New automated learning CPG for rhythmic patterns

In this paper, we suggest a new supervised learning method called Fourier based automated learning central pattern generators (FAL-CPG), for learning rhythmic signals. The rhythmic signal is analyzed with Fourier analysis and fitted with a finite Fourier series. CPG parameters are selected by direct comparison with the Fourier series. It is shown that the desired rhythmic signal is learned and reproduced with high accuracy. The resulting CPG network offers several advantages such as, modulation and robustness against perturbation. The proposed learning method is simple, straightforward and efficient. Furthermore, it is suitable for on-line applications. The effectiveness of the proposed method is shown by comparison with four other supervised learning methods as well as an industrial robotic trajectory following application.     

Iranian Medical Universities in SCIE: evaluation of address variation

Patenting and licensing is not only a significant method of university knowledge transfer, but also an important indicator for measuring academic R&D strength and knowledge utilization. The methodologies of quantitative and qualitative analysis, including a special patent h-index indicator to assess patenting quality, were used to examine university patenting worldwide. Analysis of university patenting from 1998 to 2008 showed a significant overall global increase in which Chinese academia stands out: most of the top 20 universities in patenting in 2008 were in China. However, a low rate of utilization of Chinese academic patents may have roots in: (1) university research evaluation system encourages the patent production more, rather than the utilization; (2) problems in the formal mechanisms for university technology transfer and licensing, (3) industry’s limited expectation and receptive capabilities and/or (4) a mismatch between the interests of the two institutional spheres. The next action to be taken by government, university and industry in China will be to explore strategies for improving academic patent quality and industry take-up.     

Study of the Development of Positive Streamers Along an Ice Surface

This paper presents the results of fundamental investigations on the inception and propagation of corona discharge on an ice surface stressed with a standard lightning impulse voltage. High-speed photography and photomultiplier techniques were used to observe and record the propagation of the streamers. The effects of several experimental parameters such as freezing water conductivity and HV rod electrode radius on the streamer inception parameters were investigated. Moreover, time to first streamer, inception voltage and corresponding field, as well as streamer propagation velocity and charge deposited by a streamer on ice surface were measured. The results are discussed and emphases are laid on the main factors influencing the development of positive streamers on ice surface.     

Analysis of chitin particle size on maximum power generation, power longevity, and Coulombic efficiency in solid-substrate microbial fuel cells

Microbial fuel cells (MFCs) produce bioelectricity from a wide variety of organic and inorganic substrates. Chitin can be used as a slowly degrading substrate in MFCs and thus as a long-term fuel to sustain power by these devices in remote locations. However, little is known about the effects of particle size on power density and length of the power cycle (longevity). We therefore examined power generation from chitin particles sieved to produce three average particle sizes (0.28, 0.46 and 0.78 mm). The longevity increased from 9 to 33 days with an increase in the particle diameter from 0.28 to 0.78 mm. Coulombic efficiency also increased with particle size from 18% to 56%. The maximum power density was lower for the largest (0.78 mm) particles (176 mW m⁻²), with higher power densities for the 0.28 mm (272 mW m⁻²) and 0.46 mm (252 mW m⁻²) particle sizes. The measured lifetimes of these particles scaled with particle diameter to the 1.3 power. Application of a fractal dissolution model indicates chitin particles had a three-dimensional fractal dimension between 2 and 2.3. These results demonstrate particles can be used as a sustainable fuel in MFCs, but that particle sizes will need to be controlled to achieve desired power levels.     

A general unified treatment of lamellar inhomogeneities

Consider a lamellar inhomogeneity embedded in an unbounded isotropic elastic medium. When the elastic moduli of the lamellar inhomogeneity are zero it is a crack, if its elastic moduli are infinite it is an anticrack, and when its elastic moduli are finite it is called a quasicrack. Based on the Eshelby’s equivalent inclusion method (EIM), the present paper develops a unified approach for determination of the exact closed-form expressions for modes I, II, and III stress intensity factors (SIFs) at the tips of lamellar inhomogeneities under a remote applied polynomial loading.     

Production of superhydrophobic polymer fibers with embedded particles using the electrospinning technique

Superhydrophobic materials are currently used for their water‐repelling, self‐cleaning and anti‐fouling properties but are also potentially attractive to prevent snow or ice accumulation on exposed structures. Using the electrospinning technique, polymer mats made of polystyrene and poly[tetrafluoroethylene‐co‐(vinylidene fluoride)‐co‐propylene] (PTVFP) were prepared. They were found to show highly hydrophobic properties, water contact angle (CA) between 130 and 150°, when a dual fiber–bead microstructure was observed. Superhydrophobicity, CA > 150°, was reached when PTVFP mats were electrospun from a polymer solution containing dispersed polytetrafluoroethylene (PTFE) nanoparticles. Using atomic force microscopy imaging, protruding nanosized asperities on fiber and bead surfaces were observed and this structure led to superhydrophobic properties. Materials prepared from a high‐viscosity PTVFP/ethyl acetate solution with PTFE particles, 200 nm diameter and 8% (w/w), showed an 11.2% improvement in hydrophobicity, CA = 161°, compared to the materials obtained from a particle‐free polymer solution (CA = 143°). Copyright © 2007 Society of Chemical Industry     

Effect of electron beam irradiation dose on the rheology,morphology, and thermal properties of branched polypropylene/polybutene‐1 blend

The aim of this work is to study the influence of electron beam irradiation on the structure of polypropylene (PP)/polybutene‐1 (PB‐1) blend in the branching process. The blend with 10 wt% of PB‐1 and 0.5 wt% trimethylolpropane trimethacrylate monomer is prepared and irradiated at different doses. The rheological properties of the melts in shear and extensional mode were evaluated, and their thermal behavior, crystalline structure, and morphology are studied by differential scanning calorimetry, wide‐angle X‐ray diffraction, and scanning electron microscopy. The presence of long chain branched structure is approved by higher zero‐shear viscosity (η₀), longer relaxation time and pronounced strain‐hardening behavior in the within the range of dose tested. By increasing the irradiation dose and enhancing chain scission in the backbone and long chain branches, the decline in melting temperature, duplication of melting peak, and the decrease in zero‐shear viscosity were observed. The morphological study of the blends before and after irradiation revealed no considerable change in PB‐1 droplet size and their distribution in the PP matrix. The emulsion theoretical models could predict well the rheological behavior of all samples and no significant change was observed on the interfacial interaction of PP and PB‐1. POLYM. ENG. SCI., 54:1747–1756, 2014. © 2013 Society of Plastics Engineers     

Magnetic molecularly imprinted polymer nanoparticles coupled with high performance liquid chromatography for solid‐phase extraction of carvedilol in serum samples

Herein, we report a magnetic molecularly imprinted polymers (m‐MIPs) using Fe₃O₄ as a magnetic component, carvedilol as a template molecule for the solid‐phase extraction (MISPE) as the sample clean‐up technique combined with high‐performance liquid chromatography (HPLC) and for the controlled release of carvedilol at different pH values of 1.0 (simulated gastric fluid), 6.8 (simulated intestinal fluid), and 7.4 (simulated biological fluid). The adsorption kinetics was modeled with the pseudo‐first‐order and pseudo‐second‐order kinetics, and the adsorption isotherms were fitted with Langmuir and Freundlich models. The performance of the m‐MIPs for the controlled release of carvedilol was assessed and results indicated that the magnetic MIPs also have potential applications in controlled drug release. Furthermore, the m‐MIPs were applied to the extraction of carvedilol from human blood plasma samples. Carvedilol can be quantified by this method in the 2–350 μg L^?1 concentration range. The limit of detection and limit of quantification in plasma samples are 0.13 and 0.45 μg L^?1. The results from HPLC showed good precision (3.5% for 50.0 μg L^?1) and recoveries (between 85 and 93) using m‐MIP from human plasma samples. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41209.     

Detection of broken rotor bars in induction motors using nonlinear Kalman filters

This paper presents a model-based fault detection approach for induction motors. A new filtering technique using Unscented Kalman Filter (UKF) and Extended Kalman Filter (EKF) is utilized as a state estimation tool for on-line detection of broken bars in induction motors based on rotor parameter value estimation from stator current and voltage processing. The hypothesis on which the detection is based is that the failure events are detected by jumps in the estimated parameter values of the model. Both UKF and EKF are used to estimate the value of rotor resistance. Upon breaking a bar the estimated rotor resistance is increased instantly, thus providing two values of resistance after and before bar breakage. In order to compare the estimation performance of the EKF and UKF, both observers are designed for the same motor model and run with the same covariance matrices under the same conditions. Computer simulations are carried out for a squirrel cage induction motor. The results show the superiority of UKF over EKF in nonlinear system (such as induction motors) as it provides better estimates for rotor fault detection.     

A CFD approach for modeling the rime-ice accretion process on a horizontal-axis wind turbine

The main objective of this paper is to model the rime-ice accretion process on a horizontal-axis wind turbine (HAWT) operating under icing conditions. The model calculation procedure was divided into two stages. The first stage consists of computing the two-phase flow that is composed of air and water phases. The two-phase flow was solved using the Eulerian–Eulerian approach with the help of Fluent, a commercial CFD code. At the end of the calculations, it is possible to obtain the local volume fraction and local water incidence velocity, which can be used to estimate the local collision coefficient. In the second stage, the thickness of the newly accreted ice layer was calculated and the geometry so obtained was processed with an in-house smoothing algorithm. From the model simulation, it is possible to obtain the 3-D ice shape, as well as the ice load on the HAWT blade, which can then be used to analyze the performance of the HAWT under icing conditions, or to help develop a feasible de-icing solution. The important model input parameters include: air speed, median volume diameter (MVD) of water droplets, liquid water content (LWC) and air temperature. The turbine under consideration is a NREL VI turbine that rotates along its axis at a constant angular speed. In the flow domain, a rotating reference frame was defined to account for the angular movement of the wind turbine. The results reveal, among other things, ice geometry information that can otherwise hardly be obtained by on-site observations.