There is a growing interest in autonomous driving systems that can safely rely on multiple sensors including GNSS, IMU, Radar and LiDAR to navigate with high accuracy, integrity, continuity, and availability in complex urban environments. Many existing data sets, collected with multi-sensor platforms, focus on validating different variations of visual localization algorithms like SLAM, place recognition, object detection and visual odometry that help navigate in sky-obstructed and GNSS-denied environments. However, GNSS still plays a vital role in providing the most assured navigation solution. In this thesis, we develop a robust system intended for collecting data sets that will support the design of tightly integrated navigation algorithms and the analysis of integrity risk using GNSS coupled with IMU, Radar, and LiDAR in challenging automotive environments. GNSS pseudorange, doppler, and carrier phase and IMU acceleration and angular velocities are measurements that the system is specifically designed to collect for sensor-fusion algorithm refinement. In addition, time synchronization between sensors is crucial in data sets validating tightly integrated navigation, especially in applications with high dynamics. However, there is no widely accepted accurate and stable method for synchronizing clocks between different sensor types. We implement a common-clock synchronization and a hardware-trigger clock synchronization between multiple sensors. We then collect a preliminary data set to compare the accuracy and stability of sensor time-tagging using a GNSS-receiver-generated hardware trigger versus using a local-clock ROS-based time stamping. We evaluate the impact of these synchronization methods on mapping accuracy performance. / Master of Science / There is a growing interest in vehicles that can drive themselves without human intervention. Typically, these vehicles must rely on different types of sensors that perceive the environment in different ways and complement each other to navigate complex environments. Many algorithms have been developed to use the measurements from these sensors to accurately determine the vehicle position, velocity and orientation with high accuracy. Many existing data sets intended to validate these algorithms focus on sensors that use visual perception to navigate. In this thesis, we develop a robust data collection system to support (a) the validation of innovative navigation system design that make full use of complementary sensor properties and (b) the quantification of how much trust we can put into the navigation solution. In addition, tight integration of these sensors requires accurate timing of the measurements across multiple sensors. However, there is no widely accepted method of synchronizing clocks between multiple sensor types. We implement a first method in which all sensor information is time-stamped using a common clock, and a second method in which one sensor sends a pulse to another to synchronize their two clocks. To compare the accuracy and stability of these synchronization methods, we collect a preliminary data set.

The MSU ERC UltraScope system consists of a distributed computing system, custom PCI cards, GPS receivers, and a re-radiation system. The UltraScope system allows precision timestamping of events in a distributed application on a system where the CPU and PCI clocks are phase-locked. The goal of this research is to expand the UltraScope system, using software routines and minimal hardware modifications, to allow precision timestamping of events on an asynchronous distributed system. The timestamp process is similar to the Network Time Protocol (NTP) in that it uses a series of timestamps to improve precision. As expected, the precision is less accurate on an asynchronous system than on a synchronous system. Results show that the precision is improved using this sequence of timestamps, and the major error component is due to operating system delays. The errors associated with this timestamping process are characterized using a synchronous system as a baseline.

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The act of predicting rhythmic events and coordinating these predictions with motor actions is seen in many elements of human existence (e.g., walking, dancing, or speaking). Several studies have shown that the efficiency of synchronizing actions with an anticipatable repeating stimulus differs between musicians and non-musicians. This difference is particularly evident when examining two commonly measured metrics of synchronization tasks, (a) asynchrony, or the differential in temporal distance between a recurring stimulus and its associated motor reaction; and (b) variability, or the degree to which successive synchronization actions are distanced from each other relative to repeated stimuli. The purpose of this study was to determine the extent to which differences in asynchrony and variability might be related to the type of musical experiences received in secondary school. It was hypothesized that students who received a greater amount of musical training would exhibit reduced asy / Music Education

Even without formal training, adults can easily perceive, clap, tap, and move in time to a musical beat, but these behaviours are more difficult for children and the development of these abilities in childhood is not well understood. Until the present thesis, there were no developmentally appropriate tasks to separately assess musical beat perception and beat synchronization in children. In Chapter 2, I created a child friendly video judgment task to assess beat perception in the context of both simple and complex musical timing, and demonstrated that five-year-old children’s ability to perceive both tempo- and phase-driven beat misalignments is affected by metric complexity. In Chapter 3, I again used the complex Beat Alignment Task (cBAT) to show that the detection of beat misalignment is not significantly affected by the inclusion of dynamic video stimuli compared to static images. Chapter 4 expanded the perception task by adding a tapping synchronization component, and tested both five- and seven-year-old children. The complex Beat Alignment and Tapping Task (cBATT) showed that although children’s overall perceptual sensitivity improves with age, the perceptual bias for simple structures persists. However, although children were significantly better at tapping to metronomes than to songs, musical tapping synchronization was not obviously affected by metric complexity. Instead, performance related to other acoustic characteristics of the music, such as spectral flux, energy, and density. Together, these findings suggest that musically untrained children are sensitive to phase and tempo information in a perception-only task, and show perceptual specialization for culturally typical musical metres, but this is not the case for production. Thus, beat synchronization ability appears to be somewhat dissociated from beat perception in children. These studies represent the first use of a developmentally appropriate task to separately assess children’s beat perception and synchronization while also examining the role of metre and early experience. / Thesis / Doctor of Philosophy (PhD)

Object-oriented programming has had a significant impact on software development because it provides programmers with a clear structure of a large system. It encapsulates data and operations into objects, groups objects into classes and dynamically binds operations to program code. With the emergence of multi-core processors, application developers have to explore concurrent programming to take full advantage of multi-core technology. However, when it comes to concurrent programming, object-oriented programming remains elusive as a useful programming tool. Most object-oriented programming languages do have some extensions for concurrency, but concurrency is implemented independently of objects: for example, concurrency in Java is managed separately with the Thread object. We employ a programming model called Lime that combines action systems tightly with object-oriented programming and implements concurrency by extending classes with actions and guarded methods. This provides programmers with a unified and straightforward design view for a concurrent object-oriented program. In this work, using coroutines with guarded methods and actions is proposed as a means of implementing the concurrency extension for objects. Mapping objects to coroutines can result in stack overflow as the number of objects increases. A dynamically segmented stack mechanism, which does not introduce runtime overhead, is implemented to support large-scale concurrency. Since Lime allows guarded methods and actions to "get stuck," a new user-level cooperative scheduler, and a fast coroutine context switch mechanism are implemented to improve the performance. Compared with the traditional segmented stack mechanisms, the new dynamically segmented stack mechanism gets equal performance for more common scenarios. Besides, it outperforms the contemporary stack mechanisms for deep recursion scenarios. Above all, Lime does not only provide the programmers with a unified and straightforward object-oriented programming model for concurrency, but also accomplishes a better performance than concurrent programming languages such as Erlang and Go, in fine-grained, highly concurrent benchmarks. / Thesis / Doctor of Philosophy (PhD)

No / The main attributes that have been used to conserve the energy in wireless sensor networks (WSNs) are clustering, synchronization and low-duty-cycle operation. Clustering is an energy efficient mechanism that divides sensor nodes into many clusters. Clustering is a standard approach for achieving energy efficient and hence extending the network lifetime. Synchronize the schedules of these clusters is one of the primary challenges in WSNs. Several factors cause the synchronization errors. Among them, clock drift that is accommodated at each hop over the time. Synchronization by means of scheduling allows the nodes to cooperate and transmit data in a scheduled manner under the duty cycle mechanism. Duty cycle is the approach to efficiently utilize the limited energy supplies for the sensors. This concept is used to reduce idle listening. Duty cycle, nodes clustering and schedules synchronization are the main attributes we have considered for designing a new medium access control (MAC) protocol. The proposed OLS-MAC protocol designed with the target of making the schedules of the clusters to be overlapped with introducing a small shift time between the adjacent clusters schedules to compensate the clock drift. The OLS-MAC algorithm is simulated in NS-2 and compared to some S-MAC derived protocols. We verified that our proposed algorithm outperform these protocols in number of performance matrix.

This research investigates the application of multiuser interference suppression to direct-sequence code-division multiple-access (DS-CDMA) for peer-to-peer packet radio networks. The emphasis of this work is to develop and validate efficient interference suppression techniques through selective cancellation of interference; next, the combination of interference suppression with error correction coding is studied. A decoder-assisted frame synchronization technique is proposed for future packet radio system. The performance of DS-CDMA in packet radio networks suffers from the near-far problem. This near-far problem can be alleviated by using either a multiuser receiver or a single-user adaptive receiver along with centralized or distributed power control. The first part of this dissertation compares the use of these receivers in a peer-to-peer environment. Next, we investigate how interference cancellation can be combined with forward error correction coding for throughput enhancement of the system. Although receivers using interference suppression are simple in structure, the performance degrades due to the lack of exact knowledge of the interfering signal in cancellation and also due to biased decision statistics for the parallel cancellation case. We consider a system that employs both partial parallel interference cancellation and convolutional coding. Information is shared between the operations of interference cancellation and decoding in an iterative manner, using log-likelihood ratios of the estimated coded symbols. We investigate the performance of this system for both synchronous and asynchronous CDMA systems, and for both equal and unequal signal powers. Finally, a new code-assisted frame synchronization scheme, which uses the soft-information of the decoder, is proposed and evaluated. The sync bits are placed in the mid-amble, and encoded as a part of the data sequence using the error correction encoder to resolve time ambiguities. This technique is applied for turbo decoder-assisted frame synchronization. The performance improvement of these proposed techniques over conventional synchronization techniques is explored via simulation. / Ph. D.

Phasor Measurement Units (PMUs) have been instrumental in building a reliable and robust Power System. Recent blackouts have increased the importance of PMUs and PMUs from various manufacturers are being installed in the in large quantities in the North American Grid. The interoperability and accuracy of these PMUs is important to obtain full benefit of the wide area monitoring systems. With the large number of installed PMUs it has become necessary to validate their performance and understand the limitations of each model. A test system was built by NIST in cooperation with NASPI to test for compliance to the existing IEEE C37.118 standard. This thesis presents the development of a Steady State Test System at Virginia Tech based on the NIST Steady State Testing system. The various issues that were faced during the process of development are discussed and the methodology implemented for solving these problems is described. This thesis also presents the additional benefits derived from the results obtained when different PMUs were tested using the Virginia Tech PMU Steady State Test System. / Master of Science

The objective of this experiment was to examine the effects of varying the interval from follicular wave emergence to progestin removal on follicular dynamics and the synchrony of estrus. The experimental design was a 2x2x2 factorial with GnRH or estradiol-17 beta (E2) + progesterone (P4), controlled internal drug-releasing device (CIDR) treatment duration, and PG or saline treatment as main effects. Cycling, Angus cows (n=49), on d 6 to 8 of the estrous cycle, were randomly assigned to receive a CIDR treatment for 7 or 9 d. Approximately half of the cows from each CIDR group received either GnRH (100 mcg) or E2+P4 (1 mg E2 + 100 mg P4) at CIDR insertion. Cows in GnRH or E2+P4 groups were further divided into those that received PG (37.5 mg) or saline at CIDR insertion. All cows received PG (25 mg) 1 d prior to CIDR removal. The interval from follicular wave emergence to CIDR removal was longer for cows treated with GnRH (6.6 d) or a CIDR for 9 d (6.5 d) compared to those treated with E2+P4 (4.7 d) or a 7-d CIDR (4.8 d) (P < 0.05). Cows treated with PG or GnRH at CIDR insertion or a 9-d CIDR had a larger dominant follicle (DF) at CIDR removal than those treated with saline, E2+P4, or a 7-d CIDR. (P < 0.07). Altering the interval from wave emergence to progestin removal created differences in size of the DF at CIDR removal but did not affect the synchrony of estrus. / Master of Science