166 research outputs found

    Simultaneous Identification of Moving Vehicles and Bridge Damages Considering Road Rough Surface

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    A method for the simultaneous identification of moving vehicles and the damages of the supporting structure from measured responses is presented. A two-axle vehicle model with two degrees of freedom (DOF) is adopted. The extent of the damage and the vehicle parameters were chosen as the optimisation variables, which allow ill conditioning to be avoided and decrease the number of sensors required. The identification is performed by minimising the distance between the measured responses and the computed responses to given optimisation variables. The virtual distortion method (VDM) was used, such that the response of the damaged structure can be computed from comparison with the intact structure subjected to the same vehicle excitation and to the response-coupled virtual distortions. These are related to the optimisation variables by the system impulse response matrix and are expressed by a linear system, which allowed both types of optimisation variables to be treated in a unified way. The numerical cost is reduced by using a moving influence matrix. The adjoint variable method is used for fast sensitivity analysis. A three-span bridge numerical example is presented, where the identification was verified with 5% root mean square (RMS) measurement, and model, error whilst also considering the surface roughness of the road

    Primary synovial sarcoma of the heart

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    Primary synovial sarcoma of the heart is very rare, accounting for 5% of cardiac malignancies. Of the few cases reported in the literature to date, nearly all have had a very poor outcome. We present a further case. This uncommon malignancy has no specific symptoms during its development, which results in delayed diagnosis. Echocardiography, chest computed tomography, and magnetic resonance imaging can provide effective information about this tumor. With the identification of the characteristic and diagnostic chromosomal abnormality t(X; 18), this malignancy will become increasingly recognized. Synovial sarcoma of the heart requires surgical intervention to improve the prognosis. Adjuvant and/or genetic therapy pre- or postoperation can help prolong life. Chemotherapy is usually recommended as it may benefit the patients. The key to treatment in the future is to find new therapeutic agents. Further elucidation of the effects of this chromosomal abnormality may lead to better-directed therapies in future. (Cardiol J 2011; 18, 2: 128-133

    Tailoring acidity of HZSM-5 nanoparticles for methyl bromide dehydrobromination by Al and Mg incorporation

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    Three kinds of HZSM-5 nanoparticles with different acidity were tailored by impregnating MgO or varying Si/Al ratios. Both the textural and acidic properties of the as-prepared nanoparticles were characterized by nitrogen adsorption-desorption measurements, X-ray diffraction (XRD), scanning electron microscopy (SEM), ammonia temperature-programmed desorption (NH(3)-TPD) and Fourier transform infrared spectroscopy (FTIR or Py-FTIR). It was found that the intensity of Lewis acid sites with weak strength was enhanced by impregnating MgO or reducing Al concentration, and such an enhancement could be explained by the formation of Mg(OH)(+) or charge unbalance of the MgO framework on the surface of HZSM-5 support. The effect of HZSM-5 nanoparticles' acidity on methyl bromide dehydrobromination as catalyst was evaluated. As the results, MgHZ-360 catalyst with the highest concentration of Lewis acid sites showed excellent stability, which maintained methyl bromide conversion of up 97% in a period of 400‚ÄČh on stream. Coke characterization by BET measurements and TGA/DTA and GC/MS analysis revealed that polymethylated naphthalenes species were formed outside the channels of the catalyst with higher acid intensity and higher Br√łnsted acid concentration during the initial period of reaction, while graphitic carbon formed in the channels of catalyst with lower acid intensity and higher Lewis acid concentration during the stable stage

    Comparisons of transformer thermal behaviours between conventional disc type and S disc type windings

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    From Wiley via Jisc Publications RouterHistory: received 2021-02-01, rev-recd 2021-07-08, accepted 2021-09-22, pub-electronic 2021-11-11Article version: VoRPublication status: PublishedAbstract: Controlling the highest temperature in the windings is the primary objective of transformer thermal design to guarantee designed transformer thermal life expectancy. Temperature rise test results of a transformer with computational fluid dynamics (CFD) modelling results are compared here to determine typical OD and ON flow rates in the transformer. It then presents CFD studies that compare the thermal behaviour of two types of disc‚Äźtype windings. The S disc‚Äźtype winding refers to one that has only axial cooling ducts and physically resembles a layer‚Äźtype winding. The other type is of conventional disc‚Äźtype winding. The S disc‚Äźtype winding shows robust thermal performance due to its quasi‚Äźuniform flow distributions in the axial cooling ducts, irrespective of the total oil flow rates or the cooling modes. In contrast, the conventional disc‚Äźtype windings converted from the S disc‚Äźtype winding experience uneven flow distributions in the radial cooling ducts that can cause localised overheating. Control of oil flow distribution in conventional disc‚Äźtype windings is found critical for its thermal design. Heat transfer for the S disc‚Äźtype winding is further enhanced by axially partitioning the winding into multiple sections, which is optimized based on theoretical analyses and is then verified by CFD modelling

    A review of transformer FRA measurement and diagnosis techniques

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    Frequency Response Analysis (FRA) is a successful technique to detect mechanical damage in power transformers with greater sensitivity than other measurements. The SFRA method is commonly used today and requires a benchmark FRA measurement for comparative diagnostic methods. The use of numerical indices to quantify differences in two FRA signatures is described. It is important to understand the importance of understanding the physical meaning behind the frequency responses of windings through modelling and simulation

    A review of transformer FRA measurement and diagnosis techniques

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    Frequency Response Analysis (FRA) is a successful technique to detect mechanical damage in power transformers with greater sensitivity than other measurements. The SFRA method is commonly used today and requires a benchmark FRA measurement for comparative diagnostic methods. The use of numerical indices to quantify differences in two FRA signatures is described. It is important to understand the importance of understanding the physical meaning behind the frequency responses of windings through modelling and simulation

    Iron Contamination Mechanism and Reaction Performance Research on FCC Catalyst

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    FCC (Fluid Catalytic Cracking) catalyst iron poisoning would not only influence units‚Äô product slate; when the poisoning is serious, it could also jeopardize FCC catalysts‚Äô fluidization in reaction-regeneration system and further cause bad influences on units‚Äô stable operation. Under catalytic cracking reaction conditions, large amount of iron nanonodules is formed on the seriously iron contaminated catalyst due to exothermic reaction. These nodules intensify the attrition between catalyst particles and generate plenty of fines which severely influence units‚Äô smooth running. A dense layer could be formed on the catalysts‚Äô surface after iron contamination and the dense layer stops reactants to diffuse to inner structures of catalyst. This causes extremely negative effects on catalyst‚Äôs heavy oil conversion ability and could greatly cut down gasoline yield while increasing yields of dry gas, coke, and slurry largely. Research shows that catalyst‚Äôs reaction performance would be severely deteriorated when iron content in E-cat (equilibrium catalyst) exceeds 8000‚ÄČőľg/g
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