Papers by Keyword: Localization

Abstract: The effect of hydrogen embrittlement on the localized plastic deformation of aluminum alloy D1 was investigated. The studies were performed for the test samples of aluminum alloy subjected to electrolytic hydrogenation. It is found that the mechanical properties and localized plastic deformation parameters of aluminum alloy are affected adversely by hydrogen embrittlement. The hydrogenated counterpart of alloy has a lower degree of ductility relative to the original alloy; however, the plastic flow behavior of material remains virtually unaffected. The deformation diagrams were examined for the deformed samples of aluminum alloy. These are found to show all the plastic flow stages: the linear, parabolic and pre-failure stages would occur for the respective values of the exponent n from the Ludwik-Holomon equation. Using digital speckle image technique, the local strain patterns were being registered for the original alloy D1 and the counterpart subjected to electrolytic hydrogenation for 100 h.

Abstract: The evolution of local strain during stretching of high-manganese carbon austenite (Hadfield steel) was studied. The ordered patterns of strain localization proved to be closely related to the stages in the stress–strain curve. The results of this study are compared with analogous data for chromium–nickel nitrogen austenite single crystals. The velocity of self-consistent motion of the sites where plastic strain during stretching of gamma-Fe single crystals is nonuniform was determined as a function of the strain hardening coefficient and deformation mechanism.

Abstract: In the article the research and analysis of digital signal processing and its influence on accuracy of location estimation in developed inertial navigation system was presented. The purpose of the system is to localize moving people in indoor environment. During research a measuring unit for recording selected movement parameters was made. In the article were also described author’s inertial navigation algorithms.

Abstract: This paper is experiencing the localization of a mobile platform through a multi-antenna GNSS-RTK system in order to implement the system for the localization of the mobile construction robots. The approach introduced here shows the components of the system and a manner in which the localization coordinates and errors are determined. Furthermore, it establishes the accurate localization errors based on an experiment in which the mobile platform moves in similar conditions to those of a construction site.

Abstract: The failure of a discrete elastic-damage axial system is investigated using both a discrete and anequivalent continuum approach. The discrete damage mechanics (DDM) approach is based on amicrostructured model composed of a series of periodic elastic-damage springs (axial DDM latticesystem). Such a damage discrete system can be associated with the finite difference formulation of aContinuum Damage Mechanics (CDM) evolution problem.The nonlocal CDM models considered in this paper are mainly built from a continualizationprocedure applied to centered finite difference schemes. A comparison of the discrete and thecontinuous problems for the chains shows the effectiveness of the new micromechanics-basednonlocal Continuum Damage modeling, especially for capturing scale effects.

Abstract: In the present work the possibility of simultaneous localization of two electrons in Δ¹⁰⁰ and Δ⁰⁰¹ valleys in ordered structures with Ge/Si quantum dots (QD) was verified experimentally by electron spin resonance (ESR) method. ESR spectra obtained for the ordered ten-layered QD structure in the dark shows the signal corresponding to electron localization in Si at the Ge QD base edges, in Δ¹⁰⁰, Δ⁰¹⁰ valleys (g_zz=1.9985, g_in-plane=1.999). Light illumination causes the appearance of a new ESR line (g_zz=1.999) attributed to the electrons in Δ⁰⁰¹ valley localized at the QD apexes. Observed effect is explained by enhancement of electron confienment near QD apex by Coloumb attraction to the photogenerated hole trapped in Ge QD.

Abstract: This paper concerns the simulation of Mode I fracture with a local concrete damage model in explicit finite element code LSDYNA. A reliable modeling of fracture is essential in the analysis of tension-dominated problems, as well as the prediction of concrete damage due to cracking. A special focus of this paper is placed on an effective representation of the tensile localization in finite element modeling while generalized macro material properties are employed to modeling meso-scale problems. An investigation into the use of a typical damage plasticity concrete model within LSDYNA Explicit, based on the crack band theory, is described in detail. The main focus of the current paper is on the tensile softening branch.

Abstract: As the geographical location of sensors is of great importance in the applications of a wireless sensor network, localization attracts significant research interest. Among the localization methods, received signal strength indicator (RSSI) localization algorithm is widely studied due to its low-cost. However, the radio signal transmission is affected by the factors of channel attenuation and noise, etc. Therefore, the actual location is impossible to estimate. To alleviate the effect of the RSSI measure errors, we proposed a novel error modified method for RSSI location algorithm based on neural network, short for RSSI-NN. First, we use the fitting parameters of the monitoring area to determine the parameters of RSSI model. Second, the distance between anchor node i and the unknown node L_i is calculated. Then, the error modified algorithm based on neural network is proposed. Finally, we can obtain the modified value of the output layer data. Simulations demonstrate that RSSI-NN achieves lower localization error compared with conventional RSSI-based localization algorithm.

Abstract: A finite element model for failure prediction has been used for axial compression simulation of a front side member beam with tailored material properties. A corresponding experiment has been performed. The numerical simulation is divided into forming, mapping and axial compression. The coupled thermo-mechanical hot stamping simulation includes an austenite decomposition model that accounts for carbon segregation. In the mapping step, the phase composition is first mapped and then translated into global stress-strain curves and failure parameters using two different models. An elastic-viscoplastic material model including mesh size dependent localization and crack initiation with a ductile and shear fracture model is used in the axial compression simulation. The simulation shows acceptable agreement with the experimental results.

Abstract: This paper introduces the process and main equipments of hot stamping. The equipments composition of hot stamping production line, the equipments’ performance features and key technical indices are described in detail. The parts’ microstructure and mechanical properties after hot stamping are presented. It has been proved by practical production that the key technical indices of the domestic hot stamping production line, which has completely independent intellectual property, has reached the level of advanced products in the developed countries while has obvious cost advantage.