Adaptive Control for State Synchronization of Nonlinear Haptic Telerobotic Systems with Asymmetric Varying Time Delays

In this paper, we introduce a new adaptive controller design scheme for nonlinear telerobotic systems with varying time delays where the delays and their variation rates are unknown. The designed controller has the ability to synchronize the state behaviors of the local and the remote robots. In this paper, asymptotic stability in the presence of varying time delays is of interest. Using the proposed controller, asymptotic stability of the bilateral telerobotic system subject to any bounded yet unknown varying delay with a bounded yet unknown rate of change can be guaranteed. Besides the varying time delay, the proposed adaptive controller has the ability to adapt to the parameter variations in the local and the remote robots’ dynamics. It is shown that position and velocity errors between the local and the remote manipulators converge to the zero asymptotically, thus ensuring teleoperation transparency. Experimental and simulation results with a pair of PHANToM haptic devices and a pair of planar manipulators under varying time delays in the communication channel demonstrate the effectiveness of the proposed scheme.     

Solubility of Ketoconazole in Ethanol + Water Mixtures at Various Temperatures

Ketoconazole is an important drug with low water solubility. Its low aqueous solubility could be increased using various methods such as by the addition of a pharmaceutical cosolvent. The solubility of ketoconazole in ethanol + water mixtures at 293.2, 298.2, 303.2, and 308.2 K were determined, and the results showed that the addition of ethanol increased the solubility and the maximum value was obtained at 80% of ethanol. The generated data were mathematically represented using the Jouyban–Acree model within an acceptable accuracy.     

Optimization of edible Alyssum homalocarpum seed gum-chitosan coating formulation to improve the postharvest storage potential and quality of apricot (Prunus armeniaca L.)

Edible coating based on Alyssum homalocarpum seed gum (AHSG) and chitosan for coating of fresh apricot was optimized using response surface methodology (RSM). The independent variables included concentrations of AHSG and chitosan in coating solution. The response variables studied were total soluble solid, weight loss, titratably acidity, pH, reducing sugar, moisture content, and firmness. Results indicated that RSM models were significantly (p < .05) qualified for all response variables, except for total soluble solid and titratable acidity. The regression models demonstrated R² ranging from .78 to .99. AHSG concentration influenced the weight loss, pH, and firmness, while chitosan concentration had an effect on pH and moisture content. This study showed that the coating can improve apricot firmness and stability in terms of weight loss, pH, and moisture content. The study suggested that a combination of AHSG 1.02% (w/w) and chitosan 0.33% (w/w) is the best one to achieve the desirable responses.     

Feedback Architecture

The specialist research and design unit in Aedas' London office focuses on three principal areas of research: computational design, advanced modelling and sustainable design. Christian Derix, Judit Kimpian, Abdulmajid Karanouh and Josh Mason of Aedas R&D explain how this cross-pollination of interests has led the practice to develop innovative approaches, exemplified by the design for Al Bahr Towers, the Abu Dhabi Investment Council Headquarters and the Digital Masterplanning (Digma) tool. Copyright © 2011 John Wiley & Sons, Ltd.     

Reconstruction quality and spectral content of an electromagnetic time-domain inversion algorithm

A tomographic time-domain reconstruction algorithm for solving the inverse electromagnetic problem is described. The application we have in mind is dielectric breast cancer detection but the results are of general interest to the field of microwave tomography. Reconstructions have been made from experimental and numerically simulated data for objects of different sizes in order to investigate the relation between the spectral content of the illuminating pulse and the quality of the reconstructed image. We have found that the spectral content is crucial for a successful reconstruction. The work has further shown that when imaging objects with different scale lengths it is an advantage to use a multiple step procedure. Low frequency content in the pulse is used to image the large structures and the reconstruction process then proceed by using higher frequency data to resolve small scale lengths. Good agreement between the results obtained from experimental data and simulated data has been achieved.     

The adsorption of malachite green (MG) as a cationic dye onto functionalized multi walled carbon nanotubes

Synthetic dyes are widely used by several industries to color their products. The discharge of colored wastewater into the hydrosphere causes serious environmental problems. We used functionalized multi wall carbon nanotubes as an adsorbent for the adsorption of cationic dye, malachite green, from aqueous solution. Based on information provided by the Iranian Research Institute of Petroleum Industry, carbon nanotubes are produced using a chemical vapor deposition (CVD) technique. These as-received MWCNTs were functionalized by acid treatment. The remaining dye concentration was read by UV-visible absorption spectroscopy at maximum adsorption wavelength. The effect of different operational parameters such as contact time, pH of solution, adsorbent dose and initial dye concentration were studied. The results showed that by increasing of contact time, pH and adsorbent dose the removal of dye increased, but by increasing initial dye concentration, the removal efficiency decreased. Adsorption isotherms and kinetics behavior of f-MWCNTs for removal of malachite green was analyzed, and fitted to various existing models. The experimental data were well correlated with the Langmuir isotherm with a maximum adsorption capacity (q _m ) and regression coefficient (R²) of 142.85 mg/g and 0.997, respectively. The results of this study indicate that functionalized multi wall carbon nanotubes can be used as an effective adsorbent for the removal of dyes.     

The effect of relative humidity on electrostatic charge decay of drugs and excipient used in dry powder inhaler formulation

Electrostatic forces arising from charge accumulation on drug and excipient powders cause agglomeration and adhesion of particles to solid surfaces and problems during the manufacture and use of many pharmaceutical dosage forms, including dry powder inhalers (DPIs). The ability of materials to dissipate the acquired charge is therefore important and the aim of this work was to investigate the charge decay of salbutamol sulfate, ipratropium bromide monohydrate and alpha-lactose monohydrate. Differences in tri-phasic charge decay rates of the three materials in the order ipratropium bromide > lactose > salbutamol sulfate were demonstrated after corona charging and all materials showed an increased decay rate as the relative humidity was increased up to 86%. Preformulation knowledge of charge accumulation and decay in such materials will contribute to formulation, manufacture and performance of pharmaceutical dosage forms in general, and in particular DPIs.     

A shared matrix unit for a chip multi-core processor

This paper proposes extending a multi-core processor with a common matrix unit to maximize on-chip resource utilization and to leverage the advantages of the current multi-core revolution to improve the performance of data-parallel applications. Each core fetches scalar/vector/matrix instructions from its instruction cache. Scalar instructions continue the execution on the scalar datapath; however, vector/matrix instructions are issued by the decode stage to the shared matrix unit through the corresponding FIFO queue. Moreover, scalar results from reduction vector/matrix instructions are sent back from the matrix unit to the scalar core that sent these instructions. Some dense linear algebra kernels (scalar–vector multiplication, scalar times vector plus another, apply Givens rotation, rank-1 update, vector–matrix multiplication, and matrix–matrix multiplication) as well as discrete cosine transform, sum of absolute differences, and affine transformation are used in the performance evaluation. Our results show that the improvement in the utilization of the shared matrix unit with a dual-core ranges from 9% to 26% compared to extending a matrix unit to a single-core. Moreover, the average speedup of the dual-core shared matrix unit over a single-core extended with a matrix unit ranges from 6% to 24% and the maximum speedup ranges from 13% to 46%.