Customization and automation in the future of digital forensics: live OS forensics with FENIX (forensic examiner unix)

FENIX (Forensic Examiner uNIX) is a Linux based live OS (Operating System) created to be used in remote environments for incident response and digital forensics. Between a joint effort between the Center for Information Protection (CIP) and the Iowa State University Police Department (ISUPD), FENIX has been tailored to suit the needs and requests of law enforcement forensic specialists. The very basis for FENIX is to allow ISU police officers the ability to carry an easy to operate and customize forensic toolkit with them at the scene of a crime allowing for better acquisitions and a deeper analysis to be conducted in an investigation. FENIX isn\u27t a standard forensic toolkit as others are. FENIX is a custom build of the Linux kernel with several of its own applications created for specific OS and forensic purposes and designed for a user friendly interface. However, since most users will be more familiar with existing tools those tools have the ability to interface easily with FENIX

Quantitative characterization technology for nanometer spaced head-disk systems

Master'sMASTER OF ENGINEERIN

Dynamic Characterisation of the Head-Media Interface in Hard Disk Drives using Novel Sensor Systems

Hard disk drives function perfectly satisfactorily when used in a stable environment, but in certain applications they are subjected to shock and vibration. During the work reported in this thesis it has been found that when typical hard disk drives are subjected lo vibration, data transfer failure is found to be significant at frequencies between 440Hz and 700Hz, at an extreme, failing at only Ig of sinusoidal vibration. These failures can largely be attributed to two key components: the suspension arm and the hard disk. At non-critical frequencies of vibration the typical hard disk drive can reliably transfer data whilst subjected to as much as 45g. When transferring data to the drive controller, the drive's operations are controlled and monitored using BIOS commands. Examining the embedded error signals proved that the drive predominantly failed due lo tracking errors. Novel piezo-electric sensors have been developed to measure unobtrusively suspension arm and disk motion, the results from which show the disk to be the most significant failure mechanism, with its First mode of resonance at around 440Hz. The suspension arm movement has been found to be greatest at IkHz. Extensive modelling of the flexure of the disk, clamped and unclamped, has been undertaken using finite element analysis. The theoretical modelling strongly reinforces the empirical results presented in this thesis. If suspension arm movement is not directly coupled with disk movement then a flying height variation is created. This, together with tracking variations, leads to data transfer corruption. This has been found to occur at IkHz and 2kHz. An optical system has been developed and characterised for a novel and inexpensive flying height measurement system using compact disc player technology

Comprehensive modeling and robust nonlinear control of HDD servo systems

Ph.DDOCTOR OF PHILOSOPH

Overactuated systems coordination

The economic growth inherent to our nowadays society pushes the industries toward better performances. In the mechatronic context, the increasing competition results in more and more stringent specifications. Thus, the multiple objectives to track become hard to achieve without compromises. A potential interesting solution to this problematic is overactuation, in the sense that, the considered system has more actuated degrees of freedom than the minimal number required to realize a task. Indeed, overactuation enables flexible and efficient responses to a high variety of tasks. Moreover, the coordinated combination of different subsystems enables both to combine their advantages and to cancel their disadvantages. However, the successful coordination of the supplementary degrees of freedom at our disposal, thanks to overactuation, is not trivial. As a matter of fact, the problem of unpredictable response of overactuated systems to a periodic excitation can be particularly critical. Furthermore, the flexibility brought by the overactuation is to be used efficiently in order to justify its corresponding complexity and higher costs. In this sense, the tracking of multiple simultaneous objectives are clearly enabled by the overactuation and thus constitutes a clear motivation for such a solution. As a consequence, the constructive coordination of overactuated systems, which can be very difficult, is very important to achieve stringent objectives. This thesis aims at contributing to the improvement of the coordination of such systems. In this context, three axis of research are considered: differential geometry, potential functions and closed-loop control. Each of these axis is to be taken as a separate insight on the overall coordination of overactuated systems. On the one hand, the formalism of differential geometry enables a solution to the unpredictability problem raised here above. An intelligent parameterization of the solution space to a periodic task enforces the predictability of the subsystem responses. Indeed, the periodicity of the task is transferred to the latter subsystem responses, thanks to an adequate coordination scheme. On the second hand, potential functions enable the coordination of multiple simultaneous objectives to track. A clear hierarchy in the tasks priority is achieved through their successive projections into reduced orthogonal subspaces. Moreover, the previously mentioned predictability problem is also re-examined in this context. Finally, in the frame of an international project in collaboration with the European Southern Observatory (ESO), an opto-mecatronic overactuated system, called Differential Delay Line, enables the consideration of closed-loop coordination. The successful coordination of the subsystems of the Differential Delay Line, combining their intrinsic advantages, is the key control-element ensuring the achievement of the stringent requirements. This thesis demonstrates that a constructive coordination of the supplementary degrees of freedom of overactuated systems enables to achieve, at least partly, the stringent requirements of nowadays mechatronics

REAL-TIME SIGNAL PROCESSING FOR FLYING HEIGHT MEASUREMENT AND CONTROL IN HARD DRIVES SUBJECT TO SHOCK AND VIBRATION

Merged with duplicate record 10026.1/829 on 10.04.2017 by CS (TIS)Three readback signal detection methods are investigated for real-time flying height or head disk spacing variation measurement under vibration conditions. This is carried out by theoretical analysis, numerical simulation, and experimental study. The first method (amplitude detection) provides a simple way to study the head disk spacing change. The second method ( PW50 parameter estimation) can be used effectively for real-time spacing variation measurement in normally operated hard disk drives, primarily in low frequency spacing variation conditions. The third method (thermal signal detection), on the other hand, is more effective and suitable for high frequency spacing variation measurement. By combining the PW50 estimation and thermal signal detection methods, a noval spacing variation detection method for the whole frequency range is constructed. This combined signal detection method not only has been used to study the head disk spacing variation itself, but also has the potential of being used for real time flying height control. Analytical models are developed for head disk assembly and head position servo control mechanisms to analyse the operation failure of hard disk drives under vibration conditions. Theoretical analysis and numerical simulation show their good agreement with experimental results. A novel active flying height control method is proposed to suppress the flying height or head-disk spacing variation in hard disk drives under vibration conditions. Simulation results show that this active flying height control can effectively suppress the head-disk spacing variation, therefore the performance and reliability of HDDs can be well improved when working in vibration conditions: The method has a good potential to be applied to future ruggedized hard disk drives

A Literature Review on the Application of Acoustic Emission to Machine Condition Monitoring

Acoustic emission (AE) is a common physical phenomenon, in which the strain energy is released in the form of elastic wave when a material is deformed or cracked during the stress process. The condition monitoring based on AE is a relatively new method that aims to use noise/vibration anomalies to detect machine failures. However, some challenges lie ahead of its application. This thesis aims to analyze the literature in the field of AE applications to machine condition monitoring. The principles of AE technology, relevant instruments, machine monitoring and AE signal analysis, and practical examples of AE monitoring applications will be presented. More specifically, challenges, solutions and future direction in solving signal noise and attenuation challenges will be discussed. Through the example of rotating machinery, the characteristics of AE will be explained in detail. This thesis lays the foundation for the actual use of AE to monitor and analyze the state of machinery and provides guideline for future data collection and analysis of AE signals