Bayesian networks for student model engineering

Bayesian networks are graphical modeling tools that have been proven very powerful in a variety of application contexts. The purpose of this paper is to provide education practitioners with the background and examples needed to understand Bayesian networks and use them to design and implement student models. The student model is the key component of any adaptive tutoring system, as it stores all the information about the student (for example, knowledge, interest, learning styles, etc.) so the tutoring system can use this information to provide personalized instruction. Basic and advanced concepts and techniques are introduced and applied in the context of typical student modeling problems. A repertoire of models of varying complexity is discussed. To illustrate the proposed methodology a Bayesian Student Model for the Simplex algorithm is developed.     

通信网络在智能建筑中的应用研究

对智能建筑通信网络(IBN)进行了研究，重点分析了：智能建筑信息系统(IBIS)网络的集成以及将不同的建筑系统集成于一个框架内的标准协议的应用．而ISDN与ADSL被认为是实现IBN的合适平台。     

基于CAN总线的楼宇自动化照明网络设计

为了实现楼宇自动化中的灯光照明系统的网络设计,采用CAN总线协议实现各灯光节点的通信。硬件设计中,上位机节点使用PCI-CAN接口卡,各灯光节点主控制芯片使用PICl8F258,CAN收发器使用PCA82C250,并加入光耦隔离电路。同时对上位机节点及灯光节点进行软硬件设计,使各灯光节点能够实现相互之间的灵活通信,同时可实现调光、降低能耗等功能。经试验,该系统通信稳定,满足了基本的设计要求。     

利用UML建模设计指挥自动化软件系统

指挥自动化系统是C4ISR的重要组成部分,主要用于系统的指挥、控制和协调,指挥自动化应用系统的开发是一个复杂的软件工程,结合一个指挥自动化系统工程项目,利用统一建模语言(UML)来对该系统建模和设计,展示了UML在开发指挥自动化系统的运用,表明软件工程的方法可以有效地运用于指挥自动化系统的开发。     

Flow vs. time sampling for throughput performance evaluation

We introduce two throughput metrics referred to as flow- and time-sampled throughputs. The former gives the throughput statistics of an arbitrary flow while the latter weights these throughput statistics by the flow durations. Under fair sharing assumptions, the latter is shown to coincide with the steady-state instantaneous throughput weighted by the number of flows, which provides a useful means to measure and estimate it. We give some generic properties satisfied by both the metrics and illustrate their difference on a few examples.     

面向楼宇自动化的保安探测与自动化系统

阐述了面向楼宇自动化的保安自动化系统的控制功能、构成和多种保安探测方法 ,并给出了其应用实例     

An accurate performance model for network-on-chip and multicomputer interconnection networks

In this paper, we present a mathematical background for a new approach for performances modeling of interconnection networks, based on analyzing the packet blocking and waiting time spent in each channel passing through all possible paths in the channel dependency graph. We have proposed a new, simple and very accurate analytical model for deterministic routing in wormhole networks, which is general in terms of the network topology and traffic distribution. An accurate calculation of the variance of the service time has been developed, which overcomes the rough approximation used, as a rule, in the existing models. The model supports two-dimensional mesh topologies, widely used in network-on-chip architectures, and multidimensional topologies, popular in multicomputer architectures. It is applicable even for irregular topologies and arbitrary application-specific traffic. Results obtained through simulation show that the model achieves a high degree of accuracy.     

Automatic model building and solving for optimization problems

Automatic modelling is one of the key topics in model base management in DSS. We consider the design and implementation of a system which automatically specifies an optimization model from an abstract form with a given set of data specified by a user and solves it by calling an appropriate solver. We implement our idea as a prototype in Prolog and illustrate its validity by simple examples.     

Traffic engineering of MPLS backbone networks in the presence of heterogeneous streams

Heterogeneous streams (due to issues such as disparate traffic characteristics of each stream, or competing customers’ traffic) raise the issue of whether to multiplex (some of) these streams. In an MPLS network, such multiplexing can be considered by putting different streams into a tunnel identified by a single label-switched path (LSP), assuming that the different LSPs are assigned a reserved share of the resources. This issue becomes even more important in the traffic engineering of a backbone network when a decision needs to be made on which streams to multiplex when there are constraints on tunneling and capacity along with routing requirements for tunnels. In this paper, we introduce a distortion factor due to heterogeneous streams in traffic engineering of MPLS backbone networks in the presence of tunneling and capacity constraints by formulating a distortion-aware non-linear discrete optimization problem. Furthermore, we present a two-phase heuristic approach to solve this formulation efficiently. In the first phase, the problem is decoupled into two subproblems and in the second phase we show how the non-linear problem (for one of the subproblems) can be simplified. We then present numerical results for both small and large networks to show where and how our approach helps to determine when and which streams to multiplex depending on whether the tunneling and/or capacity constraint is dominant; furthermore, by comparing our distortion-aware traffic engineering model with a distortion-ignorant traffic engineering model, we show the benefits of our approach.     

分布式网络流量预测模型的精度研究

网络流量模型是网络性能评价、网络协议设计、网络规划等的基础。本文设计基于分布式网络测试的时间与相关流量模型的方法,并采用该流量模型预测网络流量。文章提出网络流量预测精度的数学定义,网络测试实验表明,我们的流量模型具有更高的精度,并适用实际运行的网络环境。     

A team building model for software engineering courses term projects

This paper proposes a new model for team building, which enables teachers to build coherent teams rapidly and fairly for the term projects of software engineering courses. Moreover, the model can also be used to build teams for any type of project, if the team member candidates are students, or if they are inexperienced on a certain subject. The proposed model takes students’ preferences and the teacher’s considerations into account when a team building process is required for any type of course. In addition, this paper investigates how team building models (RandomM: teams are built with randomly selected students; TeacherM: teacher selects the members for each team; StudentsM: students build their own teams and the proposed model) affect team performance and how gender differences affect project activities and team performance. A three-year (five semesters) teaching experiment was performed with the participation of 248 male and 79 female university students and a total of 67 software project teams. Two different One-way ANOVA tests were applied on the experimental data, and the results indicated that the proposed model was better than RandomM, TeacherM and StudentsM models in terms of project grades, and the effect of gender differences on the teams’ performance and project activities was negligible.     

Pilot performance and preference for short cycles of automation in adaptive function allocation

The present experiment examined pilot response to the rapid cycling of automation. The experiment was conducted using a multi-task simulation environment consisting of tracking, fuel management, and system monitoring sub-tasks. Monitoring and fuel management sub-tasks were performed manually in all conditions. The tracking sub-task cycled between manual and automated control at fixed intervals of either 15, 30 or 60 sec. These cycle times were completely crossed with three levels of tracking difficulty giving nine within-subject conditions which lasted 5 min each. Performance was measured on each of the sub-tasks, as was pilot fatigue level and subjective workload for the respective conditions. Results indicated that both difficulty and cycle duration significantly affected tracking performance which was degraded with task difficulty and longer cycle times. Fuel management and system monitoring performance were unaffected by tracking difficulty and automation duration. However, a subsequent analysis was conducted using the 15 sec period immediately following each automation episode as a ‘window’ of performance. A different pattern of results was observed. Tracking performance was similarly affected by difficulty, but was no longer affected by cycle duration. Furthermore, fuel management error indicated a trend toward better performance in low difficulty conditions. Results illustrate micro trade-offs within sub-tasks and macro trade-offs between sub-tasks. Overall, the results support the contention that excessively short cycles of automation prove disruptive to performance in multi-task conditions.     

Evaluation of flexible automation investments: a model management perspective

This paper develops a model management system structure to support the design and evaluation of flexible automation systems. A modeling language suitable for one of the important, but ill-structured phases in the evaluation process is selected and used to represent a mathematical programming formulation. The experience gained is then used to propose a meta-language approach for integrating different model types required when evaluating flexible automation investments.The authors are placed in alphabetical order.     

一种通用的无线网络AAA机制的性能评价模型

目前针对AAA机制的性能分析评价主要有两种手段,即定量的数学分析和仿真对比.提出了一种基于安全关联(security association,SA)路径长度的分析评价模型,并且基于该模型给出了AAA机制性能改进的方向.分析结果表明,该模型能够更简单有效地评价对比各种AAA机制的性能优劣.     

Structure and spatial consistency of network-based space layouts for building and product design

Network-based space layouts are schematic models of whole spaces, subspaces, and related physical elements. They address diverse space modeling needs in building and product design. A schema (data model) for network-based space layouts is defined that is influenced by existing space schemas. Layout elements and selected spatial relations form a geometric network. The network is embedded in 3-space and facilitates analysis with graph and network algorithms. Spatial constraints on layout elements and spatial relations extend the schema to support spatial consistency checking. Spatially consistent layouts are required for reliable network analysis and desirable for layout modification operations. An operation is introduced that evaluates spatial constraints to detect and semi- or fully-automatically resolve spatial inconsistencies in a layout. A layout modeling system prototype that includes proof-of-concept implementations of the layout schema extended by spatial constraints and the inconsistency resolution operation is described. Layouts of a floor of an office building and a rack server cabinet have been modeled with the system prototype.     

An optimization framework for the energy management of carrier ethernet networks with Multiple Spanning Trees

We propose an energy management framework to optimize the energy consumption of networks using the Multiple Spanning Tree Protocol such as Carrier Grade Ethernet networks. The objective is to minimize the energy consumption of nodes and links while considering QoS constraints. The energy management is done through the Multiple Spanning Tree Protocol (MSTP) by choosing from a given set the most appropriate Spanning Trees and the most appropriate edges to operate while respecting the traffic demands. A trade-off framework between energy consumption and network performance is proposed. Results show that it is possible to achieve a good traffic engineering while operating the network closer to the minimum energy value.     

现代智能建筑信息化工程施工中的常见问题和监理措施

近年来,伴随着社会经济、科学技术的不断进步和发展,越来越多的人开始关注居住的环境,对居住环境的要求也在逐渐的提高。在此基础上,建筑的智能化信息化成为了新的发展方向,同时智能建筑信息化工程是民用建筑工程不可分割的一部分,越来越多的人也开始留意智能建筑,在对智能建筑工程系统的施工以及设计中,可能会面临某些问题。因此,对智能建筑信息化工程施工中的控制管理是非常重要的,下面对智能建筑信息化弱电工程在施工中常见的问题以及所采取的相应监理措施简单的阐述。     

Dimensional reduction of 3D building models using graph theory and its application in building energy simulation

Since the various people involved in the design process for a building project tend to hold conflicting views, this inevitably leads to a range of disparate models for planning and calculation purposes. In order to interpret the relevant geometrical, topological and semantical data for any given building model, we identify a structural component graph, a graph of room faces, a room graph and a relational object graph as aids and explain algorithms to derive these relations. We start with a building model by transferring its geometrical, topological and semantical data into a volume model, decomposing the latter into a so-called connection model and then extracting all air volume bodies and hulls of the model by means of further decomposition into elementary cyclic connection components. The technique is demonstrated within the scope of building energy simulation by deriving both a dimensionally reduced object model required for setting up a thermal multizone model and a geometrical model for defining single or multiple computational fluid dynamic domains in a building together with incidence matrices correlating these models. The algorithm is basically applicable to any building energy simulation tool.

On the performance of a hybrid network traffic model

We study a hybrid network traffic model that combines a fluid-based analytical model using ordinary differential equations with the packet-oriented discrete-event simulation. The hybrid model is important to large-scale real-time network simulations, where the packet-level emulation traffic is handled by discrete events and the majority of the background traffic is described more efficiently as fluids. We present a simple performance analysis of this hybrid approach. We propose three techniques—namely, pointer caching, update dampening, and dynamic time stepping—in an implementation of the hybrid model. Experiments show that these techniques can significantly improve the performance of the fluid-based network simulation.