Modularized design for cooperative control and plug-and-play operation of networked heterogeneous systems

In this paper, a cooperative control analysis and design method is investigated for heterogeneous dynamical systems that may be of arbitrary relative degree or nonminimum-phase or both. To achieve consensus or cooperative stability, a negative value of input-feedforward passivity index is used to accommodate and analyze such systems, and the magnitude of the index value is also used as the impact coefficient to quantify the impacts of heterogeneous dynamics of these systems on their networked operations. Physical-system-level designs are explicitly carried out to make individual linear and nonlinear systems (which are either feedback linearizable or nonminimum phase of certain form) become passivity-short and to embed one pure integrator into their input–output dynamics. The network-level distributed control can simply be chosen without any knowledge of the heterogeneous dynamics but with only information of an upper bound on their impact coefficients. It is shown, using the impact equivalence principle, that these controls separately designed but implemented together always ensure either local or global consensus and that a global non-trivial consensus emerges if and only if the information network has at least one globally reachable node or is varying but cumulatively connected. The proposed methodology of fully modularized designs unravels complexity of analyzing and designing cyber–physical systems and enables their plug-and-play into networked operations.     

Development of the Acidity of Zirconia-Supported Niobia Catalysts

A series of NbO _x /ZrO₂ catalysts containing up to 2.67wt Nb (ca. 80 nominal surface coverage) was prepared by incipient wetness impregnation from niobium oxalate and oxalic acid solution. The structure of the catalysts was monitored by X-ray diffraction and Raman spectroscopy. The results indicated the presence of a surface Nb phase. No evidence for the formation of crystalline Nb₂O₅ species was found. The development of the acidity as a function of Nb loading was monitored by adsorption of a basic probe molecule followed by infrared spectroscopy. The results indicated the appearance of Brnsted acid sites for a threshold of Nb loading. The abundance of Brnsted acid sites correlated well with the isopropanol dehydration activity. The overall behavior was very similar to that reported earlier for the WO _x /ZrO₂ system.     

Investigating Knowledge Management Factors Affecting Chinese ICT Firms Performance: An Integrated KM Framework

This article sets out to investigate the critical factors of Knowledge Management (KM) which are considered to have an impact on the performance of Chinese information and communication technology (ICT) firms. This study confirms that the cultural environment of an enterprise is central to its success in the context of China. It shows that a collaborated, trusted, and learning environment within ICT firms will have a positive impact on their KM performance.     

Differencing and merging of architectural views

Differencing and merging architectural views is an important activity in software engineering. However, existing approaches are still based on restrictive assumptions, such as requiring view elements to have unique identifiers or exactly matching types, which is often not the case in many application domains. We propose an approach based on structural information. We generalize a published polynomial-time tree-to-tree correction algorithm that detects inserts, renames and deletes, into a novel algorithm that additionally detects restricted moves. Our algorithm also supports forcing and preventing matches between view elements. We incorporate the algorithm into tools to compare and merge Component-and-Connector (C&C) architectural views. We provide an empirical evaluation of the algorithm. We illustrate the tools using extended examples, and use them to detect and reconcile interesting differences between real architectural views. This article is an expanded version of the following paper: Abi-Antoun, M., Aldrich, J., Nahas, N., Schmerl, B., and Garlan, D: 2006, ‘Differencing and Merging of Architectural Views’. In: Proceedings of the 21st IEEE International Conference on Automated Software Engineering, pp. 47–58.     

Optimization of quality and operational costs through improved scheduling of harvest operations

The agriculture sector still lacks the tools and models to enhance the utilization of different resources. This paper addresses the vineyard harvesting problem in developing countries, with the objective of optimizing the wine quality and minimizing the operational costs. Heuristics were introduced to better assign the harvesting days to the different grape blocks that exist in the vineyard's field. The quality of the grapes was a key target as it can transform production from a pinnacle wine to a bulk one. We solved several numerical examples for verification and demonstrative purposes and found that our proposed approach finds solutions that significantly reduce the harvesting costs in the vineyard and considerably outperform Branch and Bound algorithm especially for large problems.     

A survey and taxonomy on energy efficient resource allocation techniques for cloud computing systems

In a cloud computing paradigm, energy efficient allocation of different virtualized ICT resources (servers, storage disks, and networks, and the like) is a complex problem due to the presence of heterogeneous application (e.g., content delivery networks, MapReduce, web applications, and the like) workloads having contentious allocation requirements in terms of ICT resource capacities (e.g., network bandwidth, processing speed, response time, etc.). Several recent papers have tried to address the issue of improving energy efficiency in allocating cloud resources to applications with varying degree of success. However, to the best of our knowledge there is no published literature on this subject that clearly articulates the research problem and provides research taxonomy for succinct classification of existing techniques. Hence, the main aim of this paper is to identify open challenges associated with energy efficient resource allocation. In this regard, the study, first, outlines the problem and existing hardware and software-based techniques available for this purpose. Furthermore, available techniques already presented in the literature are summarized based on the energy-efficient research dimension taxonomy. The advantages and disadvantages of the existing techniques are comprehensively analyzed against the proposed research dimension taxonomy namely: resource adaption policy, objective function, allocation method, allocation operation, and interoperability.     

Characterization of a novel bioactive composite using advanced X-ray computed tomography

A novel bioactive, porous silica–calcium phosphate nanocomposite (SCPC) that can be used to treat large bone defects in load-bearing positions has been tested and has shown great potential for applications in tissue engineering. Porosity is essential to the performance of the composite material as a tissue engineering scaffold, as porous scaffolds provide a physical, 3-D template to support new tissue formation. However, porosity characterization using conventional techniques such as porosimetry or scanning electron microscopy requires extensive preparation of samples and may destroy important features during preparation and analysis stage. In this work, the new composite is characterized using an advanced high resolution X-ray computed tomography, which is a non-destructive testing technique that allows construction of the 3-D topology of the microstructure. The results clearly show the effectiveness and versatility of this technique in characterizing the porous architecture of the novel composite biomaterial. The pore distribution, morphology and interconnectivity in the composite scaffolds were found to be ideal for use in tissue engineering applications.     

Boundedness properties of the soft-constrained time-optimal control

We present a general analysis of the asymptotic behaviour of the soft-constrained time-optimal (SCTO) control of linear systems. We are essentially seeking to show that (1) this control is bounded, like its hard-constrained counterpart; and (2) there is a basic tradeoff between the control bounds and the speed of the response, and we seek to characterize this tradeoff. We show that if the 'No Infinite Manoeuvre in Finite Optimal Time' (NIMIFOT) condition holds, then the boundedness of the SCTO control can be easily checked, and that the above-mentioned tradeoff is clearly characterized. For instance, we show that the SCTO control is bounded for all stable systems and for many marginally stable systems provided that the NIMIFOT condition holds. We also show that a slight modification of the formulation of the SCTO control problem can ensure that the NIMIFOT condition holds. With this new formulation, the SCTO control can be shown to be bounded for most linear plants satisfying mild and easily checkable conditions.     

Thermal analysis of wirelessly powered thermo-pneumatic micropump based on planar LC circuit

This paper studies the thermal behavior of a wireless powered micropump operated using thermo-pneumatic actuation. Numerical analysis was performed to investigate the temporal conduction of the planar inductor-capacitor (LC) wireless heater and the heating chamber. The result shows that the temperature at the heating chamber reaches steady state temperature of 46.7°C within 40 seconds. The finding was further verified with experimental works through the fabrication of the planar LC heater (RF sensitive actuator) and micropump device using MEMS fabrication technique. The fabricated device delivers a minimum volume of 0.096 μL at the temperature of 29°C after being thermally activated for 10 s. The volume dispensed from the micropump device can precisely controlled by an increase of the electrical heating power within the cut-off input power of 0.22 W. Beyond the power, the heat transfer to the heating chamber exhibits non-linear behavior. In addition, wireless operation of the fabricated device shows successful release of color dye when the micropump is immersed in DI-water containing dish and excited by tuning the RF power.

     

Viscoelastic behavior of epoxy/carbon fiber/Zno nano‐rods hybrid composites

The insufficient viscoelastic resistance of fiber reinforced plastics can be retrofitted by the addition of more rigid nano fillers to the polymer matrix. In this study, carbon fibers plies were grafted with zinc oxide (ZnO) nano‐rods and the hybridized reinforcement was utilized in laminated composites. Flexural creep tests were carried out using dynamic mechanical analysis (DMA) and the time/temperature superposition principle was employed for accelerated testing. To verify the applicability of TTPS, prolonged stress relaxation tests were also carried out in flexural mode. Data from the DMA flexural creep tests revealed that the whiskerization of carbon fibers with ZnO nano rods reduced the creep compliance by 23% at elevated temperatures and prolonged durations. Also, the relaxation data confirmed the applicability of TTPS to these hybrid composites. The stress relaxation modulus improved by 65% in comparison to composites based on neat carbon fibers. POLYM. COMPOS., 36:1967–1972, 2015. © 2014 Society of Plastics Engineer