Overall kinetics and morphology of the products of austenite decomposition in a Fe-0.46 Pct C-5.2 Pct Cr alloy transformed isothermally above the bay

The overall transformation kinetics of austenite isothermal decomposition above the bay of the time-temperature-transformation (TTT) curve and the eutectoid morphology of the resulting products have been studied in a Fe-0.46 pct C-5.2 pct Cr alloy. Classical lamellar pearlite was formed at high temperatures while complex ferrite plus carbide morphologies, sometimes described as spiky pearlite, arborescent structures, or nonclassical decompositions products of austenite in Fe-Cr-C alloys, formed at low temperatures. While X-ray diffraction of extracted carbides and selected area diffraction-transmission electron microscopy (TEM) showed evidence for a mixture of M₃C and M₇C₃ carbides, thermodynamic calculations results obtained only M₇C₃ as the equilibrium carbide at the temperatures studied. A tentative explanation for the arborescent morphology is presented, based on the hypothesis of the existence of a drag force or free energy dissipation term that is locally relaxed by the partition of Cr into the carbides at the reaction front, consequently removing Cr from the interface. This article is based on a presentation made in the “Hillert Symposium on Thermodynamics & Kinetics of Migrating Interfaces in Steels and Other Complex Alloys,” December 2–3, 2004, organized by The Royal Institute of Technology in Stockholm, Sweden.     

MineCap: super incremental learning for detecting and blocking cryptocurrency mining on software-defined networking

Annals of Telecommunications - Covert mining of cryptocurrency implies the use of valuable computing resources and high energy consumption. In this paper, we propose MineCap, a dynamic online...     

Intragranular formation of austenite during delta ferrite decomposition in a duplex stainless steel

A Fe–22.5%Cr–4.53%Ni–3.0%Mo duplex stainless steel was solution treated at 1,325 °C for 1 h, quenched in water and isothermally treated at 900 °C for 5,000 s. The crystallography of austenite was studied using EBSD technique. Intragranular austenite particles formed from delta ferrite are shown to nucleate on inclusions, and to be subdivided in twin-related sub-particles. Intragranular austenite appears to have planar-only orientation relationships with the ferrite matrix, close to Kurdjumov–Sachs and Nishyiama–Wassermann, but not related to a conjugate direction. Samples treated at 900 °C underwent sparse formation of sigma phase and pronounced growth of elongated austenite particles, very similar to acicular ferrite.     

PEMPIs: A New Methodology for Modeling and Prediction of MPI Programs Performance

The evaluation and prediction of parallel programs performance are becoming more and more important, so that they require appropriate techniques to identify the factors which influence the application execution time and also the way they interact. In this paper, we present some contributions of our research in this area by describing PEMPIs, a new methodology applied to the performance analysis and prediction of MPI programs. A new task graph helps us both to understand details of the application and to increase the accuracy of the prediction models. The proposed techniques are detailed and tested through the modeling of a complete application. PEMPIs efficiency has been proved by the results of this application modeling—most tests executed in a cluster of computers showed errors up to 10.     

A Hierarchical Segmentation of Articulated Bodies

This paper presents a novel segmentation method to assist the rigging of articulated bodies. The method computes a coarse‐to‐fine hierarchy of segments ordered by the level of detail. The results are invariant to deformations, and numerically robust to noise, irregular tessellations, and topological short‐circuits. The segmentation is based on two key ideas. First, it exploits the multiscale properties of the diffusion distance on surfaces, and then it introduces a new definition of medial structures, composing a bijection between medial structures and segments. Our method computes this bijection through a simple and fast iterative approach, and applies it to triangulated meshes.     

Grammar-based immune programming

This paper describes Grammar-based Immune Programming (GIP) for evolving programs in an arbitrary language by immunological inspiration. GIP is based on Grammatical Evolution (GE) in which a grammar is used to define a language and decode candidate solutions to a valid representation (program). However, by default, GE uses a Genetic Algorithm in the search process while GIP uses an artificial immune system. Some modifications are needed of an immune algorithm to use a grammar in order to efficiently decode antibodies into programs. Experiments are performed to analyze algorithm behavior over different aspects and compare it with GEVA, a well known GE implementation. The methods are applied to identify a causal model (an ordinary differential equation) from an observed data set, to symbolically regress an iterated function f(f(x)) = g(x), and to find a symbolic representation of a discontinuous function.     

Improved similarity trees and their application to visual data classification

An alternative form to multidimensional projections for the visual analysis of data represented in multidimensional spaces is the deployment of similarity trees, such as Neighbor Joining trees. They organize data objects on the visual plane emphasizing their levels of similarity with high capability of detecting and separating groups and subgroups of objects. Besides this similarity-based hierarchical data organization, some of their advantages include the ability to decrease point clutter; high precision; and a consistent view of the data set during focusing, offering a very intuitive way to view the general structure of the data set as well as to drill down to groups and subgroups of interest. Disadvantages of similarity trees based on neighbor joining strategies include their computational cost and the presence of virtual nodes that utilize too much of the visual space. This paper presents a highly improved version of the similarity tree technique. The improvements in the technique are given by two procedures. The first is a strategy that replaces virtual nodes by promoting real leaf nodes to their place, saving large portions of space in the display and maintaining the expressiveness and precision of the technique. The second improvement is an implementation that significantly accelerates the algorithm, impacting its use for larger data sets. We also illustrate the applicability of the technique in visual data mining, showing its advantages to support visual classification of data sets, with special attention to the case of image classification. We demonstrate the capabilities of the tree for analysis and iterative manipulation and employ those capabilities to support evolving to a satisfactory data organization and classification.     

钢框架结构优化设计的多集约束和自动构件分组

对于结构优化问题,如钢框架结构的用钢量最小化,设计尺寸取决于构件横截面面积。构件横截面面积可从一些可行性表格中查得,如美国钢结构协会(AISC)提供的表格。构件的横截面尺寸bf,tf,d和tw(可为分散的或连续的)能独立确定。讨论关于设计尺寸变量的框架结构优化问题,提出一种获得理想构件分组法则。此法则考虑了制作、检查、装配和焊接的优势,而这些因素在传统预算里并没有被考虑。运用先前提出的适应性损失法,增强结构优化中的机械约束。