Autonomous assembly using the UR5e robotic arm

This bachelor thesis deals with the demonstration of the abilities of collaborative robots in practical use. These abilities are demonstrated in a task where the robot autonomously composes a predefined shape from LEGO cubes. The UR5e robot from universal Robots was used together with the OnRobot RG2 gripper to carry out this work. Communication with the robot is ensured by the Maltab environment with the use of the library created at ÚMTMB from BUT FME. The first part of the work is devoted to getting acquainted with the used hardware and introducing the functions of the library together with setting up the communication between the robot and PC. There is also paid attention to the analysis of possible solutions to the problem of stacking LEGO cubes. The second part presents the methodology and elaboration of structural elements together with control software for robot motion control and data processing from sensors. The result is a demonstration in which the user enters the input parameters of a rectangular 3D shape according to which the robot autonomously composes the given shape

Anomalous behavior of thermal expansion of α-Fe impurities in the La(Fe,Co,Si)13−La(Fe,Co,Si)_{13-} based alloys modified by Mn or selected lanthanides (Ce, Pr, Ho)

The aim of the present work was to study the negative lattice expansion of the La(Fe,Si)13 phase in the LaFe11.2Co0.7Si1.1 alloy modified by Ce, Ho, Pr or Mn. The highest change of lattice constant was observed for sample doped with Ce, which was result of the first order phase transition, previously observed in this alloy. The gradual decrease of relative change of lattice parameter with increase of Mn content was detected. Furthermore, anomalous behavior of temperature dependence of lattice constant for α-Fe phase was also observed. The X-ray diffraction analysis showed that this phenomenom is caused by negative lattice expansion of the La(Fe,Si)13 phase

Composition of α\alpha−F e nanoparticles precipitated from CuFe alloy studied by hyperfine interactions

Iron-based nanoparticles prepared by precipitation from solid solution of saturated binary Cu-Fe alloy were studied by transmission electron microscopy, high-energy X-ray diffraction and Mössbauer spectroscopy. The results showed that the investigated as-prepared nanoparticles contained two phases. The major phase was determined as $\alpha$−F e and the minor phase as $\gamma$−F e $_2$ O $_3$. Furthermore, additionally annealed samples in Ar protective atmosphere were investigated. Results showed clear decrease in contribution of $\alpha$−F e phase and also revealed the presence of various iron oxides (maghemite, magnetite, hematite and wűstite)

Recovery of Chromium from Slags Leachates by Electrocoagulation and Solid Product Characterization

Slags produced in the steelmaking industry could be a source of chromium. Slags contain, depending on different types of slags, between 2 to 5 wt.% of Cr. Roasting of slag with NaOH, followed by subsequent leaching can produce leachates which can be efficiently processed using electrocoagulation (EC). This paper provides results from the EC process optimization for Cr(VI) solutions with initial concentration 1000 mg/L of Cr(VI). Influence of pH, current intensity and NaCl concentration on the efficiency of chromium recovery, energy consumption as well as solid product composition is discussed in detail. Optimum of pH = 6 was chosen for EC processing of Cr leachates as well as current intensities of 0.1–0.5 A because of the higher Cr/Fe ratio in solid product compared to higher current intensities. Results of EC processing of four real leachates of electric arc furnace carbon steel slag (EAFC), electric arc furnace stainless steel slag (EAFS), low carbon ferrochrome slag (LC FeCr) and high carbon ferrochrome slag (HC FeCr) were evaluated. Comparison of the results of four real leachate samples is presented. Obtained final solid product was identified as (Fe0.6 Cr0.4)2O3 and with up to 20% of Cr could be used as source of chromium in the ferrochrome production

Bioleaching of Manganese Oxides at Different Oxidation States by Filamentous Fungus Aspergillus niger

This work aimed to examine the bioleaching of manganese oxides at various oxidation states (MnO, MnO·Mn2O3, Mn2O3 and MnO2) by a strain of the filamentous fungus Aspergillus niger, a frequent soil representative. Our results showed that the fungus effectively disintegrated the crystal structure of selected mineral manganese phases. Thereby, during a 31-day static incubation of oxides in the presence of fungus, manganese was bioextracted into the culture medium and, in some cases, transformed into a new biogenic mineral. The latter resulted from the precipitation of extracted manganese with biogenic oxalate. The Mn(II,III)-oxide was the most susceptible to fungal biodeterioration, and up to 26% of the manganese content in oxide was extracted by the fungus into the medium. The detected variabilities in biogenic oxalate and gluconate accumulation in the medium are also discussed regarding the fungal sensitivity to manganese. These suggest an alternative pathway of manganese oxides’ biodeterioration via a reductive dissolution. There, the oxalate metabolites are consumed as the reductive agents. Our results highlight the significance of fungal activity in manganese mobilization and transformation. The soil fungi should be considered an important geoactive agent that affects the stability of natural geochemical barriers

Role of spin-phonon and electron-phonon interactions in the phonon renormalization of (Eu1−x_{1−x}Bix_x)2_2 Ir2_2O7_7 across the metal-insulator phase transition: Temperature-dependent Raman and x-ray studies

We report temperature-dependent Raman scattering and x-ray diffraction studies of pyrochlore iridates (Eu$_{1−x}$Bi$_x$)$_2$ Ir$_2$O$_7$, for x=0, 0.02, 0.035, 0.05, and 0.1. The temperature variation in Raman experiments spans from 4 to 300 K, covering the metal-insulator phase transition accompanied by paramagnetic–to–all-in/all-out (AIAO) spin ordering (T$_N$). These systems also show a Weyl semimetal (WSM) phase at low temperatures (<∼50K). The Ir-O-Ir bond bending mode A$_{1g}$ (510 cm$^{−1}$) shows anomalous softening (for x=0.0, 0.02, 0.035, and 0.05) in the magnetically ordered AIAO state, arising primarily from the spin-phonon interaction due to the phonon modulation of the Dzyaloshinskii-Moriya spin-exchange interaction. The two stretching modes T$^{1}_{2g}$ (307 cm$^{−1}$) and T$^{2}_{2g}$ (382 cm$^{−1}$) harden significantly in the magnetic insulating phase. The T$_{2g}$ phonons (for x=0.0, 0.02, 0.035, and 0.05) also show anomalous temperature dependence of their mode frequencies above T$_N$ due to strong electron-phonon coupling. The signatures of the WSM state are observed clearly in phonon renormalization <50K (in x=0.02) due to strong electron-phonon interaction. Our experimental results establish strong magneto-elastic coupling below T$_N$ and significant electron-phonon interactions in the metallic phase above T$_N$ as well as in the low-temperature WSM state

The Effect of High Selenite and Selenate Concentrations on Ferric Oxyhydroxides Transformation under Alkaline Conditions

Iron-based nanomaterials have high technological impacts on various pro-environmental applications, including wastewater treatment using the co-precipitation method. The purpose of this research was to identify the changes of iron nanomaterial’s structure caused by the presence of selenium, a typical water contaminant, which might affect the removal when the iron co-precipitation method is used. Therefore, we have investigated the maturation of co-precipitated nanosized ferric oxyhydroxides under alkaline conditions and their thermal transformation into hematite in the presence of selenite and selenate with high concentrations. Since the association of selenium with precipitates surfaces has been proven to be weak, the mineralogy of the system was affected insignificantly, and the goethite was identified as an only ferric phase in all treatments. However, the morphology and the crystallinity of ferric oxyhydroxides was slightly altered. Selenium affected the structural order of precipitates, especially at the initial phase of co-precipitation. Still, the crystal integrity and homogeneity increased with time almost constantly, regardless of the treatment. The thermal transformation into well crystalized hematite was more pronounced in the presence of selenite, while selenate-treated and selenium-free samples indicated the presence of highly disordered fraction. This highlights that the aftermath of selenium release does not result in destabilization of ferric phases; however, since weak interactions of selenium are dominant at alkaline conditions with goethite’s surfaces, it still poses a high risk for the environment. The findings of this study should be applicable in waters affected by mining and metallurgical operations

The effect of high selenite and selenate concentrations on ferric oxyhydroxides transformation under alkaline conditions

Iron-based nanomaterials have high technological impacts on various pro-environmental applications, including wastewater treatment using the co-precipitation method. The purpose of this research was to identify the changes of iron nanomaterial's structure caused by the presence of selenium, a typical water contaminant, which might affect the removal when the iron co-precipitation method is used. Therefore, we have investigated the maturation of co-precipitated nanosized ferric oxyhydroxides under alkaline conditions and their thermal transformation into hematite in the presence of selenite and selenate with high concentrations. Since the association of selenium with precipitates surfaces has been proven to be weak, the mineralogy of the system was affected insignificantly, and the goethite was identified as an only ferric phase in all treatments. However, the morphology and the crystallinity of ferric oxyhydroxides was slightly altered. Selenium affected the structural order of precipitates, especially at the initial phase of co-precipitation. Still, the crystal integrity and homogeneity increased with time almost constantly, regardless of the treatment. The thermal transformation into well crystalized hematite was more pronounced in the presence of selenite, while selenate-treated and selenium-free samples indicated the presence of highly disordered fraction. This highlights that the aftermath of selenium release does not result in destabilization of ferric phases; however, since weak interactions of selenium are dominant at alkaline conditions with goethite's surfaces, it still poses a high risk for the environment. The findings of this study should be applicable in waters affected by mining and metallurgical operations.Web of Science2218art. no. 995