On admissible pairs and equivalent feedback—Youla parameterization in iterative learning control

This paper revisits a well-known synthesis problem in iterative learning control, where the objective is to optimize a performance criterion over a class of causal iterations. The approach taken here adopts an infinite-time setting and looks at limit behavior.The first part of the paper considers iterations without current-cycle-feedback (CCF) term. A notion of admissibility is introduced to distinguish between pairs of operators that define a robustly converging iteration and pairs that do not. The set of admissible pairs is partitioned into disjoint equivalence classes. Different members of an equivalence class are shown to correspond to different realizations of a (stabilizing) feedback controller. Conversely, every stabilizing controller is shown to allow for a (non-unique) factorization in terms of admissible pairs. Class representatives are introduced to remove redundancy. The smaller set of representative pairs is shown to have a trivial parameterization that coincides with the Youla parameterization of all stabilizing controllers (stable plant case).The second part of the paper considers the general family of CCF-iterations. Results derived in the non-CCF case carry over, with the exception that the set of equivalent controllers now forms but a subset of all stabilizing controllers. Necessary and sufficient conditions for full generalization are given.     

MMC: the Mono Model Checker

The Mono Model Checker (mmc) is a software model checker for cil bytecode programs. mmc has been developed on the Mono platform. mmc is able to detect deadlocks and assertion violations in cil programs. The design of mmc is inspired by the Java PathFinder (jpf), a model checker for Java programs. The performance of mmc is comparable to jpf. This paper introduces mmc and presents its main architectural characteristics.     

Ownership unbundling in electricity distribution: The case of The Netherlands

This paper addresses the merits of ownership unbundling of distribution networks, as exemplified in the case of The Netherlands. In essence, this problem concerns the question of whether the operation and management of electricity distribution networks in this country will evolve into a market-driven commodity business or remain a genuine public utility task. In order to deal with this problem, a framework is developed that enables the classification of different institutional regimes. Depending on the nature of the institutional regime, this case of the Netherlands illustrates how certain aspects of the liberalisation of the electricity sector can become vitally important to the continuing process of restructuring.     

Lubrication Analysis of a Connecting-Rod Bearing in a High-Speed Engine. Part II: Lubrication Performance Evaluation for Non-Circular Bearings

In this article a numerical investigation of a connecting rod bearing operating at 6,500 rpm is performed. This is a companion to an earlier article that took into account the effects of the inertial force and the variable bolt tension force, which are considered to be the principal factors that affect the connecting rod bearing lubrication characteristics of an engine running at high speed. It was found that a thinner minimum oil film and a larger peak hydrodynamic pressure are predicted in a deformed connecting rod bearing than in a rigid connecting rod bearing. Multi-peaked hydrodynamic pressure was found to appear as well because of two or more converging-diverging film regions.     

A Residual Stress Intensity Factor Solution for Knoop Indentation Cracks

The residual stress intensity factors at the surface and at the deepest point of the semi-elliptical Knoop indentation crack is determined from the stresses in the damaged zone below the indenter. For this purpose, the weight function approach by Cruse and Besuner was used and wide-range expressions of the geometric function are given. The solution is then applied to a commercial silicon nitride for which all relevant geometrical data are available.     

Agricultural anaerobic digestion power plants in Ireland and Germany: policy and practice

The process of anaerobic digestion (AD) is valued as a carbon‐neutral energy source, while simultaneously treating organic waste, making it safer for disposal or use as a fertilizer on agricultural land. The AD process in many European nations, such as Germany, has grown from use of small, localized digesters to the operation of large‐scale treatment facilities, which contribute significantly to national renewable energy quotas. However, these large AD plants are costly to run and demand intensive farming of energy crops for feedstock. Current policy in Germany has transitioned to support funding for smaller digesters, while also limiting the use of energy crops. AD within Ireland, as a new technology, is affected by ambiguous governmental policies concerning waste and energy. A clear governmental strategy supporting on‐site AD processing of agricultural waste will significantly reduce Ireland's carbon footprint, improve the safety and bioavailability of agricultural waste, and provide an indigenous renewable energy source. © 2016 Society of Chemical Industry     

Development and application of an electron spin resonance spectrometry method for the determination of oxygen free radical formation by particulate matter

Exposure to increased levels of ambient particulate matter (PM) are associated with several health effects, including cardiopulmonary diseases. The formation of reactive oxygen species (ROS) is thought to play an important role in the induction of these health effects. To quantify the ROS generating capacityof PM,we developed an improved electron spin resonance (ESR) spectrometry-based method. ROS formation was measured directly on PM-containing filters, thereby avoiding the selective extraction of components and loss of material or reactivity, which is likely to occur during filter extraction. Also, ascorbic acid was added to stimulate ROS formation. This method was applied to PM10 samples originating from different sources. The radical generating capacity of PM10 from both gasoline and diesel engine exhaust was significantly higher as compared to that of PM10 from ambient or indoor air. Furthermore, in urban PM10 and PM2.5, ROS-generating capacity significantly correlated with concentrations of polycyclic aromatic hydrocarbon content and particular transition metals. This indicates thatthis improved ESR method may be a valuable tool for evaluating the relationship between ROS formation by PM and the adverse health effects associated with this type of air pollution.