The Orion Multi-Purpose Crew Vehicle is a new spacecraft being designed by NASA and Lockheed Martin for future crewed exploration missions. The Vision Navigation Sensor is a Flash LIDAR that will be the primary relative navigation sensor for this vehicle. To obtain a better understanding of this sensor's performance, the Orion relative navigation team has performed both flight tests and ground tests. This paper summarizes and compares the performance results from the STS-134 flight test, called the Sensor Test for Orion RelNav Risk Mitigation (STORRM) Development Test Objective, and the ground tests at the Space Operations Simulation Center.

关键词：光机电；传感器；STS-134；空间操作仿真中心

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Call a bipartite graph G=(X,Y;E) balanced when |X|=|Y| Given a balanced bipartite graph G with edge costs, the assignment problem asks for a perfect matching in G of minimum total cost. The Hungarian Method can solve assignment problems in time space O(m) and time O(mn + n^2 log n), where n :=|X|=|Y| and m :=|E|. If the edge weights are integers bounded in magnitude by C > 1, then algorithms using weight scaling, such as that of Gabow and Tarjan, can lower the time to O(m sqrt(n) log(nC)).There are important applications in which G is unbalanced, with not equal to and we require a min-cost matching in G of size r := min(|X|, |Y|) or, more generally, of some specified size s <= r. The Hungarian Method extends easily to find such a matching in time O(ms + s^2 log r), but weight-scaling algorithms do not extend so easily. We introduce new machinery that allows us to find such a matching in time O(m sqrt(s) log(sC)) via weight scaling. Our results provide some insight into the design space of efficient weight-scaling matching algorithms.These ideas are presented in greater depth in HPL-2012-40R1.

关键词：分配问题；不完善匹配；最低成本匹配；不平衡的二分图；重量缩放算法

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This document is an official, public delivery of the UK collaborative project EnCoRe (Ensuring Consent and Revocation), coordinated by HP Labs. It describes the final EnCoRe Technical Architecture and solutions to support dynamic consent (whereby data subjects provide or amend informed consent - potentially in a fine- grained way - to govern access and use of their confidential and personal data), policy enforcement and controlled information sharing within and across organizational boundaries. It takes into account technical, legal, user and social requirements. This can include business-specific requirements, and education of end users about privacy risks. This work has been led by HP Labs. HP Labs designed and architected a technical solution to: enable end-users (data subjects) to have better control over their data when (and even after) disclosing this to service providers; enable organisations to enforce authorization and obligation policies when accessing, processing and disclosing data; enable the tracking of data whereabouts; support accountable information- sharing across organizations by means of sticky policy mechanisms and transparency (including notification mechanisms) to the data subject. The EnCoRe architecture and approach has been validated in three case studies. HP Labs has also built a reference implementation of the EnCoRe Architecture, referred to as the HPL EnCoRe Service Framework. This is a generic framework that can be easily configured to different business-specific scenarios. It uses state-of-the-art technology to provide the key EnCoRe capabilities by means of composable, secure services. A fully working prototype and a demonstrator are available. The EnCoRe Service Framework is also available for further exploitation opportunities by HP businesses, customers and business partners. We are currently exploring the opportunity to release a core subset of the EnCoRe Service Framework as Open Source software.

关键词：ENCORE;动态同意；策略执行；信息共享；责任；技术架构；隐私；安全性

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Seqlocks are an important synchronization mechanism and represent a significant improvement over conventional reader-writer locks in some contexts. They avoid the need to update a synchronization variable during a reader critical section, and hence improve performance by avoiding cache coherence misses on the lock object itself. Unfortunately, they rely on speculative racing loads inside the critical section. This makes them an interesting problem case for programming-language-level memory models that emphasize data-race-free programming. We analyze a variety of implementation alternatives within the C++11 memory model, and briefly address the corresponding issue in Java. In the process, we observe that there may be a use for "read-dont-modify- write" operations, i.e. read-modify-write operations that atomically write back the original value, without modifying it, solely for the memory model consequences, and that it may be useful for compilers to optimize such operations.

关键词：内存模型;；seqlocks；读写锁；内存栅栏

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In this paper, we describe T@g, a system designed for effortless and instantaneous sharing of enterprise knowledge through routine email communications and powerful harvesting of such enterprise information using text analytics techniques. T@gz is a system that enables dynamic, non-intrusive and effortless sharing of information within an enterprise and automatically harvests knowledge from such daily interactions. It also allows enterprise knowledge workers to easily subscribe to new information. It enables self organization of information in conversations while it carefully avoids requiring users to substantially change their usual work-flow of exchanging emails. Incorporating this system in an enterprise improves productivity by: a)discovery of connections between employees with converging interests and expertise, similar to social networks naturally leading to formation of interest groups b)avoiding the problem of information lost in mountains of emails c)creating expert profiles by mapping areas of expertise or interests to organizational map Harvested information includes folksonomy appropriate to an organization, tagged and organized conversations and expertise map.

关键词：设计；实验；人为因素

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This paper presents a practical and systematic approach to correctly provision server resources in data centers, such that SLA violations and energy consumption are minimized. In particular, we describe a hybrid method for server provisioning. Our method first applies a novel discretization technique on historical workload traces to identify long-term workload demand patterns that establish a "base" load. It then employs two techniques to dynamically allocate capacity: predictive provisioning handles the predicted base load at coarse time scales (e.g., hours) and reactive provisioning handles any excess workload at finer time scales (e.g., minutes). The combination of predictive and reactive provisioning achieves a significant improvement in meeting SLAs, conserving energy and reducing provisioning cost. We implement and evaluate our approach using traces from four production systems. The results show that our approach can provide up to 35% savings in power consumption and reduce SLA violations by as much as 21% compared to existing techniques, while avoiding frequent power cycling of servers.

关键词：数据中心；电源管理；性能管理；资源分配

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关键词：数据中心；冷却系统；冷却微电网；控制和优化

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We study the minimax pointwise redundancy of universal coding for memoryless models over large alphabets and present two main results: We first complete studies initiated in Orlitsky and Santhanam deriving precise asymptotics of the minimax pointwise redundancy for all ranges of the alphabet size relative to the sequence length. Second, we consider the minimax pointwise redundancy for a family of models in which some symbol probabilities are fixed. The latter problem leads to a binomial sum for functions with super-polynomial growth. Our findings can be used to approximate numerically the minimax pointwise redundancy for various ranges of the sequence length and the alphabet size. These results are obtained by analytic techniques such as tree-like generating functions and the saddle point method.

关键词：数据压缩；冗余；大字母；生成函数；鞍点法

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Hadoop and the associated MapReduce paradigm have become the de facto platform for cost-effective analytics over "Big Data". There is an increasing number of MapReduce applications associated with live business intelligence that require completion time guarantees. In this work, we introduce and analyze a set of complementary mechanisms that enhance workload management decisions for processing MapReduce jobs with deadlines. The three mechanisms we consider are the following: 1) a policy for job ordering in the processing queue; 2) a mechanism for allocating a tailored number of map and reduce slots to each job with a completion time requirement; 3) a mechanism for allocating and deallocating (if necessary) spare resources in the system among the active jobs. We analyze the functionality and performance benefits of each mechanism via an extensive set of simulations over diverse workload sets. The proposed mechanisms form the integral pieces in the performance puzzle of automated workload management in MapReduce environments.

关键词：MapReduce；Hadoop；绩效；资源分配；任务调度

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The World Wide Web and the services it provides are continually evolving. Even for a single time instant, it is a complex task to methodologically determine the infrastructure over which these services are provided and the corresponding effect on user perceived performance. For such tasks, researchers typically rely on active measurements or large numbers of volunteer users. In this paper, we consider an alternative approach, which we refer to as passive crowd-based monitoring. More specifically, we use passively collected proxy logs from a global enterprise to observe differences in the quality of service (QoS) different Web content providers. While some of these properties have been observed using active measurements, we are the first to show that many of these properties (such as location of servers) can be obtained using passive measurements of actual user activity. Passive crowd-based monitoring has the advantages that it does not add any overhead on Web infrastructure, it does not require any specific software on the clients, but still captures the performance and infrastructure observed by actual Web usage.

关键词：万维网；被动监控；以人群为基础的监测

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