Matching Items (14)
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- All Subjects: Simulation
- All Subjects: IRB process
- Creators: Aukes, Daniel
Description
Magnetic Resonance Imaging using spiral trajectories has many advantages in speed, efficiency in data-acquistion and robustness to motion and flow related artifacts. The increase in sampling speed, however, requires high performance of the gradient system. Hardware inaccuracies from system delays and eddy currents can cause spatial and temporal distortions in the encoding gradient waveforms. This causes sampling discrepancies between the actual and the ideal k-space trajectory. Reconstruction assuming an ideal trajectory can result in shading and blurring artifacts in spiral images. Current methods to estimate such hardware errors require many modifications to the pulse sequence, phantom measurements or specialized hardware. This work presents a new method to estimate time-varying system delays for spiral-based trajectories. It requires a minor modification of a conventional stack-of-spirals sequence and analyzes data collected on three orthogonal cylinders. The method is fast, robust to off-resonance effects, requires no phantom measurements or specialized hardware and estimate variable system delays for the three gradient channels over the data-sampling period. The initial results are presented for acquired phantom and in-vivo data, which show a substantial reduction in the artifacts and improvement in the image quality.
ContributorsBhavsar, Payal (Author) / Pipe, James G (Thesis advisor) / Frakes, David (Committee member) / Kodibagkar, Vikram (Committee member) / Arizona State University (Publisher)
Created2013
Description
With the advent of GPGPU, many applications are being accelerated by using CUDA programing paradigm. We are able to achieve around 10x -100x speedups by simply porting the application on to the GPU and running the parallel chunk of code on its multi cored SIMT (Single instruction multiple thread) architecture. But for optimal performance it is necessary to make sure that all the GPU resources are efficiently used, and the latencies in the application are minimized. For this, it is essential to monitor the Hardware usage of the algorithm and thus diagnose the compute and memory bottlenecks in the implementation. In the following thesis, we will be analyzing the mapping of CUDA implementation of BLIINDS-II algorithm on the underlying GPU hardware, and come up with a Kepler architecture specific solution of using shuffle instruction via CUB library to tackle the two major bottlenecks in the algorithm. Experiments were conducted to convey the advantage of using shuffle instru3ction in algorithm over only using shared memory as a buffer to global memory. With the new implementation of BLIINDS-II algorithm using CUB library, a speedup of around 13.7% was achieved.
ContributorsWadekar, Ameya (Author) / Sohoni, Sohum (Thesis advisor) / Aukes, Daniel (Committee member) / Redkar, Sangram (Committee member) / Arizona State University (Publisher)
Created2017
Description
In this paper, we discuss the methods and requirements to simulate a soft bodied beam using traditional rigid body kinematics to produce motion inspired by eels. Eels produce a form of undulatory locomotion called anguilliform locomotion that propagates waves throughout the entire body. The system that we are analyzing is a flexible 3D printed beam being actively driven by a servo motor. Using the simulation, we also analyze different parameters for these spines to maximize the linear speed of the system.
ContributorsKwan, Anson (Author) / Aukes, Daniel (Thesis director) / Marvi, Hamidreza (Committee member) / Barrett, The Honors College (Contributor) / Engineering Programs (Contributor)
Created2022-05
Description
Undulatory locomotion is a unique form of swimming that generates thrust through the propagation of a wave through a fish’s body. The proposed device utilizes a constrained compliant material with a single actuator to generate an undulatory motion. This paper draws inspiration from Anguilliformes and discusses the kinematics and dynamics of wave propagation of an underwater robot. A variety of parameters are explored through modeling and are optimized for thrust generation to better understand the device. This paper validates the theoretical spine behavior through experimentation and provides a path forward for future development in device optimization for various applications. Previous work developed devices that utilized either paired soft actuators or multiple redundant classical actuators that resulted in a complex prototype with intricate controls. The work of this paper contrasts with prior work in that it aims to achieve undulatory motion through passive actuation from a single actively driven point which simplifies the control. Through this work, the goal is to further explore low-cost soft robotics via bistable mechanisms, continuum material properties, and simplified modeling practices.
ContributorsKwan, Anson (Author) / Aukes, Daniel (Thesis advisor) / Zhang, Wenlong (Committee member) / Marvi, Hamid (Committee member) / Arizona State University (Publisher)
Created2023
Description
Laminate devices have the potential to lower the cost and complexity of robots. Taking advantage of laminate materials' flexibility, a high-performance jumping platform has been developed with the goal of optimizing jump ground clearance. Four simulations are compared in order to understand which dynamic model elements (leg flexibility, motor dynamics, contact, joint damping, etc.) must be included to accurately model jumping performance. The resulting simulations have been validated with experimental data gathered from a small set of physical leg prototypes spanning design considerations such as gear ratio and leg length, and one in particular was selected for the fidelity of performance trends against experimental results. This simulation has subsequently been used to predict the performance of new leg designs outside the initial design set. The design predicted to achieve the highest jump ground clearance was then built and tested as a demonstration of the usefulness of this simulation.
ContributorsKnaup, Jacob W (Author) / Aukes, Daniel (Thesis director) / Sugar, Thomas (Committee member) / Engineering Programs (Contributor) / Barrett, The Honors College (Contributor)
Created2019-05
Description
The creative project was to create a working prototype kit that can teach multiple lessons of the curriculum that the schools or individual families could purchase. The curriculum would be centered on the engineering and science curriculum that is introduced from fourth to sixth grade classes. By creating an interactive kit with curriculum that the students could individualize and use for multiple lessons, the goal is to get them more engaged in the material. The project would consist of a week-long project kit that will introduce different engineering topics for three to four days of the week with mini projects and a final project that pieces together the topics they learned. The biggest take away from the project was how to best get user feedback and fast track the IRB process. The IRB process for a project focusing on minors and teachers will cause some catches in the process. Included is a discussion on the IRB process for a project like this and how to best go through or avoid IRB to ensure the project can progress, while still gathering valuable information.
ContributorsHeun, Jade (Author) / Aukes, Daniel (Thesis director) / Sugar, Thomas (Committee member) / Barrett, The Honors College (Contributor) / Engineering Programs (Contributor)
Created2022-05
ContributorsHeun, Jade (Author) / Aukes, Daniel (Thesis director) / Sugar, Thomas (Committee member) / Barrett, The Honors College (Contributor) / Engineering Programs (Contributor)
Created2022-05
ContributorsHeun, Jade (Author) / Aukes, Daniel (Thesis director) / Sugar, Thomas (Committee member) / Barrett, The Honors College (Contributor) / Engineering Programs (Contributor)
Created2022-05
ContributorsHeun, Jade (Author) / Aukes, Daniel (Thesis director) / Sugar, Thomas (Committee member) / Barrett, The Honors College (Contributor) / Engineering Programs (Contributor)
Created2022-05
ContributorsHeun, Jade (Author) / Aukes, Daniel (Thesis director) / Sugar, Thomas (Committee member) / Barrett, The Honors College (Contributor) / Engineering Programs (Contributor)
Created2022-05