Intelligent control for avoiding the joint limits of redundant planar manipulators

This article presents an intelligent control system for a redundant manipulator to avoid physical limits such as joint angle limits and joint velocity limits. In this method, a back-propagation neural network (NN) is introduced for the kinematic inversion of the manipulator. Since this inverse kinematics has an infinite number of joint angle vectors, a fuzzy-neuro system is constructed to provide an approximate value for that vector. This vector is fed into the NN as a hint input vector in order to guide the output of the NN within the self-motion. Simulations and a comparative study are made based on a four-link redundant manipulator to prove the efficacy of the proposed control system.     

Advances in multibeam communications satellite antennas

The evolution of satellite antennas over the past quarter of a century is presented. Five major areas of advances in communications satellite antenna technology are reviewed: single offset reflectors with feed arrays, shaped reflector systems, active phased arrays, phased-array-fed dual reflector systems, and lightweight feed elements. Examples are given of existing systems and of the ongoing development of new technologies     

Experimental Phase Diagram Study and Thermodynamic Optimization of the Ag-Bi-O System

The Ag-Bi-O system has been experimentally studied using differential thermal analysis (DTA) and scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDX), and thermodynamically optimized. The temperatures of the eutectic, monotectic, and Bi₂O₃ allotropic transformations have been measured in N₂, in air, and in O₂ by DTA. There are no ternary phases stable at ambient pressure. Presently measured transformation temperatures have been combined with existing oxygen activity measurements in the metal liquid to optimize thermodynamic parameters describing the liquid phase. The resulting fit is excellent. EDX measurements of the composition in the oxide liquid have a rather low precision but confirm the thermodynamic optimization. However, some uncertainties remain concerning the liquid composition at the eutectic transformation and the shape of the miscibility gap at higher temperatures.     

Neuropsychology and pathology of the cerebral cortex

In all clinics we are faced with questions about certain aspects of cerebral dominance. We consider first the problem of recognition of faces where the right hemisphere plays a leading role. However, the disorders manifesting that function appear only bilateral lesions. This suggests that the left hemisphere participates in this process. The reception of language raises a problem which is analogous with the preceding: we propose the participation of both hemispheres in this activity: the left hemisphere is dominant in the analysis of phonemes and syntax, the right hemisphere seems implicated above all in the processing of prosodic aspects--in particular intonations and individual features of the voice.     

Transient intra-areal axons in developing cat visual cortex

Transient axons reaching the medialmost part of area 17 were demonstrated with anterogradely transported biocytin injected in the dorsal part of the lateral gyrus in kittens during the first and second postnatal weeks. The axons decreased in number during the third postnatal week and were only exceptionally found thereafter. Computer-aided reconstructions from serial sections demonstrated axons with different degrees of complexity. The most complex ones were found at postnatal days 7-9 and were characterized by multiple branches terminating with growth cones in the white matter. Characteristically, endings of axons that entered the cortex remained confined to the infragranular layers V and VI. A few axons entered the supragranular layers. Transient axons terminated with different endings, which may indicate different stages of maturation. A few, possibly permanent, axons were still found in the medial part of area 17 at the end of the first, and during the second postnatal months; they arborized widely in the infragranular layers, and modestly or not at all supragranularly.     

Magnetically Guided Self‐Assembly and Coding of 3D Living Architectures

In nature, cells self‐assemble at the microscale into complex functional configurations. This mechanism is increasingly exploited to assemble biofidelic biological systems in vitro. However, precise coding of 3D multicellular living materials is challenging due to their architectural complexity and spatiotemporal heterogeneity. Therefore, there is an unmet need for an effective assembly method with deterministic control on the biomanufacturing of functional living systems, which can be used to model physiological and pathological behavior. Here, a universal system is presented for 3D assembly and coding of cells into complex living architectures. In this system, a gadolinium‐based nonionic paramagnetic agent is used in conjunction with magnetic fields to levitate and assemble cells. Thus, living materials are fabricated with controlled geometry and organization and imaged in situ in real time, preserving viability and functional properties. The developed method provides an innovative direction to monitor and guide the reconfigurability of living materials temporally and spatially in 3D, which can enable the study of transient biological mechanisms. This platform offers broad applications in numerous fields, such as 3D bioprinting and bottom‐up tissue engineering, as well as drug discovery, developmental biology, neuroscience, and cancer research.     

巴西标准化发展现状概述

本文详细介绍了巴西标准化体系、标准化机构概况和标准制修订情况。作者利用较新的数据,对巴西标准制定和分布情况进行了介绍和说明。最后简要介绍了巴西合格评定体系、所涉及的监管机构以及所依据的相关标准。     

Design and optimization of ultra-wideband planar multilayer absorber based on long-carbon fiber-loaded composites

Journal of Materials Science - This article presents a strategy for designing optimal microwave planar multilayer absorbers based on epoxy foam composites loaded with carbon fibers of...     

Estimating the plant state from the compensator state

For the systemdot{w} = Swwherew = (xover{z}), this note states and proves necessary and sufficient conditions under which a)zis an estimate of a linear function ofx(i.e.,zestimatesTx), or b) a linear function ofzis an estimate ofx(i.e.,Vzestimatesx). The mappingThas been used previously by the authors to compute the estimator-controller form of a compensator whose state vectorzhad the same dimension as the plant state vectorx.