基于知识图谱的bug问题探索性搜索方法

软件bug问题在软件开发与维护过程中不可避免.然而软件历史库中的bug库与commit库之间没有直接的对应关系,并且随着bug信息、commit提交信息量的增长,搜索bug变得更加繁琐.本文提出一种基于知识图谱对bug问题进行探索性搜索的方法.通过建立bug报告、commit提交信息及相关人员（如：bug报告人、commit提交者等）信息的bug知识图谱,并结合探索性搜索的思想,不仅能准确搜索bug问题,还能提供相关辅助信息对bug问题进行探索性搜索,帮助软件开发人员更有效地理解和解决bug问题.     

Redefining collaboration through the creation of World Wide Websites

The paper argues that virtual communication spaces such as the World Wide Web (WWW) offer unique opportunities for collaboration within technical writing classrooms. Three common types of project scenarios are identified, along with the discourse communities and collaborative relationships that are supported and emphasized by each project scenario. A technical writing assignment is described that emphasizes the benefits of students collaborating within the WWW, an emerging, real world discourse community. In describing this assignment, we redefine collaboration to include activities used by WWW site developers and designers     

A Markov Decision Process based flow assignment framework for heterogeneous network access

We consider a scenario where devices with multiple networking capabilities access networks with heterogeneous characteristics. In such a setting, we address the problem of efficient utilization of multiple access networks by devices via optimal assignment of traffic flows with given utilities to different networks. We develop and analyze a device middleware functionality that monitors network characteristics and employs a Markov Decision Process (MDP) based control scheme that in conjunction with stochastic characterization of the available bit rate and delay of the networks generates an optimal policy for allocation of flows to different networks. The optimal policy maximizes, under available bit rate and delay constraints on the access networks, a discounted reward which is a function of the flow utilities. The flow assignment policy is periodically updated and is consulted by the flows to dynamically perform network selection during their lifetimes. We perform measurement tests to collect traces of available bit rate and delay characteristics on Ethernet and WLAN networks on a work day in a corporate work environment. We implement our flow assignment framework in ns-2 and simulate the system performance for a set of elastic video-like flows using the collected traces. We demonstrate that the MDP based flow assignment policy leads to significant enhancement in the QoS provisioning (higher rate allocation, lower packet delays and packet loss rates) for the flows and better access network utilization, as compared to policies that allocate flows to different networks using greedy approaches or heuristics like average available bit rate on the networks.     

电子政务系统整合研究

信息技术的应用多样性、复杂性与计算分布性,导致许多应用系统基于分布式网络由多种异构资源组成。对电子政务的各组成部门而言,各自的信息系统存在着不同时期、由不同开发商、利用不同的开发工具、在不同的开发平台上搭建起来。这就给以后的整合关联应用带来不便。为了保障数据的一致性、提高数据的共享性,就需要建立一个横跨多种异构系统的数据交换平台。文中从多个信息系统的整合需求出发,经研究分析,提出了针对性的技术解决方案。     

A unified framework and algorithm for channel assignment in wireless networks

Channel assignment problems in the time, frequency and code domains have thus far been studied separately. Exploiting the similarity of constraints that characterize assignments within and across these domains, we introduce the first unified framework for the study of assignment problems. Our framework identifies eleven atomic constraints underlying most current and potential assignment problems, and characterizes a problem as a combination of these constraints. Based on this framework, we present a unified algorithm for efficient (T/F/C)DMA channel assignments to network nodes or to inter-nodal links in a (multihop) wireless network. The algorithm is parametrized to allow for tradeoff-selectable use as three different variants called RAND, MNF, and PMNF. We provide comprehensive theoretical analysis characterizing the worst-case performance of our algorithm for several classes of problems. In particular, we show that the assignments produced by the PMNF variant are proportional to the thickness of the network. For most typical multihop networks, the thickness can be bounded by a small constant, and hence this represents a significant theoretical result. We also experimentally study the relative performance of the variants for one node and one link assignment problem. We observe that the PMNF variant performs the best, and that a large percentage of unidirectional links is detrimental to the performance in general.     

MICRON—A Framework for Connection Establishment in Optical Networks

Traffic grooming in optical networks has gained significance due to the prevailing sub-wavelength requirement of end users. Optical networks get upgraded to the latest technology slowly with time with only a subset of nodes being upgraded to the latest technology. The networks are thus comprised of nodes employing heterogeneous switching architectures. In this paper, we develop a framework called Methodology for Information Collection and Routing in Optical Networks (MICRON) for connection establishment in optical grooming networks with heterogeneous switching architectures. We illustrate with examples the information that may be collected from the links, and operators that may be used to obtain information along a path. The information can be used to select a path dynamically depending on the network status. We complete the MICRON framework by providing a generic channel assignment procedure that could be employed to implement different channel assignment schemes. Various routing and channel assignment algorithms can be developed from the proposed framework. The framework may be easily implemented with simple traffic engineering extensions to the already existing routing protocols in the wide-area networks.     

空中异构战术网络IP通信架构及协议开销分析

空中异构战术无线网络由多种不同类型的无线数据链网络构成，IP通信技术可有效解决空中平台异构无线网络的互联互通问题。给出了空中异构战术无线网络模型，并根据不同类型的无线数据链网络特点，分析了端到端通信协议栈关系以及不同无线数据链网络间协议转换与适配方式。探讨了网络静态和动态IP地址分配方法以及网络的路由架构与寻址方式，提出了不同无线数据链网络间IP报文传输的打包方式。对传输的开销性能仿真对比分析表明，基于通用成帧协议的打包方式的协议开销性能较优。     

Dynamic wavelength assignment for multicast in all-optical WDM networks to maximize the network capacity

We study the problem of wavelength assignment for multicast in order to maximize the network capacity in all-optical wavelength-division multiplexing networks. The motivation behind this work is to minimize the call blocking probability by maximizing the remaining network capacity after each wavelength assignment. While all previous studies on the same objective concentrate only on the unicast case, we study the problem for the multicast case. For a general multicast tree, we prove that the multicast wavelength assignment problem of maximizing the network capacity is NP-hard and propose two efficient greedy algorithms. We also study the same problem for a special network topology, a bidirectional ring network, which is practically the most important topology for optical networks. For bidirectional ring networks, a special multicast tree with at most two leaf nodes is constructed. Polynomial time algorithms for multicast wavelength assignment to maximize the network capacity exist under such a special multicast tree with regard to different splitting capabilities. Our work is the first effort to study the multicast wavelength assignment problem under the objective of maximizing network capacity.     

Multichannel cooperative sensing for cognitive radio with users owning heterogeneous sensing ability

Multichannel cooperative sensing (MCS) is an effective method for dynamic spectrum access in cognitive radio networks. In contrast to most existing work on MCS that considered secondary users with homogeneous sensing ability, this paper studies the MCS problem for secondary users with heterogeneous sensing ability in terms of sensing accuracy. We further take into account different parameters of primary channels such as bandwidth, probability of being idle in each sensing period, and frequency selective fading at the sensing receiver. The MCS problem is formulated as a weapon target assignment problem, where more sensing resources are assigned to channels that are more valuable. This weapon target assignment problem is transformed to an integer generalized network flow problem with convex flow costs to obtain the lower bound solution, and then solved by the branch and bound algorithm with this bound to yield the exact scheme. To reduce computational complexity, a heuristic scheme is also proposed, which has approximate performance compared with the exact scheme. Finally, extensive simulation results for different scenarios illustrate the performance improvements of the proposed schemes over the existing scheme. Copyright © 2013 John Wiley & Sons, Ltd.     

Node delay assignment strategies to support end-to-end delay requirements in heterogeneous networks

In a complex, heterogeneous network environment, such as the Internet, packets traversing different networks may be subjected to different treatments and may face different traffic loads across the routing path. This paper addresses the key issue of how to assign delay budgets to each network node along the routing path so that the end-to-end delay requirements of the supported applications are met. First, we describe a methodology to compute for a given flow a set of feasible per-node delays for the class of delay-based servers. We then formalize an optimal per-node delay assignment problem which takes into consideration the workload across the routing path. The solution, for homogeneous and heterogeneous networks, is provided. The resulting solution is optimal, but its implementation overhead is relatively high. To overcome this shortcoming, we propose two heuristics, EPH() and LBH(), to approximate the optimal strategy. EPH() uses the equi-partition concept to compute initial delay values and adjust these delay values to meet the end-to-end delay requirements. LBH() uses a relaxation factor to distribute the load proportionally across all nodes on the routing path. A simulation-based comparative analysis shows that the heuristics perform closely to the optimal schemes.     

基于.NET的专利信息管理系统的设计与实现

为了提高专利检索分析的效率,提出了一种专利信息管理系统的设计与实现方案。系统使用Visual Studio2008和SQL Server 2005进行开发,采用C/S架构。通过网络下载获取专利信息,并存入数据库。用户检索专利时直接从数据库中获取信息。系统使用水晶报表生成专利信息的统计报表以进行分析。运行结果表明,此系统检索快捷并且分析结果准确直观。     

基于区域感知贝叶斯决策的5G超密集异构网络联合垂直切换技术研究

针对无线通信异构网络切换中最优接入网的选择问题,现有研究主要集中于解决在两个网络间选择切换,而对于未来5G（5th Generation）通信系统中超密集网络的切换问题研究较少.本文就研究了5G无线通信系统中超密集异构网络的选择切换.文中提出了一种基于区域感知贝叶斯决策的联合垂直切换方式,该方案通过选择超密集异构接入网络的最优切换概率从而解决超密集网络切换问题.通过对移动用户（mobile station）从宏基站进入超密集服务小区,以及在小区内和小区间移动的不同场景进行仿真分析,研究结果表明本文决策方式能够准确地选择要切换的网络,因而该方案能够适用于超密集网络的应用场景.     

电信网管系统中报表灵活定制的设计与实现

在电信网管系统中,报表已经成为一种极为重要的呈现方式,由于其直观、统计性,深受用户欢迎。但由于其定制的过程过于繁琐,给维护人员带来很重负担,而用户也有诸多不便。因此,本文试图找出一种新的可以灵活定制而且支持多个库（本地＋异地）的灵活采集的报表系统,使网管的结果更好的以各种报表的形式,呈现给用户。     

Demand assignment for light-route TDMA

With the fluctuating inter-nodal traffic levels that characterize light-route networks, demand assignment (DA) provides the means of increasing the system's effective capacity. This paper focuses on the application of DA in light-route TDMA, and proposes a control architecture that is well-suited to service of heterogeneous traffic. The major advantage of the proposed architecture is its benefit from both the efficient resource management typical of centralized schemes, and the shorter response times of distributed schemes. The impact of the assignment algorithm on the grade of service to heterogeneous populations, and the difficulty in quantifying this impact are also addressed. Results from analytical and simulation models illustrating resource utilization are presented.     

Cellular IP address provisioning in a heterogeneous wireless network

In this article, we propose a dynamic Internet Protocol (IP) address assignment architecture for heterogeneous wireless IP devices network. The IP device could be a sensor device, a laptop, a cell phone, or any wireless device using IP communications. The proposed architecture introduces security and service reliability to the consumer while reducing the operational expenditure for the service providers. According to the proposed scheme, each node maintains an IP address pool storing the current occupancy of each IP address. Each node advertises its database whenever the ratio of negative acknowledgments from the domain name server to the total number of requests at a given node exceeds a certain threshold. We evaluate our IP assignment scheme under two traffic intensity scenarios, namely the uniform traffic intensity and the heterogeneous traffic intensity. Performance evaluation is carried out with respect to blocking probability and average IP list utilization. We define three types of blocking probability for the user requests as follows: The real blocking, the unjustified acceptance, and the unjustified rejection. We observe that the proposed scheme outperforms the uniform assignment as long as the threshold is below 1.5% for the uniform intensity scenario and 1% for the heterogeneous scenario. Furthermore, this architecture considers the security aspect of the wireless network by allowing only registered devices to communicate with other registered devices. Copyright © 2012 John Wiley & Sons, Ltd.     

网络化辐射源个体识别技术述评

在对辐射源个体识别技术向组网协同方向发展的趋势进行探讨的基础上,提出了基于跨手段异类传感器组网协同的辐射源个体识别技术架构,分析了需要研究的基于传感器能力特性的协同识别、多维度信号特征关联融合、基于元数据的智能数据处理等关键问题。     

基于异构磁盘阵列的数据备份/恢复技术研究

随着网络技术的快速发展与网络资源的日益丰富。数据的存储量级急速增长,数据保护的重要性显得尤为重要,如何快速有效地对数据进行备份/恢复成为数据保护领域亟待解决的关键问题之一。通过对异构磁盘阵列的数据分配方法进行优化,使不同磁盘阵列间进行数据备份/恢复速率提升。提出划分异构磁盘I/O带宽方式提高磁盘数据读取速度的可行性方案,与传统的数据备份/恢复相比,在时间利用率和备份性能上都得到了很大的提高。     

SIP-based IEEE802.21 media independent handover — a BT Intel collaboration

In this paper, we look at various mobility management protocols and handover frameworks in use in BT. We also report on the results from a collaborative proof of concept mixed network prototype for a seamless handover system using Intel’s early implementation of the IEEE802.21 media-independent handover standard. The paper reports the design, implementation and deployment issues/options of a handover mechanism using the Intel framework which includes a connection manager and mixed network IEEE802.21 adaptation layer together with BT’s SIP-based audio/video application in a heterogeneous Wi-Fi, WiMAX and Ethernet network environment.     

Optimized BS assignment and resource allocation in cooperative OFDM networks

Cooperative transmission (CT) and orthogonal frequency division multiple (OFDM) are promising technologies for extending coverage and increasing throughput in broadband wireless access (BWA) networks. Therefore, we propose a novel BWA network architecture, that can set up inter-cell collaboration using physical layer cooperative transmissions among distributed wired access networks with a powerful coordination capability at the central office. However, conventional base station (BS) assignment and resource allocation schemes cannot be used directly because a user can be serviced by more than one BS with cooperative transmission technology. This study proposes a novel framework of BS assignment and resource allocation in a cooperative OFDM network. We provide three approaches of resource allocation for minimizing bandwidth usage, minimizing transmission power consumption, and balancing resource costs respectively. An optimized resource allocation scheme can be implemented by flexibly choosing one of these approaches based on network load. The simulation results show the efficiency of the proposed mathematical formulations and linearization approach of our scheme. The performance benefit of CT technology on the bandwidth saving is demonstrated by comparing the new BS assignment and resource allocation scheme with conventional non-cooperative transmission.