An automated procedure for detection and identification of ball bearing damage using multivariate statistics and pattern recognition

This paper suggests an automated approach for fault detection and classification in roller bearings, which is based on pattern recognition and principal components analysis of the measured vibration signals. The signals recorded are pre-processed applying a wavelet transform in order to extract the appropriate high frequency (detailed) area needed for ball bearing fault detection. This is followed by a pattern recognition (PR) procedure used to recognise between signals coming from healthy bearings and those generated from different bearing faults. Four categories of signals are considered, namely no fault signals (from a healthy bearing) inner race fault, outer race fault and rolling element fault signals. The PR procedure uses the first six principal components extracted from the signals after a proper principal component analysis (PCA). In this work a modified PCA is suggested which is much more appropriate for categorical data. The combination of the modified PCA and the PR method ensures that the fault is automatically detected and classified to one of the considered fault categories. The method suggested does not require the knowledge/ determination of the specific fault frequencies and/or any expert analysis: once the signal filtering is done and the PC's are found the PR method automatically gives the answer if there is a fault present and its type

A review of physics-based models in prognostics: application to gears and bearings of rotating machinery

Health condition monitoring for rotating machinery has been developed for many years due to its potential to reduce the cost of the maintenance operations and increase availability. Covering aspects include sensors, signal processing, health assessment and decision-making. This article focuses on prognostics based on physics-based models. While the majority of the research in health condition monitoring focuses on data-driven techniques, physics-based techniques are particularly important if accuracy is a critical factor and testing is restricted. Moreover, the benefits of both approaches can be combined when data-driven and physics-based techniques are integrated. This article reviews the concept of physics-based models for prognostics. An overview of common failure modes of rotating machinery is provided along with the most relevant degradation mechanisms. The models available to represent these degradation mechanisms and their application for prognostics are discussed. Models that have not been applied to health condition monitoring, for example, wear due to metal–metal contact in hydrodynamic bearings, are also included due to its potential for health condition monitoring. The main contribution of this article is the identification of potential physics-based models for prognostics in rotating machinery

Expanding sensor networks to automate knowledge acquisition

The availability of accurate, low-cost sensors to scientists has resulted in widespread deployment in a variety of sporting and health environments. The sensor data output is often in a raw, proprietary or unstructured format. As a result, it is often difficult to query multiple sensors for complex properties or actions. In our research, we deploy a heterogeneous sensor network to detect the various biological and physiological properties in athletes during training activities. The goal for exercise physiologists is to quickly identify key intervals in exercise such as moments of stress or fatigue. This is not currently possible because of low level sensors and a lack of query language support. Thus, our motivation is to expand the sensor network with a contextual layer that enriches raw sensor data, so that it can be exploited by a high level query language. To achieve this, the domain expert specifies events in a tradiational event-condition-action format to deliver the required contextual enrichment

Security Evaluation of Support Vector Machines in Adversarial Environments

Support Vector Machines (SVMs) are among the most popular classification techniques adopted in security applications like malware detection, intrusion detection, and spam filtering. However, if SVMs are to be incorporated in real-world security systems, they must be able to cope with attack patterns that can either mislead the learning algorithm (poisoning), evade detection (evasion), or gain information about their internal parameters (privacy breaches). The main contributions of this chapter are twofold. First, we introduce a formal general framework for the empirical evaluation of the security of machine-learning systems. Second, according to our framework, we demonstrate the feasibility of evasion, poisoning and privacy attacks against SVMs in real-world security problems. For each attack technique, we evaluate its impact and discuss whether (and how) it can be countered through an adversary-aware design of SVMs. Our experiments are easily reproducible thanks to open-source code that we have made available, together with all the employed datasets, on a public repository.Comment: 47 pages, 9 figures; chapter accepted into book 'Support Vector Machine Applications

Solar Splash Senior Design Project

Indiana University Purdue University IndianapolisThe Solar Splash senior project is the first attempt at creating an entirely solar propelled watercraft. The initial project intent was to design and create a supplement meets the specifications and compete in the competition. With this in mind, a budget approach was taken in order to be able to fund the task at hand. As the project progressed toward the end of the low-level design phase it was evident that the competition would not occur. At the midpoint of the project, the goals and objectives had changed entirely. The new focus was targeted at proving the operation of the systems involved in the watercraft. Having been faced with a new series of objectives and an entirely new scope, the project began to appear doable. The primary focus of the project at this point entirely relied on simulation data and data analysis. The idea was not reinventing the wheel but rather verifying that the wheel rolled. Using the designed propulsion, solar and sensors systems, with the help of a combination of software programs, the idea of a budget solution can be seen. The software used tell the story of the boat that would have been created had the project continued down the original proposed path. As systems were tested and analyzed, they were also adjusted and improved upon. The analysis process consumed a lot of time but acted as a highlighter for all the flaws that the system suffered from. This document introduces the design concepts and schematics of the Solar Splash senior design project. Within are detailed drawings and diagrams for the electrical systems devised for the construction operation of the watercraft. This report is a means of displaying the layout of the final product and how all systems tie together. The report will contain detailed information on not only hardware aspects but also software and how those will bridge together. The report is meant to be in layman’s terms and should be easily interpreted at all levels. The bulk of the information found in the report will be found in the testing sections where analysis of a theoretical boat is done. The motor design, solar design, and fluid dynamic analysis of the boat hull and propeller can be found in their respective section. The innerworkings, testing processes and thoughts behind each decision can also be found in these sections. The document begins with a table of contents identifying each main and subcategory of information. The next page is the document identification, revision history, and lesser known definitions. Following that is the introduction and scope. Specification requirements for the ‘general requirements’, ‘electrical requirements’ and ‘mechanical requirements’ are found on the following page. A system flowchart can be found in the high-level Design along with the design decision matrices for each system. The design portion then begins starting with the System-wide design changes and decisions. The hardware and software designs and schematics follow and cover the proposed schematics and drawings for the system. Cost breakdowns for each individual system are also found in the low-level section. Testing methodologies, results and an explanation of the testing software can be found after the low-level design. A summation of all these testing results is found near the tail of the document. Conclusions, recommendations, and appendixes can be found as the last three sections, respectively.Electrical Engineering Technolog

Framework for a space shuttle main engine health monitoring system

A framework developed for a health management system (HMS) which is directed at improving the safety of operation of the Space Shuttle Main Engine (SSME) is summarized. An emphasis was placed on near term technology through requirements to use existing SSME instrumentation and to demonstrate the HMS during SSME ground tests within five years. The HMS framework was developed through an analysis of SSME failure modes, fault detection algorithms, sensor technologies, and hardware architectures. A key feature of the HMS framework design is that a clear path from the ground test system to a flight HMS was maintained. Fault detection techniques based on time series, nonlinear regression, and clustering algorithms were developed and demonstrated on data from SSME ground test failures. The fault detection algorithms exhibited 100 percent detection of faults, had an extremely low false alarm rate, and were robust to sensor loss. These algorithms were incorporated into a hierarchical decision making strategy for overall assessment of SSME health. A preliminary design for a hardware architecture capable of supporting real time operation of the HMS functions was developed. Utilizing modular, commercial off-the-shelf components produced a reliable low cost design with the flexibility to incorporate advances in algorithm and sensor technology as they become available