Password Generators:Old Ideas and New

This paper considers password generators, i.e. systems designed to generate site-specific passwords on demand. Such systems are an alternative to password managers. Over the last 15 years a range of password generator systems have been described. This paper proposes the first general model for such systems, and critically examines options for instantiating this model; options considered include all those previously proposed as part of existing schemes as well as certain novel possibilities. The model enables a more objective and high-level assessment of the design of such systems; it has also been used to sketch a possible new scheme, AutoPass, intended to incorporate the best features of the prior art whilst also addressing many of the most serious shortcomings of existing systems through the inclusion of novel features.Comment: This is the full version of a paper with the same title due to be published in the proceedings of WISTP 2016 in September 201

Effects of Organic Load on Basic Geotechnical Properties of Compacted Sand-kaolinite Mixture

In the laboratory, four PVC sand-kaolinite mixture columns, each of 150 cm depth and 15 cm diameter, were fed with solutions of sodium acetate equivalent to 20,000 p.p.m., 30,000 p.p.m., 40,000 p.p.m., and 50,000 p.p.m. BOD (biochemical oxygen demand). Soil physical and chemical properties, such as Atterberg limits, specific gravity, soil pH and soil organic content, altered markedly within 40 days of continuous feeding. The results showed that feed with higher BOD values increased the soil organic content as well as soil pH; and thereby the specific gravity and Atterberg limits were lowered

Multi-Objective Stochastic Optimization for Preventive Maintenance Planning

PresentationMaintenance is an essential part of mechanical integrity programs and aims to prevent the occurrence of process safety incidents and costly unplanned shutdowns. Maintenance can increase the reliability of equipment in productive systems and effective preventive maintenance programs enable maintenance activities to be planned proactively. However, maintenance planning is subject to resource scarcity and is rendered nontrivial due to system complexity, reliability model nonlinearity, and parametric uncertainty. Multi-objective stochastic mixed-integer nonlinear programming is well suited to addressing these challenges and is adopted here to optimize the time intervals in which to perform maintenance on different pieces of equipment. Following presentation of an optimal maintenance planning framework, a model is formulated and optimized accounting for: the effect of imperfect repair using an effective age model, equipment failure behavior using a Weibull reliability model, endogenous uncertainty in reliability model parameters, and the simultaneous need to satisfy the competing objectives of cost minimization and reliability maximization using the ε-constraint method. The results of the research consist of optimal maintenance plans, plots of resultant equipment and system reliability over time, and a Pareto frontier of optimal solutions from which the decision maker can select. The approach adopted here is illustrated with a case study and can be extended to improving the overall availability, effectiveness, and resilience of a variety of productive systems