective equipment for working at height must meet the following demands: a) Linking equipment should be manufactured of pressed or formed steel or similar material; b) The linking equipment should have anti-corrosion ends and a smooth surface to prevent damaging the system components. Personal protective equipment for working at height must provide for arresting the falling employee at 1.8 m height above the ground surface. Body harness, other equipment and components should be used for the employee safety protection only. Their use for lifting/handling other materials is prohibited.

Weighted Jump in Random Walk graph sampling

Graph sampling is a challenging problem in network analysis due to the complex structures of networks. Currently, a series of graph sampling algorithms based on random walks achieve good results in graph sampling tasks. However, the existing methods often reduce the conductance of graphs, causing the sampler to stay in the same node for a long time. This results in undersampling. In this paper, we propose a novel Weighted Jump Random Walk (WJRW) algorithm to generate representative samples. We design a parameter in the WJRW algorithm that can adjust the proportions of random walk and random jump in every step. According to the issue of repeated sample nodes in the Generalized Maximum Degree (GMD) method and the problem of large deviations in the Simple Random Walk (SRW), WJRW addresses the weaknesses of the GMD method and enhances the diffusion of a random walker on graphs, leading to a more representative sample. Then, WJRW addresses the issue of large deviations in SRW and enhances the efficiency of the unbiased estimator. By generating smoother stationary distributions. Numerical experiments with extensive real-world networks verify that our method achieves higher accuracy than classical and state-of-the-art methods in estimating distribution estimation.

An algorithm and maximum deficiency energy of some graphs

The deficiency [Formula: see text] of a vertex [Formula: see text] is the deviation between the degree of the vertex [Formula: see text] and the maximum degree of the graph. The maximum deficiency matrix [Formula: see text] of a simple graph [Formula: see text] is square matrix whose [Formula: see text]th entry is max([Formula: see text], if the vertices [Formula: see text] and [Formula: see text] are adjacent and [Formula: see text], otherwise. Maximum deficiency energy [Formula: see text] is the absolute sum of eigenvalues of maximum deficiency matrix [Formula: see text]. In this paper, we find maximum deficiency energy of some classes of graphs. Moreover, we construct an algorithm and Python 3.8 program to find out spectrum and maximum deficiency energy of [Formula: see text].

STUDY OF THE TECHNOLOGY FOR OBTAINING A MIXTURE OF SILICOFLUORIDE AND SODIUM FLUORIDE FROM A BY-PRODUCT OF HYDROFLUORIC ACID PRODUCTION

The article presents the results of research on the technology of processing and utilization of by-product of hydrofluoric acid production – a mixture of fluorosilicic and hydrofluoric acids using sodium hydroxide and sodium chloride (local mineral raw materials) to obtain fluoride salts – a mixture of silicofluoride and sodium fluoride. As a result of laboratory studies, the optimal parameters of the process of acid mixture processing using sodium hydroxide and sodium chloride to obtain a mixture of SSF and sodium fluoride were determined: temperature – 20-25 °C, duration – 10-20 min, concentration of sodium hydroxide and sodium chloride – 20-25%; in this case the maximum degree of extraction of SSF and sodium fluoride is achieved. The product obtained when sodium hydroxide was used under these optimum conditions was chemically analyzed and found to consist of 67.8% Na2SiF6 and 31.5% NaF. In the case of sodium chloride, the resulting mixture contains 95.8% of Na2SiF6 and 3.5% of NaF. To confirm the reliability of the results of chemical analysis and the found optimal parameters, as well as to determine the mineralogical composition of the obtained fluoride salts, X-ray phase analysis was carried out using an upgraded Dron-2 unit. The obtained product can be used in electrolysis production for obtaining aluminosilicon alloy (silumin) and electrolyte melt, as well as for fluoridation of drinking water and in the production of acid-resistant cements. On the basis of the conducted laboratory studies, the basic technological scheme of processing of the mixture of FSA and hydrofluoric acid with the use of sodium hydroxide and sodium chloride was developed.

Degree-based indices of hypergraphs: Definitions and first results

For a [Formula: see text]-uniform hypergraph [Formula: see text], we introduce degree-based indices such as the general sum-connectivity index [Formula: see text] and the general Randić index [Formula: see text], where [Formula: see text], [Formula: see text] is the set of hyperedges of [Formula: see text] and [Formula: see text] is the degree of a vertex [Formula: see text] in [Formula: see text]; [Formula: see text] and [Formula: see text]. Other indices such as the first and second Zagreb index, first and second hyper-Zagreb index, classical sum-connectivity index, classical Randić index and harmonic index of a hypergraph [Formula: see text] are special cases of the general indices. For [Formula: see text], we obtain upper bounds on [Formula: see text] and [Formula: see text] for a uniform hypergraph [Formula: see text] with given order, order and number of isolated vertices, order and maximum degree, order and diameter at least [Formula: see text], and lower bounds for uniform hypergraphs with given order and no isolated vertices, order and minimum degree, and order and maximum possible degree. We also present extremal graphs for all the bounds. Bounds on Zagreb indices follow from our results on general indices.

Decomposing graphs of nonnegative characteristic into subgraphs with degree restrictions

A (d,h)-decomposition of G is a pair (H1,H2) such that H2 is a subgraph of G of maximum degree at most h and H1 is d-degenerate such that H1=G−E(H2). A graph G is (d,h)-decomposable if G has a (d,h)-decomposition. A graph G is a NC-graph if it can be embedded in a surface of nonnegative characteristic. In this paper, we prove the following results. (1) Every NC-graph G is (4,2)-decomposable. Moreover, G is (4,1)-decomposable if and only if G is not 6-regular triangulation, which generalizes a result of Cho et al. (2022) [2]. (2) Every NC-graph is (5,1)-decomposable. (3) Every NC-graph is (2,8)- or (3,4)-decomposable, which generalizes a result of Zhu (2000) [15] and a result of Goncalves (2009) [5]. Let hd be the minimum integer such that every NC-graph is (d,hd)-decomposable. We determine that h5=1, h4=2, 3≤h3≤4 and 4≤h2≤8.

Equitable coloring of planar graphs with maximum degree at least eight

The Chen-Lih-Wu Conjecture states that each connected graph with maximum degree Δ≥3 that is not the complete graph KΔ+1 or the complete bipartite graph KΔ,Δ admits an equitable coloring with Δ colors. For planar graphs, the conjecture has been confirmed for Δ≥13 by Yap and Zhang and for 9≤Δ≤12 by Nakprasit. In this paper, we present a proof that confirms the conjecture for graphs embeddable into a surface with non-negative Euler characteristic with maximum degree Δ≥9 and for planar graphs with maximum degree Δ≥8.

A novel grade assessment method for cybersecurity situation of online retailing with decision makers’ bounded rationality

The online retailing cybersecurity situations grade assessment (GS) is a key issue in cybersecurity management, which can be regarded as a type of multi-attributes GS problems. However, traditional GS methods rarely discuss the boundary fuzziness and hesitation in the grade classification of attributes, as well as the monotony relation and interrelation between entropy fuzziness and intuitionism. A novel GS method with respect to decision makers’ bounded rationality is proposed. To get the method, the membership functions (MFs) and non-membership functions (NMFs) of attributes’ eigenvalue grade considering decision maker s’ bounded rationality and hesitation are proposed. An axiomatic definition of IF entropy on the basis of isentropic arcs is proposed, providing the formula of the monotony relation and interrelation between fuzziness and intuitionism. We, considering the reliability and the IF grade assessment method, propose the similarity of IF grade eigenvalue, which identifies grades reasonably and distinguishes the ranking of the same grade, and overcomes the defect that the maximum membership degree principle ignores the position differences of each grade assessment level.

Maximum k-Plex Computation: Theory and Practice

The k-plex model relaxes the clique model by allowing each vertex to miss up to k neighbors, including the vertex itself. A 1-plex is a clique. Many exact algorithms have been recently designed for finding the k-plex with the largest number of vertices, known as the maximum k-plex computation problem. However, all the existing algorithms, except BS, has the trivial worst-case time complexity of O*(2n) when ignoring polynomial factors. On the other hand, although BS improves the time complexity to O*(βkn) where βk < 2 is a constant depending only on k, its practical performance is not satisfactory. In this paper, we study the maximum k-plex computation problem from both theory and practice. We first propose two new reduction rules and a new branching rule and prove that the base of the exponential time complexity is reduced to γk when the new reduction and branching rules are incorporated into a standard backtracking algorithm; here γk < βk. We then design a two-stage approach kPlexT to improve the exponent of the time complexity by separating the search of large k-plexes from the search of small ones. We prove that kPlexT runs in O*((α Δ)k+1 γ_kα) time when the maximum k-plex size Ωk(G) is at least 2k-1, and in O*((α Δ)k+1 γ_kα + min(γkn, n2k-2)) time otherwise; here, α is the degeneracy and Δ is the maximum degree of the input graph. We also prove that with slight modification, kPlexT runs in O*((αΔ)k+1 (k+1)α+k-Ωk(G)) time when ømega_k(G) ≥ 2k-1. Finally, we propose another reduction rule and a better initialization method to improve the practical performance of kPlexT. Extensive empirical studies demonstrate that kPlexT achieves state-of-the-art practical performance. We also show that our improved time complexity carries over to other related problems such as enumerating all maximal k-plexes, quasi-cliques, and k-biplexes.

Functional status of blood neutrophils in congenital defects of antibody production

We evaluated some functional indices of neutrophils in 100 adult patients with a verified diagnosis of primary antibody production deficiency (44 patients with common variable immunodeficiency – CVID, and 56 patients with selective IgA deficiency – SigAD). The diagnosis was made according to the criteria of the Pan-American Group for Immunodeficiency and European Society for Immunodeficiency. The criteria for diagnosis were based on clinical data, medical history and results of laboratory tests. All patients with CVID received regular immunoglobulin replacement therapy, and the SIgAD patients received symptomatic treatment on demand. The examination was performed beyond the infectious episodes, inflammatory events or exacerbation of chronic disorders upon admission for planned hospitalisation, before any therapeutic and diagnostic procedures. In addition to standard clinical and laboratory examination appointed for the mentioned diseases, we assessed fnctional status of neutrophils: superoxide-anion radical production, NETosis, phagocytosis and apoptosis. Taking into account clinical manifestations, the patients with CVID were divided into 6 clinical subgroups: without CVID-related complications (13.6%); with infectious complications, i.e., bronchiectatic disease (15.9%), autoimmune syndromes (22.7%), polyclonal lymphoid infiltration (13.6%), enteropathic syndrome (34.1%), and malignant neoplasms (9.1%). Four phenotypes were identified in the patients with SIgAD: absence of SIgAD-related complications (28.6%); autoimmune syndrome (16.1%), non-malignant lymphoproliferation (3.6%) and enteropathy (28.6%). Higher incidence of non-infectious complications (autoimmune syndrome, non-malignant lymphoproliferation, enteropathies) was found in СVID compared to SIgAD patients (χ2 = 10.27; p = 0.001). Patients from the both groups showed changes in neutrophil reactivity compared to control values expressing higher basal generation of superoxide radicals (p < 0.001), NETosis activity (p = 0.005) and apoptosis (p < 0.001) with decreased phagocytic function (p < 0.001) and lower reserve for reactive oxygen species formation (p < 0.001). The maximal degree of changes in phagocytosis and superoxide-producing activity was observed in СVID; altered NETosis was revealed in SIgAD. The development of non-infectious complications was accompanied by a significant increase in stimulated NETosis indexes, thus suggesting a promising index in order to assess stability of clinical course and to predict development of complications in congenital defects of antibody production.

Tight Bounds for the N₂-Chromatic Number of Graphs

Let $G$ be a connected graph. A vertex coloring of $G$ is an $N_2$-vertex coloring if, for every vertex $v$, the number of different colors assigned to the vertices adjacent to $v$ is at most two. The $N_2$-chromatic number of $G$ is the maximum number of colors that can be used in an $N_2$-vertex coloring of $G$. In this paper, we establish tight bounds for the $N_2$-chromatic number of a graph in terms of its maximum degree and its diameter, and characterize those graphs that attain these bounds.

Extraction of gallium from carbon concentrate - Aluminum industry waste

A complex approach to the extraction of gallium from a carbon concentrate (CC), a waste product of the aluminum industry, was considered. Ashing of CC made it possible to remove the main component - carbon and obtain ash, which is an oxide mineral-like compound, from which gallium was leached with solutions of inorganic acids and their mixtures. The maximum degree of leaching (98%) of gallium was achieved with 6 M HCl for ash after ashing the CC at 600 °C. It was shown that Purolite anion exchangers with highly basic tertiary and quaternary ammonium base groups recovered gallium(III) from 2 to 10 M HCl, where the sorption equilibrium was attained after 60 min. The maximum extraction was observed from 6 M HCl. Under optimal conditions, the maximum sorption capacities for gallium(III) were achieved for Purolite A300 (2.7 mmol g−1) and Purolite A500 (2.2 mmol g−1) sorbents. Gallium(III) was quantitatively (99%) eluted from the sorbents with distilled water. Sorption of gallium(III) and its subsequent desorption with water made it possible to separate it from the predominant amounts of transition metal ions: Fe(III), Ni(II), Co(II), Zn(II), V(V) and other cations: Al3+, Ca2+, Mg2+, Na+ and K+. The addition of sodium hydroxide to the concentration of 200 g L−1 resulted in the cementation of gallium on aluminum gallama (liquid gallium‑aluminum alloy).