1,302 research outputs found

    Cross-Border Investment, Conflict of Laws, and the Privatization of Securities Law

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    The rapid acceleration of transnational investing is occurring in an environment in which emerging markets, and foreign interest in these markets, are exploding. The issues involved with cross-border investment, conflict of laws and the privatization of securities law are examined

    Redundancy resolution in tasks with parametrizable uncertainty

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    Redundant robots motion planning and control in uncertain task is addressed by model-based approach. Instead of control and adapt the environment to the robot or apply a complex visual servoing system, we have modeled the redundancy resolution (RR) on the parameter spaces that quantify uncertainties of the task. A modeling tool was Successive Approximations (SA). It provides very advantageous properties: small computational effort and small model size, accurate output, extrapolation, and generalization across parameter set obtained by random addressing of the model. The task discussed is press loading with typical two-dimensional uncertainties in pick-up and unloading locations. The robot used is 4 DOF planar robot. The SA-based models of redundancy resolution in the 2D parameter spaces are highly efficient: for more that 30 times less computational efforts resulted in a zero end-point errors, regardless of the task uncertainty

    Data-based design of high-performance motion controllers

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    This paper presents a data-based design of a linear feedback controller which realizes desired closed-loop sensitivity and complementary sensitivity transfer functions. These transfer functions are specified via a single model-based performance cost. The data-based equivalent of this cost is derived, and its utility for the feedback design is demonstrated. A designer can prescribe the controller structure and complexity. Experimental results obtained in a direct-drive robot motion control problem confirm the effectiveness of the design

    Modeling and identification of an RRR-robot

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    A dynamic model of a robot with 3 rotational degrees of freedom is derived in closed form. A systematic procedure for estimation of model dynamic parameters is suggested. It consists of the following steps: (i) identification of friction model parameters for each joint; (ii) calculation of optimal exciting trajectories, required for estimation of the remaining dynamic model parameters; (iii) estimation of these parameters using a least-squares method. The estimated model satisfactory reconstructs experimental control signals, justifying its use in model-based nonlinear control

    Discrete-time sliding mode control of a direct-drive robot manipulator

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    This paper investigates application of a recently introduced discrete-time sliding mode algorithm, in robot motion control. This algorithm was developed to ensure chattering-free discrete-time sliding mode control in finite time. Robustness against disturbances and modeling errors are the additional merits of this algorithm. Here, the algorithm is adapted for the robot motion control problem, and it is used to design feedback controllers of a benchmark direct-drive robot. Theory and experiments confirm the applicability of the algorithm. However, they also reveal restrictions in controller tuning, that may result in undesirable amplification of noise and in excitation of parasitic dynamics

    The TPR-containing domain within Est1 homologs exhibits species-specific roles in telomerase interaction and telomere length homeostasis

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    <p>Abstract</p> <p>Background</p> <p>The first telomerase-associated protein (Est1) was isolated in yeast due to its essential role in telomere maintenance. The human counterparts EST1A, EST1B, and EST1C perform diverse functions in nonsense-mediated mRNA decay (NMD), telomere length homeostasis, and telomere transcription. Although Est1 and EST1A/B interact with the catalytic subunit of yeast and human telomerase (Est2 and TERT, respectively), the molecular determinants of these interactions have not been elaborated fully.</p> <p>Results</p> <p>To investigate the functional conservation of the EST1 protein family, we performed protein-protein interaction mapping and structure-function analysis. The domain in hEST1A most conserved between species, containing a TPR (tricotetrapeptide repeat), was sufficient for interaction of hEST1A with multiple fragments of hTERT including the N-terminus. Two mutations within the hTERT N-terminus that perturb <it>in vivo </it>function (NAAIRS<sub>92</sub>, NAAIRS<sub>122</sub>) did not affect this protein interaction. ScEst1 hybrids containing the TPR of hEST1A, hEST1B, or hEST1C were expressed in yeast strains lacking <it>EST1</it>, yet they failed to complement senescence. Point mutations within and outside the cognate ScEst1 TPR, chosen to disrupt a putative protein interaction surface, resulted in telomere lengthening or shortening without affecting recruitment to telomeres.</p> <p>Conclusions</p> <p>These results identify a domain encompassing the TPR of hEST1A as an hTERT interaction module. The TPR of <it>S. cerevisiae </it>Est1 is required for telomerase-mediated telomere length maintenance in a manner that appears separable from telomere recruitment. Discrete residues in or adjacent to the TPR of Est1 also regulate telomere length homeostasis.</p

    Compression and strength behaviour of viscose/polypropylene nonwoven fabrics

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    Compression and strength properties of viscose/polypropylene nonwoven fabrics has been studied. Compressionbehavior of the nonwoven samples (sample compressibility, sample thickness loss &amp; sample compressive resilience) havebeen analyzed considering the magnitude of applied pressure, fabric weight, fabric thickness, and the porosity of thesamples. Based on the calculated porosity of the samples, pore compression behavior (pore compressibility, porosity loss &amp;pore compressive resilience) are determined. Equations for the determination of pore compressibility, porosity loss, and porecompressive resilience, are established. Tensile strength and elongation as well as bursting strength and ball traverseelongation are also determined. The results show that the sample compression behavior as well as pore compressionbehavior depend on the magnitude of applied pressure. At the high level of applied pressure, a sample with highercompressibility has the lower sample compressive resilience. Differences in pore compressibility and porosity loss betweeninvestigated samples have also been registered, except in pore compressive resilience. Sample with the higher fabric weight,higher thickness, and lower porosity shows the lower sample compressibility, pore compressibility, sample thickness loss,porosity loss, and tensile elongation, but the higher tensile strength, bursting strength, and ball traverse elongation
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