The Experts below are selected from a list of 261 Experts worldwide ranked by ideXlab platform
Yoshinori Onishi - One of the best experts on this subject based on the ideXlab platform.
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system parameter identification theory and uncertainty analysis methods for multi zone building heat transfer and infiltration
Building and Environment, 2012Co-Authors: Hiroyasu Okuyama, Yoshinori OnishiAbstract:Abstract Methods for on-site Measurement of building thermal performance system parameters such as coefficient of heat loss, solar heat gain, effective thermal capacity, infiltration rate, and effective mixing volume are very important, yet a nontrivial task. Although these are steady-state parameters, on-site Measurements are exposed to changing meteorological conditions and are affected by the thermal capacity of the building. In addition, these parameters should generally be estimated by using a multi-zone model such as inter-zone flow rates. In this regard, a state space equation model, referred to as a “thermal network model,” has been devised to generalize such multi-zone heat transfer system and tracer gas diffusion system Measurements. This model is composed of three parameter types, and we have developed a system parameter identification theory and uncertainty analysis method using least squares, as well as actual Measurement systems. In the present paper, we improve the least-squares regression equation, the uncertainty analysis method, and the reliability evaluation method. We investigate appropriate excitation waveforms and frequencies for heating and tracer gas release, as well as a low-pass filter for pre-processing Measurement data. We verify these theories and methods using computer-Simulated Measurement.
Robert B. Randall - One of the best experts on this subject based on the ideXlab platform.
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Fluid-structure interaction study of gas turbine blade vibrations
Australian Journal of Mechanical Engineering, 2011Co-Authors: Gareth L. Forbes, Osama N. Alshroof, Robert B. RandallAbstract:A recent research program has identified the possibility of using the analysis of casing wall pressures in the direct Measurement of gas turbine rotor blade vibration amplitudes. Currently the dominant method of non-contact Measurement of gas turbine blade vibrations employs the use of a number of proximity probes located around the engine periphery measuring the blade tip (arrival) time. Despite the increasing ability of this method there still exist some limitations, ie. the requirement of a large number of sensors for each engine stage, sensitivity to sensor location, difficulties in dealing with multiple excitation frequencies and sensors being located in the gas path. Analytical modelling of the casing wall pressures and reconstruction of rotor blade vibration amplitudes from the analysis of these Simulated pressure signals has shown significant improvement over current non-contact rotor blade vibration Measurement limitations by requiring only a limited number of sensors and providing robust rotor blade vibration amplitude estimates in the presence of Simulated Measurement noise. However, this modelling was conducted with some fundamental assumptions about the casing wall pressures being made. One of these assumptions presumed that during blade motion the pressure profile around the rotor blades follows the blade's motion while it oscillates around its equilibrium position. This assumption is investigated in this paper through the numerical modelling of the fully coupled two-way rotor blade motion and fluid pressure interaction.
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Fluid-structure interaction study of gas turbine blade vibrations
2010Co-Authors: Gareth L. Forbes, Osama N. Alshroof, Robert B. RandallAbstract:A recent research program has identified the possibility of using the analysis of casing wall pressures in the direct Measurement of gas turbine rotor blade vibration amplitudes. Currently the dominant method of non-contact Measurement of gas turbine blade vibrations employs the use of a number of proximity probes located around the engine periphery measuring the blade tip (arrival) time (BTT). Despite the increasing ability of this method there still exist some limitations, viz: the requirement of a large number of sensors for each engine stage, sensitivity to sensor location, difficulties in dealing with multiple excitation frequencies and sensors being located in the gas path. Analytical modelling of the casing wall pressures and reconstruction of rotor blade vibration amplitudes from the analysis of these Simulated pressure signals has shown significant improvement over current non-contact rotor blade vibration Measurement limitations by requiring only a limited number of sensors and providing robust rotor blade vibration amplitude estimates in the presence of Simulated Measurement noise. However, this modelling was conducted with some fundamental assumptions about the casing wall pressures being made. One of these assumptions presumed that during blade motion the pressure profile around the rotor blades follows the blade's motion while it oscillates around its equilibrium position. This assumption is investigated in this paper through the numerical modelling of the fully coupled two-way rotor blade motion and fluid pressure interaction.
Lynne Cassimeris - One of the best experts on this subject based on the ideXlab platform.
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Spectral analysis of microtubule assembly dynamics
Aiche Journal, 1996Co-Authors: David J Odde, Helen M. Buettner, Lynne CassimerisAbstract:Microtubules are linear polymers of the cytoskeleton that serve to organize the cytoplasm of eukaryotic cells. Understanding how microtubule polymers self-assemble is important in biotechnology, including the development of novel cancer therapies and proper guidance of regenerating neurons. The assembly of microtubules occurs by a unique process whereby an individual microtubule undergoes abrupt and apparently stochastic switching between alternating steady states of growth and shrinkage, a phenomenon known as microtubule dynamic instability. To characterize these oscillations spectral (frequency-domain) analysis, commonly used in engineering for system identification, was applied. Power spectra of the individual microtubule-length life histories revealed oscillations within growth phases, directly reflecting acceleration and deceleration in the growth process. These fluctuations were not accounted for by the standard two-state model commonly used in the analysis of microtubule assembly, despite the inclusion of Simulated Measurement error in the model. Thus, the spectral analysis of microtubule assembly permitted characterization of assembly process dynamics independent of particular assembly models, and as such represents a powerful analytical framework within which to study microtubule dynamic instability and assess its function in vivo.
Alexander Tessler - One of the best experts on this subject based on the ideXlab platform.
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shape sensing of 3d frame structures using an inverse finite element method
International Journal of Solids and Structures, 2012Co-Authors: Marco Gherlone, Priscilla Cerracchio, Massimiliano Corrado Mattone, Marco Di Sciuva, Alexander TesslerAbstract:Abstract A robust and efficient computational method for reconstructing the elastodynamic structural response of truss, beam, and frame structures, using measured surface-strain data, is presented. Known as “shape sensing”, this inverse problem has important implications for real-time actuation and control of smart structures, and for monitoring of structural integrity. The present formulation, based on the inverse Finite Element Method (iFEM), uses a least-squares variational principle involving section strains (also known as strain measures) of Timoshenko theory for stretching, torsion, bending, and transverse shear. The present iFEM methodology is based on strain–displacement relations only, without invoking force equilibrium. Consequently, both static and time-varying displacement fields can be reconstructed without the knowledge of material properties, applied loading, or damping characteristics. Two finite elements capable of modeling frame structures are derived using interdependent interpolations, in which interior degrees of freedom are condensed out at the element level. In addition, relationships between the order of kinematic-element interpolations and the number of required strain gauges are established. Several example problems involving cantilevered beams and three-dimensional frame structures undergoing static and dynamic response are discussed. To simulate experimentally measured strains and to establish reference displacements, high-fidelity MSC/NASTRAN finite element analyses are performed. Furthermore, numerically Simulated Measurement errors, based on Gaussian distribution, are also considered in order to verify the stability and robustness of the methodology. The iFEM solution accuracy is examined with respect to various levels of discretization and the number of strain gauges.
Hiroyasu Okuyama - One of the best experts on this subject based on the ideXlab platform.
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system parameter identification theory and uncertainty analysis methods for multi zone building heat transfer and infiltration
Building and Environment, 2012Co-Authors: Hiroyasu Okuyama, Yoshinori OnishiAbstract:Abstract Methods for on-site Measurement of building thermal performance system parameters such as coefficient of heat loss, solar heat gain, effective thermal capacity, infiltration rate, and effective mixing volume are very important, yet a nontrivial task. Although these are steady-state parameters, on-site Measurements are exposed to changing meteorological conditions and are affected by the thermal capacity of the building. In addition, these parameters should generally be estimated by using a multi-zone model such as inter-zone flow rates. In this regard, a state space equation model, referred to as a “thermal network model,” has been devised to generalize such multi-zone heat transfer system and tracer gas diffusion system Measurements. This model is composed of three parameter types, and we have developed a system parameter identification theory and uncertainty analysis method using least squares, as well as actual Measurement systems. In the present paper, we improve the least-squares regression equation, the uncertainty analysis method, and the reliability evaluation method. We investigate appropriate excitation waveforms and frequencies for heating and tracer gas release, as well as a low-pass filter for pre-processing Measurement data. We verify these theories and methods using computer-Simulated Measurement.