The self-adaptation of weights for joint-limits and singularity avoidances of functionally redundant robotic-task

Kinematic redundancy of a pair of manipulator-task can be classified into intrinsic and functional redundancies. With the help of redundancy, the manipulator is able to approximate a secondary task while completing the main task. However, the success of the redundancy resolution relies on a proper choice of weights, that plays an important role in balancing the different components of the secondary task. In order to ensure the fulfillment of both the main and secondary tasks, the weights have to be tuned for each given manipulator-task. In this paper, a self-adaptation system is presented in replacement of the low-effective manual tuning of weights. The self-adaptation system is integrated into the twist decomposition algorithms, and is successfully applied to the examples of joint-limits and singularity avoidances as secondary task.     

High‐resolution solid‐state NMR investigation of the filler–rubber interaction: 2. High‐speed [1H] magic‐angle spinning NMR spectroscopy in carbon‐black‐filled polybutadiene

This work investigates the behaviour of elastomeric chains (polybutadienes of identical molecular weight but different microstructures) in the close vicinity of carbon black surfaces in order to attain a better understanding of the structure and properties of interphases. Elastomer–filler interactions are assessed through the study of the thermal properties and NMR relaxation characteristics of the corresponding materials. Three series of samples were compared: pure polymers, raw polymer–filler blends (filler loading ratio: 50 phr) and solvent‐extracted blends (so as to get rid of any polymer which is not under the influence of the solid surface). While differential scanning calorimetry points to the existence of an elastomer fraction which is not detected as undergoing the glass transition, ie is strongly immobilized, [¹H] high‐resolution high‐speed magic‐angle spinning solid‐state NMR provides information on the effect exerted by polymer–filler interactions on the mobility of the various constitutive species of the macromolecular backbone. A systematic study of the evolution of the spectral lines yielded by the samples indicates that 1,2‐polybutadiene moieties have a particular affinity towards the carbon black surface which suggests the occurrence of specific interactions at the elastomer–filler interface. © 2001 Society of Chemical Industry     

Pullulan–STMP hydrogels: a way to correlate crosslinking mechanism,structure and physicochemical properties

Rheological and swelling properties of hydrogels based on pullulan crosslinked with sodium trimetaphosphate (STMP) are explained according to various polymer and crosslinking agent concentrations using ³¹P-nuclear magnetic resonance study. This method has allowed determining the amount of all the species present in the medium when varying both pullulan and STMP concentrations. We have clearly demonstrated with a good agreement by both ³¹P-NMR and rheology that a critical STMP concentration occurs which is function of pullulan concentration. This typical crosslinking agent concentration delimitates the maximum of gel structure together with the minimum of swelling.     

Efficient computer analysis of ideal switched-capacitor circuits using matrix compaction techniques

In this paper we describe how three simple observations can be used in order to obtain an efficient algorithm for the computer analysis of ideal switched-capacitor circuits. the resulting algorithm is linear in the number of phases. the first observation uses the structure of the r-domain MNA-matrix to come up with a new LU-decomposition scheme which is gradual per timeslot. the second observation allows a great reduction in size of the z-domain MNA-matrix by a matrix compaction algorithm which also operates gradually per timeslot and which can be interleaved with the first gradual LU-decomposition process. This leads to a small matrix which can then be used for a time- and direct frequency-domain analysis. Third, the computations of transfer functions, aliasing functions and sensitivities can be optimized by applying appropriate excitations and making appropriate combinations of the terms in the expressions. These algorithms have been implemented in the SC-analysis program DIANA.SC. the usefulness and efficiency of the program is then illustrated with some examples.     

Changes in proteasome activity during postmortem aging of bovine muscle

The effects of adding commercial-grade and eggshell calcium lactate on the microbiological and physicochemical properties of Nhams (Thai-style fermented pork sausage) were studied. The Nham calcium levels were 150, 300 and 450 mg/100 g. Compared to controls (no added calcium), calcium fortification did not affect the number of lactic acid bacteria or the colour value. The shear force of Nhams fortified with eggshell calcium lactate decreased (P<0.05) from 32.2 N in the controls to 19.5-22.8 N in Nhams fortified with eggshell calcium lactate. However, Nhams fortified with commercial calcium lactate had the same shear force as the controls. Sensory scores of sour taste, flavour and overall acceptance were not different between the control and calcium-fortified Nhams at a calcium level of 150 mg/100 g.     

Multigrid preconditioned conjugate-gradient method for large-scale wave-front reconstruction

We introduce a multigrid preconditioned conjugate-gradient (MGCG) iterative scheme for computing open-loop wave-front reconstructors for extreme adaptive optics systems. We present numerical simulations for a 17-m class telescope with n = 48756 sensor measurement grid points within the aperture, which indicate that our MGCG method has a rapid convergence rate for a wide range of subaperture average slope measurement signal-to-noise ratios. The total computational cost is of order n log n. Hence our scheme provides for fast wave-front simulation and control in large-scale adaptive optics systems.     

Multiple-scattering lidar retrieval method: tests on Monte Carlo simulations and comparisons with in situ measurements

A multiple-field-of-view (MFOV) lidar measurement and solution technique has been developed to exploit the retrievable particle extinction and size information contained in the multiple-scattering contributions to aerosol lidar returns. We describe the proposed solution algorithm. The primary retrieved parameters are the extinction coefficient at the lidar wavelength and the effective particle diameter from which secondary products such as the extinction at other wavelengths and the liquid-water content (LWC) of liquid-phase clouds can be derived. The solutions are compared with true values in a series of Monte Carlo simulations and with in-cloud measurements. Good agreement is obtained for the simulations. For the field experiment, the retrieved effective droplet diameter and LWC for the available seven cases studied are on average 15% and 35% (worst case) smaller than the measured data, respectively. In the latter case, the analysis shows that the differences cannot be attributed solely to lidar inversion errors. Despite the limited penetration depth (150-300 m) of the lidar pulses, the results of the studied cases indicate that the retrieved lidar solutions remain statistically representative of measurements performed over the full cloud extent. Long-term MFOV lidar monitoring could thus become a practical and economical option for cloud statistical studies but more experimentation on more varied cloud conditions, especially for LWC, is still needed.     

Fast quantification of humic substances and organic matter by direct analysis of sediments using DRIFT spectroscopy

A simple method based on diffuse reflectance coupled with infrared Fourier transform spectroscopy (DRIFTS) has been developed for the quantification and the characterization of sedimentary (or soil, peat, etc.) humic substances. Under optimized conditions, the quantification of humic substances or total organic matter is possible with DRIFTS at a frequency of 2930 cm(-1) using whole dry sediment samples. A study of the operational parameters that affect the DRIFTS signal shows the importance of normalizing analysis conditions, especially the diffuse reflectance accessory alignment, the particle size and compaction, and the homogeneity of the powdered samples, to obtain reproducible quantitative analyses. The quantification of total humic substances by DRIFTS correlates well with the concentrations determined using classical extraction methods. DRIFTS analysis requires only a few minutes instead of tedious extractions of humic substances. Moreover, the distribution of total organic matter and of fulvic acids, humic acids, and humin can also be obtained. Analysis of natural samples indicates that a calibration using humic material representative of the studied area provides the most accurate quantification. The fast screening of organic matter fractions by DRIFTS on intact natural samples provides useful quantitative and qualitative information that can be used in environmental or monitoring studies.