8,679 research outputs found

    Graduate Catalog of Studies, 2023-2024

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    A Preliminary Study of the Effect of the Chirped Rotating Wall on a Positron Cloud

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    The density of the positron cloud is a crucial parameter in many applications ofaccumulated positrons. Previous work has shown that adjusting the frequency ofthe rotating wall potential following positron accumulation can be used to controlthe density of positron clouds. In this work, positron clouds were studied afterbeing compressed using a linear rotating wall frequency sweep under a selection ofrotating wall drive amplitudes and cooling gas pressures following an initial staticfrequency compression. This was performed for SF6, CF4, and briefly for CO. Theeffect of changing the cooling gas appears congruent to that shown by the staticfrequency case. The results are in qualitative agreement with previous work byDeller et al., and compare briefly but favourably to a simplistic numerical model

    Approximate Computing Survey, Part I: Terminology and Software & Hardware Approximation Techniques

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    The rapid growth of demanding applications in domains applying multimedia processing and machine learning has marked a new era for edge and cloud computing. These applications involve massive data and compute-intensive tasks, and thus, typical computing paradigms in embedded systems and data centers are stressed to meet the worldwide demand for high performance. Concurrently, the landscape of the semiconductor field in the last 15 years has constituted power as a first-class design concern. As a result, the community of computing systems is forced to find alternative design approaches to facilitate high-performance and/or power-efficient computing. Among the examined solutions, Approximate Computing has attracted an ever-increasing interest, with research works applying approximations across the entire traditional computing stack, i.e., at software, hardware, and architectural levels. Over the last decade, there is a plethora of approximation techniques in software (programs, frameworks, compilers, runtimes, languages), hardware (circuits, accelerators), and architectures (processors, memories). The current article is Part I of our comprehensive survey on Approximate Computing, and it reviews its motivation, terminology and principles, as well it classifies and presents the technical details of the state-of-the-art software and hardware approximation techniques.Comment: Under Review at ACM Computing Survey

    Architecture and Advanced Electronics Pathways Toward Highly Adaptive Energy- Efficient Computing

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    With the explosion of the number of compute nodes, the bottleneck of future computing systems lies in the network architecture connecting the nodes. Addressing the bottleneck requires replacing current backplane-based network topologies. We propose to revolutionize computing electronics by realizing embedded optical waveguides for onboard networking and wireless chip-to-chip links at 200-GHz carrier frequency connecting neighboring boards in a rack. The control of novel rate-adaptive optical and mm-wave transceivers needs tight interlinking with the system software for runtime resource management

    Magnetic Material Modelling of Electrical Machines

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    The need for electromechanical energy conversion that takes place in electric motors, generators, and actuators is an important aspect associated with current development. The efficiency and effectiveness of the conversion process depends on both the design of the devices and the materials used in those devices. In this context, this book addresses important aspects of electrical machines, namely their materials, design, and optimization. It is essential for the design process of electrical machines to be carried out through extensive numerical field computations. Thus, the reprint also focuses on the accuracy of these computations, as well as the quality of the material models that are adopted. Another aspect of interest is the modeling of properties such as hysteresis, alternating and rotating losses and demagnetization. In addition, the characterization of materials and their dependence on mechanical quantities such as stresses and temperature are also considered. The reprint also addresses another aspect that needs to be considered for the development of the optimal global system in some applications, which is the case of drives that are associated with electrical machines

    Dynamic Nanophotonic Structures Leveraging Chalcogenide Phase-Change Materials

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    Chip-scale nanophotonic devices have the potential to enable next-generation imaging, computing, communication, and engineered quantum systems with very stringent performance requirements on size, power, integrability, stability, and bandwidth. The emergence of meta-optic devices with deep subwavelength features has enabled the formation of ultra-thin flat optical structures to replace bulky conventional counterparts in free-space applications. Nevertheless, progress in meta-optics has been slowed due to the passive nature of existing devices and the urgent need for a reliable, fast, low-power, and robust reconfiguration mechanism. In this research, I devised a new material and device platform to resolve this challenge. Through detailed theoretical design, nanofabrication, and experimental demonstration, I demonstrated the unique features of my proposed platform as an essential building block of truly scalable adaptive flat optics for the active manipulation of optical wavefronts. One of the key attributes of this research is the integration of CMOS-compatible materials for the fabrication of passive devices with phase-change materials that provide the largest known modulation of the index of refraction upon stimulation with an optical or electrical signal. A unique selection of phase-change materials for operation in the near-infrared and visible wavelengths has been made, followed by developing the optimum deposition and fabrication processes for the realization of nanophotonics devices that integrate these functional materials with semiconductor and plasmonic materials. A major breakthrough in this process was the design and realization of integrated electrical stimulation circuitry with far better performance compared to existing solutions. Using this platform, I experimentally demonstrated the first electrically tunable meta-optic structure for fast optical switching with a high contrast ratio and dynamic wavefront scanning with a large steering angle. This is a major achievement as it essentially allows the engineering of a desired optical wavefront with fast reconfigurability at low power consumption. In an independent work, I demonstrated, for the first time, a nonvolatile meta-optic structure for high-resolution, wide-gamut, and high-contrast microdisplays with added polarization controllability and the possibility of implementation on a flexible substrate. Further features of this metaphotonic display include: 1) full addressability at the microscale pixel via fast electrical pulses; 2) super-resolution pixels with controllable brightness and contrast; and 3) a wide range of colors with high saturation and purity. Lastly, for the first time, I realized a hybrid photonic-plasmonic meta-optic platform with active control over the spatial, spectral, and temporal properties of an optical wavefront. This is a major achievement as it essentially allows the engineering of a desired optical wavefront with fast reconfigurability at low power consumption. These demonstrations are now being pursued in different directions for novel systems for imaging, sensing, computing, and quantum applications, just to name a few.Ph.D

    Partial Discharge Mitigation in Power Modules using an Automation-Driven Design Rule Development Method

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    Power modules used for the conversion and conditioning of electrical power for applications like electric vehicles, more-electric aircraft, the power grid, etc., are largely designed manually by engineers. Design automation of power modules is starting to gain recognition as a timely and necessary alternative to intuitive manual design and fabrication. With increasing need for wide bandgap materials that can operate at higher voltages, and the need to make modules more compact, hazards like electrical breakdown are more likely. Partial discharge (PD) is a silent and invisible precursor to electrical breakdown. It is compounded with compaction, creating a potential for electrical breakdown and catastrophic failure of the module package. Instead of being the limiting factor, or even a hazard, power module packages need to keep pace with the advancements being made in wide bandgap technology. While the automation of power module design is still new, and research and standards on PD in power modules are limited, this dissertation is a significant step in designing for high voltage operation while assessing tradeoffs against module compaction in an electronic design automation tool. This dissertation describes a method of systematically accounting for partial discharge in power modules using a unique approach where improvements to a module layout are determined in terms of design rules. Trace gaps, in this method, are designed to be functions of operating voltage, substrate and encapsulant material choice, and layer thicknesses of the substrate. These design rules are based on simulations that are validated by physical PD experiments. Furthermore, filleting is performed on the final layouts to further reduce PD by reducing the E-field concentrations by a third. This methodology has been implemented in PowerSynth, an in-house hardware-validated electronic design automation tool that performs electro-thermal and mechanical layout optimization. Before the implementation of this work, layouts were agnostic to PD. From the contribution of this work, the layouts now generated by the tool are PD-mitigated, with a maximum operating voltage for each layer stack. Below the rated voltage, the user can choose multiple voltage-trace gap trade off options for the layout. Demonstrating this implementation in this work shows that the user can achieve either a 24% improvement in voltage level, or a 20% improvement in area reduction, or a trade-off combination of the two. As layouts increase in complexity, these improvements will likely grow. The implementation of this work allows room for growth by allowing customized PD data libraries from various manufacturing lines to inform design rules much like a process design kit in the field of integrated circuit design. The designer using PowerSynth can: 1.) Use default libraries for design rules, or 2.) Perform their own simulations to augment the existing PD data library according to the method presented here, or 3.) Fabricate their own test structures and design corresponding simulations to develop their own complete PD data library and import it to PowerSynth. The manufacturable modules resulting from this tool are thus designed to be practical and reliable for high voltage operation

    Colloquium: Quantum and Classical Discrete Time Crystals

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    The spontaneous breaking of time translation symmetry has led to the discovery of a new phase of matter - the discrete time crystal. Discrete time crystals exhibit rigid subharmonic oscillations, which result from a combination of many-body interactions, collective synchronization, and ergodicity breaking. This Colloquium reviews recent theoretical and experimental advances in the study of quantum and classical discrete time crystals. We focus on the breaking of ergodicity as the key to discrete time crystals and the delaying of ergodicity as the source of numerous phenomena that share many of the properties of discrete time crystals, including the AC Josephson effect, coupled map lattices, and Faraday waves. Theoretically, there exists a diverse array of strategies to stabilize time crystalline order in both closed and open systems, ranging from localization and prethermalization to dissipation and error correction. Experimentally, many-body quantum simulators provide a natural platform for investigating signatures of time crystalline order; recent work utilizing trapped ions, solid-state spin systems, and superconducting qubits will be reviewed. Finally, this Colloquium concludes by describing outstanding challenges in the field and a vision for new directions on both the experimental and theoretical fronts.Comment: 29 pages, 13 figures; commissioned review for Reviews of Modern Physic

    2023-2024 Boise State University Undergraduate Catalog

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    This catalog is primarily for and directed at students. However, it serves many audiences, such as high school counselors, academic advisors, and the public. In this catalog you will find an overview of Boise State University and information on admission, registration, grades, tuition and fees, financial aid, housing, student services, and other important policies and procedures. However, most of this catalog is devoted to describing the various programs and courses offered at Boise State
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