The goal of this thesis is to study these trade-offs between the computational and statistical aspects of learning problems. This line of research results in several natural questions, some of which are partially addressed in this thesis and others present interesting challenges for future work.

关键词：交流；计算权衡；统计学；数据集；非结构化数据；大数据

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物联网产业是指涉及数据采集、传感器网络组网和协同信息处理、网络通信、智能处理、系统集成、信息安全等各种活动的集合，涵盖传感器芯片、微能源等核心基础产业，传感器、射频识别（RFID）为主的感知制造业，通信网络设备制造、传感器网络设备制造以及机器到机器（M2M）网络设备制造等为主的基础网络制造业，和提供网络传输、信息处理以及运营服务等的应用服务业等。

关键词：物联网；产业资讯；动态监测

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Estimating the running time, number of qubits and other resources needed by realistic models of quantum computers is the rst necessary step to reducing these resource requirements. This report describes our Quantum Resource Estimator (QuRE) toolbox which we used to calculate resource estimates for a cross product of several quantum algorithms, quantum technologies, and error-correction techniques. The focus of this work is on the estimation methodology, overhead caused by error correction, and the software tools that we developed. Our toolbox simulates error correction with the Steane code [1, 2], Bacon-Shor code, Knill's post-selection scheme, and surface code, representing codes from both the concatenated and topological error-correcting code families.

关键词：量子计算；量子资源估计工具箱；估算

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This work studies the revenue-maximizing auction of a single block of spectrum that can be awarded either for exclusive licensed use by one operator or reserved for unlicensed use. A number of operators bid for exclusive licensed use and a group of non-colluding agents bid to keep the spectrum unlicensed. The revenue of this auction is compared to that of a Vickrey-Clarke-Groves (VCG) auction and that of another auction recently proposed.

关键词：收入最优化；代理商；无牌谱

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A common development task is to take a behavior exercised in a single function (e.g., a failing unit test), and to produce an input to the entire program (a system test) with the same behavior. In security, when the behavior is a potential vulnerability, this is constructing a proof-of-concept exploit. This task is challenging because it requires precise reasoning over an entire program. To automate instances of this task, our approach uses symbolic execution to generate program inputs that undergo transformations before they are used. Using information about the relationship of data structures and transformations in a program, our approach works backward, one transformation at a time, and applies optimized symbolic execution to search for transformation pre-images. Our techniques out-perform standard symbolic execution by several orders of magnitude, and construct exploits against two vulnerable document-processing applications without using source code.

关键词：系统测试；符号执行；数据结构转化；

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A challenging problem in dissent networking is that of circumventing large-scale communication blackouts imposed by oppressive governments. Although prior work has not focused on the need for user anonymity, we contend that it is essential. Without anonymity, governments can use communication networks to track and persecute users. A key challenge for decentralized networks is that of resource allocation and control. Network resources must be shared in a manner that deprioritizes unwanted traffic and abusive users. This task is typically addressed through reputation systems that conflict with anonymity. Our work addresses this paradox: We prioritize resources in a privacy-preserving manner to create an attack-resilient, anonymity-preserving, mobile ad-hoc network. Our prioritization mechanism exploits the properties of a social trust graph to promote messagesre layed via trusted nodes. We present Rangzen,a microblogging solution that uses smartphones to opportunistically relay messages among citizens in a delay-tolerant network (DTN) that is independent of government or corporatecontrolled infrastructure.

关键词：通信通电；分散网络；RANGZEN

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We ask whether strictly causal components form well de ned systems when arranged in feedback con gurations. The standard interpretation for such con gurations induces a xed-point constraint on the function modelling the component involved. We de ne strictly causal functions formally, and show that the corresponding xed-point problem does not always have a well de ned solution. We examine the relationship between these functions and the functions that are strictly contracting with respect to a generalized distance function on signals, and argue that these strictly contracting functions are actually the functions that one ought to be interested in. We prove a constructive xed-point theorem for these functions, introduce a corresponding induction principle, and study the related convergence process.

关键词：严格因果分量；反馈配置；定点理论；函数

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The tremendous success of Internet services has led to the rapid growth of Warehouse-Scale Computers (WSCs). The networking infrastructure has become one of the most vital components in a datacenter. With the rapid evolving set of workloads and software, evaluating network designs really requires simulating a computer system with three key features: scale, performance, and accuracy. To avoid the high capital cost of hardware prototyping, many designs have only been evaluated with a very small testbed built with off-the-shelf devices, often running unrealistic microbenchmarks or traces collected from an old cluster. Many evaluations assume the workload is static and that computations are only loosely coupled with the very adaptive networking stack. We argue the research community is facing a hardware-software co-evaluation crisis.In this dissertation, we propose a novel cost-efficient evaluation methodology, called Datacenter-in-a-Box at Low cost (DIABLO), which uses Field-Programmable Gate Arrays (FPGAs) and treats datacenters as whole computers with tightly integrated hardware and software. Instead of prototyping everything in FPGAs, we build realistic reconfigurable abstracted performance models at scales of O(10,000) servers. Our server model runs the full Linux operating system and open-source datacenter software stack, including production software such as memcached. It achieves two orders of magnitude simulation speedup over software-based simulators. This speedup enables us to run the full datacenter software stack for O(100) seconds of simulated time. We have built a DIABLO prototype of a 2,000-node simulated cluster with runtime-configurable 10 Gbps interconnect using 6 multi-FPGA BEE3 boards.

关键词：网络基础设施；网络评估；模拟集群

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Since the beginnings of the semiconductor revolution, device engineering and material development have been deeply interconnected. Innovations in one invariably spurred development in the other. One of the most important current challenges are developing techniques which enable deposition of materials on arbitrary substrates and the design constraints of devices fabricated via these techniques. This thesis focuses on furthering the materials development-device design cycle for three techniques: (i) epitaxial lift-off, (ii) nanowire growth via the vapor-liquid-solid growth mode, and (iii) the thin-film vapor-liquid-solid growth technique. The physics of devices made via (i) and (ii) are discussed in chapters two and three, the material science of (iii) is discussed in chapter four, and a method to engineer the physical and electronic properties of individual nanowires made via (ii) is discussed in chapter two deals with the device physics and performance of ultra-thin compound semiconductor on insulator field effect transistors. Due to its excellent electron transport properties, InAs is used as the material of choice for the transistors, termed XOI FETs. These devices are fabricated utilizing an epitaxial layer transfer technique, enabling highly lattice mismatched single-crystalline layers of InAs to be deposited on Si wafers. Allowing devices which combine the excellent transport properties of compound-semiconductors and the established processing infrastructure for silicon. Chapter three discusses the design constraints and guidelines for nanopillar photovoltaics, specifically those fabricated utilizing the CdS/CdTe material system. Critically, the materials parameters that are favorable to non-planar cells are discussed, and the performance expectations for CdS/CdTe nanopillar photovoltaics are discussed.

关键词：器件物理；材料科学；技术发展

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In 1965 Klyuev and Kokovkin-Shcherbak proved that that n^3/3n3+O(n^2)multiplications are necessary to solve an n-by-n system of linear equations. In 1969 Strassen proved O(n^(log2 7)) multiplications are sucient. They could both be right because they considered di erent models of permitted algorithms. Here we propose yet another algorithmic model, closer in spirit to Klyuev and Kokovkin-Shcherbak, but suciently more general to be able to provide lower bounds on the number of arithmetic operations required to perform dense, sparse or \structured" one-sided matrix factorizations: The simplest (and overly restrictive) version of our assumption is that each scalar result is computed using only the data on which it depends mathematically. We compare these lower bounds with a variety of algorithms and matrix sparsity patterns and algebraic structures (such as Vandermonde). Depending on the sparsity patterns and structures, conventional algorithms may or may not attain the lower bounds. In some cases when they do not, we present new algorithms that do. These bounds are based on a simple, general lower bound for the arithmetic complexity of computing rational functions.

关键词：算法模型；代数结构；算数运算；

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