The corrosion of mild and stainless steel in alkaline anaerobic conditions representing the Belgian “supercontainer” concept and the Swiss L/ILW repository

Deep geological repositories for radioactive waste contain metallic materials, either used to construct disposal canisters or as low-/intermediate-level waste (L/ILW). The safety relevance of corrosion is linked to canister lifetime in the former case and gas generation in the latter. More specifically, the Belgian “supercontainer” concept envisages mild steel for the used fuel disposal canister, and in the case of the Swiss L/ILW repository, mild steels are the largest metallic waste component due to the decommissioning of civilian power-generating facilities. For these circumstances, the corrosion environment is dominated by the chemistry of cement, which is used as buffer or backfill material. The corrosion behaviour of mild steel in anoxic environments was studied through the analysis of the hydrogen end-product. Hydrogen analysis was conducted by periodically purging the cell head-space and analysing the gas using a solid-state hydrogen sensor. While this method is limited to providing only uniform corrosion rates averaged over periods of time, ranging from weeks to months, it provides excellent resolution and sensitivity. The test cell environments were matched against the anticipated Belgian high-level waste and Swiss L/ILW repository environments, and also against experiments that have been conducted by other researchers for comparative purposes. Samples were exposed to synthetic cement pore waters, representing fresh and degraded cement. In young cement waters, the formation of initial corrosion products resulted in steel wire corrosion rates of the order of µm/year, which, at 80°C rapidly declined to ∼10 nm/year. In contrast, SA516 grade 70 steel plate corroded much more slowly under similar conditions. In aged cement waters, initial corrosion rates were higher but declined faster towards a longer-term rate of ∼10 nm/year. 316L stainless steel, embedded in cementitious material, corroded at a rate of <1 nm/year at 50°C.     

Resource allocation on computational grids using a utility model and the knapsack problem

This work introduces a utility model (UM) for resource allocation on computational grids and formulates the allocation problem as a variant of the 0–1 multichoice multidimensional knapsack problem. The notion of task-option utility is introduced, and it is used to effect allocation policies. We present a variety of allocation policies, which are expressed as functions of metrics that are both intrinsic and external to the task and resources. An external user-defined credit-value metric is shown to allow users to intervene in the allocation of urgent or low priority tasks. The strategies are evaluated in simulation against random workloads as well as those drawn from real systems. We measure the sensitivity of the UM-derived schedules to variations in the allocation policies and their corresponding utility functions. The UM allocation strategy is shown to optimally allocate resources congruent with the chosen policies.     

Job Security

Some consider unmaintainable code a tool that provides job security. At the low level, you can obtain such code through incorrect or inconsistent formatting, naming, and commenting. Complex and gratuitous coupling, lack of assertions, and failure to use a language's type system can further complicate the picture. At a higher level, deep and wide class hierarchies, lack of cohesion, and unhelpful package relationships can hinder maintainability. Finally, at the development process level, lack of version control, subpar build-and-release procedures, a lacking testing infrastructure, and the hiring of mediocre developers will hammer the last nails into a project's maintainability coffin.     

Workflow analysis of production lines with complete inspection and rework loops

We study the flows induced by different rework loops in serial manufacturing systems with inspection stations. Average values of these flows and queuing network formulas are used for performance evaluation and optimisation of production lines. An application is presented for solving jointly the problems of inventory control and inspection station allocation in a CONWIP production line.     

Where's My Jetpack?

Software development tools often fail to deliver on inflated promises. Rather than the predicted progression toward ever-increasing levels of abstraction, two simple trends have driven the evolution of currently available software development tools: integration at the source-code level and a focus on quality. Thus source code has become the bus that tools tap into for communicating with other tools. Also, focus has shifted from defect removal in the later phases to defect prevention in the earlier phases. In the future, tools are likely to support higher levels of abstraction, perhaps in the form of domain-specific languages communicated using XML.     

Electrosorption from dilute solutions of solvents with asymmetric molecules

The general model for organic electrosorption from multicomponent systems developed previously [J. phys. Chem. 91, 101 (1987); Electrochim. Acta 32, 1279 (1987)] is applied to the case of adsorption from dilute solutions of solvents which have asymmetric molecules. The model predicts a concentration dependent adsorption maximum, non-congruent isotherms and non-linear plots for the inner layer potential differences. These features are compared with the experimental behaviour of the adsorption of triphenylphosphine oxide and tri-(itn)-octylphosphine oxide on mercury from 1-pentanol solutions of 0.1 M LiCl. The above systems have been studied by means of electrocapillary measurements. It is shown that the predictions of the model are at least in qualitative agreement with experiment. Capacitance data concerning the interface Hg/LiCl electrolyte solutions of normal alcohols are also presented and discussed in an attempt for a further clarification of solvent behaviour at these interfaces.     

How to reach O.R. Wisdom

This paper identifies the Operations Research (O.R.) problems from a systems view of information, knowledge and understanding. This systems view is examined as a basis for a developmental approach to problem solving and decision making processes. O.R. wisdom lies in achieving a balance between short-and long-term goals through a process of participation and learning.     

Unix tools as visual programming components in a GUI‐builder environment

Development environments based on ActiveX controls and JavaBeans are marketed as ‘visual programming’ platforms; in practice their visual dimension is limited to the design and implementation of an application's graphical user interface (GUI). The availability of sophisticated GUI development environments and visual component development frameworks is now providing viable platforms for implementing visual programming within general‐purpose platforms, i.e. for the specification of non‐GUI program functionality using visual representations. We describe how specially designed reflective components can be used in an industry‐standard visual programming environment to graphically specify sophisticated data transformation pipelines that interact with GUI elements. The components are based on Unix‐style filters repackaged as ActiveX controls. Their visual layout on the development environment canvas is used to specify the connection topology of the resultant pipeline. The process of converting filter‐style programs into visual controls is automated using a domain‐specific language. We demonstrate the approach through the design and the visual implementation of a GUI‐based spell‐checker. Copyright © 2001 John Wiley & Sons, Ltd.