Modern manufacturing systems rely on multiple types of sensors to monitor the manufacturing processes and machine faults to ensure product quality. The costs associated with sensor installation, ...maintenance, data transmission, and data storage are high. In this paper, a new data fusion method based on physics-constrained dictionary learning is proposed to improve the efficiency of data collection and the accuracy of fault diagnosis. In the proposed dictionary learning method, the measurement, basis, and classification matrices are optimized for the effective use of compressed sensing technique in process monitoring. With the optimized matrices, full-scale high-resolution signals can be reconstructed from a small number of sensor measurements. At the same time, machine states can be identified based on the sparse measurements. An adaptive weight scheme is introduced to combine low-cost sensor data so that the accuracy of fault diagnosis can be improved. The proposed method is tested with an experimental dataset of gearbox vibrations caused by gear cracks and different levels of crack severities are classified. The results show that up to 70% of data collection can be saved with the new approach while more than 95% of diagnosis accuracy is achieved. The sensitivities of the performance with respect to the number of measurements and number of sensors are also studied.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The aggregate gradation of the hot mix asphalts (HMA) used in southern Nevada before 1989 generally fell above the maximum density line (fine graded aggregate mix). Various asphaltic concrete ...pavements using an aggregate gradation curve that resides below the maximum density line for any nominal size aggregate have been placed in the southern Nevada area over the past few years. These pavements have shown improved resistance to rutting and permanent deformation. This paper presents mix design and performance (rutting) data of four (post-1990) projects in which the gradations range from continuous coarse graded to skip coarse graded aggregates (gradation curves that dropped sharply from the 3 4 in. sieve to the 1 2 in. sieve size then continued in a well-graded fashion). Maximum rut depths were measured for all traffic lanes at major intersections, and average rut depths were then calculated for each project. Rutting measurements were made after at least one annual cycle of operation. These measurements show a 50% rutting reduction when the continuous coarse graded aggregate HMA was used instead of the pre-1989 fine graded aggregate HMA. The rutting was further reduced by 50% when skip graded aggregate HMA was used instead of the continuous coarse graded HMA.
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DOBA, FGGLJ, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
The probability of unusually good research ideas being accepted in a four-tier research hierarchy was investigated, based on the assumption that these ideas are Poisson distributed & reviewed in a ...manner characteristic of a Markov chain random walk with an absorption level. The conclusion was reached that unusually good ideas are vetoed so effectively that only one good idea in thirty is ever actually adopted through the hierarchy. Methods of improving the odds are discussed & it is concluded that extraofficial documentation & exterior reinforcement are somewhat effective, but that transcendence of supervisory cognizance (bypassing) is the most effective means available. In addition, methods for improving the effectiveness of the hierarchy are considered, & it is suggested that reducing the number of levels in the hierarchy is effective. It is also proposed that promotion on an unselective basis, eg, seniority or consanguinity, is probably an effective management procedure as compared to promotion solely on the basis of merit or qualification. 2 Figures. HA.
Absorption is the process in which asphalt flows into a porous aggregate, under the driving force of capillary pressure. Asphalt absorption is of interest because it represents an economic loss of ...effective binder, and because it may change the properties of the resulting asphalt film and lead to premature pavement distress. Incorrect air voids estimation may also result from failure to properly account for asphalt absorption in pavement design. The present review of asphalt absorption is divided into two parts. In part I of the review we have examined the literature over the past 70 years to determine the practical consequences of asphalt absorption, its fundamental physicochemical mechanims, and the influence of asphalt and aggregate properties on the process. Our review shows a need for additional fundamental research if the complex absorption phenomena is to be adequately understood and modeled.
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