Oxidation Processes for Alloys in the Ni – Zr System. Part 1. Structure of Ni – Zr Alloys. Oxidation Kinetics for Ni7Zr2

We have studied the synthesis conditions and crystal structures for one-phase intermetallic alloys Ni₅Zr, Ni₇Zr₂, and NiZr. We used the continuous weighing method to study the oxidation kinetics in air for the alloy Ni₇Zr₂ in the range 500-1000°C. We have shown that the oxidation process is described mainly by a parabolic law. The kinetic isotherms for the change in mass suggest that over time, the rate constant for parabolic oxidation K _p decreases due to improvement in the protective properties of the scale. The temperature dependence of the oxidation rate suggests a change in the oxidation mechanism for T > 800°C, due to changes in the defect structure of the ZrO₂ lattice.     

Development of catalysts for hydrogen generation from hydride compounds

Catalytic hydrolysis of NaBH₄ and NH₃BH₃ has been studied. It was shown that the nature of the support and the active component of the catalyst affect the H₂ generation rate. Despite similar sizes of rhodium particles formed on the surface of different supports (γ-Al₂O₃, TiO₂, carbon), their reactivity is different. Rh/TiO₂ with low rhodium concentration (1 wt.%) is the most active catalyst both in the hydrolysis of NaBH₄ and NH₃BH₃. The obtained results show that the rhodium chloride interaction with titania determines the reactivity of rhodium particles formed under action of NaBH₄ medium. TEM, DRS UV–vis and XPS were used to characterize the catalysts.     

H∞ control versus disturbance-observer-basedcontrol

In the motion control field, a disturbance observer-based disturbance canceling control is often used as a robust control methodology. However, this method is nothing more than an alternative design of an integral controller, and the robust stability issue cannot be directly accounted for. In this paper, an extended H_∞ control scheme is proposed as a new robust motion control method which achieves the disturbance cancellation ability and guarantees robust stability automatically     

Development of calibration models for quality control in the production of ethylene/propylene copolymers by FTIR spectroscopy,multivariate statistical tools,and artificial neural networks

Principal component regression (PCR), partial least squares (PLS), StepWise ordinary least squares regression (OLS), and back‐propagation artificial neural network (BP‐ANN) are applied here for the determination of the propylene concentration of a set of 83 production samples of ethylene–propylene copolymers from their infrared spectra. The set of available samples was split into (a) a training set, for models calculation; (b) a test set, for selecting the correct number of latent variables in PCR and PLS and the end point of the training phase of BP‐ANN; (c) a production set, for evaluating the predictive ability of the models. The predictive ability of the models is thus evaluated by genuine predictions. The model obtained by StepWise OLS turned out to be the best one, both in fitting and prediction. The study of the breakdown number of samples to be included in the training set showed that at least 52 experiments are necessary to build a reliable and predictive calibration model. It can be concluded that FTIR spectroscopy and OLS can be properly employed for monitoring the synthesis or the final product of ethylene–propylene copolymers, by predicting the concentration of propylene directly along the process line. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Laws of Formation of Electrospark Coatings from Alloys of the Ni – Cr – Al – Y System

The main parameters of electrospark alloying of steel 45 with anodes made from Ni – Cr – Al – Y alloys have been investigated. The anodes were fabricated by casting and hot pressing. The highest values of the mass transfer coefficient were observed in the case of electrospark alloying with hot-pressed alloys. Microstructure and x-ray phase analyses of electrospark coatings revealed the presence of solid solutions based on nickel, iron, chromium as well as intermetallic compounds. Coatings obtained by electrospark alloying with hot-pressed alloy are more wear-resistant than are coatings obtained by alloying with cast alloys.     

Analysis of antireflection coatings using the FD-TD method with the PML absorbing boundary condition

A step-index optical waveguide with an antireflection coating is analyzed using the finite-difference time-domain (FD-TD) method combined with the perfectly matched layer absorbing boundary condition (PML-ABC). It is demonstrated that the numerical simulations having a dynamic range over that for the Mur absorbing boundary condition can be obtained for a single-layer coating. The analysis of a double-layer coating reveals the transient behavior of reflected fields.     

FPGA-Based Decentralized Control of Arrayed MEMS for Microrobotic Application

In this paper, the authors have developed and implemented a decentralized decision-making strategy using field-programmable gate array (FPGA) technology as a prototype for an integrated controller of a microelectromechanical systems (MEMS) array for air-flow planar micromanipulation. The MEMS array was proposed to be integrated in a hybrid multichip module containing the FPGA-based controller. Algorithms and architectures, used for the decentralized control implementation and the hardware resource optimization, are described. A charge-coupled device camera was used to make each MEMS like an autonomous system when the distributed MEMS chip was tested. Finally, under air-flow condition, the FPGA-based decentralized control system successfully performed an object manipulation.     

Myositis caused by hydroxyurea in a patient with chronic myelogenous leukemia

A 59-year-old man with chronic myelogenous leukemia (CML) had a white-blood-cell (WBC) count of 55,400/microliter when admitted in July 1997, and was placed on oral hydroxyurea (HU) of 1,500 mg/day. Treatment with 600 MU/day of interferon alpha (IFN alpha) was started on August 5. HU was discontinued when the patient's WBC count dropped to 8,100/microliter on August 18. However, HU was resumed about a month later, after his WBC count increased to 10,100/microliter, but discontinued when the patient started to complain of chills, high fever, and bilateral femoral pain. HU treatment was initiated again one week later, after the patient's WBC count had begun rising but ceased again after he experienced chills, high fever, and bilateral femoral pain. The patient's myogenetic enzymes were found to be increasing the following day, and a lymphocyte stimulation test (LST) with HU showed a high stimulation index of 41.7%. The elevation of myogenetic enzymes and the results of the LST suggested that myositis due to HU was the cause of the patient's clinical manifestations. His myositis spontaneously disappeared after HU was discontinued. Although the patient is no longer receiving HU, IFN alpha has brought his CML under control. To our knowledge, this is the first reported case of myositis caused by HU.