Comparison Of Separation Methods Research Articles

FORMATION OF THE SURFACE LAYER DURING HYDROABRASIVE SEPARATION OF METALS

[For the English abstract and full text of the article please see the attached PDF-File (English version follows Russian version)].ABSTRACT The range of physicomechanical properties and structure of materials processed by the method of hydroabrasive cutting is considered. Technological capabilities of hydroabrasive separation of metals by a high-pressure jet are given and its comparison with such progressive methods, such as laser, plasma, and erosion. Keywords: transport engineering, machine parts, hydroabrasive separation of metals, comparison of separation methods, quality of the separation surface.

Comparison of separation methods on biological characteristics of rabbit bone marrow mesenchymal stem cells

Objective By comparing the different separation methods of rabbit bone marrow mesenchymal stem cells (BMSCs),to find suitable BMSCs culture ways.Methods BMSCs were obtained by whole bone marrow adherent culture,half red blood cell lysis,whole red blood cell lysis and Ficoll density gradient centrifugation.Methyl thiazolyl tetrazolium (MTT) assay was used to evaluate the growth of BMSCs at 4th,7th,10th,and 13th day.The growth curves of BMSCs at generation of2nd,3rd,4th and 5th were drawn by MTT.Inverted phase contrast microscope was used to observe the morphological changes of cells.CD34 and CD44 antigens of BMSCs were identified by flow cytometry and immunofluorescence.Results BMSCs could be separated by each method.The adherent cells showed shuttle or multiple angle shapes,with rich cytoplasm,and the positive rate of BMSCs labeled by CD44 antigen was 95.57％,and that by CD34 antigen was 0.99％.The more cell number,larger colonies and shortest primary culture time were presented in whole bone marrow adherent culture group (P ＜ 0.05).The 4th-generation BMSCs showed more excellent proliferative activity,higher cell growth rate and more count of cells obtained than other generations (P ＜ 0.05).Conclusion Whole bone marrow adherent culture is the best suitable cultured ways of rabbit BMSCs.The 4th-generation BMSCs exerted the strongest proliferation capacity. Key words: Bone marrow mesenchymal stem cells; Cell culture

A comparison of methods for separation of deterministic and random signals

A comparison of methods for separation of deterministic and random signals

A comparison of methods for separation of transient and oscillatory signals in EEG

Brain oscillations constitute a prominent feature of electroencephalography (EEG), in both physiological and pathological states. An efficient separation of oscillation from transient signals in EEG is important not only for detection of oscillations, but also for advanced signal processing such as source localization. A major difficulty lies in the fact that filtering transient phenomena can lead to spurious oscillatory activity. Therefore, in the presence of a mixture of transient and oscillatory events, it is not clear to which extent filtering methods are able to separate them efficiently.The objective of this study was to evaluate methods for separating oscillations from transients. We compared three methods: finite impulse response (FIR) filtering, wavelet analysis with stationary wavelet transform (SWT), time–frequency sparse decomposition with Matching Pursuit (MP). We evaluated the quality of reconstruction and the results of automatic detection of oscillations intermingled with transients. The emphasis of our study was on epileptic signals and single channel processing.In both simulations and on real data, FIR performed generally worse than the time–frequency methods. Both SWT and MP showed good results in separation and detection, each method having its advantages and its limitations. The SWT had good results in separation and detection of transients due to the time invariance property, but still did not completely resolve the frequency overlap for the oscillation during the time–frequency thresholding. The MP provides a sparse representation, and gave good results for simulated data. However, in the real data, we observed distortions introduced by the subtractive approach, and departure from dictionary waveforms. Future directions are proposed for overcoming these limitations.