Coordinated Universal Time (UTC) is the standard civil time scale available via time signals in use in most parts of the world today. Leap seconds are the means to keep civil time, or UTC, aligned with adjusted Universal Time (UT1), a time based on Earth rotation corrected for polar variation. They are intentional adjustments to UTC that are instituted to prevent the difference between UT1 and UTC from exceeding +/- 0.9 seconds, based upon international agreement. Over a decade ago various technical communities for whom a continuous time scale would be more suitable than UTC, as disseminated in real-time, currently provides began making a case that the definition of UTC should be changed to eliminate leap seconds as a way to specify time unambiguously. This issue was discussed at the 2012 World Radiocommunications Conference (WRC), but consensus for elimination of the leap second was not achieved and a decision was postponed until the 2015 WRC. This report examines the leap second debate by summarizing general concepts of time and basic aspects of the leap second, followed by a discussion of non-technical considerations, technical aspects, and possible solutions. / text

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One of the currently explored strategies for interference avoidance and improving Signal to Noise Ratio (SNR) for mobile communication systems is Coordinated MultiPoint (CoMP) transmission. The general idea of the strategy is to let two or more base stations serve the same user. Due to delay factors, the channels from each serving base station needs to be predicted to obtain an adaptive CoMP system. In this thesis, a user interface is created to act as an experimental platform for a set of measured downlink channel data. The user interface supports editing of the channel data, model estimation, Kalman filtering and prediction and evaluation of the channel statistics. The user interface and the measured channel downlink data is then used to examine how well we can predict the weakest channel in a CoMP setup with three base stations. The predictions are carried out using an m-step Kalman predictor which uses an AR4 model, estimated from previous channel data. For the investigation, the user moves at pedestrian speed and the signals from the three different base stations use orthogonal Common Reference Signals (CRS). A comparison of different CRS patterns is also included in the investigation. It is concluded that 5 ms predictions of the weakest channel achieves a normalized mean squared error (NMSE) of -8 dB or lower provided that the weakest signal has an SNR of at least 5 dB and is no more than 15 dB lower than the combined received signal. Additionally, it is found that predictions are more accurate for CRS patterns spread over time than over subcarriers.

Since Texas contains less than 5% public land, private landowners are critical to the success of environmental management initiatives in the state. This has implications for resources that traverse property boundaries, such as wildlife and groundwater. Texas landowners are increasingly capitalizing on the income potential of fee-based hunting, and many have banded together to form Wildlife Management Associations (WMAs). Not only can such landowner associations enhance the coordination of resource management decisions, they also have the potential to increase social capital, which is reflected by interpersonal trust, reciprocity and civic participation. To improve the management of common-pool resources it is important to understand the relationship between social capital and coordinated resource management because long-term community stability and resource sustainability appear to be highly correlated. A 600-landowner mail survey (with 48.1% response) was conducted in the Edwards Plateau region of Texas to compare the land management characteristics and social capital of landowners who are members of WMAs with non-member landowners. The goal of this research was to determine how WMA membership, property size, and location affect levels of social capital and interest in cooperative resource management. It was hypothesized that members, large landowners, and northern landowners would be more interested in cooperative management and exhibit higher social capital. While WMA members and large-property owners were more involved in wildlife management than non-members and small-property owners, this interest in resource management did not carry over to groundwater. These groups were not more involved in groundwater management activities, and all survey groups were disinterested in joining private cooperatives for groundwater marketing. Social capital differences were more evident between large- and small-property owners than between WMA members and non-members. Members scored higher only on community involvement, while large owners scored higher on community involvement as well as trust. These results suggest that WMA membership per se does not significantly increase social capital among Edwards Plateau landowners, but do not necessarily refute the importance of social capital within WMAs. Differences in trust between members were positively correlated with increased communication and meeting frequency, suggesting ways WMAs can improve intra-association social capital.

This report compares programmes of coordinated recipient control for rivers in northern Sweden. The aim was to investigate differences in the programme of the Ume and Vindel Rivers compared with those of Skellefte, Torne, Kalix and Ångerman Rivers. Future impacts on Ume and Vindel Rivers, and consequently the programme, were also studied. A quantitative method, namely meta-analysis, was used in order to collect data of programmes on Water Information System Sweden (VISS). The results of this study showed that the programme for the streams is slightly different regarding measured parameters, number of sampling points and sampling frequency. However, the similarities between the programmes of Ume and Vindel Rivers and Torne and Kalix Rivers are greater than compered to Skellefte River. The conclusion is that the differences in the programmes may have a natural explanation such as different emissions to the recipients, but can also indicate different ambitions. The programme may be affected and in need of change if a potential nickel sulphide mine in Tärnaby, Storuman is established and joins the water conservation association of the Ume and Vindel Rivers. Intensified forestry might also increase future impacts.

Coordinated Power Management in Heterogeneous Processors Indrani Paul 164 pages Directed by Dr. Sudhakar Yalamanchili With the end of Dennard scaling, the scaling of device feature size by itself no longer guarantees sustaining the performance improvement predicted by Moore’s Law. As industry moves to increasingly small feature sizes, performance scaling will become dominated by the physics of the computing environment and in particular by the transient behavior of interactions between power delivery, power management and thermal fields. Consequently, performance scaling must be improved by managing interactions between physical properties, which we refer to as processor physics, and system level performance metrics, thereby improving the overall efficiency of the system. The industry shift towards heterogeneous computing is in large part motivated by energy efficiency. While such tightly coupled systems benefit from reduced latency and improved performance, they also give rise to new management challenges due to phenomena such as physical asymmetry in thermal and power signatures between the diverse elements and functional asymmetry in performance. Power-performance tradeoffs in heterogeneous processors are determined by coupled behaviors between major components due to the i) on-die integration, ii) programming model and the iii) processor physics. Towards this end, this thesis demonstrates the needs for coordinated management of functional and physical resources of a heterogeneous system across all major compute and memory elements. It shows that the interactions among performance, power delivery and different types of coupling phenomena are not an artifact of an architecture instance, but is fundamental to the operation of many core and heterogeneous architectures. Managing such coupling effects is a central focus of this dissertation. This awareness has the potential to exert significant influence over the design of future power and performance management algorithms. The high-level contributions of this thesis are i) in-depth examination of characteristics and performance demands of emerging applications using hardware measurements and analysis from state-of-the-art heterogeneous processors and high-performance GPUs, ii) analysis of the effects of processor physics such as power and thermals on system level performance, iii) identification of a key set of run-time metrics that can be used to manage these effects, and iv) development and detailed evaluation of online coordinated power management techniques to optimize system level global metrics in heterogeneous CPU-GPU-memory processors.

Made available in DSpace on 2014-10-09T12:33:11Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:06:13Z (GMT). No. of bitstreams: 0 / Tese (Doutoramento) / IPEN/T / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

Made available in DSpace on 2014-10-09T12:33:11Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:06:13Z (GMT). No. of bitstreams: 0 / Os Programas Interlaboratoriais (PIs) de proficiência são parte integrante do processo de obtenção de confiabilidade metrológica para medições e resultados analíticos gerados em laboratórios, ambientes de prática da atividade metrológica. Entre as diretrizes estratégicas do Comitê Brasileiro de Metrologia (CBM) estão incentivar a implantação de PIs que permitam aos laboratórios verificar e demonstrar a confiabilidade de seus resultados e acreditar provedores de PIs. O Instituto de Pesquisas Tecnológicas do Estado de São Paulo IPT, órgão subordinado à Secretaria de Desenvolvimento do Estado de São Paulo, apesar de ter sido um dos pioneiros na oferta de PIs, não é atualmente um grande provedor. O objetivo desta pesquisa é propor um modelo de estrutura organizacional de provedor de Programas Interlaboratoriais (PIs), aplicado ao Instituto de Pesquisas Tecnológicas do Estado de São Paulo IPT. O desenvolvimento deste modelo se apoia em revisão teórica, em estratégias advindas da análise SWOT do estudo de dez programas interlaboratoriais oferecidos pelo IPT no período de 2000 a 2009, em fatores condicionantes do IPT, em políticas governamentais atuais, em modelos de estrutura existentes no mercado e em componentes principais de uma estrutura organizacional. O modelo proposto, constituído de dois núcleos principais, o de Coordenação dos Provedores de PIs (COPPI) e o de Gerentes de PIs (GEPI), apresenta os elementos necessários para elevar o IPT à condição de provedor de PIs que atenda, de modo sustentável, às demandas governamentais e de setores produtivos. / Tese (Doutoramento) / IPEN/T / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

Multi-robot systems (MRS) offer many performance benefits over single robots for tasks that can be completed by one robot. They offer potential redundancies to the system to improve robustness and allow tasks to be completed in parallel. These benefits, however, can be quickly offset by losses in productivity from diminishing returns caused by interference between robots and communication problems. This dissertation developed and evaluated MRS control architectures to solve the dynamic multi-robot autonomous routing problem. Dynamic multi-robot autonomous routing requires robots to complete a trip from their initial location at the time of task allocation to an assigned destination. The primary concern for the control architectures was how well the communication requirements and overall system performance scaled as the number of robots in the MRS got larger. The primary metrics for evaluation of the controller were the effective robot usage rate and the bandwidth usage. This dissertation evaluated several different approaches to solving dynamic multi-robot autonomous routing. The first three methods were based off of common MRS coordination approaches from previous research. These three control architectures with distributed control without communication (a swarm-like method), distributed control with communication, and centralized control. An additional architecture was developed to solve the problem in a way that scales better as the number of robots increase. This architecture, mixed mode autonomy, combines the strengths of distributed control with communication and centralized control. Like distributed control with communication, mixed mode autonomy's performance degrades gracefully with communication failures and is not dependent on a single controller. Like centralized control, there is oversight from a central controller to ensure repeatable high performance of the system. Each of the controllers other than distributed control without communication is based on building world models to facilitate coordination of the routes. A second variant of mixed mode autonomy was developed to allow robots to share parts of their world models with their peers when their models were incomplete or outdated. The system performance was evaluated for three example applications that represent different cases of dynamic multi-robot autonomous routing. These example applications were the automation of open pit mines, container terminals, and warehouses. The effective robot usage rates for mixed mode autonomy were generally significantly higher than the other controllers with a higher numbers of robots. The bandwidth usage was also much lower. These performance trends were also observed across a wide range of operating conditions for dynamic multi-robot autonomous routing. The original contributions from this work were the development of a new MRS control architecture, development of system model for the dynamic multi-robot autonomous routing problem, and identification of the tradeoffs for MRS design for the dynamic multi-robot autonomous routing problem. / Ph. D.