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Internal combustion (IC) engine based powertrains are one of the most commonly used transmission systems in various industries such as train, ship and power generation industries. The powertrains, acting as the cores of machinery, dominate the performance of the systems; however, the powertrain systems are inevitably degraded in service. Consequently, it is essential to monitor the health of the powertrains, which can secure the high efficiency and pronounced reliability of the machines. Conventional vibration based monitoring approaches often require a considerable number of transducers due to large layout of the systems, which results in a cost-intensive, difficultly-deployed and not-robust monitoring scheme. This study aims to develop an efficient and cost-effective approach for monitoring large engine powertrains. Our model based investigation showed that a single measurement at the position of coupling is optimal for monitoring deployment. By using the instantaneous angular speed (IAS) obtained at the coupling, a novel fault indicator and polar representation showed the effective and efficient fault diagnosis for the misfire faults in different cylinders under wide working conditions of engines; we also verified that by experimental studies. Based on the simulation and experimental investigation, it can be seen that single IAS channel is effective and efficient at monitoring the misfire faults in large powertrain systems.

This study presented a novel method to determine the volume of sensitivity (VOS) for dielectric sensors by frozen soil columns radially thawing from outside inward. The method is based on physical equivalence of the dielectric properties between soil drying-wetting and freezing-thawing transitions. We applied this method to determine/compare (i) the VOSs of two types of fringe field prohes (one tuhe type and one cone type) with sandy silt loam samples at a middle level of soil moisture content (6^ = 0.20 cm^ cm~^), (ii) the VOSs of the cone-type probe with sandy silt loam samples at three levels (9y = 0.10, 0.20, and 0.28 cm^ cm"^), and (iii) the VOSs of the tuhetype prohe with three soil textural samples (sand, sandy silt loam, and silty clay). The determined radii of the cone-type sensor ranged from 3.0 to 4.1 cm and those of the tuhe-type sensor from 5.1 to 8.5 cm. These results could he beneficial for improving the technical design of soil dielectric sensors and understanding the effect of soil physical properties on the VOS.Abbreviations: ED, frequency domain; HESS, high frequency structure simulator; REHE, radial heat exchange; TDR, time domain reflectometry; VOS, volume of sensitivity.

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