Derivation of a ‘designer's guide’ for interactive ‘grey-box’ identification of nonlinear stochastic objects

The problem of using an ‘identification tool box’ for the design of ‘grey-box’ models for nonlinear dynamic objects is non-trivial. The design is an interactive process, and it is not given a priori in what order to execute the various subtasks that the tool box supports what design parameters to manipulate and how to interpret the intermediate results. The difficulties are enhanced when the uncertainty of the designer's a-priori information and the quality of the experiment are such that a model contains other stochastic elements than measurement error.

This paper derives a systematic procedure for design of such models, assuming a generic tool box. The origin is the basic procedure commonly used in natural sciences, namely that of repeated refinement and falsification of hypotheses. The derivation is based on statistical decision theory and leads to the specification of a ‘designer's guide’ for grey-box identification. The procedure has been tested on two industrial processes, using the IdKit tool box, and a prototype of the guide has been implemented as a Unix shell. A simulated example illustrates the procedure.     

Cross-organizational collaboration supported by Augmented Reality

This paper presents a study where Augmented Reality (AR) technology has been used as a tool for supporting collaboration between the rescue services, the police and military personnel in a crisis management scenario. There are few studies on how AR systems should be designed to improve cooperation between actors from different organizations while at the same time supporting individual needs. In the present study, an AR system was utilized for supporting joint planning tasks by providing organization specific views of a shared map. The study involved a simulated emergency event conducted in close to real settings with representatives from the organizations for which the system is developed. As a baseline, a series of trials without the AR system was carried out. Results show that the users were positive toward the AR system and would like to use it in real work. They also experience some performance benefits of using the AR system compared to their traditional tools. Finally, the problem of designing for collaborative work as well as the benefits of using an iterative design processes is discussed.     

Smith's principle for congestion control in high-speed datanetworks

In high-speed communication networks, large propagation delays could have an adverse impact on the stability of feedback control algorithms. In this paper, the classical control theory and Smith's principle are exploited to design an algorithm for controlling “best effort” traffic in high-speed asynchronous transfer mode (ATM) networks. The designed algorithm guarantees the stability of network queues, along with the fair and full utilization of network links, in a realistic traffic scenario in which multiple available bit rate connections, with different propagation delays, share the network with high priority traffic     

Scenario Views for Visual Behavior Models in GenGED

Visualizing and simulating the behavior of formal models in an adequate and flexible way becomes increasingly important in the design of complex systems. With GenGED, a tool is available which automatically generates a visual environment to process (create, edit, check, simulate) visual models in a specified formalism (a visual language). Both the specification of the formalism and the model manipulation are based on graph grammars. In this paper we present the means to transform a formal model into different application domain oriented views (scenario views). We show how the behavior of the model is transferred to the views and animated there (i.e. simulated in the layout of the application domain). Possible extensions towards animation modules (animated scenario views defined by GenGED that are accessible from other tools) are discussed.     

基于802.11b MAC协议的Ad Hoc路由算法仿真与比较

主要利用NS2仿真分析了Ad Hoc网络模式中几个主要的路由（DSR、DSDV、TORA、AODV）算法进行研究.首先,利用NS-2测试4种路由协议的性能,讨论Ad Hoc模式下路由协议的设计.不同的路由协议,主要包括先验式和反应式两大类,有不同的适用场合,混合式的路由协议（AODV）有一定的优越性;然后,测试节点个数和数据包容量对无线网络MAC层性能（包括延迟、丢包率和吞吐率）的影响.结论为不同场合路由协议的进一步应用和优化提供理论依据.     

Emergent behaviors and scalability for multi-agent reinforcement learning-based pedestrian models

This paper analyzes the emergent behaviors of pedestrian groups that learn through the multiagent reinforcement learning model developed in our group. Five scenarios studied in the pedestrian model literature, and with different levels of complexity, were simulated in order to analyze the robustness and the scalability of the model. Firstly, a reduced group of agents must learn by interaction with the environment in each scenario. In this phase, each agent learns its own kinematic controller, that will drive it at a simulation time. Secondly, the number of simulated agents is increased, in each scenario where agents have previously learnt, to test the appearance of emergent macroscopic behaviors without additional learning. This strategy allows us to evaluate the robustness and the consistency and quality of the learned behaviors. For this purpose several tools from pedestrian dynamics, such as fundamental diagrams and density maps, are used. The results reveal that the developed model is capable of simulating human-like micro and macro pedestrian behaviors for the simulation scenarios studied, including those where the number of pedestrians has been scaled by one order of magnitude with respect to the situation learned.     

A real‐time field experiment on search and rescue operations assisted by unmanned aerial vehicles

This paper reports on the performance of a novel system for supporting search and rescue activities, known as SARUAV (search and rescue unmanned aerial vehicle), in a field experiment during which a real‐world search scenario was simulated. The experiment took place on March 2–3, 2017, at two sites located in southwestern Poland. Three groups acted in the experiment: (1) SARUAV and unmanned aerial vehicle (UAV) operators, (2) ground searchers, and (3) participants who simulated being lost. In the uncomplicated topography without snow cover, the system identified the lost persons, and ground searchers found them 31 min after the SARUAV report had been disseminated. In the mountainous area covered with snow, one person was found within 9 min after searchers received the SARUAV report; however, the other two persons were not identified by SARUAV. The field experiment served as a proof of concept of the SARUAV system, confirmed its potential in person identification studies, and helped to identify numerous scientific and technical problems that need to be solved to develop a mature version of the system.     

Scenario management from reactivity to proactivity

Scenarios have a far greater potential to help organizations boost preparedness, manage multiple systems, and anticipate the consequences of their actions. In the IT world, project managers react to rather than proactively counter new developments. In other areas of system development (such as education, training, and development) and system maintenance, scenario use is nearly nonexistent. When applied appropriately, scenarios can improve planning and provide training that can help reduce costly on-the-job mistakes. Instead of tossing inexperienced managers into the IT project shark tank, an organization can have them work through complex and realistic scenarios in training sessions, learn how to deal with the issues, improve their knowledge and experience, and then take on a real project. This approach can significantly lower the probability of costly on-the-job hiccups and increase the communication skills - who needs to know what and when - that managers sorely need when a project goes awry.     

EPC系统中的中间件研究

介绍了无线射频技术及其在物品信息网中的应用,并针对将无线射频技术用在物品信息网中产生的海量数据难以处理的情况,设计了一种基于事件状态变化的数据过滤算法.该算法主要参考了Auto-ID Center制订的Savant Specification 1.0,以其中提到的Savant为中间件的构架.算法靠功能列表和事件队列维护信息,过滤阅读器上报的重复信息,只向上层应用报告关于标签出现、消失等状态变化情况,采用gsoap工具包实现规范中要求的soap通信功能,并结合上层应用,实验证明算法的可行性.     

Learning to Importance Sample in Primary Sample Space

Importance sampling is one of the most widely used variance reduction strategies in Monte Carlo rendering. We propose a novel importance sampling technique that uses a neural network to learn how to sample from a desired density represented by a set of samples. Our approach considers an existing Monte Carlo rendering algorithm as a black box. During a scene‐dependent training phase, we learn to generate samples with a desired density in the primary sample space of the renderer using maximum likelihood estimation. We leverage a recent neural network architecture that was designed to represent real‐valued non‐volume preserving (“Real NVP”) transformations in high dimensional spaces. We use Real NVP to non‐linearly warp primary sample space and obtain desired densities. In addition, Real NVP efficiently computes the determinant of the Jacobian of the warp, which is required to implement the change of integration variables implied by the warp. A main advantage of our approach is that it is agnostic of underlying light transport effects, and can be combined with an existing rendering technique by treating it as a black box. We show that our approach leads to effective variance reduction in several practical scenarios.     

Theoretical underpinning and prototype implementation of scenario bundle-based logical control for simulation of human–artifact interaction

This article presents a new methodology that enables designers to include in simulations not only the physics aspects of artifact behavior, but also human actions. The motivation for this research came from the fact that none of the conventional approaches to engineering simulations includes manipulative control of products by users as foreseen by designers. By implementing control over physics simulations, changes in parameters can be introduced that alter the course of the simulated process. As a means to do this, we propose to use scenario bundles, with which designers can operationalize their conjectures of how human users interact with products as a series of interconnected simulations. For the imaginary use process described in a scenario bundle, the designer can specify various product designs, user characteristics, and environments, which may in each case lead to different concatenations of simulation actions. The proposal facilitates the exploration of possible mismatches and anomalies in use processes. In this article, we describe the theoretical fundamentals and the overall concept of the proposed methodology, as well as its realization as a proof-of-concept implementation. This implementation can be used as a tool to specify scenario bundles and to perform controlled simulations of human–product interaction. The use of the tool is demonstrated through a practical example. Although the implementation has proven to be successful in terms of executing scenario bundles, two bottlenecks need further attention: (i) devising stable algorithms for large deformations in physical interaction simulation and (ii) incorporation of already existing algorithms for simulation of low-level human motion control.     

Hipikat: a project memory for software development

Sociological and technical difficulties, such as a lack of informal encounters, can make it difficult for new members of noncollocated software development teams to learn from their more experienced colleagues. To address this situation, we have developed a tool, named Hipikat that provides developers with efficient and effective access to the group memory for a software development project that is implicitly formed by all of the artifacts produced during the development. This project memory is built automatically with little or no change to existing work practices. After describing the Hipikat tool, we present two studies investigating Hipikat's usefulness in software modification tasks. One study evaluated the usefulness of Hipikat's recommendations on a sample of 20 modification tasks performed on the Eclipse Java IDE during the development of release 2.1 of the Eclipse software. We describe the study, present quantitative measures of Hipikat's performance, and describe in detail three cases that illustrate a range of issues that we have identified in the results. In the other study, we evaluated whether software developers who are new to a project can benefit from the artifacts that Hipikat recommends from the project memory. We describe the study, present qualitative observations, and suggest implications of using project memory as a learning aid for project newcomers.     

Maximizing throughput in multi-queue switches

We study a basic problem in Multi-Queue switches. A switch connectsm input ports to a single output port. Each input port is equipped with an incoming FIFO queue with bounded capacityB. A switch serves its input queues by transmitting packets arriving at these queues, one packet per time unit. Since the arrival rate can be higher than the transmission rate and each queue has limited capacity, packet loss may occur as a result of insufficient queue space. The goal is to maximize the number of transmitted packets. This general scenario models most current networks (e.g. IP networks) which only support a “best effort” service in which all packet streams are treated equally. A 2-competitive algorithm for this problem was designed in [5] for arbitraryB. Recently, a (17/9 ≈ 1.89)-competitive algorithm was presented forB>1 in [3]. Our main result in this paper shows that forB which is not too small our algorithm can do better than 1.89, and approach a competitive ratio ofe/(e − 1) ≈ 1.58. The research of Yossi Azar was supported in part by the Israeli Ministry of Industry and Trade and by the Israel Science Foundation.     

APEX: adaptive disk scheduling framework with QoS support

APEX is an adaptive disk scheduling framework with Quality-of-Service (QoS) support designed for environments with highly varying disk bandwidth usage. APEX is based on a three-layer scheduling architecture: (1) the upper layer realizes different service classes using a set of queues; (2) the mid-layer distributes available disk bandwidth among these queues; and (3) the lower layer is handled by the disk itself, which does the final ordering of disk requests. We demonstrate the use of APEX in an example scenario, a Learning-on-Demand (LoD) application supported by a multimedia system, where students can search for and playback multimedia-based learning material. In this paper, we present the scheduling concepts of APEX which are based on an extended token bucket algorithm. The disk requests scheduled for service are assembled into batches in order to exploit the intelligence of modern disks. Combined with a specialized work-conservation scheme, this enables APEX to apply bandwidth where it is needed, without the loss of efficiency. We demonstrate, through simulations, that APEX provides both higher throughput and lower response times than other mixed-media disk schedulers while still avoiding deadline violations for real-time requests. We also show its robustness with respect to misaligned bandwidth allocation. The work was conducted while Ketil Lund was an employee at UniK – University Graduate Center, Kjeller, Norway.     

A conflict between the use of estimating and planning tools in the management of information systems

This paper argues that there is a difference between how software development project managers perceive the task of estimating project costs and duration and the way in which commercially available estimating tools are designed to be used. A model of the early estimating/planning stages of a project (the EEPS model) is presented which suggests estimation could be first carried out either before or during the first detailed planning stage. A survey was carrried out which confirmed that project managers typically perceive the ‘true’ process of estimation as being part of planning. This result may explain why estimating tools are not widely used: planning tools are being used instead. By making a temporal distinction between the points at which project information first becomes available, however, it can also be seen that even planning must be driven by some assessment of the size and complexity of a project. At this point only estimating tools are available to provide such estimates. The conclusion seems to be that estimating tools do have a role to play in project management, but they must be explicitly task-based in order to fit the way in which project managers currently perceive estimation.     

基于VB和XPC目标环境的轮胎压力监测数据采集系统

针对轮速信号的特点及轮胎压力监测系统的设计需求,利用VB的可视化编程语言和MATLAB实时仿真工具箱XPC Target及多种数据采集卡的支持,实现了汽车行驶中轮速信号的实时数据采集,并设计了基于VB和MATLAB的间接轮胎压力监测系统。     

两级嵌入式系统的消息驱动和快速传送

提出了两级调度嵌入式操作系统的运行原理和任务、子任务的消息驱动机制,设计了一种新的描述消息的数据结构,用以满足两级调度嵌入式操作系统的运行.利用这种数据结构,可以用零拷贝的方式来传送消息,极大地提高了系统的效率.在两级嵌入式操作系统中,构建了完全独立的、由不同类型消息所组成的任务级消息队列和子任务级消息队列.最后,分析了这两种消息队列和各种不同类型消息的特点,并分析了利用消息驱动任务和子任务的方法.     

一种改进的基于Smith原则的计算机高速通信网络的拥塞控制方案

1.引言 ATM网络是一类虚拟的电路交换网络,它融入了电路交换技术和包交换技术。在这两个系统融入以前它们是独立的,若要互相通信必须获得彼此的通信参数才能建立虚拟连接。而ATM网络通过存储技术和统计复用来共享网络资源,网络资源的共享使得通信费用大大减少。ATM是以定长的信元(cell)作为高速通信信息的载体,它具有高速、低比特错误率、动态分配带宽和高复合能力的优点,这些使得它非常适宜于需要保证服务质量(Quality of Service,QoS)的多媒体数据流。由于多媒体业务流的特性,常引起网络拥塞并降低服务的质量。因此必须采取一定的流量管理控制机制来避免网络的拥塞。     

A simulation approach to modelling baggage handling systems at an international airport

The baggage handling system is a critical component of an airport’s operations, coordinating many different elements and agents in different areas of the facility. Due to the complexity of their interrelationships, an effective analysis of the impact of different operating strategies on the system must consider these elements and agents not in isolation from each other but rather as an integrated whole. This paper presents a microscopic simulation model for a baggage handling system that fully integrates all baggage-related subsystems. These include passenger arrival to check-in queues, baggage check-in, security screening, sorting, transport to the aircraft and loading. Under this approach, not only the individual subsystems but also their interactions can be simulated and studied. The proposed simulator is applied to the case of Santiago International Airport in Chile where passenger demand has grown beyond the existing baggage handling system’s operating capacity. The principal contributions of this study are the extension and adaptation of a vehicle traffic simulator software to the baggage handling problem and the development of a platform that models baggage handling as an integrated unit. The tool is applied to the analysis of the overall system and its components under a number of different real-world scenarios. In this application, the movement of bags and their interactions with the rest of the system are simulated in great detail for a given period. This level of granularity permits the simulator to analyse accurately the effects of different scenarios and how they are propagated through the system.     

Design Principles-Based Interactive Learning Tool for Solving Nonlinear Equations

Interactive learning tools can facilitate the learning process and increase student engagement, especially tools such as computer programs that are designed for human-computer interaction. Thus, this paper aims to help students learn five different methods for solving nonlinear equations using an interactive learning tool designed with common principles such as feedback, visibility, affordance, consistency, and constraints. It also compares these methods by the number of iterations and time required to display the result. This study helps students learn these methods using interactive learning tools instead of relying on traditional teaching methods. The tool is implemented using the MATLAB app and is evaluated through usability testing with two groups of users that are categorized by their level of experience with root-finding. Users with no knowledge in root-finding confirmed that they understood the root-finding concept when interacting with the designed tool. The positive results of the user evaluation showed that the tool can be recommended to other users.