Line-of-sight task-space sensing methodology for the localization of robotic end-effectors

In this paper, the implementation of a line-of-sight (LOS) task-space sensing methodology is presented for guidance-based microlocalization of robotic end-effectors. The novelty of the overall system is its applicability to cases that do not allow for the direct proximity measurement of the end-effector's pose (position and orientation). The mobility of the localization application dictates the minimum number and the type (planar or spatial) of the LOS that would be necessary to use and, consequently, the exact configuration of the sensing system. Although the main focus of the paper is the presentation of the proposed LOS sensing system, a brief discussion of a robot-guidance method, which relies on the use of this sensing system, is also included. Extensive experiments conducted for a high-precision 3-DOF (degrees of freedom) planar robotic platform utilizing the overall guidance system validated our research.     

Modular analysis and design of log-domain circuits based on LIN↔ELIN transformations

We systematized and developed some procedures for the modular design of externally-linear internally nonlinear (ELIN) circuits resulting in a general LIN↔ELIN transformation procedure. This one was also extended to analysis of these types of circuits. The procedure is exemplified on log-domain circuits. In the design one starts with the linear block diagram (LIN) described by transfer functions and one substitutes directly each linear building block by a corresponding nonlinear one. The parameters of each nonlinear component depend on the given parameters of its linear correspondent. Input F ⁻¹ and output F blocks are added. In the analysis one identifies the nonlinear basic circuit components and each of them is substituted by its corresponding linear building block. Input and output F ⁻¹-F cells are removed. The ideal transfer function can be calculated on the linear block diagram now. The LIN↔ELIN transformations make a direct connection between equivalent linear and ELIN circuits, simplify their design and analysis procedures and permit the development of CAD procedures.     

Voltage–frequency converter for laser welding control

An experimental model of a voltage–frequency converter was realised and utilised for the control of the thermal behaviour by the laser welding of thermoplastic polymer materials. The input signal of 0–10?V comes from a thermal–optical real-time analysing device of the welding process. The output signal of 0–300?Hz is introduced to the input interface of a laser welding equipment, for setting the laser pulse frequency. Operation tests were performed on the laser welding equipment type HL 124P LCU. The pulses have rectangular waveform, with the amplitude of 20?V. The frequency is very stable, with deviations of less than 0.5?Hz. The waveform and the frequency response at the converter output are appropriate.     

The Effect of Sintering Temperature in Bi1.7Pb0.2Sb0.1Sr2Ca2Cu3O y Superconductors

In this study, the effects of sintering temperature on the Bi-2223 phase formation and the influence of minor phases on the intergranular properties of Sb substituted Bi-2223 samples were investigated. The samples were prepared by solid-state reaction method with different sintering temperatures ranging from 800 to 855 °C. The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and density measurements. We observed the optimal temperature of the Sb + Pb substituted Bi-2223 system as 845 °C.     

Failure Analysis of a Location Axle in Tracked Tractor

In this study, a failure analysis was performed on the location axle (brace axle) of a blade on a tracked tractor used in agricultural areas. The analysis included evaluation of the macrostructure of the damage and the microstructure of the material, as well as a chemical analysis of the material. A commercial finite element method software package was used to determine the behavior of the location axle under the defined boundary conditions. After all the examination steps were completed, the main reason for the damage was determined to be manufacture and material error despite the presence of fatigue tracks in the damaged area. In addition, a heat treatment was carried out with the specimens taken from the damaged area and microstructure was re-examined. The experimental and simulation evaluation results provide a technical basis for suggestions to prevent future damage to the location axle.     

The investigation of effects of digital proofing systems used in colour management on print quality with neural networks

The aim of this study is to assist users and to determine how digital proofing systems used in colour management effect print qualities. Also the main theme of this study is to determine the effects of digital proofing systems used in colour management on print quality by artificial neural network (ANN). The R² values are obtained 0.99702 and 0.99688 for training data as matte and cuated papers, respectively. Similarly, these values for testing data are 0.994707 and 0.99629, respectively. The ANN approach shows greater accuracy for evaluating colour management. Based on the outputs of the study, ANN model can be used to estimate the effects of digital proofing systems used in colour management on print quality with highly confidence.     

Effects of environmental factors on the adhesion and durability characteristics of epoxy-bonded concrete prisms

This work is concerned with the effects of environmental factors on the adhesion and durability characteristics of epoxy-bonded concrete prisms. The results indicate that the presence of liquid water at the interfacial zone during the epoxy injection process disrupts the initial bond configurations. The freezing and thawing up to about 40 cycles do not have a significant effect on the bond stability. An adequate degree of chemical stability is maintained in the bond line by the epoxy adhesives after 120 days of exposure to corrosive environments such as MgSO₄ and MgCl₂. However, there is a pronounced effect of these chemical substances on the concrete strength. The load-bearing capacity of epoxy-bonded concrete prisms decreases with increasing temperature. Despite this fact, the EP3-bonded concrete prisms give relatively high joint strengths at temperatures up to 100 °C.     

Effect of particle type on the mechanisms of break up of nanoscale particle clusters

Nanoparticles tend to form large clusters (aggregates and agglomerates) which need to be broken up when dispersing in a liquid. The dispersion of nanoparticle clusters has been studied to investigate the kinetics and mechanisms of break up with two types of particles: fumed silica and aluminium oxide. Results obtained under different processing conditions using an in-line rotor-stator are reported. It could be concluded that break up occurs predominantly through erosion in the case of silica and shattering with aluminium oxide.     

Effects of chromium (VI) on the activities of ureolytic mixed culture

BACKGROUND: Ureolytic microbial carbonate precipitation (MCP) is a novel process for removing excess calcium from industrial effluents. This process is based on the hydrolization of urea to provide a suitable medium for the precipitation of Ca as CaCO₃. RESULT: A toxicity identification evaluation was conducted on synthetic wastewater simulating wastewater from paper recycling to determine the inhibition or toxicity of chromium(VI) ions on the activities of a ureolytic mixed culture (UMC) with respect to the removal rate of COD and removal of Ca²⁺ in batch reactors. The 50% inhibiting concentration (IC₅₀) and the 25% inhibiting concentration (IC₂₅) values of Cr(VI) on UMC were determined as 40 and 18 mg L^?1, respectively, for an exposure time of 1 day. The inhibitory effects of Cr(VI) were lower on UMC after longer exposure times of 3, 4 and 5 days. COD removal rate, ammonium production and Ca removal of samples with 512 mg Cr(VI) L^?1 were significantly inhibited. CONCLUSION The present study has shown that the effects of different metallic species, organic toxicants and other environmental factors should be taken into account when removing problematic Ca and other possible elements from the environment using UMC. Copyright © 2008 Society of Chemical Industry     

Storage of hydrogen in nanostructured carbon materials

Recent developments focusing on novel hydrogen storage media have helped to benchmark nanostructured carbon materials as one of the ongoing strategic research areas in science and technology. In particular, certain microporous carbon powders, carbon nanomaterials, and specifically carbon nanotubes stand to deliver unparalleled performance as the next generation of base materials for storing hydrogen. Accordingly, the main goal of this report is to overview the challenges, distinguishing traits, and apparent contradictions of carbon-based hydrogen storage technologies and to emphasize recently developed nanostructured carbon materials that show potential to store hydrogen by physisorption and/or chemisorption mechanisms. Specifically touched upon are newer material preparation methods as well as experimental and theoretical attempts to elucidate, improve or predict hydrogen storage capacities, sorption–desorption kinetics, microscopic uptake mechanisms and temperature–pressure–loading interrelations in nanostructured carbons, particularly microporous powders and carbon nanotubes.