The Experts below are selected from a list of 144 Experts worldwide ranked by ideXlab platform

Chung Moon Um - One of the best experts on this subject based on the ideXlab platform.

  • Rheological characterization of composites using a vertical oscillation rheometer.
    Dental Materials, 2006
    Co-Authors: Chung Moon Um
    Abstract:

    Abstract Objectives The purpose of this study was to investigate the viscoelastic properties related to the handling characteristics of composites. Methods A custom-designed vertical oscillation rheometer (VOR) was used for the rheological measurements of composites. The VOR consists of three parts: (1) a measuring Unit, (2) a deformation Induction Unit, and (3) a force-detecting Unit. Two medium-viscous composites, Z100 and Z250, and two packable composites, P60 and SureFil, were tested. A dynamic oscillatory test was used to evaluate the storage modulus ( E ′), loss modulus ( E ″), and loss tangent (tan  δ ) of the composites as a function of frequency ( ω ) from 0.1 to 20 Hz at 23 °C. Results The E ′ and E ″ increased with increasing frequency and showed differences in magnitude among brands. The complex moduli E * of the composites at ω  = 2 Hz, normalized to that of Z100, were 2.16 (Z250), 4.80 (P60), and 25.21 (SureFil). The magnitudes and frequency characteristic of loss tangent differed significantly among brands. The relationship among the complex modulus E * , the phase angle δ , and the frequency ω was represented by the frequency domain phasor form E * ( ω )e i δ  =  E * ( ω )∠ δ . Significance The viscoelasticities of composites, which influence handling characteristics, are significantly different among brands. The VOR is a relatively simple device for the dynamic rheological measurement of dental composites. The loci of the frequency domain phasor plots in a complex plane are a valuable method of representing the viscoelastic properties of composites.

  • Rheological characterization of composites using a vertical oscillation rheometer
    The Journal of Korean Academy of Conservative Dentistry, 2004
    Co-Authors: Chung Moon Um
    Abstract:

    Objective: The purpose of this study was to investigate the viscoelastic properties related to handling characteristics of composite resins, Methods: A custom designed vertical oscillation rheometer (VOR) was used for rheological measurements of composites. The VOR consists of three parts: (1) a measuring Unit, (2) a deformation Induction Unit and (3) a force detecting Unit, Two medium viscous composites, Z100 and Z250 and two packable composites, P60 and SureFil were tested. The viscoelastic material function, including complex modulus and phase angle , were measured. A dynamic oscillatory test was used to evaluate the storage modulus (E'), loss modulus (E") and loss tangent () of the composites as a function of frequency () from 0.1 to 20 Hz at . Results: The E' and E" increased with increasing frequency and showed differences in magnitude between brands. The of composites at , normalized to that of Z100, were 2.16 (Z250), 4,80 (P60) and 25.21 (SureFil). The magnitudes and patterns of the change of of composites with increasing frequency were significantly different between brands. The relationships between the complex modulus , the phase angle and the frequency \omega were represented by frequency domain phasor form, . Conclusions: The viscoelasticity of composites that influences handling characteristics is significant different between brands, The VOR is a relatively simple device for dynamic, mechanical analysis of high viscous dental composites. The locus of frequency domain phasor plots in a complex plane is a valuable method of representing the viscoelastic properties of composites.

Xiaosong Zhang - One of the best experts on this subject based on the ideXlab platform.

  • Performance Evaluation and Experimental Study of the Induction Radiant Air-conditioning System
    Procedia Engineering, 2020
    Co-Authors: Qiang Si, Xiaosong Zhang
    Abstract:

    Abstract In this paper the air-conditioning system which combined the inducement ventilation and radiant air-conditioning is proposed. The indoor terminal device is the Induction Unit which is processed to be combined with the radiant panel on which the copper pipes with rigid aluminum diffusion fins are installed. The radiant panel can be cooled and heated by both water and air. The two-stage evaporator chiller with the non-azeotropic refrigerant is utilized in the system. The experiments of performance test for the novel air type Induction radiant air-conditioning system were carried out to verify the feasibility of the system. With the radiation to heat the building envelope of the laboratory, the system can form an overall uniform indoor temperature field both in the vertical direction and the horizontal direction. When the upside return air inlet which shown better performance was used, the space under height 2m had a moderate temperature difference. The system can greatly reduce the sensation of draught which reduces comfort.

  • Experimental and Numerical Study of the Radiant Induction-Unit and the Induction Radiant Air-Conditioning System
    Energies, 2016
    Co-Authors: Qiang Si, Xiaosong Zhang
    Abstract:

    In this paper we proposed the novel air-conditioning system which combined Induction ventilation and radiant air-conditioning. The indoor terminal device is the radiant Induction-Unit (RIDU). The RIDU is the Induction Unit combined with the pore radiant panel on which the copper pipes with rigid aluminum diffusion fins are installed. The two-stage evaporator chiller with the non-azeotropic mixture refrigerant is utilized in the system to reduce the initial investment in equipment. With the performance test and the steady state heat transfer model based on the theory of radiative heat transfer, the relationship between the Induction ratio of the RIDU and the characteristic of the air supply was studied. Based on this, it is verified that the RIDU has a lower dew-point temperature and better anti-condensation performance than a traditional plate-type radiant panel. The characteristics of the radiation and convection heat transfer of the RIDU were studied. The total heat exchange of the RIDU can be 16.5% greater than that of the traditional plate-type radiant terminal.

V. Kondratjuk - One of the best experts on this subject based on the ideXlab platform.

  • The state standard of magnetic Induction Unit
    Proceedings of 20th Biennial Conference on Precision Electromagnetic Measurements, 1996
    Co-Authors: W. Zingerman, Y. Zilbersteyn, O. Bagaley, V. Kondratjuk
    Abstract:

    An instrumental complex for reproduction, maintenance and transfer of the magnetic Induction Unit in the range from 0.05 to 2 T has been developed and researched. Homogenous magnetic fields of different values are created in a multiband electrical magnet. A special system for stabilization of the magnetic field provides standard deviation of the measurement result up to 1/spl middot/10/sup -6/. The nuclear-resonant teslameter makes it possible to measure the reproduced value with nonexcluded systematic uncertainty of 3/spl middot/10/sup -6/.

Qiang Si - One of the best experts on this subject based on the ideXlab platform.

  • Performance Evaluation and Experimental Study of the Induction Radiant Air-conditioning System
    Procedia Engineering, 2020
    Co-Authors: Qiang Si, Xiaosong Zhang
    Abstract:

    Abstract In this paper the air-conditioning system which combined the inducement ventilation and radiant air-conditioning is proposed. The indoor terminal device is the Induction Unit which is processed to be combined with the radiant panel on which the copper pipes with rigid aluminum diffusion fins are installed. The radiant panel can be cooled and heated by both water and air. The two-stage evaporator chiller with the non-azeotropic refrigerant is utilized in the system. The experiments of performance test for the novel air type Induction radiant air-conditioning system were carried out to verify the feasibility of the system. With the radiation to heat the building envelope of the laboratory, the system can form an overall uniform indoor temperature field both in the vertical direction and the horizontal direction. When the upside return air inlet which shown better performance was used, the space under height 2m had a moderate temperature difference. The system can greatly reduce the sensation of draught which reduces comfort.

  • Experimental and Numerical Study of the Radiant Induction-Unit and the Induction Radiant Air-Conditioning System
    Energies, 2016
    Co-Authors: Qiang Si, Xiaosong Zhang
    Abstract:

    In this paper we proposed the novel air-conditioning system which combined Induction ventilation and radiant air-conditioning. The indoor terminal device is the radiant Induction-Unit (RIDU). The RIDU is the Induction Unit combined with the pore radiant panel on which the copper pipes with rigid aluminum diffusion fins are installed. The two-stage evaporator chiller with the non-azeotropic mixture refrigerant is utilized in the system to reduce the initial investment in equipment. With the performance test and the steady state heat transfer model based on the theory of radiative heat transfer, the relationship between the Induction ratio of the RIDU and the characteristic of the air supply was studied. Based on this, it is verified that the RIDU has a lower dew-point temperature and better anti-condensation performance than a traditional plate-type radiant panel. The characteristics of the radiation and convection heat transfer of the RIDU were studied. The total heat exchange of the RIDU can be 16.5% greater than that of the traditional plate-type radiant terminal.

Abhas Parajuli - One of the best experts on this subject based on the ideXlab platform.