864 research outputs found

    Evolving concepts of lunar architecture: The potential of subselene development

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    In view of the superior environmental and operational conditions that are thought to exist in lava tubes, popular visions of permanent settlements built upon the lunar surface may prove to be entirely romantic. The factors that will ultimately come together to determine the design of a lunar base are complex and interrelated, and they call for a radical architectural solution. Whether lunar surface-deployed superstructures can answer these issues is called into question. One particularly troublesome concern in any lunar base design is the need for vast amounts of space, and the ability of man-made structures to provide such volumes in a reliable pressurized habitat is doubtful. An examination of several key environmental design issues suggests that the alternative mode of subselene development may offer the best opportunity for an enduring and humane settlement

    Machine vibration monitoring for diagnostics through hypothesis testing

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    Nowadays, the subject of machine diagnostics is gathering growing interest in the research field as switching from a programmed to a preventive maintenance regime based on the real health conditions (i.e., condition-based maintenance) can lead to great advantages both in terms of safety and costs. Nondestructive tests monitoring the state of health are fundamental for this purpose. An effective form of condition monitoring is that based on vibration (vibration monitoring), which exploits inexpensive accelerometers to perform machine diagnostics. In this work, statistics and hypothesis testing will be used to build a solid foundation for damage detection by recognition of patterns in a multivariate dataset which collects simple time features extracted from accelerometric measurements. In this regard, data from high-speed aeronautical bearings were analyzed. These were acquired on a test rig built by the Dynamic and Identification Research Group (DIRG) of the Department of Mechanical and Aerospace Engineering at Politecnico di Torino. The proposed strategy was to reduce the multivariate dataset to a single index which the health conditions can be determined. This dimensionality reduction was initially performed using Principal Component Analysis, which proved to be a lossy compression. Improvement was obtained via Fisher’s Linear Discriminant Analysis, which finds the direction with maximum distance between the damaged and healthy indices. This method is still ineffective in highlighting phenomena that develop in directions orthogonal to the discriminant. Finally, a lossless compression was achieved using the Mahalanobis distance-based Novelty Indices, which was also able to compensate for possible latent confounding factors. Further, considerations about the confidence, the sensitivity, the curse of dimensionality, and the minimum number of samples were also tackled for ensuring statistical significance. The results obtained here were very good not only in terms of reduced amounts of missed and false alarms, but also considering the speed of the algorithms, their simplicity, and the full independence from human interaction, which make them suitable for real time implementation and integration in condition-based maintenance (CBM) regimes

    Pengembangan Modul Berbasis Problem Based Learning (PBL) Materi Sistem Ekskresi Manusia

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    The teacher has a very important role in the development of education, namely as a teacher and as an educator. One of the ways to develop education is in the development of the learning process. Module development is part of the development of the learning process. The module developed in this study with the Problem Based Learning (PBL). This study aims to determine the feasibility of developing a Problem Based Learning (PBL) module on Human Excretion System Material for class XI students. This type of research used in this research is development. The development model used is ADDIE development which consists of 5 stages, namely Analysis, Design, Development, Implementation, Evaluation. Based on observations at Taman Madya Senior High School, the modules used have not been able to improve student intelligence and have not shown the integration of biological concepts. This study aims to see, the feasibility and effectiveness of the inner module can be used as an understanding of students in class XII SMA Taman Madya, on the subject matter of the Excretion System in humans. The design of this research is ADDIE. Based on the research results, it shows that the PBL-based process has been developed and is declared feasible to be tested. The quality of the module based on the results of material expert validation is Very Good (B) with a proportion of 66%, media expert is Very Good (SB) with a proportion of 76%

    Wind turbine drive-train condition monitoring through tower vibrations measurement and processing

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    A new method for wind turbine drive-train condition monitoring is proposed: the innovative idea is that vibrations are measured at the tower. The critical point is extracting knowledge about the drive-train from tower measurements: this is achieved by measuring simultaneously at the highest possible number of nearby wind turbines. One wind turbine is selected as target and the others are used as reference. The data are analyzed in the time domain basing on statistical features (root mean square, peak, crest factor, skewness, kurtosis). The data set in the feature space reduces to a matrix, from which the observations at the target wind turbine should be distinguishable. The application of this algorithm is supported by univariate statistical tests and by Principal Component Analysis. A novelty index based on the Mahalanobis distance is finally used to detect the statistical novelty of the damaged wind turbine. This work is based on field measurement campaigns, performed by the authors in 2018 and 2019 at wind farms owned by the Renvico company
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