Thermal Stability of the Structure and Microhardness of the Al–0.05 vol % Al2O3 Nanocomposite Fabricated by Accumulative Roll Bonding

Russian Journal of Non-Ferrous Metals - The evolution of the microstructure and microhardness of the Al–0.05 vol % nAl2O3 nanocomposite (where nAl2O3 are aluminum nanoparticles) and aluminum...     

Effect of complexation of oxidised corn starch with mineral elements on physicochemical properties

The objective of this study was to determine the effect of complexation of oxidised starch with mineral elements on its physicochemical properties. Corn starch was oxidised with sodium hypochlorite and, afterwards, modified with ions of potassium, magnesium and iron. Thus, native and modified starches were analysed for: contents of mineral elements, colour parameters (L*a*b*), water binding capacity and solubility in water at temperature of 60 and 80 °C. Thermodynamic characteristics of gelatinisation by DSC, molecular weight distribution by GPC, intrinsic viscosity and pasting properties by RVA were studied. The efficiency of incorporation of metal ions into oxidised corn starch was about 30%, 20% and 20% for potassium, magnesium and iron ions, respectively. The complexation with potassium ions caused the greatest changes in the molecular weight distribution and the intrinsic viscosity of starches and viscosity of starch pastes. Only modification of starch with iron ions affected the colour parameters of the starch. Incorporation of metal ions into starch resulted also in changes in its water binding capacity and solubility in water.     

Chaotic pulse position modulation to improve the efficiency of sonar sensors

Ultrasonic devices are widely used in robotics as exteroceptive sensors for ranging measurements. Robotic applications often involve a large number of sonars operating concurrently, giving rise to the phenomenon of crosstalk. In this work, the problem of improving performance of ultrasonic devices in the presence of crosstalk and noise is addressed. In order for each device to discriminate its own echo, chaos is exploited to create unique firing sequences. In particular, the firing scheme described in this work is inspired to a modulation scheme used in chaotic communications, called chaotic pulse position modulation (CPPM). The evaluation of the time of flight is performed by a detection filter. The experimental setup consists of a Polaroid 600 electrostatic transducer driven by a continuous CPPM modulator. Experimental results confirm the suitability of the approach.     

Design and control of an IPMC wormlike robot.

This paper presents an innovative wormlike robot controlled by cellular neural networks (CNNs) and made of an ionic polymer-metal composite (IPMC) self-actuated skeleton. The IPMC actuators, from which it is made of, are new materials that behave similarly to biological muscles. The idea that inspired the work is the possibility of using IPMCs to design autonomous moving structures. CNNs have already demonstrated their powerfulness as new structures for bio-inspired locomotion generation and control. The control scheme for the proposed IPMC moving structure is based on CNNs. The wormlike robot is totally made of IPMCs, and each actuator has to carry its own weight. All the actuators are connected together without using any other additional part, thereby constituting the robot structure itself. Worm locomotion is performed by bending the actuators sequentially from "tail" to "head," imitating the traveling wave observed in real-world undulatory locomotion. The activation signals are generated by a CNN. In the authors' opinion, the proposed strategy represents a promising solution in the field of autonomous and light structures that are capable of reconfiguring and moving in line with spatial-temporal dynamics generated by CNNs.     

Age-dependent MRI-detected lesions at early stages of transient global ischemia in rat brain

Although ischemic stroke has higher incidence and severity in aged than in young humans, the age factor is generally neglected in ischemia animal models. This study was aimed at comparing age-dependent effects at early stages of transient global cerebral ischemia (TGCI) in rats. TGCI was induced in two groups of rats (3–6 and 20–24 months old, respectively) by exposure to 15% oxygen and 15 min occlusion of the two common carotid arteries. Brains were analysed in vivo by MRI–apparent diffusion coefficient (ADC) and T₂ maps–at 1–3 h post-TGCI and in vitro by histochemical examination of triphenyltetrazolium chloride (TTC)-stained slices. At 1–3 h post-TGCI, a higher incidence of lesions was found in aged than in young rats especially in the hippocampus and cortex (occipital plus parietal) but not in the thalamus. The lesioned regions showed lower ADC values in aged than in younger rats. The most substantial ADC decreases were associated with enhanced spin-spin relaxation and lower TTC staining. The different responses of the two age groups support the use of aged animals for investigations on different ischemia models. Our model of brain ischemia appears appropriate for further studies including drug effects.     

Induction Motor Identification by a Microcomputer-Based Structure

The paper deals with the parameter estimation of an induction motor performed through a microcomputer-based data acquisition system and recursive identification algorithms (RLS and RGLS) implemented by means of a general purpose computer. The microcomputer-based data acquisition system is essentially made by connecting the Z80 CPU with its peripherals and auxiliary memories through a bus standard. The motor is represented by a classical fifth-order model linearized around a usual working point; an approximate third-order model, obtained via balanced realization, is in good correlation with the original one according to the identification aims and to the measurement set efficiency. An original CAD procedure is utilized to determine the electrical parameters.     

Transient global brain ischemia in young and aged rats: differences in severity and progression, but not localisation, of lesions evaluated by magnetic resonance imaging

A model of transient global brain ischemia consisting of bilateral occlusion of common carotid arteries for 10 min and mild hypoxia (15% O₂−85% N₂) for 20 min was studied by means of MRI in young and aged Fischer 344 rats (3–4 and 24–26 months, respectively). Ischemia was assessed by full suppression of spontaneous EEG activity, which reappeared and normalized similarly in the two age-groups. The survival of young with respect to aged rats was considerably higher both at 24 h (20/20, i.e. 100% vs 12/16, i.e. 75%) and at 48 h (16/20, i.e. 80% vs 6/16, i.e. 38%). The localisation of brain lesions, their severity and progression were evaluated by a diffusion-weighted MRI (DWI) sequence at 24 and 48 h post-ischemia. There were no DWI-detectable lesions in eight out of 20 young and two out of 12 aged rats. The localisation of DWI-detected lesions was rather similar in rats of the two age-groups. In fact, the cerebral cortex, mainly parietal, occipital and temporal lobes were damaged in 83% of young and 90% of aged rats. The respective percentages for the thalamus were 83 and 60%, for the striatum 58 and 50%, and for the hippocampus 25 and 30%. The lesions present in the cerebral cortex and the thalamus were considerably more severe in aged than in young rats. In conclusion, in spite of similar localisation of ischemic lesions in the two age-groups, their incidence was higher, appearance more rapid and severity more pronounced in aged with respect to young rats. This resulted in a considerably higher mortality of the former. The overall data indicate that the age issue is very important in experimental ischemia research.     

Generators of the ideal of an algebraic space curve

In this paper we show that the ideal of any algebraic curve in affine 3-space whose Jacobian matrix has rank at least 1 at every singular point of the curve can be generated by three polynomials and we give constructive procedures to compute such generators.     

Membership function shape and the dynamic behaviour of fuzzy systems

In this paper the influence of the shape of the membership functions on the dynamic behaviour of a fuzzy controlled system is investigated. Although several works on fuzzy logic have been presented in the literature, few efforts have been made to characterize the dynamic behaviour of a fuzzy system through the shape of the membership functions. A parametrization for a class of membership functions is introduced in this work, resulting in a variety of shapes. Various system steady state dynamics are analysed as a consequence of this change in shape and chaotic dynamics is shown to arise for some membership function shapes.     

The Adult Attachment Interview and self-reports of attachment style: An empirical rapprochement.

Although 10 studies have been published on the empirical overlap of the Adult Attachment Interview (AAI) and measures of self-reported attachment style, results in this literature have been inconsistently interpreted in narrative reviews. This report was designed as a rapprochement of the AAI and attachment style literatures and includes 3 studies. Study 1 (combined N = 961) is a meta-analytic review showing that by J. Cohen's (1992) criteria (mean r = .09), the association between AAI security and attachment style dimensions is trivial to small. Study 2 (N = 160) confirms meta-analytic results with state-of-the-art assessments of attachment security and also examines attachment dimensions in relation to the Big 5 personality traits. Finally, Study 3 is an investigation of 50 engaged couples that shows that developmental and social psychological measures of attachment security predict somewhat distinct--though theoretically anticipated--aspects of functioning in adult relationships. (PsycINFO Database Record (c) 2010 APA, all rights reserved)