VisuaLeague: Player performance analysis using spatial-temporal data

In recent years, the phenomenon of eSports has been a growing trend and consequently, in addition to players, other groups of users, including coaches and analysts, took an interest in online video games and the data extracted from them. Among many types of video games, one of the most widely played is the MOBA (Multiplayer Online Battle Arena) League of Legend (LoL) game. Similary to traditional sports, players and coaches/analysts analyse all game events, such as, players’ movements, to understand how they play to define new strategies and improve their performance. Our main goal is to get a better understanding of which visualizations techniques are more adequate to handle this type of spatio-temporal information data, associated to player performance analysis in video games. To address this goal, we inquired players to identify the analytical questions they need to support for performance analysis and designed the VisuaLeague prototype for the visualization of in-game player trajectories, using animated maps, and events during a LoL match. This paper presents a user study to evaluate the adequacy of animated maps and the analytical strategies followed by players when using spatio-temporal data to analyse player performance. The results support the adequacy of using the animated maps technique to convey information to users in this context. Moreover, they also point out towards a high degree of importance given to the spatio-temporal components of the data for player performance analysis.

     

基于最小延迟代价的Web缓存替换算法研究

命中率、字节命中率和延迟时间是Web缓存系统中最重要的性能指标,但是却难以准确、合理地度量不同大小的Web对象的访问延迟.引入字节延迟的概念,为不同的对象延迟建立了一个比较合理的评价标准.提出最小延迟代价的Web缓存替换算法LLC,使用户访问的延迟时间尽可能缩短.实验结果表明,与常用的缓存替换算法相比,LLC算法在有效减少用户感知的访问延迟方面具有较好的性能表现.     

基于MMORPG的网络同步问题的研究与实现

结合多人在线角色扮演游戏系统,根据网络同步问题产生的原因,分别从客户端到服务器同步、服务器广播、客户端到客户端同步三个方面对解决同步问题进行探讨分析,从而得到一个改进的综合解决方案系统采用IOCP、线程池技术、被动检测算法,给予客户端一定决策权,并对Time Warp算法和Dead Reckoning算法进行改进。系统在校园网内进行实验,测试数据表明该方案能较好地解决MMORPG中的同步问题。     

High performance medical robot requirements and accuracy analysis

The treatment of disease using particle beams requires highly accurate patient positioning. Patients must be well immobilized and precisely aligned with the treatment beam to take full advantage of the dose localization potential. Robots can be used as high accuracy patient positioning systems. In this paper, the first such implementation using robotics techniques for patient positioning will be discussed. This robot is being developed for the Northeast Proton Therapy Center at the Massachusetts General Hospital. The unique requirements and design characteristics of the patient positioning system are presented. Of special interest is the system's patient positioning accuracy. A systematic methodology to perform the error analysis of serial link manipulators and its application to the PPS is described. Experimental measurements that verified the validity of the method are shown.     

Facial expression recognition using tracked facial actions: Classifier performance analysis

In this paper, we address the analysis and recognition of facial expressions in continuous videos. More precisely, we study classifiers performance that exploit head pose independent temporal facial action parameters. These are provided by an appearance-based 3D face tracker that simultaneously provides the 3D head pose and facial actions. The use of such tracker makes the recognition pose- and texture-independent. Two different schemes are studied. The first scheme adopts a dynamic time warping technique for recognizing expressions where training data are given by temporal signatures associated with different universal facial expressions. The second scheme models temporal signatures associated with facial actions with fixed length feature vectors (observations), and uses some machine learning algorithms in order to recognize the displayed expression. Experiments quantified the performance of different schemes. These were carried out on CMU video sequences and home-made video sequences. The results show that the use of dimension reduction techniques on the extracted time series can improve the classification performance. Moreover, these experiments show that the best recognition rate can be above 90%.     

Runtime latency detection and analysis

Detecting latency‐related problems in production environments is usually carried out at the application level with custom instrumentation. This is enough to detect high latencies in instrumented applications but does not provide all the information required to understand the source of the latency and is dependent on manually deployed instrumentation. The abnormal latencies usually start in the operating system kernel because of contention on physical resources or locks. Hence, finding the root cause of a latency may require a kernel trace. This trace can easily represent hundreds of thousands of events per second. In this paper, we propose and evaluate a methodology, efficient algorithms, and concurrent data structures to detect and analyze latency problems that occur at the kernel level. We introduce a new kernel‐based approach that enables developers and administrators to efficiently track latency problems in production and trigger actions when abnormal conditions are detected. The result of this study is a working scalable latency tracker and an efficient approach to perform stateful tracing in production. Copyright © 2016 John Wiley & Sons, Ltd.     

Network processor requirements and benchmarking

This paper intends to explore the demands put on Network Processors by evaluating their claim to address adequately the needs of Broadband Integrated Services Digital Networks, based on variable length packet communication.It starts by giving an overview of the elementary functions that are seen as essential capabilities to cover the broadening spectrum of packet communication applications.Besides functionality, performance is also critical in modern packet-based communication networks, not only for performing the elementary functions in isolation, but particularly for combinations of functions, to be executed by a Network Processor in the presence of live traffic, in a true contemporary network environment.The discussion of the requirements imposed by the external world is complemented by a brief overview of needs forthcoming from inter-working with another technologically demanding part of a packet network node: the switch fabric.Requirements for functionality and performance are one thing. The capability to meet them is another. The third part of the paper will discuss the strengths and weaknesses of some possible Network Processor architectures, when trying to meet these requirements. Aspects like packet classification, packet editing, data store access, packet scheduling and packet segmentation and re-assembly for cell-based switch fabrics will be addressed.     

实时网络视频播放控件的优化与实现

采用了流媒体技术、ActiveX技术、数字签名技术,基于开源代码VLC和Uvc555开发出用于B/S系统中的实时网络视频播放控件,解决了三个技术问题:降低VLC视频传递延迟,扩展快照录制功能,提供控件的安全传递能力.该控件可以在IE浏览器中播放来自网络经MPEG-4标准压缩的RTP实时流,具有播放画质好、延迟小等特点;快照和录制的视频控制功能,使该控件可用于交通、银行等多领域的实时视频监控系统;控件可在浏览器默认安全级别下下载运行,具有可靠性、安全性.     

Hierarchical Mobility Label Based Network: System model and performance analysis

Hierarchical Mobility Label Based Network (H-MLBN) is a new approach to the network layer mobility management problem that relies on MPLS-aware control plane and MPLS-based forwarding plane to provide IP mobility support for IPv4 and IPv6 mobile hosts and routers while being able to ensure optimal traffic delivery between the communicating devices. The hierarchical system is capable of both macro- and micro-mobility support without the use of Mobile IP and its derivatives thus eliminating the user and network facing performance penalties associated with triangular routing and bi-directional tunneling. This paper presents a system model and provides performance analysis for H-MLBN and compares its performance with the Mobile IP based schemes. The results indicate significant performance improvements in the forwarding plane traffic delivery as well as the control plane network update costs.     

基于ICMP的网络性能分析

从TCP/IP入手，讨论利用编程对象ICMP(网际控制报文协议)和编程工具Windows Sockets API，在PC机上收发ICMP数据报文，实现网络性能分析，从而为开发PC机上的网络管理软件提供基础。     

Effectiveness and performance analysis of model-oriented security requirements engineering to elicit security requirements: a systematic solution for developing secure software systems

Software systems are becoming more and more critical in every domain of human society. These systems are used not only by corporates and governments, but also by individuals and across networks of organizations. The wide use of software systems has resulted in the need to contain a large amount of critical information and processes, which certainly need to remain secure. As a consequence, it is important to ensure that the systems are secure by considering security requirements at the early phases of software development life cycle. In this paper, we propose to consider security requirements as functional requirements and apply model-oriented security requirements engineering framework as a systematic solution to elicit security requirements for e-governance software systems. As the result, high level of security can be achieved by more coverage of assets and threats, and identifying more traces of vulnerabilities in the early stages of requirements engineering. This in turn will help to elicit effective security requirements as countermeasures with business requirements.     

Aligning requirements and testing through metamodeling and patterns: design and evaluation

Requirements Engineering - Poorly executed requirements engineering activities profoundly affect the deliverables’ quality and project’s budget and schedule. High-quality requirements...     

Information requirements for multi-level-of-development BIM using sensitivity analysis for energy performance

The concept of multi-Level-of-Development (multi-LOD) modelling represents a flexible approach of information management and compilation in building information modelling (BIM) on a set of consistent levels. From an energy perspective during early architectural design, the refinement of design parameters by addition of information allows a more precise prediction of building performance. The need for energy-efficient buildings requires a designer to focus on the parameters in order of their ability to reduce uncertainty in energy performance to prioritise energy relevant decisions. However, there is no method for assigning and prioritising information for a particular level of multi-LOD. In this study, we performed a sensitivity analysis of energy models to estimate the uncertainty caused by the design parameters in energy prediction. This study allows to rank the design parameters in order of their influence on the energy prediction and determine the information required at each level of multi-LOD approach. We have studied the parametric energy model of different building shapes representing architectural design variation at the early design stage. A variance-based sensitivity analysis method is used to calculate the uncertainty contribution of each design parameter. The three levels in the uncertainty contribution by the group of parameters are identified which form the basis of information required at each level of multi-LOD BIM approach. The first level includes geometrical parameters, the second level includes technical specification and operational design parameters, and the third level includes window construction and system efficiency parameters. These findings will be specifically useful in the development of a multi-LOD approach to prioritise performance relevant decisions at early design phases.     

基于网络计算机的流媒体播放器的研究与实现

针对目前网络计算机等网络终端设备在处理流媒体信息时没有专门的播放软件,且缓冲区长度设置不合理和占用网络带宽较大的问题,描述了一个以网络计算机为基础平台的流媒体播放器技术实现方法;利用RTSP协议,实现了对网络流媒体文件播放的实时控制功能。实践证明该播放器不但能良好地播放网络中的各种流媒体文件,而且占用较小的网络带宽,在设备资源的占用率与流媒体播放效果之间做出了良好的平衡,在一定程度上提高了资源受限的网络终端设备对大容量流媒体资源的处理效果。     

基于网络计算机的流媒体播放器的研究与实现

针对目前网络计算机等网络终端设备在处理流媒体信息时没有专门的播放软件,且缓冲区长度设置不合理和占用网络带宽较大的问题,描述了一个以网络计算机为基础平台的流媒体播放器技术实现方法;利用RTSP协议,实现了对网络流媒体文件播放的实时控制功能.实践证明该播放器不但能良好地播放网络中的各种流媒体文件,而且占用较小的网络带宽,在设备资源的占用率与流媒体播放效果之间做出了良好的平衡,在一定程度上提高了资源受限的网络终端设备对大容量流媒体资源的处理效果.     

Task performance in a head-mounted display: The impacts of varying latency

The purpose of this study was to determine how latency in a head-mounted display (HMD) affects human performance. Virtual environments (VEs) are used frequently for training. However, VEs can cause simulator sickness. Prior work in our laboratory has examined the role of varying latency in simulator sickness. However, the effect of varying latency on task performance has not been examined. Subjects participated in a repeated measures study where they were exposed to two different latency conditions in an HMD: constant (70 ms) and varying (70–270 ms). During each HMD exposure, subjects used a laser pointer to repeatedly “shoot” at laser targets while accuracy and time-to-hit were recorded. Subjects scored fewer hits and took longer to hit targets in the varying latency condition. These findings indicate that individuals exposed to varying latency perform worse than individuals exposed to a lower constant latency.     

Listener latency profiling: Measuring the perceptible performance of interactive Java applications

When developers need to improve the performance of their applications, they usually use one of the many existing profilers. These profilers generally capture a profile that represents the execution time spent in each method. The developer can thus focus her optimization efforts on the methods that consume the most time. In this paper we argue that this type of profile is insufficient for tuning interactive applications. Interactive applications respond to user events, such as mouse clicks and key presses. The perceived performance of interactive applications is directly related to the response time of the program.In this paper we present listener latency profiling, a profiling approach with two distinctive characteristics. First, we call it latency profiling because it helps developers to find long latency operations. Second, we call it listener profiling because it abstracts away from method-level profiles to compute the latency of the various listeners. This allows a developer to reason about performance with respect to listeners, also called observers, the high level abstraction at the core of any interactive Java application.We present our listener latency profiling approach, describe LiLa, our implementation, validate it on a set of microbenchmarks, and evaluate it on a complex real-world interactive application. We then perform case studies where we use LiLa to tune the perceptible performance of two interactive applications, and we show that LiLa is able to pinpoint performance problems even if their causes are embedded in the largest interactive Java application we are aware of.