Search

An optimal control system that enables a subject to stand without hand support in the sagittal plane was designed. The subject was considered as a double inverted pendulum structure with a voluntarily controlled degree of freedom in the upper trunk and artificially controlled degree of freedom in the ankle joints. The control system design was based on a minimization of cost function that estimated the effort of the ankle joint muscles through observation of the ground reaction force position relative to the ankle joint axis. By maintaining the centre of pressure close to the ankle joint axis the objective of the upright stance is fulfilled with minimal ankle muscle energy cost. The performance of the developed controller was evaluated in a simulation-based study. The results were compared with the responses of an unimpaired subject to different disturbances in the sagittal plane. The proposed cost function was shown to produce a reasonable approximation of human natural behaviour. [ABSTRACT FROM AUTHOR]

This study describes the application of the modified Gran I and II methods for determination of equivalence volume in redox titrations and for calibration, i.e. for determination of the correct slope of the redox indicator electrodes, which appears to be a major problem in using these electrodes. The four new versions of the Gran II method, denoted as MG(II)B, MG(II)C, MG(II)D and MG(II)E methods, in which the problem of calibration and determination of equivalence volume are considered simultaneously are suggested and compared with MG(I)S and MG(II)A methods known hitherto. All the methods are experimentally tested and discussed.

We report on the synthesis and characterization of new a nano-wire-like material with chemical formula Mo6S4.5I4.5. The material can be synthesized in a single step reaction from elements in bulk quantities. The material has a fur-like appearance and is composed of nanowires that are weakly bound in bundles. Bundles itself can be dispersed using an ultrasonic bath in various organic solvents and water. Elemental analysis, X-ray diffraction, thermal analysis (TG, DTA), and electron microscopy were used to characterize the new material in the shape of nanowires. Due to their monodisperse and metallic nature, molybdenum-sulphur-iodine nanowires are an interesting alternative to carbon nanotubes for some applications.