CABLE-SUSPENDED CPR-D TYPE PARALLEL ROBOT

This paper deals with the analysis and synthesis of a newly selected Cable-suspended Parallel Robot configuration, named CPR-D system. The camera carrier workspace has the shape of a parallelepiped. The CPR-D system has a unique Jacobian matrix that maps the relationship between internal and external coordinates. This geometric relationship is a key solution for the definition of the system kinematic and dynamic models. Because of the CPR-D system complexity, the Lagrange principle of virtual work has been adapted. Two significant Examples have been used for the CPR-D system analysis and validation

Sintered Materials Based on Copper and Alumina Powders Synthesized by a Novel Method

Synthesis of nanocomposite Cu-Al2O3 powder suitable for obtaining multiple strengthened systems could be successfully performed by combination of the thermo-chemical procedure and the mechanical alloying. To optimize the whole scope of properties that are expected from these materials, the combination of thermo-chemical procedures and the procedure of mechanical alloying is a completely new approach to the synthesis of powders. Thus obtained powders allow obtaining the final product with the excellent effects of strengthening. Presented results show possibility of usage composite powders based on copper and alumina synthesized by novel method for production of compacts with suitable properties for exploitation at elevated temperatures, i.e. increased hardness with electrical conductivity appropriate for oxide dispersion strengthened copper alloys intended for application at elevated temperatures. Achieved values after thermo-mechanical treatment for hardness are 57HRF and for electrical conductivity 61%IACS. Limitation for dispersoide content is 1wt. %, due to the decomposition of compacts with higher Al2O3 content during mechanical processing. Increased Al2O3 content could be achieved by using hot extrusion process

The Reconfigurable Machinery Efficient Workspace Analysis Based on the Twist Angles

A novel methodology for the calculation, visualisation and analysis of the Reconfigurable Machinery Efficient Workspace (RMEW), based on the twist angles, is presented in this paper. The machinery\u27s kinematic parameters are used for calculating the workspace, while the efficient workspace is associated with the machinery\u27s path and includes the end-effector position and orientation. To analyse and visualise many different machinery efficient workspaces at the same time, the calculation is based on the previously developed and validated complex reconfigurable machinery\u27s kinematic structure named n-DOF Global Kinematic Model (n-GKM). An industrial robot is used as an example to demonstrate an application of n-GKM model. It is calculated only for the tool\u27s perpendicular orientation relative to the floor. Four different kinematic configurations based on twist angles (αi) were selected to demonstrate the outcomes. Their graphical representations show how the twist angles significantly affect the shape and size of the efficient workspace. RMEW can be used as a design tool for new machinery\u27s kinematic structure and layout design. This methodology can be applied for any tool orientation

Wear Resistance and Dynamic Fracture Toughness of Hypoeutectic High-Chromium White Cast Iron Alloyed with Niobium and Vanadium

The influence of mass fractions 1.5 % Nb and 1.5 % V, added singly and in combination, on the microstructural characteristics and properties relevant to the service performance of the hypoeutectic high-chromium white iron containing 18 % Cr and 2.9 % C, namely, the wear resistance and the fracture toughness, has been examined. The Fe-Cr-C-Nb-V alloy gives the best compromise between the wear resistance and the fracture toughness. The dynamic fracture toughness of this alloy is larger by about 42 % and the abrasion wear resistance is larger by about 33 % than the properties of the basic Fe-Cr-C alloy. The presence of NbC carbides in the structure, caused by adding niobium to the alloy, contributes to an improvement of the wear resistance and the dynamic fracture toughness. On the other hand, the higher fracture toughness was attributed to the strengthening during fracture, since very fine secondary carbide particles were present, mainly in the austenitic matrix (as a result of the vanadium addition). The secondary carbides that precipitate in the matrix regions also influence the abrasion behaviour. By increasing the matrix strength through a dispersion-hardening effect, the fine secondary carbides can increase the mechanical support of M7C3 eutectic carbides

A Toxic Hepatitis Caused the Kombucha Tea – Case Report

Background: Toxic hepatitis may clinically manifest as other diseases of the liver, where it must always be considered in differential diagnoses of unexplained liver damage, such as poisoning with kombucha tea.Case report: 47-year old female patient was hospitalized and has consumed daily ounces of kombucha tea. During hospitalization patient was diagnosed with toxic hepatitis and treated with intravenous solutions of hepatic protective and ursodeoxycholic-acid (effective therapy). Conclusion: Examinations showed that kombucha tea has potential to revert the CCl4-induced hepatic toxicity, but used in overdose can induce toxicity himself

Turning dilemmas into opportunities: a UNU/SCN capacity development network in public nutrition in Central and Eastern Europe

Capacity development in nutrition is a process whereby individuals, groups, institutions, organizations and societies enhance their abilities to identify and meet challenges in a sustainable manner. To address these issues, in 2001 the UN System Standing Committee on Nutrition (SCN) established a Working Group on Capacity Development under die joint coordination of the United Nations University (UNU) and the International Union of Nutritional Sciences. Several regional professional networks have developed under this working group, the latest for the Central and Eastern Europe (CEE) Countries. Ten CEE Countries formed a network in 2006 and identified major nutritional challenges in the region, which included: irregular meal patterns; low consumption of fruits/vegetables, milk products and fish; low intake of some micronutrients; and high intakes of fat, Sugar and salt. Public policies in nutrition were either weak or absent. Some countries had recently developed nutrition plans. Higher education in nutrition was seen as very important for public nutrition work by professionals in the region, who considered it a prerequisite for reversing the negative trend of the nutrition transition. The network will continue to work on issues that are still not covered adequately. Its activities to date and prospects for the future are assessed against ten principles for good capacity development suggested by the United Nations Development Programme

Evolution of artificial defects during shape rolling

Very often defects are present in rolled products. For wire rods, defects are very deleterious since the wire rods are generally used directly in various applications. For this reason, the market nowadays requires wire rods to be completely defect-free. Any wire with defects must be rejected as scrap which is very costly for the production mill. Thus, it is very important to study the formation and evolution of defects during wire rod rolling in order to better understand and minimize the problem, at the same time improving quality of the wire rods and reducing production costs. The present work is focused on the evolution of artificial defects during rolling. Longitudinal surface defects are studied during shape rolling of an AISI M2 high speed steel and a longitudinal central inner defect is studied in an AISI 304L austenitic stainless steel during ultra-high-speed wire rod rolling. Experimental studies are carried out by rolling short rods prepared with arteficial defects. The evolution of the defects is characterised and compared to numerical analyses. The comparison shows that surface defects generally reduce quicker in the experiments than predicted by the simulations whereas a good agreement is generally obtained for the central defect.QC 2010110

Evolution of artificial defects during shape rolling

Very often defects are present in rolled products. For wire rods, defects are very deleterious since the wire rods are generally used directly in various applications. For this reason, the market nowadays requires wire rods to be completely defect-free. Any wire with defects must be rejected as scrap which is very costly for the production mill. Thus, it is very important to study the formation and evolution of defects during wire rod rolling in order to better understand and minimize the problem, at the same time improving quality of the wire rods and reducing production costs. The present work is focused on the evolution of artificial defects during rolling. Longitudinal surface defects are studied during shape rolling of an AISI M2 high speed steel and a longitudinal central inner defect is studied in an AISI 304L austenitic stainless steel during ultra-high-speed wire rod rolling. Experimental studies are carried out by rolling short rods prepared with arteficial defects. The evolution of the defects is characterised and compared to numerical analyses. The comparison shows that surface defects generally reduce quicker in the experiments than predicted by the simulations whereas a good agreement is generally obtained for the central defect

New form of the Euler-Bernoulli rod equation applied to robotic systems

This paper presents a theoretical background and an example of extending the Euler-Bernoulli equation from several aspects. Euler-Bernoulli equation (based on the known laws of dynamics) should be supplemented with all the forces that are participating in the formation of the bending moment of the considered mode. The stiffness matrix is a full matrix. Damping is an omnipresent elasticity characteristic of real systems, so that it is naturally included in the Euler-Bernoulli equation. It is shown that Daniel Bernoulli's particular integral is just one component of the total elastic deformation of the tip of any mode to which we have to add a component of the elastic deformation of a stationary regime in accordance with the complexity requirements of motion of an elastic robot system. The elastic line equation mode of link of a complex elastic robot system is defined based on the so-called 'Euler-Bernoulli Approach' (EBA). It is shown that the equation of equilibrium of all forces present at mode tip point ('Lumped-mass approach' (LMA)) follows directly from the elastic line equation for specified boundary conditions. This, in turn, proves the essential relationship between LMA and EBA approaches. In the defined mathematical model of a robotic system with multiple DOF (degree of freedom) in the presence of the second mode, the phenomenon of elasticity of both links and joints are considered simultaneously with the presence of the environment dynamics - all based on the previously presented theoretical premises. Simulation results are presented.