A thermodynamic model was constructed to analyze the negative capacitance effect in the presence of piezoelectricity. The model demonstrated that while piezoelectricity can lead to negative capacitance in principle, it is not strong enough in practice due to the unphysical amounts of charge and strain required. The inclusion of higher-order electromechanical coupling such as electrostriction can make the negative capacitance region accessible at a lower amount of charge. However, the required strains are still unphysical on the order of tens of percent. Furthermore, the material must possess a negative electrostriction coefficient, or else the negative capacitance effect will be suppressed by positive electrostriction. Most commonly used oxides, however, possess positive electrostriction coefficients. Finally, piezoelectricity, electrostriction, and ferroelectricity were analyzed together to show that a negative capacitance effect occurs but due to ferroelectricity and not piezoelectricity. The model ultimately demonstrates that for all practical purposes, pure electromechanical coupling is not strong enough to provide a negative capacitance effect.

关键词：热力学模型;负电容;机电耦合

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Computer graphics rendering is undergoing a renaissance, with physically-based rendering methods based on accurate Monte-Carlo image synthesis replacing ad-hoc techniques in a variety of applications including movie production. In interactive applications like product visualization or video games, physically-based lighting effects are increasingly popular. However, producing photo-realistic images at interactive speeds still remains a challenge.

关键词：计算机图形渲染；基于物理；合成取代

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In recent years, the push for low power wireless sensor networks has called for the introduction of RF-MEMS transceiver devices capable of operating on scavenged power. The design of ultra-low power MEMS based transceivers stands to revolutionize the fields of industrial monitoring, environmental monitoring, and biomedical imaging.

关键词：MEMS;晶体管电路;无线传感器网络

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We present a new model of semantic change that traces the evolution of a word’s meaning through a phylogeny. By mapping meaning changes to Word Net paths, we are able to identify common kinds of semantic change. We find optimal weights for our model using expectation maximization (EM), and use the results to conjecture about the relative frequency of different kinds of semantic change.

关键词：语义变化;概率模型;模型期望最大化（EM）

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The power consumption of a radio generally goes as the number and strength of the RF signals it must process. In particular, a radio receiver would consume much less power if the signal presented to its electronics contained only the desired signal in a tiny percent bandwidth frequency channel, rather than the typical mix of signals containing unwanted energy outside the desired channel. Unfortunately, a lack of filters capable of selecting single channel bandwidths at RF forces the front-ends of contemporary receivers to accept unwanted signals, and thus, to operate with sub-optimal efficiency.

关键词：电力消耗;射频信号;射频滤波器

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We propose Bloom cookies that encode a user’s profile in a compact and privacy-preserving way, without preventing online services from using it for personalization purposes. The Bloom cookies design is inspired by our analysis of a large set of web search logs that shows drawbacks of two profile obfuscation techniques, namely profile generalization and noise injection, today used by many privacy-preserving personalization systems. We find that profile generalization significantly hurts personalization and fails to protect users from a server linking user sessions over time. Noise injection can address these problems, but only at the cost of a high communication overhead and a noise dictionary generated by a trusted third party. In contrast, Bloom cookies leverage Bloom filters as a privacy-preserving data structure to provide a more convenient privacy, personalization, and network efficiency tradeoff: they provide similar (or better) personalization and privacy than noise injection (and profile generalization), but with an order of magnitude lower communication cost and no noise dictionary. We discuss how Bloom cookies can be used for personalized web search, present an algorithm to automatically configure the noise in Bloom cookies given a user’s privacy and personalization goals, and evaluate their performance compared to the state-of-the-art.

关键词：噪声注入;轮廓概括;网络搜索;个性化

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This document describes the RISC-V privileged architecture, which covers all aspects of RISC-V systems beyond the user-level ISA, including privileged instructions as well as additional functionality required for running operating systems and attaching external devices.

关键词：RISC-V;生物医学成像;操作系统

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This project report covers the development of a computational 3D microscope, NoScope. Using tomographic and light field algorithms, we present a method to reconstruct 3D volumes of microscopic samples taken with a lensless sensor. Business and intellectual property strategies for commercializing NoScope are detailed in the first three sections. The remaining sections highlight the project’s technical accomplishments and methods.

关键词：3D显微镜;断层;光场

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Fast optical circuit switches with large port count will allow flexible bandwidth allocation in data center networks by augmenting electrical packet switching. Here we report microsecond speed optical circuit switch with 50x50 port counts implemented on silicon photonics platform using MEMS actuated directional couplers. The switch has fast switching speed (2.5 μs response time), high on-off extinction ratio (25 dB), small footprint (9x9 mm2), and simple fabrication process (3 lithography steps). We believe that our switch port-count can be scaled up to 100 x 100 and beyond.

关键词：光学电路;硅光子;MEMS;带宽

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The sister fields of control and communication share many common goals. While communication aims to reduce uncertainty by communicating information about the state of the world, control aims to reduce uncertainty by moving the state of the world to a known point. Furthermore, transmitters must communicate over the unreliability in the communication channel, while controllers must overcome unreliability in the sensing and actuation channels of the system to stabilize it. Extensive work in information theory has provided a framework with which we can understand the fundamental limits on the communication capacity of a communication channel. This dissertation builds on the information-theoretic perspective to understand the limits on the ability of controllers to actively dissipate uncertainty in systems.

关键词：控制;通讯;参数系统;不确定性

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