| 1. |
- Johnsson, Roger, et al.
(författare)
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Cylinder pressure reconstruction from vibration and speed measurements on IC engines
- 2004
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Ingår i: Noise and vibration engineering. - Heverlee : Katholieke Univ. Leuven. - 9073802822 ; , s. 965-974
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Konferensbidrag (refereegranskat)abstract
- Knowledge of the in-cylinder pressure pulse in IC engines is of main importance in order to fulfill the requirements on low fuel consumption, exhaust emissions and noise. Direct measurements of the in-cylinder pressure are not suitable outside the laboratory environment due to a number of drawbacks. In this paper a combined indirect method for the measurement of the cylinder pressure pulse is developed and verified. The method is based on linear transfer functions between cylinder pressure and engine vibration and crankshaft speed, respectively. The combined method shows better results than achieved by either method separately. The low frequency part of the pressure pulse is reconstructed from crankshaft speed measurements while the high frequency part is reconstructed from vibration measurements. However, there is still a frequency region between the methods where neither method gives a reliable prediction.
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| 2. |
- Kari, Leif
(författare)
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Magneto sensitive material in noise and vibration engineering
- 2005
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Ingår i: Proceedings of ISMA 2004. - 9073802822 ; , s. 217-223
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Konferensbidrag (refereegranskat)abstract
- Structure-borne sound properties of magneto sensitive material, with possible applications in automotive and aerospace engineering, are presented. The dynamic properties of isotropic magneto sensitive polymer are examined through experiments within the audible frequency range while applying an external magnetic field. The shear modulus for this manufacturer convenient material, consisting of dispersed irregular, micro-meter sized iron particles in a rubber matrix, is found to depend strongly on both frequency and magnetic field, while the loss factor is almost independent of those factors. Magneto sensitive material applied in noise and vibration engineering promise to have more functionality than conventional materials while actively, rapidly, continuously and reversibly change the dynamic properties. A highly interesting example is the smart vibration isolator where the magneto sensitive rubber rapidly and actively changes the rigid body and dynamic stiffness peak frequencies thereby effectively increasing the isolation also within the audible frequency domain.
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| 3. |
- Tinnsten, Mats, et al.
(författare)
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Important spruce properties determined by the use of numerical optimization.
- 2004
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Ingår i: International Symposium on Musical Acoustics, March 31st to April 3rd, 2004, in Nara/Japan. - 9073802822
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Konferensbidrag (refereegranskat)abstract
- Numerical modeling of violins, or parts of it, can be used in order to enhance the understanding on how different parameters affects the vibration properties and the characteristics of the sound emanating from it. Crucial for the results from these studies is the correctness of the input data for the numerical analysis. One very important, and not easily obtained, group of input data is the wooden material parameters for the part of the violin subjected to analysis. In this study a new method for determining these important material parameters for blanks for violin tops is proposed. In the proposed method a FEM-code is linked together with a stochastic optimization algorithm in order to, in an automatic fashion, determine the material parameters.
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