QCD Radiative Correction to the Hadronic Annihilation Rate of 1+−1^{+-} Heavy Quarkonium

Hadronic annihilation rate of $1^{+-}$ heavy quarkonium is given to next-to-leading order in $\alpha_s$ and leading order in $v^2$ using a recently developed factorization formalism which is based on NRQCD. The result includes both the annihilation of P-wave color-singlet $Q\bar{Q}$ component, and the annihilation of S-wave color-octet $Q\bar{Q}$ component of the quarkonium. The notorious infrared divergences due to soft gluons, i.e., the Logarithms associated with the binding energy, encountered in previous perturbative calculations of $1^{+-}$ quarkonium decays are found to be explicitly cancelled, and a finite result for the decay width to order $\alpha_s^3$ is then obtained.Comment: 15 pages latex (6 figures included). In this revised version a update reference and acknowledgement are include

Routing issues for dynamic networks

The routing is one very important function implemented in computer communication networks. It collects information about optimal paths within a network;The purpose of this dissertation is to study the routing function in large networks which are characterized by frequent topological changes. The study focuses on constructing routing protocols with some desirable properties such as distributed computation, adaptation to flow variations within the network, failsafe against arbitrary topological changes, loop-free route tables for all destinations at all times, bounded values for variables, and fast recovery from topological changes;At present, most routing protocols use the next-node routing technique, a technique in which each node keeps only the next node identification for a particular destination. A different type of routing scheme provided in some protocol standards is called source routing. A source routing protocol builds complete paths from a source to all destinations in the network. Several source routing algorithms are derived with desirable properties;Most distributed routing algorithms use one or more variables to store unbounded values such as update cycle numbers. Distributed routing protocols with bounded update cycle numbers are proposed. The proposed protocols possess desirable properties and are obtained by applying the sliding window idea for flow control in networks to the routing protocols which employ unbounded update cycle numbers;How fast an algorithm provides optimal paths from every node to every other node in a network after a topological change is an important consideration in the design of routing algorithms. Several algorithms for achieving shortest paths to all destinations in the network with improved recovery speed from topological changes are presented

Characterization of lightning induced voltages on overhead power lines

The transient voltage surge caused by lightning is the major source contributed to the disturbance on power systems. The calculation of induced voltages, which is the propagated voltage surge on overhead power lines due to indirect lightning strokes, has been the subject of theoretical and experimental studies. The objective of this research is to develop a comprehensive numerical method to study the induced voltages on an overhead power line caused by a lightning return stroke with arbitrary shapes, for examples inclined lightning, zigzag lightning, etc. A finite-length lightning channel of any direction in 3-D space has been modelled and closed-form expressions of the inducing potentials have been derived from image theory. The total inducing scalar potential and inducing vector potential caused by an arbitrarily shaped lightning stroke are evaluated by superposition. Because that the presented numerical model simulates the realistic state and takes into account the retarded-height difference between the original sources and the image sources, the bipolar characteristic of the inducing scalar potential as well as the bipolar induced voltage waves are observed. The final induced voltage is completely composed of two components, one is the traveling voltage wave created by the inducing scalar potential, and the other is the standing voltage wave created by the vertical component of the inducing vector potential. The induced voltage on the power line is calculated by solving the partial differential equations in which the horizontal component of the inducing vector potential is taken into consideration. A computer program has been developed to perform the comprehensive calculations with the use of the finite-difference time-domain method in which the differential equations are converted into difference equations. Through this numerical program, the induced voltage is evaluated as functions of time and space on the power line. The numerical algorithm has been validated by a simulation test on a Gaussian pulse propagation. With the use of the program, parametric effects on the induced voltage caused by a vertical lightning stroke are inspected systematically. The comparisons of the induced voltage caused by inclined lightning strokes are made under various conditions. The effect of the horizontal component of the inducing vector potential has been illustrated. The results show that the severity of the inclined return stroke on the overhead power line is considerably harmful, especially when the return-stroke velocity gets faster or the inclined angle increases. This high voltage surge should be taken into account in the lightning protection design of transmission lines as well as distribution lines

Live in the Moment: The Essence of Life

I have thought about the essence of human life ever since I witnessed the impermanence of people\u27s lives through a near-death experience I had when I was nineteen years old. Life is a given amount of time, space, and memory, and every person, event, and object in the universe is stored up in time, space, and memory. These three factors combine to create the unique experience, character, and life of each individual person. A number of experts from different fields, as well as international celebrities, have publicly expressed various thoughts on life. However, most of their theories are explained with difficult words or equations. As an artist and architect, I want to depict the appearance of human life via my understanding of these theories as well as my own experiences. In my eyes, the complex world in which we live is composed of geometric patterns. Every object, every room, every person, and every living creature, from the micro to the macro, is defined by a form derived from a geometric pattern. Nature itself is full of geometric patterns that define and redefine every structure, each moment, and all events as they unfold. In this thesis paper, I discuss my main influences as an artist and the inspiration behind my thesis topic, as well as the background of each piece in my body of work. I want to use my artwork to signify, through these patterns, that the present moment is the most important point in time of a person\u27s life. The present moment is the only thing that people can change; yet, people are constantly regretting their pasts and planning their futures. Neither the past nor the future is changeable: we cannot turn back time and the future does not yet exist. Therefore, the present moment is the only point in time that matters. In this moment, people exist as they are; in the next moment, they will be different. Our lives will be led in other directions as time moves forward. This is a major theme in my pursuit of art

GraphMP: An Efficient Semi-External-Memory Big Graph Processing System on a Single Machine

Recent studies showed that single-machine graph processing systems can be as highly competitive as cluster-based approaches on large-scale problems. While several out-of-core graph processing systems and computation models have been proposed, the high disk I/O overhead could significantly reduce performance in many practical cases. In this paper, we propose GraphMP to tackle big graph analytics on a single machine. GraphMP achieves low disk I/O overhead with three techniques. First, we design a vertex-centric sliding window (VSW) computation model to avoid reading and writing vertices on disk. Second, we propose a selective scheduling method to skip loading and processing unnecessary edge shards on disk. Third, we use a compressed edge cache mechanism to fully utilize the available memory of a machine to reduce the amount of disk accesses for edges. Extensive evaluations have shown that GraphMP could outperform state-of-the-art systems such as GraphChi, X-Stream and GridGraph by 31.6x, 54.5x and 23.1x respectively, when running popular graph applications on a billion-vertex graph

GraphH: High Performance Big Graph Analytics in Small Clusters

It is common for real-world applications to analyze big graphs using distributed graph processing systems. Popular in-memory systems require an enormous amount of resources to handle big graphs. While several out-of-core approaches have been proposed for processing big graphs on disk, the high disk I/O overhead could significantly reduce performance. In this paper, we propose GraphH to enable high-performance big graph analytics in small clusters. Specifically, we design a two-stage graph partition scheme to evenly divide the input graph into partitions, and propose a GAB (Gather-Apply-Broadcast) computation model to make each worker process a partition in memory at a time. We use an edge cache mechanism to reduce the disk I/O overhead, and design a hybrid strategy to improve the communication performance. GraphH can efficiently process big graphs in small clusters or even a single commodity server. Extensive evaluations have shown that GraphH could be up to 7.8x faster compared to popular in-memory systems, such as Pregel+ and PowerGraph when processing generic graphs, and more than 100x faster than recently proposed out-of-core systems, such as GraphD and Chaos when processing big graphs

Exploring the commercial value of social networks: enhancing consumers’ brand experience through Facebook pages

Purpose – The purpose of this paper is to understand the factors which impact upon the consumers’ willingness to utilise company Facebook pages and e-word-of mouth by proposing and testing a conceptual framework which is inspired by theories in marketing and information systems fields. The authors believe that only by applying both theories will provide a more complete understanding of the relationship between brand experience and Facebook. The research model attempts to illustrate the factors according to customers’ intrinsic and extrinsic motivations and their impact on brand experience, brand Facebook page loyalty and e-word-of-mouth (E-WOM). Design/methodology/approach – The authors adopted an online survey method for data collection. The subjects the authors used were Facebook users. The data were collected in Taiwan over spring 2011. The authors then used the structural equation model to analyse the data collected. Findings – The findings suggest that users are influenced by the technical characterises of a brand Facebook page, such as ease of use and usefulness, which might be combated by attempting to reduce customer effort when accessing Facebook pages. The authors conclude that customer effort influenced brand experience and consequently loyalty to brand Facebook pages and E-WOM. Research limitations/implications – The limitations of this study relate to the investigation of consumer perspectives in a specific geographical context and time frame. Originality/value – The study’s contributions are both theoretical and practical, as it offers new insights into brand experience attitudes in an online environment and useful insights to companies willing to market themselves on Facebook. Keywords Marketing, Facebook, Virtual community, Extrinsic motivations, Intrinsic motivations Paper type Research pape

Safety-quantifiable Line Feature-based Monocular Visual Localization with 3D Prior Map

Accurate and safety-quantifiable localization is of great significance for safety-critical autonomous systems, such as unmanned ground vehicles (UGV) and unmanned aerial vehicles (UAV). The visual odometry-based method can provide accurate positioning in a short period but is subjected to drift over time. Moreover, the quantification of the safety of the localization solution (the error is bounded by a certain value) is still a challenge. To fill the gaps, this paper proposes a safety-quantifiable line feature-based visual localization method with a prior map. The visual-inertial odometry provides a high-frequency local pose estimation which serves as the initial guess for the visual localization. By obtaining a visual line feature pair association, a foot point-based constraint is proposed to construct the cost function between the 2D lines extracted from the real-time image and the 3D lines extracted from the high-precision prior 3D point cloud map. Moreover, a global navigation satellite systems (GNSS) receiver autonomous integrity monitoring (RAIM) inspired method is employed to quantify the safety of the derived localization solution. Among that, an outlier rejection (also well-known as fault detection and exclusion) strategy is employed via the weighted sum of squares residual with a Chi-squared probability distribution. A protection level (PL) scheme considering multiple outliers is derived and utilized to quantify the potential error bound of the localization solution in both position and rotation domains. The effectiveness of the proposed safety-quantifiable localization system is verified using the datasets collected in the UAV indoor and UGV outdoor environments