Verification and Control of Partially Observable Probabilistic Real-Time Systems

We propose automated techniques for the verification and control of probabilistic real-time systems that are only partially observable. To formally model such systems, we define an extension of probabilistic timed automata in which local states are partially visible to an observer or controller. We give a probabilistic temporal logic that can express a range of quantitative properties of these models, relating to the probability of an event's occurrence or the expected value of a reward measure. We then propose techniques to either verify that such a property holds or to synthesise a controller for the model which makes it true. Our approach is based on an integer discretisation of the model's dense-time behaviour and a grid-based abstraction of the uncountable belief space induced by partial observability. The latter is necessarily approximate since the underlying problem is undecidable, however we show how both lower and upper bounds on numerical results can be generated. We illustrate the effectiveness of the approach by implementing it in the PRISM model checker and applying it to several case studies, from the domains of computer security and task scheduling

Vehicle simulations of fuel economy for an automatic transmission and a ratio limited continuously variable transmission

An automatic transmission (AT) of a vehicle was compared with a ratio limited Continuously Variable Transmission (CVT). Dynamic model of a passenger car was simulated to compare the overall efficiency of the vehicle equipped with these different types of transmissions. The overall efficiencies were calculated in terms of fuel consumption of the vehicle. The results are based on the Environmental Protection Agency\u27s (EPA) city and highway driving cycles. A Modular approach is taken to model an existing vehicle. The complete model is subdivided into an engine model, road load model, throttle and brake pedal models, and a transmission model. The model is simulated in MATLAB/Simulink software. The automatic transmission model was then replaced by a CVT model and simulated under similar conditions to compare the overall gain in the fuel economy. The simulation results for the automatic transmission closely match with the data obtained from the EPA. The results for the ratio limited CVT indicate improvement in the fuel economy of the vehicle under both the urban and highway driving cycles

Verification and control of partially observable probabilistic systems

We present automated techniques for the verification and control of partially observable, probabilistic systems for both discrete and dense models of time. For the discrete-time case, we formally model these systems using partially observable Markov decision processes; for dense time, we propose an extension of probabilistic timed automata in which local states are partially visible to an observer or controller. We give probabilistic temporal logics that can express a range of quantitative properties of these models, relating to the probability of an event’s occurrence or the expected value of a reward measure. We then propose techniques to either verify that such a property holds or synthesise a controller for the model which makes it true. Our approach is based on a grid-based abstraction of the uncountable belief space induced by partial observability and, for dense-time models, an integer discretisation of real-time behaviour. The former is necessarily approximate since the underlying problem is undecidable, however we show how both lower and upper bounds on numerical results can be generated. We illustrate the effectiveness of the approach by implementing it in the PRISM model checker and applying it to several case studies from the domains of task and network scheduling, computer security and planning

Advanced flight control system study

A fly by wire flight control system architecture designed for high reliability includes spare sensor and computer elements to permit safe dispatch with failed elements, thereby reducing unscheduled maintenance. A methodology capable of demonstrating that the architecture does achieve the predicted performance characteristics consists of a hierarchy of activities ranging from analytical calculations of system reliability and formal methods of software verification to iron bird testing followed by flight evaluation. Interfacing this architecture to the Lockheed S-3A aircraft for flight test is discussed. This testbed vehicle can be expanded to support flight experiments in advanced aerodynamics, electromechanical actuators, secondary power systems, flight management, new displays, and air traffic control concepts

In my Wish List, an Automated Tool for Fail-Secure Design Analysis: an Alloy-Based Feasibility Draft

A system is said to be fail-secure, sometimes confused with fail-safe, if it maintains its security requirements even in the event of some faults. Fail-secure analyses are required by some validation schemes, such as some Common Criteria or NATO certifications. However, it is an aspect of security which as been overlooked by the community. This paper attempts to shed some light on the fail-secure field of study by: giving a definition of fail-secure as used in those certification schemes, and emphasizing the differences with fail-safe; and exhibiting a first feasibility draft of a fail-secure design analysis tool based on the Alloy model checker.Comment: In Proceedings ESSS 2014, arXiv:1405.055

Separation via multi-column pH parametric pumping

This thesis presents the study of multi-column pH parametric pumping, a separation technique which applies the principle of parametric pumping and uses pH as control variable. Studies emphasize the mass transfer and the capability of separation by multi-column pH parametric pumping. Many operation modes of multi-column pH parapump are developed for varied objectives of separation. A Two-pH Levels Parapump is capable of enriching the product stream with solute components; a Three-pH Levels Parapump is capable of splitting components into two product streams. The separation capability of multi-column parapump is greatly superior to that of single-column parapump. As compared to cycling zone operation, parametric pumping gives a higher separation factor. Hemoglobin and albumin are chosen for the experimental model system to demonstrate the separation capability of multi-column pH parametric pumping, and to verify the predictability of the models. Presented are the theoretical basis, mathematical models and methods, results of experimental studies and computer exploration, and the correlation of data with models

Solubility studies of ultra pure transition elements in ultra pure alkali metals

Solubility of pure iron, molybdenum, niobium, and tantalum in liquid potassiu

Airborne measurements of cloud-forming nuclei and aerosol particles in stabilized ground clouds produced by solid rocket booster firings

Airborne measurements of cloud volumes, ice nuclei and cloud condensation nuclei, liquid particles, and aerosol particles were obtained from stabilized ground clouds (SGCs) produced by Titan 3 launches at Kennedy Space Center, 20 August and 5 September 1977. The SGCs were bright, white, cumulus clouds early in their life and contained up to 3.5 g/m3 of liquid in micron to millimeter size droplets. The measured cloud volumes were 40 to 60 cu km five hours after launch. The SGCs contained high concentrations of cloud condensation nuclei active at 0.2%, 0.5%, and 1.0% supersaturation for periods of three to five hours. The SGCs also contained high concentrations of submicron particles. Three modes existed in the particle population: a 0.05 to 0.1 micron mode composed of aluminum-containing particles, a 0.2 to 0.8 micron mode, and a 2.0 to 10 micron mode composed of particles that contained primarily aluminum

Involvement of construction management professionals in property-level flood adaptation

Flooding is a significant concern across the UK that has caused property damage, economic impact and health and safety concerns. The national climate change risk assessment for the UK projects the risk of flooding to increase in the future, and thus flood risk management is identified as an area that requires serious action. Whilst community level flood protection measures have been and are being put in places where there is an economic case for such intervention, the need for implementing property level flood adaptation (PLFA) is increasingly highlighted. This industry is worth £2.1 billion globally; with a forecasted UK growth at a rate of 7.1% by 2017-18. The aim of this research is to identify the ability of construction managers to provide PLFA advice to homeowners. Interviews were conducted with 10 professionals currently involved in flood adaptation product/service provision to gather their views on construction manager involvement within this niche area. Majority of participants interviewed accepted that construction managers could enter the PLFA industry. However, there has been a lack of evidence that suggest that construction managers have played a key role in this field. The paper suggests that there are several barriers that have resulted in the lack of involvement of construction managers in the PLFA industry. Previous research recognises lack of relevant skills and knowledge required to provide PLFA advice as a key barrier, this is supported by participants interviewed mentioning that the qualification, knowledge and training required were a barrier for construction managers to enter into the PLFA industry

Report on the 2011 Proficiency Test of the European Union Reference Laboratory for Mycotoxins, for the Network of National Reference Laboratories: Determination of aflatoxin B1 in baby food, maize powder, animal feed and test solution

This report presents the results of a proficiency test of the EU-RL for Mycotoxins which focused on the determination of aflatoxin B1 in food and feed samples. Sixty nine participants from 28 countries registered for the exercise. Sixty-one sets of results were reported for the solution, 58 for the baby food, 67 for the maize powder and 62 for the animal feed. One laboratory did not report any results. In total about 90% of the attributed z scores were below an absolute value of two, which indicated that most of the participants performed satisfactory or better.JRC.D.5-Food Safety and Qualit