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The purpose of this research was to predict the amount of wear on exhaust valve seats in durability testing of gasoline engines. Through the rig wear test, a prediction formula was constructed with multiple factors as variables. In the rig test, the wear rate was measured in some cases where a number of factors of valve seat wear were within a certain range. Through these tests, sensitivity for each factor was determined from the measured wear data, and then a prediction formula for calculating the amount of wear was constructed with high sensitivity factors. Combining the wear amount calculation formula with the operation mode of the actual engine, the wear amount in that mode can be calculated. The calculated wear amount showed a high correlation with the wear amount measured in bench tests and the wear amount measured in vehicle tests.

Source identification applied to a truck engine and using inverse numerical acoustics is presented. The approach is based on acoustic transfer vectors (ATV) and truncated singular value decomposition (SVD). Acoustic transfer vectors are arrays of transfer functions between surface normal velocity and acoustic pressure at response points. They can be computed using boundary element methods (indirect, direct or multi-domain direct formulations) or finite element methods (in physical or modal coordinates). Regularization techniques such as the so-called L-curve approach are used to identify the optimum SVD truncation. To increase the reliability of the source identification, the approach can use velocity measurements on the boundary surface as well as the standard nearfield pressure measurements. It also allows for linear or spline interpolation of the acoustic transfer vectors in the frequency domain, to increase computational speed.

“Noise and vibration are not invented here!”. Undesirable structural dynamic behaviour is normally experienced on final assemblies, by which time the underlying cause of the problem is difficult to solve intuitively. Solving the problems classically involves the partial breakdown of assemblies and the application of various structural dynamics testing and analysis procedures. Preferably, noise and vibration problems should be avoided by designing the product right the first time, by the use of various integrated analysis and testing disciplines, from the component level to the final assembly. Such an approach is referred to, in a broader sense, by trendy themes as concurrent engineering, forward engineering, simultaneous engineering.... This paper analyzes trends in analytical and experimental structural dynamics toward better integration of the various discipline oriented techniques that are currently used.

The present study experimentally investigated cyclic variation of combustion characteristics of a diesel engine with hydrogen added to the intake air in detail. As the result, there were three ignition modes: (1) hydrogen ignition mode, (2) hydrogen-assisted ignition mode, and (3) diesel-fuel ignition mode. Ignition timing fluctuated from cycle to cycle in each ignition mode and between one ignition mode and another mode. As the coolant temperature was increased, the number of cycles in diesel-fuel ignition mode decreased, and indicated thermal efficiency and cyclic variation was improved. In the case with the blow-by gas introduced to intake port, preflame reaction of blow-by gas first occurred, ignited hydrogen, and then diesel-fuel was ignited by hydrogen combustion in hydrogen ignition mode and hydrogen-assisted ignition mode.