A high-order material point method

The material point method (MPM) is a version of the particle-in-cell (PIC) which has substantial advantages over pure Lagrangian or Eulerian methods in numerical simulations of problems involving large deformations. Using MPM helps to avoid mesh distortion and tangling problems related to Lagrangian methods and the advection errors associated with Eulerian methods are avoided. In this paper a novel high-order material point method within an isogeomeric analysis (IGA) framework is developed. Utilizing high order basis functions enables more accurate determination of physical state variables e.g. stress. The smooth spline function spaces, B-splines, are used to eliminate the non-physical effects are caused by use of standard high-order finite element basis function i.e. based on Lagrange polynomials

Adjust or invest : what is the best option to green a supply chain?

Greening a supply chain can be achieved by considering several options. However, companies lack of clear guidelines to assess and compare these options. In this paper, we propose to use multiobjective optimization to assess operational adjustment and technology investment options in terms of cost and carbon emissions. Our study is based on a multiobjective formulation of the economic order quantity model called the sustainable order quantity model. The results show that both options may be effective to lower the impacts of logistics operations. We also provide analytical conditions under which an option outperforms the other one for two classical decision rules, i.e. the carbon cap and the carbon tax cases. The results allow deriving some interesting and potentially impacting practical insight

Distributed algorithms for low stretch spanning trees

Given an undirected graph with integer edge lengths, we study the problem of approximating the distances in the graph by a spanning tree based on the notion of stretch. Our main contribution is a distributed algorithm in the CONGEST model of computation that constructs a random spanning tree with the guarantee that the expected stretch of every edge is O(log3 n), where n is the number of nodes in the graph. If the graph is unweighted, then this algorithm can be implemented to run in O(D) rounds, where D is the hop-diameter of the graph, thus being asymptotically optimal. In the weighted case, the run-time of our algorithm matches the currently best known bound for exact distance computations, i.e., Õ(min{√nD, √nD1/4 + n3/5 + D}). We stress that this is the first distributed construction of spanning trees leading to poly-logarithmic expected stretch with non-trivial running time

An implicit high-order material point method.

The material point method (MPM) is a version of the particle-in-cell (PIC) which has substantial advantages over pure Lagrangian or Eulerian methods in numerical simulations of problems involving large deformations. The MPM helps to avoid mesh distortion and tangling problems related to Lagrangian methods and as well as the advection errors associated with Eulerian methods. Despite the MPM being promoted for its ability to solve large deformation problems the method suffers from instabilities when material points cross between elements. These instabilities are due to the lack of smoothness of the grid basis functions used for mapping information between the material points and the background grid. In this paper a novel high-order MPM is developed to eliminate the cell-crossing instability and improve the accuracy of the MPM method

Implementation of international cooperation in gas and hydrogen energy between Qatar and Ukraine

The work defines the economic essence and basic principles of international cooperation in the energy sector. The author studied the content and types of export-import strategies in energy. The main methods of assessing the level of efficiency and productivity of energy enterprises have been determined. The trends in the development of the energy sector in the world, as well as countries such as Qatar and Ukraine, are analyzed. The efficiency and productivity of investment projects in the energy sector were evaluated. Strategies for the development of hydrogen energy in the world economy are also analyzed. The directions for improvement of the international cooperation between Qatar and Ukraine in the energy sector have been duly determined. Diversification of energy sources in international cooperation is proposed. The economic justification of international energy projects has been formed.У роботі визначено економічну сутність та основні принципи міжнародного співробітництво в енергетичній сфері. Автор досліджував зміст і види експортно-імпортних стратегій в енергетиці. Визначено ефективність і продуктивність енергетичних підприємств, тенденції розвитку енергетики у світі, а також в Катарі та Україні. Проведено оцінку інвестиційних проектів в енергетиці. Проаналізовано стратегії розвитку водневої енергетики у світовій економіці. Визначено напрями вдосконалення міжнародного співробітництва між Катаром і Україна в енергетиці. Запропоновано диверсифікацію міжнародного співробітництва в енегетичній сфері. Економічно обґрунтовано міжнародні енергетичні проекти

Distributed Symmetry Breaking in Hypergraphs

Fundamental local symmetry breaking problems such as Maximal Independent Set (MIS) and coloring have been recognized as important by the community, and studied extensively in (standard) graphs. In particular, fast (i.e., logarithmic run time) randomized algorithms are well-established for MIS and $\Delta +1$-coloring in both the LOCAL and CONGEST distributed computing models. On the other hand, comparatively much less is known on the complexity of distributed symmetry breaking in {\em hypergraphs}. In particular, a key question is whether a fast (randomized) algorithm for MIS exists for hypergraphs. In this paper, we study the distributed complexity of symmetry breaking in hypergraphs by presenting distributed randomized algorithms for a variety of fundamental problems under a natural distributed computing model for hypergraphs. We first show that MIS in hypergraphs (of arbitrary dimension) can be solved in $O(\log^2 n)$ rounds ($n$ is the number of nodes of the hypergraph) in the LOCAL model. We then present a key result of this paper --- an $O(\Delta^{\epsilon}\text{polylog}(n))$-round hypergraph MIS algorithm in the CONGEST model where $\Delta$ is the maximum node degree of the hypergraph and $\epsilon > 0$ is any arbitrarily small constant. To demonstrate the usefulness of hypergraph MIS, we present applications of our hypergraph algorithm to solving problems in (standard) graphs. In particular, the hypergraph MIS yields fast distributed algorithms for the {\em balanced minimal dominating set} problem (left open in Harris et al. [ICALP 2013]) and the {\em minimal connected dominating set problem}. We also present distributed algorithms for coloring, maximal matching, and maximal clique in hypergraphs.Comment: Changes from the previous version: More references adde

On Lagrangian mechanics and the implicit material point method for large deformation elasto-plasticity

The material point method is ideally suited to modelling problems involving large deformations where conventional mesh-based methods would struggle. However, total and updated Lagrangian approaches are unsuitable and non-ideal, respectively, in terms formulating equilibrium for the method. This is due to the basis functions, and particularly the derivatives of the basis functions, of material point methods normally being dened based on an unformed, and sometimes regular, background mesh. It is possible to map the basis function spatial derivatives using the deformation at a material point but this introduces additional algorithm complexity and computational expense. This paper presents a new Lagrangian statement of equilibrium which is ideal for material point methods as it satises equilibrium on the undeformed background mesh at the start of a load step. The formulation is implemented using a quasi-static implicit algorithm which includes the derivation of the consistent tangent to achieve optimum convergence of the global equilibrium iterations. The method is applied to a number of large deformation elasto-plastic problems, with a specic focus of the convergence of the method towards analytical solutions with the standard, generalised interpolation and CPDI2 material point methods. For the generalised interpolation method, dierent domain updating methods are investigated and it is shown that all of the current methods are degenerative under certain simple deformation elds. A new domain updating approach is proposed that overcomes these issues. The proposed material point method framework can be applied to all existing material point methods and adopted for implicit and explicit analysis, however its advantages are mainly associated with the former

Ki-67/MIB-1 as a prognostic marker in cervical cancer - a systematic review with meta-analysis

Background: In cervical cancer patients it has been reported that there in a significant Ki-67/MIB-1 expression is correlated with survival in cervical cancer patients. However, the prognostic value is still not well understood. Materials and Methods: In the present meta-analysis the prognostic value of Ki-67/MIB-1 with regard to overall survival (OS) and disease-free survival (DFS) in cervical cancer was investigated. The databases of PubMed, ISI Web of Science, Cochrane Central Register of Controlled Trials, EMBASE, Science Direct and Wiley Online Library were used to identify appropriate literature. Results: In order to explore the relationship between Ki-67/MIB-1 and cervical cancer, we have included 13 studies covering 894 patients in the current meta-analysis. The effect of Ki-67/MIB-1 on OS for pooled random effects HR estimate was 1.63 (95confidence interval (CI) 1.09-2.45; P0.05) and the subgroup analysis indicated Ki-67/MIB1 was associated with DFS (HR=3.67, 95CI 2.65-5.09) in Asians. Conclusions: According to this meta-analysis, Ki-67/MIB-1 has prognostic value for OS in patients suffering from cervical cancer. For better evaluation of the prognostic role of Ki-67/MIB-1 on DFS, studies with larger numbers of patients are needed to validate present findings in the future