Theses (Electrical Engineering and Computer Science)
http://hdl.handle.net/1957/8163
2016-08-17T02:37:49ZA Structural Theorem For Shortest Vertex-Disjoint Paths Computation in Planar Graphs
http://hdl.handle.net/1957/59656
A Structural Theorem For Shortest Vertex-Disjoint Paths Computation in Planar Graphs
Zafarani, Farzad
Given k terminal pairs (s₁,t₁),(s₂,t₂),..., (s[subscript k],t[subscript k]) in an edge-weighted graph G, the k Shortest Vertex-Disjoint Paths problem is to find a collection P₁, P₂,..., P[subscript k] of vertex-disjoint paths with minimum total length, where P[subscript i] is an s[subscript i]-to-t[subscript i] path. As a special case of the multi-commodity flow problem, computing vertex disjoint paths has found several applications, for example in VLSI design, or network routing. In this thesis we describe a Structural Theorem for a special case of the Shortest Vertex-Disjoint Paths problem in undirected planar graphs where the terminal vertices are on the boundary of the outer face. At a high level, our Structural Theorem guarantees that the i[superscript th] path of the k Shortest Vertex-Disjoint paths does not cross j[superscript th] (j ≠ i) path of the k-1 Vertex-Disjoint Paths problem.
Graduation date: 2017
2016-05-20T00:00:00ZModeling, Fabrication, and Characterization of Magnetic Thin Films for Integrated Inductor and MRAM Applications
http://hdl.handle.net/1957/59655
Modeling, Fabrication, and Characterization of Magnetic Thin Films for Integrated Inductor and MRAM Applications
Buford, Benjamin
Magnetic thin films have potential to improve devices such as on-chip inductors, and enable new technologies such as magnetic random access memory (MRAM).
The use of magnetic cores in on-chip inductors is typically limited to applications well under 1 GHz. At higher frequencies, the performance of the magnetic core is severely limited by eddy current losses and ferromagnetic resonance. This work investigates the feasibility of using shape anisotropy to increase the ferromagnetic resonance frequency and thus allow the use of thin-film magnetic cores at frequencies up to 3 GHz. Magnetic cores are fabricated on top of existing chip- scale inductors. The effect of core shape and oxide layers, which are added to reduce eddy currents, on the magnetic properties of the film are investigated.
Magnetic tunnel junctions (MTJs) are of interest in MRAM and spintronic logic circuit ap- plications due to their non-volatility, low-power operation, and size scalability. One limitation to the creation of scalable magnetic random access memory is thermal stability. For large devices, this energy barrier is proportional to the exchange stiffness of a material. Typically the thermal stability is measured in fabricated MRAM devices, and is used to back-calculate the exchange stiff- ness. This work presents a novel approach which uses images of magnetic domains, in conjunction with vibrating sample magnetometer and ferromagnetic resonance measurements, to measure the exchange stiffness in unpatterned films. This allows for estimation of the thermal stability that can be obtained by a given magnetic free layer without need to fabricate and measure completed de- vices. Using this approach, the exchange stiffness and expected thermal stability in MgO / CoFeB / spacer / CoFeB / MgO free layer structures with various spacer layer materials and thicknesses are compared.
Graduation date: 2017; Access restricted to the OSU Community, at author's request, from August 9, 2016 - August 9, 2018
2016-07-21T00:00:00ZAssessment of Barrier Heights between ZrCuAlNi Amorphous Metal and SiO₂, Al₂O₃, HfO₂, and ZrO₂ using Internal Photoemission Spectroscopy
http://hdl.handle.net/1957/59653
Assessment of Barrier Heights between ZrCuAlNi Amorphous Metal and SiO₂, Al₂O₃, HfO₂, and ZrO₂ using Internal Photoemission Spectroscopy
Klarr, Tyler D.
As scaling of silicon (Si) based devices approaches fundamental limits, thin film metal-insulator-metal (MIM) tunnel diodes are attracting interest due to their potential for high speed operation. Because operation of these devices is based on tunneling, electrode / interfacial roughness is critical. Recently, it was shown that combining ultra-smooth bottom electrodes with insulators deposited via atomic layer deposition (ALD) enables reproducible fabrication of MIM diodes with stable I-V behavior. Key performance parameters of MIM diodes include high I-V asymmetry and low turn-on voltage. The standard way to achieve asymmetry relies on the use of non-equivalent work function metal electrodes to induce a built-in field that creates polarity dependent electron tunneling barrier. Thus the electrical performance of MIM diodes are directly impacted by the nature of the energy barriers at the interfaces.
In this work, we report the first use of internal photoemission spectroscopy (IPE) to measure barrier heights between an amorphous zirconium copper aluminum nickel (ZCAN) metal alloy bottom electrode and several high-k dielectrics deposited via ALD. In IPE, the conduction band offset between two materials is characterized by measuring the additional current created by photo-excitation of carriers under an applied bias (V[subscript app]). Devices were tested in a custom built IPE system.
Graduation date: 2017; Access restricted to the OSU Community, at author's request, from August 9, 2016 - August 9, 2018
2016-05-20T00:00:00ZJoint Resource Scheduling and Peak Power Shaving for Cloud Data Centers with Distributed Uninterruptible Power Supply
http://hdl.handle.net/1957/59652
Joint Resource Scheduling and Peak Power Shaving for Cloud Data Centers with Distributed Uninterruptible Power Supply
AlAnazi, Sultan (Sultan Abdulaziz)
The grid company enforces high penalties for the peak power demands of cloud data centers. These high penalties result in high electricity bills that can be avoided by relying on the servers' Uninterruptible Power Supply (UPS) as a source of energy during peak load periods. This thesis proposes a management framework that exploits the distributed UPS batteries in order to minimize the cluster's total electricity bill. Our framework consists of: i) a scheduler that accounts for both the amount of stored energy and the available resource slacks when making workload placement decision, and ii) a power distributor that decides which UPS battery should store energy and by how much in order to increase the amount of energy that can be accessible during peak periods. Several evaluations based on real Google traces show that our proposed framework achieves significant monetary savings.
Graduation date: 2017; Access restricted to the OSU Community, at author's request, from August 9, 2016 - February 8, 2017
2016-07-25T00:00:00Z