Predicting dust concentrations in Newcastle,NSW

Two models were used to estimate wind-blown dust in the Kooragang and Inner Newcastle area of NSW in Australia. The first was DUSTCON, which is a screening model for fugitive dust emissions, and the second was DISPMOD, a Gaussian plume air quality model which was modified to incorporate an algorithm for dust emissions that accounted for the dust suppression effects of rainy days. Contours of dustball, and of total suspended particles obtained from the models were similar in shape and reflected the strong meteorological influence on dust transport. However, when the results are compared to observations it is apparent that dust suppression activities practiced by industry, but not included in the inventory used as inpu to the models, reduce emissions very significantly.     

Computational methods for income transfer analysis

The analysis of transfer systems that include both social benefit and taxation programs is complicated by the fact that the component programs comprising those systems interact. This paper develops a mathematical framework for the analysis of such systems at the micro‐level, i.e., using an individual or family as the unit of analysis. The first section describes the importance of income transfer issues and identifies criteria for evaluating proposed methodologies. Subsequent sections address the foundations for appropriate methods from two perspectives. The first perspective examines transfer systems using elementary concepts drawn from set theory, real analysis, and welfare economics; the assumptions and theorems presented allow the derivation of relevant system properties and serve to ensure that the systems discussed are well‐defined. The second perspective concentrates on the numerical methods required to execute income transfer analyses. The final section describes an implementation of this framework and briefly discusses the associated software.     

Suppression of chaotic behavior in horizontal platform systems based on an adaptive sliding mode control scheme

This work presents an adaptive sliding mode control scheme to elucidate the robust chaos suppression control of non-autonomous chaotic systems. The proposed control scheme utilizes extended systems to ensure that continuous control input is obtained in order to avoid chattering phenomenon as frequently in conventional sliding mode control systems. A switching surface is adopted to ensure the relative ease in stabilizing the extended error dynamics in the sliding mode. An adaptive sliding mode controller (ASMC) is then derived to guarantee the occurrence of the sliding motion, even when the chaotic horizontal platform system (HPS) is undergoing parametric uncertainties. Based on Lyapunov stability theorem, control laws are derived. In addition to guaranteeing that uncertain horizontal platform chaotic systems can be stabilized to a steady state, the proposed control scheme ensures asymptotically tracking of any desired trajectory. Furthermore, the numerical simulations verify the accuracy of the proposed control scheme, which is applicable to another chaotic system based on the same design scheme.     

Fully PCA-based approach to optimization of multiresponse-multistage problems with stochastic considerations

Manufacturing systems have several stages of operations in which different quality characteristics are formed so it is an important objective to ensure that the final products meet the predefined specification limits. Due to the stream of variations in such systems, controlling and improving the product quality level becomes more complicated rather than the single stage ones. To deal with such problems, Response Surface Methodology has received much more attention in recent years. In the context of quality engineering, these problems usually include correlated response variables as well as correlated covariates. This study presents a new framework for product quality improvement in multistage manufacturing systems with multiple correlated responses and covariates in each stage. Stochastic aspects of this model include probabilistic covariates and statistical distributions of estimated parameters in the response surfaces. To cover these considerations, multistage stochastic programming is used together with the Principal Component Analysis technique to make the responses as well as the covariates uncorrelated at each stage of the operations. At the end, a numerical example has been analyzed by the proposed approach and for large-scale cases some meta-heuristic algorithms have been applied to solve the model.     

Periodic capacitated arc-routing problem with inventory constraints

The purpose of this paper is to study the periodic arc-routing problem when the arcs of a network behave as customers, and sufficient material is delivered so that each achieves its desired inventory level. Therefore, routing and inventory decisions are made simultaneously. Applications include dust suppression in open-pit mines or forest roads and plant watering along sidewalks or street medians. A truck periodically sprays water along the edges of a network. The humidity reaches a desired level and is then consumed over time until water is delivered again. The quantity of water delivered can be fixed or variable; we consider both scenarios and propose a mathematical model for each. Results are reported to validate the model. The contribution of this paper is the first mathematical model that combines inventory and routing decisions in the arc-routing domain.     

Systems of Set-Valued Quasivariational Inclusion Problems

We propose four kinds of systems of set-valued quasivariational inclusion problems in product spaces, which include many known systems of equilibrium problems and systems of variational inequalities as well as inclusion problems. Sufficient conditions for the solution existence are established. When applied to special cases, these conditions improve many existing results in the literature. To ensure the generality of our problem setting and results, applications in fixed-point theory and quasioptimization problems are included. This work was partially supported by the Vietnam national program on basic research in natural sciences. A part of the work of the first author was completed during his stay at the Department Mathematics of Namur University and its hospitality is gratefully acknowledged. The authors are indebted to an anonymous referee for valuable remarks.     

Single Parameter Dissipativity and Attractors in DiscreteTirne Asynchronous Systems ∗

Discrete time nonautonomous dynamical systems generated by nonautonomous difference equations are formulated as discrete time skew—product systems consisting of cocycle state mappings that are driven by discrete time autonomous dynamical systems. Forwards and pullback attractors are two possible generalizations of autonomous attractors to such systems. Their existence follows from appropriate forwards or pullback dissipativity conditions. For discrete time nonautonomous dynamical systems generated by asynchronous systems with frequency updating components such a dissipativity condition is usually known for a single starting parameter value of the driving system. Additional conditions that then ensure the existence of a forwards or pullback attractor for such an asynchronous system are investigated here     

Multi-parallel work centers scheduling optimization with shared or dedicated resources in low-volume low-variety production systems

A new methodology for modeling large-scale scheduling problems in low-volume low-variety production systems is proposed through this paper. Such scheduling problems are constrained by limited time and resources, where each work center is assigned a unique statement of work, to be completed on-time with the budgeted number of resources. Products assembled in low-volume low-variety production systems are processed through a series of stations referred to as work centers, where varying levels and classifications of resources are deployed onto the product. Aircraft, heavy aero-structures, and heavy military equipment are examples of products assembled in low-volume low-variety production systems. To ensure products are delivered on-time and on-budget, it is crucial to execute to a detailed schedule, such that all precedence, resource, zonal, and other constraints and characteristics inherent in such production systems are successfully satisfied. Despite the criticality of detailed schedules in delivering products on-time and on-budget, limited research is reported on mixed-integer programming approaches for scheduling optimization of activities in low-volume low-variety production systems. The discrete-time linear mixed-integer mathematical programming model developed in this paper fills the gap in the current literature with a direct impact on the organizations’ service levels and bottom line. The proposed mathematical programming models are validated through a real-world case-study of the assembly process of a narrow body aircraft to ensure compatibility in the modeling of large-scale industrial problems.     

Reduced-order feedback control of distributed parameter systems via singular perturbation methods

Implementable feedback control of distributed parameter systems must often be based on reduced-order models due to the infinite dimensional nature of the actual open-loop system. The behavior of controllers designed via reduced-order models obtained with singular-perturbation techniques is analyzed. When such controllers are used in the actual distributed parameter system, the closed-loop stability is in question. The results presented here provide bounds on the smallness of the singular perturbation parameter to ensure stable operation; such a priori bounds may be used to evaluate potential reduced-order controllers for distributed parameter systems.     

Incremental stability analysis of stochastic hybrid systems

In this paper, we study the incremental stability of stochastic hybrid systems, based on the contraction theory, and derive sufficient conditions of global stability for such systems. As a special case, the conditions to ensure the second moment exponential stability which is also called exponential stability in the mean square of stochastic hybrid systems are obtained. The theoretical results in this paper extend previous works from deterministic or stochastic systems to general stochastic hybrid systems, which can be applied to qualitative and quantitative analysis of many physical and biological phenomena. An illustrative example is given to show the effectiveness of our results.     

A Theoretical Model for Particulate Transport from an Elevated Source in the Atmosphere

An analytical model for the transport of dust released froman elevated source into the atmosphere is presented. This treatmentincorporates horizontal advection with the airflow past thesource, vertical settling under gravity and dispersion due toatmospheric turbulence. Mathematical features include the derivationof a fairly simple solution, expressed in terms of well-knownfunctions. Expressions for the maximum ground level concentrationof dust are given in terms of the particle density and size.It is suggested that the validity of these upper bounds couldbe tested by field surveys around power stations.     

Generation and suppression of a new hyperchaotic nonlinear model with complex variables

In this paper, we introduce a new hyperchaotic complex Chen model. This hyperchaotic complex system is constructed by adding a complex nonlinear term to the third equation of the chaotic complex Chen system with consideration it’s all variables are complex. The new system is a 6-dimensional continuous real autonomous hyperchaotic system. The properties of this system including invariance, dissipation, equilibria and their stability, Lyapunov exponents, Lyapunov dimension, bifurcation diagrams and hyperchaotic behavior are studied. Different forms of hyperchaotic complex Chen systems are constructed. We suppress the hyperchaotic behavior of our system via passive control method by using one complex controller. The hyperchaotic attractors of the new system are converted to its unstable trivial fixed point and tracked to its unstable non trivial fixed points and periodic orbits. Block diagrams of our system are designed by using Matlab/Simulink after and before the suppression process to ensure the validity of the analytical results.     

Synchronization of nonlinear systems with delays via periodically nonlinear intermittent control

In this paper, the synchronization for a class of nonlinear chaotic systems with delays is proposed by using periodically intermittent nonlinear feedback control. Some synchronization criteria are derived based on Lyapunov functional theory and several differential inequalities such as Halanay inequality. As a special case, some sufficient conditions are obtained to ensure the synchronization of nonlinear systems without delays. Finally, some numerical simulations are presented to verify the theoretical results.     

Recursiveness of zero structures for system matrices of interconnected linear systems via module theoretic tools

The importance of the zeros of multivariable linear systems is well-known in terms of measure obstructions to the controllability and the observability. In this paper, a recursive decomposition of interconnected systems is outlined by taking into account the sequential structure of the connections. The paper extends the coordinate, module-theoretic studies from the elementary algebraic systems theory to include the case of such linear interconnected systems which need not to be controllable or observable. Also, the properties of controllability and observability, the decoupling zeros and the signal bloking issues are characterized.     

Some simple global synchronization criterions for coupled time-varying chaotic systems

Based on the Lyapunov stabilization theory and matrix measure, this paper proposes some simple generic criterions of global chaos synchronization between two coupled time-varying chaotic systems from a unidirectional linear error feedback coupling approach. These simple criterions are applicable to some typical chaotic systems with different types of nonlinearity, such as the original Chua’s circuit and the Rössler chaotic system. The coupling parameters are determined according to the new criterion so as to ensure the coupled systems’ global chaos synchronization.     

A general formalism for synchronization in finite dimensional dynamical systems

In this paper, an attempt is made to propose a general definition of synchronization for finite dimensional dynamical systems. The synchronization is defined here for two coupled dynamical systems with control inputs. Output functions of such systems are introduced to describe the systems’ properties on which the synchronization problem focus. Exact synchronization, asymptotic synchronization, and approximate synchronization are, respectively, defined by comparing the output functions in the corresponding ways. The definition here can also include chaos control and anti-control. The definition here covers various synchronization investigated in the references.     

Optimal Control of Non-stationary Differential Linear Repetitive Processes

Differential repetitive processes are a distinct class of continuous-discrete 2D linear systems of both systems theoretic and applications interest. The feature which makes them distinct from other classes of such systems is the fact that information propagation in one of the two independent directions only occurs over a finite interval. Applications areas include iterative learning control and iterative solution algorithms for classes of dynamic nonlinear optimal control problems based on the maximum principle, and the modelling of numerous industrial processes such as metal rolling, and long-wall cutting etc. The new results in is paper solve a general optimal problem in the presence of non-stationary dynamics.     

选择性维护决策的研究进展与挑战

在工业生产和军事领域中,生产设备或技术装备往往要求连续执行多个任务,并且在任务间隔期内需要对系统中老化或失效的部件进行维护以确保完成后续任务.然而,由于受有限的成本、时间、设备及人员等维护资源的限制,在任务间隔期内难以修复系统中的所有组成部件,决策者只能有策略地选择部分部件进行维护,从而最大程度地确保完成后续任务,这类维护决策问题被称为选择性维护.现主要介绍选择性维护决策的基本模型和特点,并从系统建模、维护程度、资源约束与资源消耗、任务特性与应用环境、优化算法五个方面综述国内外关于选择性维护决策的研究进展和发展动态,并讨论其发展趋势和挑战.     

ON THE EXISTENCE AND UNIQUENESS OF POSITIVE SOLUTIONS FOR A CLASSOF DEGENERATE ELLIPTIC SYSTEMS

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Stability of interconnected impulsive switched systems subject to state dimension variation

The contribution of this article is twofold. First we deal with the stability of continuous-time interconnected impulsive switched systems for which the dimension of the system’s state vector may change at different modes. A dwell time condition is derived to ensure the exponential convergence of the state trajectories, and when the system is subject to a non-vanishing perturbation, a superior bound of the state trajectories is provided as well. The main advantage of the solution we propose is its direct application to practical fields such as metallurgy or traffic control through the use of semi-definite programming solvers. Second, we introduce in the framework a platoon of vehicles in automated highway systems where vehicles may join or leave the platoon. Then, we detail the longitudinal stability problem of such a system and illustrate the features of the proposed stability conditions through numerical simulations.