EMG FEATURE SELECTION FOR MOVEMENT CONTROL OF A CYBERNETIC ARM

Abstract

A variety of electromyographic (EMG) features have been evaluated for control of myoelectric cybernetic prosthetic arms. Movement class discrimination, robustness, and computational complexity of these features have been investigated for different window sizes and noise levels. An adaptive selection of window size for feature extraction has also been developed and evaluated. The experiments were done on the data acquired from the residual biceps and triceps muscle of an above-elbow amputee.     

Changes in physicochemical and organoleptic properties of traditional Iranian cheese Lighvan during ripening

Lighvan cheese was studied to determine the physicochemical and biochemical changes over 90 days of ripening in brine. Acidity, pH, dry matter, fat values, lipolysis level, water‐soluble nitrogen (WSN), total nitrogen (TN), ripening index (RI), trichloroacetic acid‐soluble nitrogen (TCA‐SN) and organoleptic assessments were analysed. Dry matter and fat values decreased during ripening. Lipolysis level, RI, TCA‐SN values and salt content increased continuously until the end of the ripening period, but total nitrogen decreased throughout a 90‐day storage period. The ripening stage was the main factor affecting the cheese’s sensory properties.     

Synthesis and properties of new polyimide/clay nanocomposite films

A series of polymer–clay nanocomposite (PCN) materials consisting of polyimide and typical clay were prepared by solution dispersion. Quaternary alkylammonium modified montmorillonite, Cloisite 20A, was used as organoclay. Poly(amic acid) solution was prepared from the reaction of benzophenone-4,4′,3,3′-tetracarboxylic dianhydride and 2-(5-(3,5-diaminophenyl)-1,3,4-oxadiazole-2-yl) pyridine in dimethylacetamide. Thermal imidization was performed on poly(amic acid)/organoclay dispersion in a regular temperature-programmed circulation oven. The study of interlayer d-spacing with X-ray diffraction pattern indicates that an exfoliated structure may be present in the nanocomposite 1%. Intercalated structures were obtained at higher organoclay loadings. Nanocomposites were studied using thermogravimertic analysis and differential scanning calorimetry. Nanocomposites exhibit higher glass transition temperature and improved thermal properties compared to neat polyimide due to the interaction between polymer matrix and organoclay particles. The results are also compared with data of a similar work. Morphology study with scanning electron microscopy showed that the surface roughness in nanocomposite 1% increased with respect to pristine polyimide. Solvent uptake measurements were also carried out for the prepared materials. Maximum solvent adsorption was observed for dimethyl sulfoxide (DMSO). It was found that the solvent uptake capacity decreased with increasing clay content.     

Nanohydroxyapatite synthesis using optimized process parameters for load-bearing implant

In this study, nanohydroxyapatite (NHA) was synthesized using calcium nitrate tetrahydrate and diammonium hydrogen phosphate via the precipitation method assisted with ultrasonication. Three independent process parameters: temperature (T) (70, 80 and 90°C), ultrasonication time (t) (20, 25 and 30 min), and amplitude (A) (60, 65 and 70%) were studied and optimized using response surface methodology based on 3 factors and 5 level central composite design. The responses of the model were analysed with the help of the particle size measured from field-emission scanning electron microscopy and Brunauer–Emmett–Teller (BET). The surface area of particle was measured with BET and the thermal stability of the powder was measured using thermogravimetric analysis. Finally, with the optimized process parameters obtained from the model, the NHA powder was synthesised and validated against the predicted value. The results show a good agreement with an average error 8% between the actual and predicted values. Moreover, the thermal stability and porosity of synthesized NHA was further improved after calcination. This improvement could be due to the removal of impurities from the NHA powder after calcination as indicated by the Fourier transform infrared spectroscopy and energy-dispersive X-ray spectroscopy.     

Effect of chemical composition and alumina content on structure and properties of ceramic insulators

In the present work, six electrical porcelain compositions with different amount of alumina and silica have been prepared and fired in an industrial furnace at 1300 °C. Density, porosity, bending strength and electrical strength were measured in the samples. In order to find a relationship between properties and sample microstructures, samples were analyzed by scanning electron microscope (SEM) and x-ray diffraction (XRD) techniques. The results showed that, with chemical composition of 53·5 wt.% SiO₂ and 37·5 wt.% alumina, highest electrical strength of 21·97 kV/mm was achieved in fabricated electrical porcelains. Increasing amount of alumina up to 30 wt.% decreases quartz and cristobalite phases, but increases corundum phase 3 to 5 times. SEM observation revealed that dense particles and uniform distribution of long and thin needle shaped mullite are predominant in sample microstructures with highest electrical strength.     

叠后地震数据的自相似分段和多重分形

地质分层是石油工程中的一项重要的基础工作.叠后地震数据和测井数据的时间序列能反映地下分层.由于地层的非均质性和不同成因特性,它们表现出具有复杂模式的多重分形特性.在多重分形结构中,序列中的任何部分都具有不同的赫斯特(Hurst)指数,可反映其性质,并可用于分区检测.时间序列是井眼附近的叠后地震道和测井数据.自相似自回归...     

The effects of inoculant variables on the physicochemical and organoleptic properties of Doogh

The combined effects of probiotic sequential inoculation (before or after fermentation), type of native Bifidobacterium strain (Bifidobacterium animalis spp. lactis PTCC 1631 and Bifidobacterium bifidum PTCC 1644) and final pH of fermentation (4.5 or 4.2) on qualitative aspects of typical Iranian fermented milk drink (Doogh) were investigated. The blends inoculated with yoghurt bacteria only and with final fermentation pH of 4.5 had the shortest fermentation time. The highest viability of bifidobacteria in all treatments at the end of fermentation and throughout the refrigerated storage was observed for B_lY‐40‐4.5 (B. lactis co‐cultured with yoghurt starter bacteria and incubated at 40 °C until final pH of 4.5) and then for B_bY‐40‐4.5 (containing B. bifidum). The most acceptable organoleptic properties were observed for treatments B_lY‐40‐4.2 and B_bY‐40‐4.2, and then for B_bY‐40‐4.5.