Multi-vehicle consensus with a time-varying reference state

In this paper, we study the consensus problem in multi-vehicle systems, where the information states of all vehicles approach a time-varying reference state under the condition that only a portion of the vehicles (e.g., the unique team leader) have access to the reference state and the portion of the vehicles might not have a directed path to all of the other vehicles in the team. We first analyze a consensus algorithm with a constant reference state using graph theoretical tools. We then propose consensus algorithms with a time-varying reference state and show necessary and sufficient conditions under which consensus is reached on the time-varying reference state. The time-varying reference state can be an exogenous signal or evolve according to a nonlinear model. These consensus algorithms are also extended to achieve relative state deviations among the vehicles. An application example to multi-vehicle formation control is given as a proof of concept.     

Goal and predictive coordination in two level hierarchical systems

The multilevel system theory applies two general methods of coordination, which influences the manner of subsystem management—goal and predictive coordinations. Both these general types of coordination perform multiple data transfer between the hierarchical levels and delay the evaluation and implementation of a global optimal solution of a control problem. The paper demonstrates a coordination policy, which decreases the information transfer in the hierarchical system, titled “noniterative” coordination. The last is developed both for goal and predictive coordination strategies. The mathematical foundations of these two noniterative coordination strategies are presented. Comparative analysis is performed to identify peculiarities and drawbacks for the real time management of two level hierarchical systems. Assessment of the computational workload and speed of the coordination, expressed as “flops” numbers is done for the case of nonlinear optimization problems. Both the noniterative coordination strategies benefit the real time operation in the multilevel system by reducing the iterative computations and the data transfer between the hierarchical levels. The predictive coordination has potential in speeding the management process and resource allocation, due to the decomposition approach, which is applied.     

A vendor managed inventory model under contractual storage agreement

Vendor managed inventory (VMI) is a supply chain partnership strategy that allows a supplier to place orders on behalf of its customers. This paper considers a supply chain composed of a single vendor and multiple retailers operating under a VMI contract that specifies limits on retailers' stock levels. We address the problem of synchronizing the vendor's cycle time with the buyers' unequal ordering cycles by developing a mixed integer non-linear program that minimizes the joint relevant inventory costs under storage restrictions. We also propose a cost efficient heuristic to solve the developed optimization problem. We conducted computational experiments to assess the reduction in the total supply chain costs resulting from relaxing the restriction of equal ordering cycles. It is found that the heuristic generates greater cost savings in cases of increased variability in retailers' demand and cost parameters.     

Calculation of the ligand–lanthanide ion energy transfer rate in coordination compounds: contributions of exchange interactions

Recently, one of us (O.L.M.) developed a theoretical approach to the energy transfer process between a ligand and a lanthanide ion in luminescent compounds. This approach takes into account the direct Coulomb interaction only. Here we present further calculations which also include the exchange Coulomb interaction (isotropic and anisotropic). The selection rules on the total angular momentum, J, of the lanthanide 4f states, derived from each interaction are different. They are in fact complementary. We discuss the case of energy transfer to the ⁵D₁ manifold of the Eu³⁺ ion, which is forbidden when only the direct Coulomb interaction is considered but becomes allowed through the exchange interaction. In this case numerical estimates show that, depending on resonance conditions and the nature of the ligand donor state, the transfer rate may assume very high values. It is also emphasised that, according to the present approach, energy transfer to the ⁵D₀ level of the Eu³⁺ ion is forbidden by both mechanisms, provided J-mixing between the ⁷F₀ and ⁷F₂ manifolds is neglected.     

基于协调中心的敏捷供应链系统的研究

供应链管理是当前国内外关注的热点问题之一。本文分析了现有供应链技术与系统的局限性及动态联盟对供应链系统需求的基础上，提出了基于协调中心的敏捷供应链系统，给出了系统的模型、组成与功能。借鉴信息经济学的有关理论与方法说明了系统的管理模式及动作方式。     

Conformance notions for the coordination of interaction components

In component-based development, software components are taken as units of composition. Nevertheless, to achieve the widely disseminated status of components being plugged together as simple ‘Lego Pieces’, the integration of components must be carefully designed, systematised and verified; only this can ensure reliable architectures. In this work, we propose some conformance notions to predict the precise nature of some forms of composition, considering coordination patterns used in the integration. These notions are formalised in terms of the denotational semantics of the process algebra CSP, and assist the designer in common activities during integration, such as the substitution of component specifications by implementations, contract adaptations, and system extensions. To support mechanical verifications using FDR (a model-checker for CSP), we derive test characterisations from the denotational definitions of conformance. We illustrate the application of these notions through a systematic composition strategy of software frameworks, and we mechanically verify the preservation of behavioural component properties in these compositions. Moreover, we characterise the well-formedness of a coordination pattern used in this strategy at the design stage, before components are assembled.     

Novel Cd(II) and Co(II) 2-D frameworks based on terephthalate and 1-substitutedimidazole mixed-ligands

The two Cd(II) and Co(II) 2-D frameworks have been prepared by means of self-assemblies of Cd(II) or Co(II) salts and 1-substituted imidazole and terephthalic acid, and structurally characterized by X-ray diffraction analyses. In complex 1 2-D frameworks with rhombic cavity are formed, in which the each top point of rhombus contains one hexa and two heptacoordinated Cd(II). In complex 2 2-D networks with rectangular cavities are formed, and the opposite benzene rings from carboxyls in each rectangular cavity are parallel.     

Coordination Approaches and Systems – Part II: An Operational Perspective

This is the second of two papers surveying research in coordination approaches and systems. This paper is concerned with operational coordination, which is aimed at coordinating activities such that the design process can be performed in a near optimal manner with respect to time, and the allocation and utilisation of resources. Aspects of coordination categorised as operational include resource management, scheduling and planning. The first of these two papers presents a review of coordination from a strategic perspective, which is concerned with the decision management aspects of coordination. Greater emphasis is now being placed on the significance of organising the design process as this affects time to market, product quality, cost, and consequently product success. The aim of this paper is to present a fundamental review of operational coordination approaches and systems. The 1990s has seen much progress being made towards a greater understanding and appreciation of coordination in various disciplines through the development of a wide range of approaches and systems. However, there remains a requirement to formally identify the key issues involved in coordination such that a widely accepted representation can be agreed upon. Consequently, research should continue to be supported in the exploration for a unified approach to coordination which will permit a broader and greater understanding of those aspects involved.     

Assembly of a novel luminescent coordination polymer from europium nitrate and a new semirigid bridging podand

One-dimensional zig-zag coordination polymer has been rationally assembled by the reaction of europium nitrate and a new amide type semirigid bridging podand 1,4-bis{[(2′-m-picolylaminoformyl)phenoxyl]methyl}naphthalene (L). The coordination chains are further linked by the intermolecular hydrogen bonds to form two-dimensional supramolecular layer structure. At the same time, the luminescent properties of the Eu(III) complex were also investigated. Under the excitation, the complex exhibited characteristic emissions of europium ion.     

Coordination-induced formation of nanobelts of organic-inorganic hybrid materials at room temperature

The unexpected finding that the direct mix of o-phenylenediamine and H₂PdCl₄ aqueous solution at room temperature leads to supramolecular nanobelts of coordination polymers was reported. The morphology of the structures was characterized by scanning electron microscopy (SEM) and the chemical composition was examined by energy-dispersed spectrum (EDS) and X-ray maps analysis. The possible formation process of such supramolecular nanobelts is given and the influence of the molar ratio of reactants on the formation of these nanobelts is also examined. It is also found that the molar ratio of reactants has strong influence on the formation of the supramolecular structures.