An iterative learning approach to formation control of multi-agent systems

In this paper, an efficient framework is proposed to the formation control problem of multiple agents with unknown nonlinear dynamics, by means of the iterative learning approach. In particular, a distributed D-type iterative learning scheme is developed for the multi-agent system with switching topology, whose switching time and sequence are allowed to be varied at different iterations according to the actual trajectories of agents, and a sufficient condition is derived to ensure that the desired formation can be always preserved from the initial starting location to the final one after some iterations. Simulation results are provided to verify the effectiveness of the proposed approach.     

An interactive system for the construction and animation of systems dynamics models

An interactive system, SIMILE, for the construction, manipulation and animation of systems dynamics models is described. The system is intended to be used primarily as an educational tool, to allow users to experiment with and develop systems dynamics models. However, the system also may be used for creating films of these models.

A model is represented pictorially as a graph, where nodes represent components and edges show relations between these components. One is able to graphically create and modify a particular model. In executing or running a model, the graphic configuration is itself animated; this animation may take place at a display terminal, or the system output may be routed to a microfilm plotter to produce a film of the model.

At the terminal, the execution may be speeded up or slowed down; also one may step through the model (with respect to time), or examine the state of the model at any point in the simulation. Plots of the values of selected variables against time may also be obtained. In addition, changes to a model, or in a model's parameters, can be easily made and the effects of these changes can be immediately seen.

A number of short films have been produced by the system. These include a film which illustrates certain aspects of feedback loops and another showing the effect of specific parameters on a model of an influenza epidemic.     

需求依赖减排水平和价格的供应链决策与协调机制

针对由一个低碳产品制造商与一个零售商组成的供应链, 考虑需求同时受减排水平和销售价格的影响, 分别研究寄售契约、收益共享契约以及收益共享与减排成本共担3 种契约下供应链企业的优化决策, 并进一步探讨当需求的确定部分为和式、随机部分服从均匀分布时的供应链系统的最优决策. 从理论上证明了制造商与零售商之间的合作利于促进减排水平的提升, 也利于供应链系统期望总利润的增加. 最后, 探讨了不同参数对协调供应链绩效的影响.

     

A comparison of catchment water quality models and direct estimation techniques

Information on water quality, in particular on sediment, phosphorus and nitrogen exports from catchments, is required by catchment managers and other stakeholder groups to determine appropriate management options for water quality issues. However intensive spatial and temporal data on concentrations or loads of these nutrients is relatively scarce. Given this constraint, nutrient export models which can provide useful information on nutrient loads with only sparse data inputs are required. In addition, more complex physics and conceptually based models which are commonly available worldwide are often inappropriate for predicting loads in catchments. Consequently, models of a simpler conceptual and/or empirical type are used where input data are sparse and key processes are catchment dependent. This paper compares four such models (CMSS, AQUALM, Moss model and IHACRES-WQ) and several methods based on direct estimation for their ability to predict loads in Australian catchment situations. The implications of the limited available input data sets for load prediction in Australian catchments are discussed. In particular the importance of coordinated data collection over longer time periods and sufficiently fine temporal scales, covering a broad range of event sizes, is emphasised.     

Optimal sequencing of water supply options at the regional scale incorporating alternative water supply sources and multiple objectives

In recent years, the sequencing of water supply projects has become increasingly complex, as a result of the need to consider alternative water sources and additional objectives. In order to address this problem, two sequencing approaches are presented in this paper to assist in identifying the optimal sequence of water supply projects. The methods are applied to a case study based on the southern Adelaide water supply system, South Australia, over a 40-year planning horizon. Desalination plants, rainwater and stormwater sources are considered in addition to existing surface water sources. The objectives used include the present value of cost and greenhouse gas (GHG) emissions and optimal sequences are obtained for a range of demand and discount rate scenarios. The results demonstrate that there are noticeable tradeoffs between costs and GHG emissions when favouring different objectives, but that the impacts of uncertain demands and discount rates are potentially more significant.     

An iterative approach to determine the complexity of local models for robust identification of nonlinear systems

In this paper, a new multi-model approach is proposed for identification of nonlinear systems. In similar identification methods, the operating space is partitioned and a local model is suggested for each partition. In such approaches, since the same linear structure is often used for all local models; huge number of local linear models is usually required to reasonably model an operating region with severely nonlinear dynamics. Therefore the size of the global model may exponentially increase; and as a result model robustness may decrease. In the proposed approach the best model structure is selected for the particular nonlinear study system in an iterative approach. At each iteration, a choice is made to increase number of local models and/or increase the local model complexity. Furthermore, it determines the complexity of local models based on increasing the model accuracy and ensuring the model robustness. In order to optimize the model approximation capability and model robustness, a model term selection approach based on a forward orthogonal least squares algorithm and a criterion that minimizes the sum of the variance of the parameter estimates is applied. Simulation results show that the proposed method results in an excellent validation performance with fewer parameters.     

An event-driven high level model for the specification of laws in open multi-agent systems

The agent development paradigm poses many challenges to software engineering researchers, particularly when the systems are distributed and open. They have little or no control over the actions that agents can perform. Laws are restrictions imposed by a control mechanism to deal with uncertainty and to promote open system dependability. In this paper, we present a high level event-driven conceptual model of laws. XMLaw is an alternative approach to specifying laws in open multi-agent systems that presents high level abstractions and a flexible underlying event-based model. Thus XMLaw allows for flexible composition of the elements from its conceptual model and is flexible enough to accept new elements.     

An iterative Kalman smoother/least-squares algorithm for the identification of delta-ARX models

Additive measurement noise on the output signal is a significant problem in the δ-domain and disrupts parameter estimation of auto-regressive exogenous (ARX) models. This article deals with the identification of δ-domain linear time-invariant models of ARX structure (i.e. driven by known input signals and additive process noise) by using an iterative identification scheme, where the output is also corrupted by additive measurement noise. The identification proceeds by mapping the ARX model into a canonical state-space framework, where the states are the measurement noise-free values of the underlying variables. A consequence of this mapping is that the original parameter estimation task becomes one of both a state and parameter estimation problem. The algorithm steps between state estimation using a Kalman smoother and parameter estimation using least squares. This approach is advantageous as it avoids directly differencing the noise-corrupted ‘raw’ signals for use in the estimation phase and uses different techniques to the common parametric low-pass filters in the literature. Results of the algorithm applied to a simulation test problem as well as a real-world problem are given, and show that the algorithm converges quite rapidly and with accurate results.     

Project verification and construction of superchip tests at the RTL level

Methods were proposed for project verification and directed design of the superchip tests represented in VHDL at the RTL level. The problem of test design and project verification was solved on the basis of the CNF-satisfiability of some system of Boolean functions.     

GPR data analysis using multi-agent and clustering approaches: A tool for technical management of water supply systems

In this paper a combination of the multi-agent paradigm and a very well known clustering technique is used for unsupervised classification of subsoil characteristics working on a collection of ground penetrating radar (GPR) survey files. The main objective is to assess the feasibility of extracting features and patterns from radargrams. By optimizing both the field work and the interpretation of the raw images our target is to obtain visualizations that are automatic, fast, and reliable so to suitably assess the characteristics of the prospected areas and extract relevant information. The architecture of the system may be split into three interrelated processes: (a) pre-processing, (b) hierarchical agglomerative clustering, and (c) retrieval and visualization. The proposed system shows the viability of arranging GPR data from survey files into clusters, thus reducing the amount of information to be dealt with, while preserving its reliability. The system also helps characterize subsoil properties in a very natural and fast way, favors GPR files interpretation by non-highly qualified personnel, and does not require any assumptions about subsoil parameters. A powerful tool to analyze underground components in water supply systems is thus generated that acts in a non-destructive way and supports decision-making in water supply management.     

智慧校园供水系统的可视化及其关系模型的构建

智慧校园供水系统是智慧校园的重要组成,为了提升智慧校园的服务和管理水平,文章就供水系统的用水可视化及用水量预测这两个问题展开分析和研究.利用可视化技术和回归模型对校园供水情况进行深入挖掘和分析,为智慧校园供水系统的智能化管理提供更多的信息和帮助.     

基于供水全生命周期管控的智慧水务平台研建

为解决供水全流程、各环节的有效管控,确保城乡居民用水安全,应用新科技和互联网思维促进和带动水务现代化,提升水务行业社会管理和公共服务能力,提出基于供水全生命周期管控的智慧水务平台解决方案。该平台充分利用物联网、大数据、移动互联网等新技术,汇聚生产、输配、运营、管理各类关键数据,进行多源信息融合处理、存储、分析,实现水源监管、生产管理、管网监控、营收管理、河湖长制、智慧应用等各类业务的供水全生命周期智慧化管控,平台的投入使用提高水务公司日常的运营效率,有效降低供水管网爆管率及漏损率,提升水务公司公共服务能力和水平,增强供水各环节多源异构数据的融合共享及智慧应用。     

Multipoint efficient iterative methods and the dynamics of Ostrowski's method

ABSTRACT

In this work, we introduce a modification into the technique, presented in A. Cordero, J.L. Hueso, E. Martínez, and J.R. Torregrosa [Increasing the convergence order of an iterative method for nonlinear systems, Appl. Math. Lett. 25 (2012), pp. 2369–2374], that increases by two units the convergence order of an iterative method. The main idea is to compose a given iterative method of order p with a modification of Newton's method that introduces just one evaluation of the function, obtaining a new method of order p+2, avoiding the need to compute more than one derivative, so we improve the efficiency index in the scalar case. This procedure can be repeated n times, with the same approximation to the derivative, obtaining new iterative methods of order p+2n. We perform different numerical tests that confirm the theoretical results. By applying this procedure to Newton's method one obtains the well known fourth order Ostrowski's method. We finally analyse its dynamical behaviour on second and third degree real polynomials.     

Analytical model of adoption of item level RFID in a two-echelon supply chain with shelf-space and price-dependent demand

We investigate whether it is possible for the manufacturer as well as the retailer to derive economic benefits from item-level RFID. We consider two supply chain contracts. In the first instance the manufacturer sets the wholesale price for his product and in response the retailer sets the retail price and allocates the shelf-space. We find that in this setting item-level RFID is adopted in a decentralized supply chain at the same levels of RFID costs as in an integrated supply chain with a single decision maker. The second case that we consider involves a powerful retailer setting product shelf-space prices. In this setting the manufacturer essentially rents shelf-space from the retailer. We find that in this setting, the retailer may force the adoption of RFID even if it does not maximize the chain's total profit.     

Paradigm shift to enhanced water supply planning through augmented grids,scarcity pricing and adaptive factory water: A system dynamics approach

This paper details a system dynamics model developed to simulate proposed changes to water governance through the integration of supply, demand and asset management processes. To effectively accomplish this, interconnected feedback loops in tariff structures, demand levels and financing capacity are included in the model design, representing the first comprehensive life-cycle modelling of potable water systems. A number of scenarios were applied to Australia's populated South-east Queensland region, demonstrating that introducing temporary drought pricing (i.e. progressive water prices set inverse with availability), in conjunction with supply augmentation through rain-independent sources, is capable of efficiently providing water security in the future. Modelling demonstrated that this alternative tariff structure reduced demand in scarcity periods thereby preserving supply, whilst revenues are maintained to build new water supply infrastructure. In addition to exploring alternative tariffs, the potential benefits of using adaptive pressure-retarded osmosis desalination plants for both potable water and power generation was explored. This operation of these plants for power production, when they would otherwise be idle, shows promise in reducing their net energy and carbon footprints. Stakeholders in industry, government and academia were engaged in model development and validation. The constructed model displays how water resource systems can be reorganised to cope with systemic change and uncertainty.     

省级建设系统政务信息化监管平台建设与应用系统集成

本文从省级政务信息监管平台和应用系统集成两个方面入手,就如何在省级政务信息网上搭建一套标准统一、功能完备、性能先进、安全可靠的省级信息化监管系统软件进行研究.研究的目的在于规范业务流程,提高工作效率和监管水平,构筑更加公正、高效、规范、有序、开放的政务信息化平台,从制度上防止建筑领域的腐败问题的产生.     

An iterative approach to the optimal co-design of linear control systems

This paper investigates the optimal co-design of both physical plants and control policies for a class of continuous-time linear control systems. The optimal co-design of a specific linear control system is commonly formulated as a nonlinear non-convex optimisation problem (NNOP), and solved by using iterative techniques, where the plant parameters and the control policy are updated iteratively and alternately. This paper proposes a novel iterative approach to solve the NNOP, where the plant parameters are updated by solving a standard semi-definite programming problem, with non-convexity no longer involved. The proposed system design is generally less conservative in terms of the system performance compared to the conventional system-equivalence-based design, albeit the range of applicability is slightly reduced. A practical optimisation algorithm is proposed to compute a sub-optimal solution ensuring the system stability, and the convergence of the algorithm is established. The effectiveness of the proposed algorithm is illustrated by its application to the optimal co-design of a physical load positioning system.