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.     

Reduction of 4-cyclohexyl-1-[(1R)-1,2-diphenylethyl]-piperazine-induced memory impairment of passive avoidance performance by sigma 1 receptor agonists in mice

The laryngeal chemoreflex (LCR) is a potentially life-threatening reflex that is elicited in immature animals by the topical application of water to the laryngeal mucosa. The reflex response is characterized by immediate apnea and laryngeal adduction and delayed cardiovascular instability. The cardiorespiratory changes of the LCR may be life-threatening, particularly in very immature animals such as piglets under 2 weeks of age. The afferent and efferent limbs of the LCR are mediated through the vagus nerve, but the neuromediators responsible for the reflex changes have not yet been clearly elucidated. Previous agonist and antagonist studies in immature dogs demonstrated that substance P, a sensory tachykinin, mediates the life-threatening esophagolaryngeal adductor reflex elicited by distal esophageal sensory nerve stimulation. This study was conducted to determine if substance P also plays a role in mediating the LCR. The LCR response was compared before and after treatment with intravenous substance P antagonist (Pfizer CP-96,345-1) in eight piglets (mean 27.7 days of age). The laryngeal and cardiovascular responses of the animals following intravenous administration of the tachykinins substance P, neurokinin A, and neurokinin B were also assessed. Pretreatment with substance P antagonist did not alter the LCR's duration of apnea (p > .10), laryngeal adductor response, or early change in mean arterial pressure (p > .10), although the early maximal heart rate response was significantly altered (p < .01). Intravenous substance P, neurokinin A, and neurokinin B did not reproduce the laryngeal respiratory response of the LCR. We conclude that substance P, neurokinin A, and neurokinin B are not key neurotransmitters of the LCR.     

Microfluidic motion for a direct investigation of solvent interactions with PDMS microchannels

Solid surface/liquid interactions play an important role in microfluidics and particularly in manipulation of films, drops and bubbles, a basic requirement for a number of lab-on-chip applications. The behavior of solvents in coated microchannels is difficult to be predicted considering theories; therefore, experimental methods able to estimate the properties at the interface in real time and during the operational regime are amenable. Here, we propose to use an experimental setup to evaluate the effective dynamics of solvents inside PDMS microchannels. The influence of the solvent properties as well as of the channel wall’s wettability on the fluid movements was evaluated. Modification of the channel properties was achieved by introducing Teflon coatings that allow producing stable hydrophobic microchannel walls. The results were fitted according to Washburn-type power-law and compared with theoretical calculations of the parameter β that expresses the dependence of capillary dynamics on surface tension γ, liquid viscosity η, contact angles θ and the hydraulic radius R _H. A comparison between the calculated and the experimental values reveled that parameters other than the contemplated ones influenced the measurements. The main parameter that affects the flow of solvents such as water, methanol ethanol, dimethylformamide, acetonitrile and acetone was found to be the γ/η ratio. Considering these results, the investigation tool described here is believed to be promising to predict the dynamics of common organic solvents inside integrated functional fluidic devices and to accurately control solvent flow, particularly in capillary-driven pumpless systems, a basic requirement for widening the application range of PDMS lab-on-chip devices.     

IgGs-Abzymes from the Sera of Patients with Multiple Sclerosis Recognize and Hydrolyze miRNAs

Autoantibodies-abzymes hydrolyzing DNA, myelin basic protein, and oligosaccharides have been revealed in the sera of patients with multiple sclerosis (MS). In MS, specific microRNAs are found in blood and cerebrospinal fluid, which are characterized by increased expression. Autoantibodies, specifically hydrolyzing four different miRNAs, were first detected in the blood of schizophrenia patients. Here, we present the first evidence that 23 IgG antibodies of MS patients effectively recognize and hydrolyze four neuroregulatory miRNAs (miR-137, miR-9-5p, miR-219-2-3p, and miR-219-5p) and four immunoregulatory miRNAs (miR-21-3p, miR-146a-3p, miR-155-5p, and miR-326). Several known criteria were checked to show that the recognition and hydrolysis of miRNAs is an intrinsic property of MS IgGs. The hydrolysis of all miRNAs is mostly site-specific. The major and moderate sites of the hydrolysis of each miRNA for most of the IgG preparations coincided; however, some of them showed other specific sites of splitting. Several individual IgGs hydrolyzed some miRNAs almost nonspecifically at nearly all internucleoside bonds or demonstrated a combination of site-specific and nonspecific splitting. Maximum average relative activity (RA) was observed in the hydrolysis of miR-155-5p for IgGs of patients of two types of MS—clinically isolated syndrome and relapsing-remitting MS—but was also high for patients with primary progressive and secondary progressive MS. Differences between RAs of IgGs of four groups of MS patients and healthy donors were statistically significant (p < 0.015). There was a tendency of decreasing efficiency of hydrolysis of all eight miRNAs during remission compared with the exacerbation of the disease.