Communication, i.e., moving data, between levels of a memory hierarchy or between parallel processors on a network, can greatly dominate the cost of computation, so algorithms that minimize communication can run much faster (and use less energy) than algorithms that do not. Motivated by this, attainable communication lower bounds were established for a variety of algorithms including matrix computations. The lower bound approach used initially for Theta(N3) matrix multiplication, and later for many other linear algebra algorithms, depended on a geometric result by Loomis and Whitney: this result bounded the volume of a 3D set (representing multiply-adds done in the inner loop of the algorithm) using the product of the areas of certain 2D projections of this set (representing the matrix entries available locally, i.e., without communication). Using a recent generalization of Loomis' and Whitney's result, we generalize this lower bound approach to a much larger class of algorithms, that may have arbitrary numbers of loops and arrays with arbitrary dimensions as long as the index expressions are a ne combinations of loop variables. In other words, the algorithm can do arbitrary operations on any number of variables like A(i(sub 1), i(sub 2), i(sub 2) - 2i(sub 1), 3 - 4i(sub 3) + 7i(sub 4), ...). Moreover, the result applies to recursive programs, irregular iteration spaces, sparse matrices, and other data structures as long as the computation can be logically mapped to loops and indexed data structure accesses. We also discuss when optimal algorithms exist that attain the lower bounds; this leads to new asymptotically faster algorithms for several problems.

关键词：微分方程；线性代数；通信；数据结构；数据传输

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Devices that provide hearing protection, situational awareness and radio communications are often referred to as Communications and Hearing Protection Systems (C&HPS). Soldiers use these systems to maintain auditory awareness within their environment, communicate with their team members and protect their hearing. Each of the three features of select C&HPS (hearing protection, speech communication and situational awareness) were independently evaluated by the U.S. Army Research Laboratory (ARL). This report is the third in a series of three and focuses on the auditory localization performance obtained from two commercially available C&HPS: Nacre QuietPro and Silynx QuietOps. These two systems were selected from three C&HPS evaluated for attenuation characteristics in the first report and speech intelligibility in the second report; the third system provided insufficient attenuation to be included. Results of the auditory localization testing indicated that both C&HPS negatively affected auditory localization accuracy performed in background noise, but the observed decrement was not significantly different between the two systems. Evidence from objective measures of the systems such as directivity, calculation of interaural level differences (ILDs), and the measurement of input/output functions indicate that changes in binaural intensity difference cues were the primary factor driving the reduction in performance.

关键词：通信和广播系统;背景噪音;语音通信;输入输出处理

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With the growth of the digital economy, more economic activities are taking place on the Internet, potentially reducing geographic constraints, increasing efficiency, and improving growth prospects for rural communities. Rural America, however, may be at a disadvantage in reaping the benefits of this growth because rural households are still less likely to subscribe to the Internet than are urban households. By 2010, only 62 percent of U.S. rural households and farms had home subscriptions to the Internet, compared with 73 percent of urban households. Broadband technology has become the technology of choice for Internet users (wherever it is available)-96 percent of urban and 92 percent of rural household Internet subscribers use broadband. Nevertheless, broadband Internet connections (which offer higher speed Internet access than dial-up connections) are not available as often, nor used as readily by rural households as by urban households.

关键词：农村地区；宽带；电信；通讯网络

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This paper presents a concept for a human mission to Mars orbit that features direct robotic exploration of the planet s surface via teleoperation from orbit. This mission is a good example of Human Exploration using Real-time Robotic Operations (HERRO), an exploration strategy that refrains from sending humans to the surfaces of planets with large gravity wells. HERRO avoids the need for complex and expensive man-rated lander/ascent vehicles and surface systems. Additionally, the humans are close enough to the surface to effectively eliminate the two-way communication latency that constrains typical robotic space missions, thus allowing real-time command and control of surface operations and experiments by the crew. Through use of state-of-the-art telecommunications and robotics, HERRO provides the cognitive and decision-making advantages of having humans at the site of study for only a fraction of the cost of conventional human surface missions. It is very similar to how oceanographers and oil companies use telerobotic submersibles to work in inaccessible areas of the ocean, and represents a more expedient, near-term step prior to landing humans on Mars and other large planetary bodies. Results suggest that a single HERRO mission with six crew members could achieve the same exploratory and scientific return as three conventional crewed missions to the Mars surface.

关键词：火星任务；指挥和控制；即时操作；通信

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Ensuring the effectiveness and reliability of communications networks is essential to national security, the economy, and public health and safety. The communications networks (including core and access networks) can be threatened by both natural and human-caused events, including increasingly sophisticated and prevalent cyber-based threats. GAO has identified the protection of systems supporting the nation's critical infrastructure--which includes the communications sector--as a government-wide high-risk area. GAO was asked to (1) identify the roles of and actions taken by key federal entities to help protect communications networks from cyber-based threats, (2) assess what is known about the extent to which cyber incidents affecting the communications networks have been reported to the FCC and DHS, and (3) determine if Defense's pilot programs to promote cybersecurity in the defense industrial base can be used in the communications sector. To do this, GAO focused on core and access networks that support communication services, as well as critical components supporting the Internet. GAO analyzed federal agency policies, plans, and other documents; interviewed officials; and reviewed relevant reports.

关键词：通信；计算机网络；计算机安全；国家安全

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This document describes the process in which people receive and process information in order to take action during emergencies. Then, the document presents guidance on how to create and disseminate emergency information in the face of rapid-onset disasters providing guidance on the dissemination of alert signals, the creation of the warning message, the formatting of messages for both visual and audible means, and the dissemination of the warning message. The document ends with a discussion of research questions still left unanswered, and future efforts necessary to complete a comprehensive document on emergency message creation and dissemination for building disasters.

关键词：通信和无线电系统；建筑；报警系统；预警系统

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Papers published via IEEE and AIAA conferences have presented an overview of how social media could benefit NASA working environments in general and proposed three specific social applications to benefit space flight control operations. 

关键词：飞行控制；通信；控制电路板；信息系统

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The General Dynamics (GD) S-Band software defined radio (SDR) in the Space Communications and Navigation (SCAN) Testbed on the International Space Station (ISS) will provide experimenters an opportunity to develop and demonstrate experimental waveforms in space. The GD SDR platform and initial waveform were characterized on the ground before launch and the data will be compared to the data that will be collected during on-orbit operations. A desired function of the SDR is to estimate the received signal to noise ratio (SNR), which would enable experimenters to better determine on-orbit link conditions. The GD SDR does not have an SNR estimator, but it does have an analog and a digital automatic gain control (AGC). The AGCs can be used to estimate the SDR input power which can be converted into a SNR. Tests were conducted to characterize the AGC response to changes in SDR input power and temperature. This purpose of this paper is to describe the tests that were conducted, discuss the results showing how the AGCs relate to the SDR input power, and provide recommendations for AGC testing and characterization.

关键词：自动增益控制;表征;无线电通信;空间通信;空间导航

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Mobile devices have, in many ways, replaced traditional desktops in usability, usefulness, and availability. Improvements to computational power, battery life, device capabilities, and user experience will continue to drive people to stop using desktops and solely use mobile devices. Applications are vital to maximize usefulness of these devices. Development of these applications proceeds with a rapidity that surpasses the development pace of the devices themselves. Current methods are inadequate when attempting to verify and validate the behavior of the applications to ensure they perform correctly as the customer expect and correctly with respect to the software specifications. The current V&V methods are limited to environments that do not reflect the typical operational environment for mobile devices. These methods lead to false beliefs that the results of V&V tests prove correctness of the software, when they are only proving that the software works in a non-mobile environment. To solve this problem, we propose that application log files be used to capture the execution behavior while operating in their typical environment. The log file along with customer requirements, represented formally as statechart assertions, will provide a mechanism to conduct automated V&V on the behavior of the application while it was operating in its planned, mobile environment.

关键词：行为;移动通信系统;预期寿命（使用寿命）;验证

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With a focus on complex environments,the present paper describes a new algorithm in scale changed object tracking through color feature.Mean shift (MS) iterative procedure is the best color-based algorithm to find the location of an object.The algorithm performance is not acceptable once tracking scale changed objects in complex environments.In this paper,the main aim is to improve the MS method,using corrected background-weighted histogram (CBWH) algorithm to reduce the interference of background in target localization.To fit the object scale change,the sum of gradient mode (SGM) is employed.The experimental results show that the proposed method is superior to the traditional mean shift tracking in the following aspects:1) it provides consistent object tracking throughout the video; 2) it is not influenced by the tracked objects scale changes; 3) it is less prone to the background clutter.

关键词：目标跟踪;均值漂移;背景资料;梯度模式的总和;通信

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