Giora Rosenhouse - Academia.edu (original) (raw)
Uploads
Papers by Giora Rosenhouse
Mech Syst Signal Process, 1994
International Journal For Numerical Methods in Engineering, 1996
A method based on expanding the boundary integral equation into a trigonometric series or a high-... more A method based on expanding the boundary integral equation into a trigonometric series or a high-order polynom is proposed, depending on the domain geometry. It is a non-element method which yields solutions to elastostatic and potential problems, using a small computer memory, yet obtaining more precise results as compared with other common numerical methods. When the geometry of the problem contains circles and straight lines, all the integrations required for solution of the boundary integral are solved analytically. Some elastostatic problems are solved here, and compared with the boundary element method (BEM), which shows some remarkable advantages of the boundary strip method over the BEM.
A simple and efficient algorithm for the generation of hierarchical hybrid rectangular finite ele... more A simple and efficient algorithm for the generation of hierarchical hybrid rectangular finite elements for two-dimensional elasticity problems is presented. A significant saving in computational effort needed for calculating the stiffness matrices of the various finite elements is gained by using symbolic algebra for calculating exactly the necessary integrals. Hierarchical matrices G and H, corresponding to a stress field up to a cubic approximation and a displacement field up to a quadratic approximation, are detailed. The described method for generating hierarchical hybrid stress elements could easily be extended for higher-order elements.
Ultrasonics, 2009
A theoretical model was suggested for qualitative evaluation of a sound pressure field in fruit t... more A theoretical model was suggested for qualitative evaluation of a sound pressure field in fruit tissue, as affected by ultrasonic probe dimensions and fruit properties. The classic directivity pattern of an ideal fluid model, expressed by Bessel function of the first kind, was extended to include energy dissipation of a real material. The directional characteristics of wave propagation, as influenced by transmitter frequency and diameter, and by fruit properties, were discussed. The model indicates how to select the parameters of the ultrasonic transducer (transducer diameter, frequency and excitation power) to control the magnitude and directivity of the ultrasonic waves in the fruit tissue. The suggested theoretical model represented fairly well the experimental sound wave distribution over the half-cut surface of potato and avocado (R(2)>0.862 and 0.977, respectively); the same theoretical model could not represent the sound wave distribution over a half-cut melon. Results of the study were applied in a new probe design for ultrasonic testing of whole fruit.
International Journal for Numerical Methods in Engineering, 1990
A modified global approach to choosing stress terms for hybrid finite elements in plane stress pr... more A modified global approach to choosing stress terms for hybrid finite elements in plane stress problems is based on the known requirement of minimum number of stress parameters. Let nS be the number of independent B-stress parameters, n, the number of nodal displacements and nR the number of rigid body degrees of freedom, then the satisfaction of the criterion na 2 n, -nR of the assembled structure instead of the individual element enables the reduction of np. New rectangular hybrid transition elements applied in adaptive mesh refinement and a new eight node rectangular invariant element including only 12 / I parameters, based on the modified criterion, are presented here.
International Journal for Numerical Methods in Engineering, 1997
IEEE Transactions on Biomedical Engineering, 2006
We evaluated the acoustic frequency response of endotracheal tubes (ETs) to assess their effect o... more We evaluated the acoustic frequency response of endotracheal tubes (ETs) to assess their effect on respiratory system sound transmission studies. White noise 150-3300 Hz was introduced into 4.0-, 6.0-, and 8.0-mm ETs and recorded at their proximal and distal ends. Four tubes of each size were studied at their original and normalized lengths, in straight and bent configurations, and at circuit pressures from 0 to 20 cmH2O. The characteristics of the sound transmission were compared using an analysis of variance for repeated measures. The average transmission amplitude varied directly with tube diameter. The position of peaks and troughs on the amplitude frequency distribution depended on tube length but not on tube diameter. The angle of the phase-frequency plot correlated well with the length of the tube and was independent of its diameter. A 90 degrees bend in the tube had no effect on its sound transmission. Increasing the circuit pressure above ambient modified the frequency response only if volume changes occurred in the test lung. When used to conduct sound into the respiratory system an ET affects the incident signal predictably depending on its length and diameter but not on its curvature or circuit pressure.
Engineering Computations, 1998
Computer Methods in Applied Mechanics and Engineering, 1996
A method based on expanding the boundary integral equation into a trigonometric series or a high-... more A method based on expanding the boundary integral equation into a trigonometric series or a high-order polynom is proposed, depending on the domain geometry. It is a non-element method which yields solutions to elastostatic and potential problems, using a small computer memory, yet obtaining more precise results as compared with other common numerical methods. When the geometry of the problem contains circles and straight lines, all the integrations required for solution of the boundary integral are solved analytically. Some elastostatic problems are solved here, and compared with the boundary element method (BEM), which shows some remarkable advantages of the boundary strip method over the BEM.
Applied Composite Materials, 1995
The boundary strip method (BSM) is applied for evaluation of the transverse mechanical properties... more The boundary strip method (BSM) is applied for evaluation of the transverse mechanical properties of fibrous composites with random and periodical fiber distributions. This special semi numerical method helps find the link between the microscopic behavior of the composite material and its macroscopic response in a rather detailed manner, enabling definition of stress and strain magnitudes at each point of the cross section. Here, specifically statistical model based on the boundary strip method, is used for assessment of the transverse effective moduli of fibrous composites. Random fiber distributions are compared with periodic fiber distributions having square or hexagonal array arrangements. Those are the common models used nowadays and modeled by the finite element or the boundary element. A comparison with the bounds of the polarization extremum principles is conducted too. The influence of the randomly distributed fibers on the transverse effective moduli is investigated and a good correlation is found between the results of the present model and the lower bound of the polarization extremum principles.
Applied Acoustics, 1993
A BS TRA C T In this paper the importance of the radiat&n impedance in determining the input impe... more A BS TRA C T In this paper the importance of the radiat&n impedance in determining the input impedance of musical horns is examined. The results thus obtained enable the finding that the 'horn.function', as defined by Benade and Jansson (Acustica, 31 (1974) [79][80][81][82][83][84][85][86][87][88][89][90][91][92][93][94][95][96][97][98], contains most of the information needed to compute the input impedance. Following this conclusion, a convenient method .for computing the input impedance through this parameter is suggested. Finally, an initial attempt is made at perturbing the shape of existing horns to achieve the desired results in the frequency domain.
Annals of Biomedical Engineering, 2005
We studied the mechanisms by which turbulent flow induces tracheal wall vibrations detected as tr... more We studied the mechanisms by which turbulent flow induces tracheal wall vibrations detected as tracheal breath sounds (TRBSs). The effects of flow rate at transitional Reynold's numbers (1300-10,000) and gas density on spectral patterns of TRBSs in eight normal subjects were measured. TRBSs were recorded with a contact sensor during air and heliox breathing at four flow rates (1.0, 1.5, 2.0, and 2.5 l/s). We found that normalized TRBSs were proportional to flow to the 1.89 power during inspiration and to the 1.59 power during expiration irrespective of gas density. The amplitude of TRBSs with heliox was lower than with air by a factor of 0.33 +/- 0.12 and 0.44 +/- 0.16 during inspiration and expiration, respectively. The spectral resonance frequencies were higher during heliox than air breathing by a factor of 1.75 +/- 0.2-approximately the square root of the reciprocal of the air/heliox wave propagation speed ratio. In conclusion, the flow-induced pressure fluctuations inside the trachea, which cause tracheal wall vibrations, were detected as TRBSs consist of two components: (1) a dominant local turbulent eddy component whose amplitude is proportional to the gas density and nonlinearly related to the flow; and (2) a propagating acoustic component with resonances whose frequencies correspond to the length of the upper airway and to the free-field sound speed. Therefore, TRBSs consist primarily of direct turbulent eddy pressure fluctuations that are perceived as sound during auscultation.
Architectural Science Review, 2007
Sunshades may influence the acoustics of a building. As there are many ways to design external su... more Sunshades may influence the acoustics of a building. As there are many ways to design external sunshades that are climatically efficient, it is important to consider the acoustical effect of their geometry as well. For this purpose, Acoustical Performance of Sunshades (APS), a preliminary computerized model was developed, allowing acoustical evaluations of different geometries of climatically satisfying sunshades. The evaluation
Mech Syst Signal Process, 1994
International Journal For Numerical Methods in Engineering, 1996
A method based on expanding the boundary integral equation into a trigonometric series or a high-... more A method based on expanding the boundary integral equation into a trigonometric series or a high-order polynom is proposed, depending on the domain geometry. It is a non-element method which yields solutions to elastostatic and potential problems, using a small computer memory, yet obtaining more precise results as compared with other common numerical methods. When the geometry of the problem contains circles and straight lines, all the integrations required for solution of the boundary integral are solved analytically. Some elastostatic problems are solved here, and compared with the boundary element method (BEM), which shows some remarkable advantages of the boundary strip method over the BEM.
A simple and efficient algorithm for the generation of hierarchical hybrid rectangular finite ele... more A simple and efficient algorithm for the generation of hierarchical hybrid rectangular finite elements for two-dimensional elasticity problems is presented. A significant saving in computational effort needed for calculating the stiffness matrices of the various finite elements is gained by using symbolic algebra for calculating exactly the necessary integrals. Hierarchical matrices G and H, corresponding to a stress field up to a cubic approximation and a displacement field up to a quadratic approximation, are detailed. The described method for generating hierarchical hybrid stress elements could easily be extended for higher-order elements.
Ultrasonics, 2009
A theoretical model was suggested for qualitative evaluation of a sound pressure field in fruit t... more A theoretical model was suggested for qualitative evaluation of a sound pressure field in fruit tissue, as affected by ultrasonic probe dimensions and fruit properties. The classic directivity pattern of an ideal fluid model, expressed by Bessel function of the first kind, was extended to include energy dissipation of a real material. The directional characteristics of wave propagation, as influenced by transmitter frequency and diameter, and by fruit properties, were discussed. The model indicates how to select the parameters of the ultrasonic transducer (transducer diameter, frequency and excitation power) to control the magnitude and directivity of the ultrasonic waves in the fruit tissue. The suggested theoretical model represented fairly well the experimental sound wave distribution over the half-cut surface of potato and avocado (R(2)>0.862 and 0.977, respectively); the same theoretical model could not represent the sound wave distribution over a half-cut melon. Results of the study were applied in a new probe design for ultrasonic testing of whole fruit.
International Journal for Numerical Methods in Engineering, 1990
A modified global approach to choosing stress terms for hybrid finite elements in plane stress pr... more A modified global approach to choosing stress terms for hybrid finite elements in plane stress problems is based on the known requirement of minimum number of stress parameters. Let nS be the number of independent B-stress parameters, n, the number of nodal displacements and nR the number of rigid body degrees of freedom, then the satisfaction of the criterion na 2 n, -nR of the assembled structure instead of the individual element enables the reduction of np. New rectangular hybrid transition elements applied in adaptive mesh refinement and a new eight node rectangular invariant element including only 12 / I parameters, based on the modified criterion, are presented here.
International Journal for Numerical Methods in Engineering, 1997
IEEE Transactions on Biomedical Engineering, 2006
We evaluated the acoustic frequency response of endotracheal tubes (ETs) to assess their effect o... more We evaluated the acoustic frequency response of endotracheal tubes (ETs) to assess their effect on respiratory system sound transmission studies. White noise 150-3300 Hz was introduced into 4.0-, 6.0-, and 8.0-mm ETs and recorded at their proximal and distal ends. Four tubes of each size were studied at their original and normalized lengths, in straight and bent configurations, and at circuit pressures from 0 to 20 cmH2O. The characteristics of the sound transmission were compared using an analysis of variance for repeated measures. The average transmission amplitude varied directly with tube diameter. The position of peaks and troughs on the amplitude frequency distribution depended on tube length but not on tube diameter. The angle of the phase-frequency plot correlated well with the length of the tube and was independent of its diameter. A 90 degrees bend in the tube had no effect on its sound transmission. Increasing the circuit pressure above ambient modified the frequency response only if volume changes occurred in the test lung. When used to conduct sound into the respiratory system an ET affects the incident signal predictably depending on its length and diameter but not on its curvature or circuit pressure.
Engineering Computations, 1998
Computer Methods in Applied Mechanics and Engineering, 1996
A method based on expanding the boundary integral equation into a trigonometric series or a high-... more A method based on expanding the boundary integral equation into a trigonometric series or a high-order polynom is proposed, depending on the domain geometry. It is a non-element method which yields solutions to elastostatic and potential problems, using a small computer memory, yet obtaining more precise results as compared with other common numerical methods. When the geometry of the problem contains circles and straight lines, all the integrations required for solution of the boundary integral are solved analytically. Some elastostatic problems are solved here, and compared with the boundary element method (BEM), which shows some remarkable advantages of the boundary strip method over the BEM.
Applied Composite Materials, 1995
The boundary strip method (BSM) is applied for evaluation of the transverse mechanical properties... more The boundary strip method (BSM) is applied for evaluation of the transverse mechanical properties of fibrous composites with random and periodical fiber distributions. This special semi numerical method helps find the link between the microscopic behavior of the composite material and its macroscopic response in a rather detailed manner, enabling definition of stress and strain magnitudes at each point of the cross section. Here, specifically statistical model based on the boundary strip method, is used for assessment of the transverse effective moduli of fibrous composites. Random fiber distributions are compared with periodic fiber distributions having square or hexagonal array arrangements. Those are the common models used nowadays and modeled by the finite element or the boundary element. A comparison with the bounds of the polarization extremum principles is conducted too. The influence of the randomly distributed fibers on the transverse effective moduli is investigated and a good correlation is found between the results of the present model and the lower bound of the polarization extremum principles.
Applied Acoustics, 1993
A BS TRA C T In this paper the importance of the radiat&n impedance in determining the input impe... more A BS TRA C T In this paper the importance of the radiat&n impedance in determining the input impedance of musical horns is examined. The results thus obtained enable the finding that the 'horn.function', as defined by Benade and Jansson (Acustica, 31 (1974) [79][80][81][82][83][84][85][86][87][88][89][90][91][92][93][94][95][96][97][98], contains most of the information needed to compute the input impedance. Following this conclusion, a convenient method .for computing the input impedance through this parameter is suggested. Finally, an initial attempt is made at perturbing the shape of existing horns to achieve the desired results in the frequency domain.
Annals of Biomedical Engineering, 2005
We studied the mechanisms by which turbulent flow induces tracheal wall vibrations detected as tr... more We studied the mechanisms by which turbulent flow induces tracheal wall vibrations detected as tracheal breath sounds (TRBSs). The effects of flow rate at transitional Reynold's numbers (1300-10,000) and gas density on spectral patterns of TRBSs in eight normal subjects were measured. TRBSs were recorded with a contact sensor during air and heliox breathing at four flow rates (1.0, 1.5, 2.0, and 2.5 l/s). We found that normalized TRBSs were proportional to flow to the 1.89 power during inspiration and to the 1.59 power during expiration irrespective of gas density. The amplitude of TRBSs with heliox was lower than with air by a factor of 0.33 +/- 0.12 and 0.44 +/- 0.16 during inspiration and expiration, respectively. The spectral resonance frequencies were higher during heliox than air breathing by a factor of 1.75 +/- 0.2-approximately the square root of the reciprocal of the air/heliox wave propagation speed ratio. In conclusion, the flow-induced pressure fluctuations inside the trachea, which cause tracheal wall vibrations, were detected as TRBSs consist of two components: (1) a dominant local turbulent eddy component whose amplitude is proportional to the gas density and nonlinearly related to the flow; and (2) a propagating acoustic component with resonances whose frequencies correspond to the length of the upper airway and to the free-field sound speed. Therefore, TRBSs consist primarily of direct turbulent eddy pressure fluctuations that are perceived as sound during auscultation.
Architectural Science Review, 2007
Sunshades may influence the acoustics of a building. As there are many ways to design external su... more Sunshades may influence the acoustics of a building. As there are many ways to design external sunshades that are climatically efficient, it is important to consider the acoustical effect of their geometry as well. For this purpose, Acoustical Performance of Sunshades (APS), a preliminary computerized model was developed, allowing acoustical evaluations of different geometries of climatically satisfying sunshades. The evaluation