FloodNet: Coupling Adaptive Sampling with Energy Aware Routing in a Flood Warning System

We describe the design of FloodNet, a flood warning system, which uses a grid-based flood predictor model developed by environmental experts to make flood predictions based on readings of water level collected by a set of sensor nodes. To optimize battery consumption, the reporting frequency of sensor nodes is required to be adaptive to local conditions as well as the flood predictor model. We therefore propose an energy aware routing protocol which allows sensor nodes to consume energy according to this need. This system is notable both for the adaptive sampling regime and the methodology adopted in the design of the adaptive behavior, which involved development of simulation tools and very close collaboration with environmental experts.     

Object－Oriented Modeling of Virtual Assembly Process

Virtual assembly is a Virtual Reality (VR) based engineering application which allows engineers to evaluate, analyze, and plan the assembly of mechanical systems. To model the virtual assembly process, new methodology must be applied. Based on the idea that the virtual assembly system is an event driven system, the interactive behavior and information model is proposed to describe the dynamic process of virtual assembly. Definition of the object-oriented model of virtual assembly is put forward.     

A Formal Approach to Protocol Interoperability Testing

Porotocol Interoperability testing is an important means to ensure the interconnection and interoperation between protocol products.In this paper,we proposed a formal approach to protocol interoperability testing based on the operational semantics of Concurrent TTCN.We define Concurrent TTCN‘s operational semantics by using Labeled Transition System,and describe the interoperability test execution and test verdict based on Concurrent TTCN.This approach is very helpful for the formation of formal interoperability testing theory and construction of general interoperability testing system.     

Guaranteed cost control for networked control systems

The guaranteed cost control problem for networked control systems (NCSs) is addressed under conmmnication constraints and varying sampling rate. First of all, a simple inFormation-scheduling scheme is presented to describe the scheduling approach of system signals in NCSs. Then, based on such a scheme and given sampling method, the design procedure in dynarmic output feedback manner is also derived which renders the closed loop system to be asymptotically stable and guarantees an upper bound of the LQ pefformance cost function.     

End-to-End Utilization Control for Aperiodic Tasks in Distributed Real-Time Systems

An increasing number of DRTS （Distributed model. The key challenges of such DRTS are guaranteeing Real-Time Systems） are employing an end-to-end aperiodic task utilization on multiple processors to achieve overload protection, and meeting the end-to-end deadlines of aperiodic tasks. This paper proposes an end-to-end utilization control architecture and an IC-EAT （Integration Control for End-to-End Aperiodic Tasks） algorithm, which features a distributed feedback loop that dynamically enforces the desired utilization bound on multiple processors. IC-EAT integrates admission control with feedback control, which is able to dynamically determine the QoS （Quality of Service） of incoming tasks and guarantee the end-to-end deadlines of admitted tasks. Then an LQOCM （Linear Quadratic Optimal Control Model） is presented. Finally, experiments demonstrate that, for the end-to-end DRTS whose control matrix G falls into the stable region, the IC-EAT is convergent and stable. Moreover,it is capable of providing better QoS guarantees for end-to-end aperiodic tasks and improving the system throughput.     

A Variable-Parameter-Model-Based Feedforward Compensation Method for Tracking Control

Base on the accurate inverse of a system, the feedforward compensation method can compensate the tracking error of a linear system dramatically. However, many control systems have complex dynamics and their accurate inverses are difficult to obtain. In the paper, a variable parameter model is proposed to describe a system and a multi-step adaptive seeking approach is used to obtain its parameters in real time. Based on the proposed model, a variable-parameter-model-based feedforward compensation method is proposed, and a disturbance observer is used to overcome the influence of the model uncertainty. Theoretical analysis and simulation results show that the variable-parametermodel-based feedforward compensation method can obtain better performance than the traditional feedforward compensation.     

A Web-based visual analytics system for real estate data

Real estate is an important industry in most countries.However,the analysis of the real estate market is very challenging as the data are high dimensional and have complex spatial and temporal patterns.In this paper,we present a novel Web-based visual analytics system,which integrates state-of-the-art interactive visualizations to enable end users to create their own visualizations and gain insight into the real estate market.The system is implemented using the new features in HTML5,which are natively supported in current browsers.We adopt a coordinated view design in our system consisting of four major components:a map view to show the geographical information of houses,a stacked graph view to show the evolution of house sales over time,a pixel-bar view to visualize multiple attributes of houses,and a treemap view to present the hierarchical structure of the data.Novel clutter reduction methods and rich user interactions are further proposed to enhance the flexibility and analytical ability of the whole system.We have applied our system to real property market data and obtained some interesting findings.Moreover,feedback from the end users of our system is very positive.     

Automated postoperative blood pressure control

It is very important to maintain the level of mean arterial pressure (MAP) . The MAP control is applied in many clinical situations ,including limiting bleeding during cardiac surgery and promoting healing for patient’s post-surgery. This paper presents a fuzzy controller- based multiple-model adaptive control system for postoperative blood pressure management . Multiple-model adaptive control (MMAC) algorithm is used to identify the patient model ,and it is a feasible system identification method even in the presence of large noise. Fuzzy control (FC) method is used to design controller bank. Each fuzzy controller in the controller bank is in fact a nonlinear proportional- integral (PI) controller ,whose proportional gain and integral gain are adjusted continuously according to error and rate of change of error of the plant output , resulting in better dynamic and stable control performance than the regular PI controller , especially when a nonlinear process is involved. For demonstration , a nonlinear , pulsatile-flow patient model is used for simulation ,and the results show that the adaptive control system can effectively handle the changes in patient’s dynamics and provide satisfactory performance in regulation of blood pressure of hypertension patients.     

Dynamical Immune Intrusion Detection System for IPv6

We have set up a project aiming at developing a dynamical immune intrusion detection system for IPv6 and protecting the next generation Internet from intrusion. We focus on investigating immunological principles in designing a dynamic multi-agent system for intrusion detection in IPv6 environment, instead of attempting to describe all that is intrusion in the network try and describe what is normal used and defined ＇non-selr as intrusion. The proposed abnormal detection model is designed as flexible, extendible and adaptable in order to meet the needs and preferences of network administrators for IPv6 environment.     

Reliability Growth Modeling and Optimal Release Policy Under Fuzzy Environment of an N-version Programming System Incorporating the Effect of Fault Removal Efficiency

Failure of a safety critical system can lead to big losses.Very high software reliability is required for automating the working of systems such as aircraft controller and nuclear reactor controller software systems.Fault-tolerant softwares are used to increase the overall reliability of software systems.Fault tolerance is achieved using the fault-tolerant schemes such as fault recovery (recovery block scheme),fault masking (N-version programming (NVP)) or a combination of both (Hybrid scheme).These softwares incorporate the ability of system survival even on a failure.Many researchers in the field of software engineering have done excellent work to study the reliability of fault-tolerant systems.Most of them consider the stable system reliability.Few attempts have been made in reliability modeling to study the reliability growth for an NVP system.Recently,a model was proposed to analyze the reliability growth of an NVP system incorporating the effect of fault removal efficiency.In this model,a proportion of the number of failures is assumed to be a measure of fault generation while an appropriate measure of fault generation should be the proportion of faults removed.In this paper,we first propose a testing efficiency model incorporating the effect of imperfect fault debugging and error generation.Using this model,a software reliability growth model (SRGM) is developed to model the reliability growth of an NVP system.The proposed model is useful for practical applications and can provide the measures of debugging effectiveness and additional workload or skilled professional required.It is very important for a developer to determine the optimal release time of the software to improve its performance in terms of competition and cost.In this paper,we also formulate the optimal software release time problem for a 3VP system under fuzzy environment and discuss a the fuzzy optimization technique for solving the problem with a numerical illustration.     

DOPS——分布式面向对象编程系统

ＤＯＰＳ是我们在Ｓｕｎ工作站网络中设计实现的分布式面向对象编程系统。目前包括并发面向对象编程语言ＣＣ＋＋和该语言在松散耦合分布式环境中的运行支撑系统ＤＲＴＳ。本文分别介绍ＣＣ＋＋和ＤＲＴＳ的设计与实现，最后给出检测结果。     

Traffic-aware stress testing of distributed real-time systems based on UML models using genetic algorithms

This paper presents a model-driven, stress test methodology aimed at increasing chances of discovering faults related to network traffic in distributed real-time systems (DRTS). The technique uses the UML 2.0 model of the distributed system under test, augmented with timing information, and is based on an analysis of the control flow in sequence diagrams. It yields stress test requirements that are made of specific control flow paths along with time values indicating when to trigger them. The technique considers different types of arrival patterns (e.g., periodic) for real-time events (common to DRTSs), and generates test requirements which comply with such timing constraints. Though different variants of our stress testing technique already exist (that stress different aspects of a distributed system), they share a large amount of common concepts and we therefore focus here on one variant that is designed to stress test the system at a time instant when data traffic on a network is maximal. Our technique uses genetic algorithms to find test requirements which lead to maximum possible traffic-aware stress in a system under test. Using a real-world DRTS specification, we design and implement a prototype DRTS and describe, for that particular system, how the stress test cases are derived and executed using our methodology. The stress test results indicate that the technique is significantly more effective at detecting network traffic-related faults when compared to test cases based on an operational profile.     

Experience and challenges with UML-driven performance engineering of a Distributed Real-Time System

ContextPerformance-related failures of Distributed and Real-Time Software Systems (DRTS’s) can be very costly, e.g., explosion of a nuclear reactor. We reported in a previous work a stress testing methodology to detect performance-related Real-Time (RT) faults in DRTS’s based on the design UML model of a System Under Test (SUT). The stress methodology aimed at increasing the chances of RT failures (violations in RT constraints).ObjectiveAfter stress testing a SUT and finding RT faults, an important immediate question is how to fix (debug) those RT faults and prevent the same RT violations in the future and after deployment. If appropriate solutions to this challenge cannot be found, stress testing and its findings (detection of RT faults) will be of no or little use to the quality assurance goals of the development team.MethodTo move towards systematically solving performance-related problems causing RT faults, we develop a customized version of the standard Software Performance Engineering process and conduct an experiment on a DRTS. The process is iteratively applied to a SUT, while results from stress testing reveal that there are still scenarios in which RT constraints are violated.ResultsApplication of the performance engineering paradigm in this context on a real DRTS enables systematic analysis of performance-related defects and their fixations.ConclusionThe contributions of this work are an initial approach to software performance engineering based on stress testing, and an analysis, based on experimentation, of the open issues that need to be addressed in order to improve the approach.     

生产过程中人的极限工作时间研究

操作工人在长时间的工作过程中,由于精神和身体的疲劳会产生失误,人的可靠性降低,导致生产残次品,甚至危及人身安全。为了了解在保证可靠性的前提下,操作者最长可持续的工作时间(极限工作时间,LWT),提出了一种结合SPCC和ARIMA的方法来进行确定。用连续时间中单位时间间隔内的次品率衡量人的可靠度,并形成次品率时序序列(DRTS)。一方面使用该数列基于ARIMA构建SPCC,并确定样本的UCL、LCL和极限时间范围;另一方面使用ARIMA和SVM配合RTA对需要确定LWT的某一操作者的DRTS进行预测。最后将预测曲线置于SPCC中来确定该操作者LWT的范围。通过对10个操作者8小时,每隔10分钟采样得到的DRTS分析,表明该类工作参数的范围为UCL=[3.89,4.66]、LCL=[-4.98,-3.90]、LWT=[393,450]分钟。确定了一个新操作者的LWT为[435,452]分钟,即435分钟时该操作者就应该停止工作进行休息。     

分布式系统的可信性研究

本文首先介绍了构造高可信性计算机系统的技术与方法，然后对分布系统的可信性研究现状与存在的问题进行了综述。     

A UML-based quantitative framework for early prediction of resource usage and load in distributed real-time systems

This paper presents a quantitative framework for early prediction of resource usage and load in distributed real-time systems (DRTS). The prediction is based on an analysis of UML 2.0 sequence diagrams, augmented with timing information, to extract timed-control flow information. It is aimed at improving the early predictability of a DRTS by offering a systematic approach to predict, at the design phase, system behavior in each time instant during its execution. Since behavioral models such as sequence diagrams are available in early design phases of the software life cycle, the framework enables resource analysis at a stage when design decisions are still easy to change. Though we provide a general framework, we use network traffic as an example resource type to illustrate how the approach is applied. We also indicate how usage and load analysis of other types of resources (e.g., CPU and memory) can be performed in a similar fashion. A case study illustrates the feasibility of the approach.

分布实时仿真系统静态负载平衡策略的研究

研究负载平衡是保证分布仿真系统高效运行的重要前提,分布实时仿真在实时性方面的要求,实现负载平衡需要考虑更多的因素。分别通过对仿真任务和仿真节点的分析,从影响负载平衡的主要因素出发,建立的仿真任务和分布实时仿真系统的数学模型,并根据仿真任务映射到仿真节点上的等效计算量,确定了目标函数,并依此提出了局部最优平衡策略。在假设模型上,对调度策略进行了验证,结果表明采用策略能够获得较小的调度长度,同时由于实时性的考虑,在平衡中存在一定的不平衡。     

End-to-end deadline control for aperiodic tasks in distributed real-time systems

A category of Distributed Real-Time Systems (DRTS) that has multiprocessor pipeline architecture is increasingly used. The key challenge of such systems is to guarantee the end-to-end deadlines of aperiodic tasks. This paper proposes an end-to-end deadline control model, called Linear Quadratic Stochastic Optimal Control Model (LQ-SOCM), which features a distributed feedback control that dynamically enforces the desired performance. The control system considers the aperiodic task arrivals and execution times’ variation as the two external factors of the system unpredictability. LQ-SOCM uses discrete time state space equation to describe the real-time computing system. Then, in the actuator design, a continuous manner is adopted to deal with discrete QoS (Quality of Service) adaptation. Finally, experiments demonstrate that the system is globally stable and can statistically provide the end-to-end deadline guarantee for aperiodic tasks. At the same time, LQ-SOCM is capable of effectively improving the system throughput.

MVL条件下k—out—of-n：S系统的研究

复杂网络环境下的系统组件往往处于多种不同状态,二值逻辑(BL)在描述多种组件状态时显得无能为力.本文提出了采用多值逻辑(MVL)分析组件状态,重点描述k-out-of-n:S系统模型,并采用Minkowski距离和定义可生存性函数描述系统状态和可生存性.实验表明,MVL条件下的k-out-of-n:S模型很好地描述了系统的状态扣可生存性.