title: Formal modelling and analysis of safety-critical Interactive systems using Coloured Petri Nets

authors: Jaidka, Sapna

subjects: Formal Methods

abstract: To gain confidence in safety-critical interactive systems, formal modelling and analysis plays a vital role. Generally, existing techniques focus either on modelling the user interface or on modelling the functionality of a system. Although there are many benefits to using the individual models for different purposes, it requires a lot of work to do the coupling of functional behaviour with interactive elements for analysis. Therefore, further investigation into the modelling and analysis techniques was required that models all the parts (user interface, interaction and functional) into a single model. 

This research aims to apply formal methods for modelling and specifying the user interface, interaction and functional aspects of a safety-critical system in a single model using Coloured Petri Nets (CPN), then investigating the model to ensure that the system behaves as expected. The approach developed in this thesis has its starting point in several existing, accepted formal specification techniques. From this existing basis, we create a Coloured Petri Net model of a system which has the required features of existing formalisms, taking into account all three aspects (user interface, interaction and functional), hence our investigation of the combination of formalisms to achieve their combined strength.

There are several reasons for using Coloured Petri Nets. Coloured Petri Nets provide a graphical representation and hierarchical structuring mechanism, and a state space verification technique, which allows querying the state space to investigate behaviours of a system. There are several tools that support Coloured Petri Nets including the CPN Tool which helps in building CPN models and allows simulation and analysis using state spaces.

In this thesis, the findings of our investigation into modelling and analysis of safety-critical interactive systems are presented. We describe the technique developed to model and analyze an interactive system using Coloured Petri Nets. The technique is illustrated using a simplified infusion pump example. Then we present a case study of the Niki T34 Infusion Pump to show that we have retained all the expressiveness that we need of existing formalisms. Lastly, we present a small example of a nuclear reactor control system to show that now we can use the Coloured Petri Nets alone to model and analyze the user interface, interaction and functionality of safety-critical interactive systems and also to show that the scope of this technique is not limited to just the medical domain.

text: Formal modelling and analysis of safety-critical Interactive systems using Coloured Petri Nets To gain confidence in safety-critical interactive systems, formal modelling and analysis plays a vital role. Generally, existing techniques focus either on modelling the user interface or on modelling the functionality of a system. Although there are many benefits to using the individual models for different purposes, it requires a lot of work to do the coupling of functional behaviour with interactive elements for analysis. Therefore, further investigation into the modelling and analysis techniques was required that models all the parts (user interface, interaction and functional) into a single model. 

This research aims to apply formal methods for modelling and specifying the user interface, interaction and functional aspects of a safety-critical system in a single model using Coloured Petri Nets (CPN), then investigating the model to ensure that the system behaves as expected. The approach developed in this thesis has its starting point in several existing, accepted formal specification techniques. From this existing basis, we create a Coloured Petri Net model of a system which has the required features of existing formalisms, taking into account all three aspects (user interface, interaction and functional), hence our investigation of the combination of formalisms to achieve their combined strength.

There are several reasons for using Coloured Petri Nets. Coloured Petri Nets provide a graphical representation and hierarchical structuring mechanism, and a state space verification technique, which allows querying the state space to investigate behaviours of a system. There are several tools that support Coloured Petri Nets including the CPN Tool which helps in building CPN models and allows simulation and analysis using state spaces.

In this thesis, the findings of our investigation into modelling and analysis of safety-critical interactive systems are presented. We describe the technique developed to model and analyze an interactive system using Coloured Petri Nets. The technique is illustrated using a simplified infusion pump example. Then we present a case study of the Niki T34 Infusion Pump to show that we have retained all the expressiveness that we need of existing formalisms. Lastly, we present a small example of a nuclear reactor control system to show that now we can use the Coloured Petri Nets alone to model and analyze the user interface, interaction and functionality of safety-critical interactive systems and also to show that the scope of this technique is not limited to just the medical domain.

year: 2020

title: The Effect of Nitrate Supplementation on Cycling Performance in the Heat in Well-Trained Cyclists

authors: McQuillan, Joseph A.

abstract: Purpose:
The aim of this study was to determine the effect of NO₃⁻ consumption on measures of perception, thermoregulation and cycling performance in hot conditions.

Methods:
Using a randomised, double-blind, crossover-design, 8 well-trained cyclists (mean ± SD: age: 25 ± 8 y, V̇O2peak: 64 ± 5 ml·kg⁻¹·min⁻¹) performed 2 separate trials, in hot (35°C, 60% relative humidity) environments, having ingested either 140 ml NO3--rich beetroot juice ~8 mmol NO₃⁻ (NIT), or placebo (PLA), daily for 3-days with a 7-day washout period separating trials. Trials consisted of 2 × 10 min bouts at 40 and 60% peak power output (PPO) to determine physiological and perceptual responses in the heat, followed by a 4 km cycling time-trial.

Results:
Basal [nitrite] was substantially elevated in NIT (2.70 ± 0.98 μM) vs PLA (1.10 ± 0.61 μM) resulting in a most likely (ES = 1.58 ± 0.93) increase after 3-days. There was a very likely trivial increase in rectal temperature [Tᵣₑ] in NIT at 40% (PLA;37.4 ± 0.2°C vs NIT;37.5 ± 0.3°C, 0.1 ± 0.2°C) and 60% (PLA;37.8 ± 0.2°C vs NIT;37.9 ± 0.3°C, 0.1 ± 0.2°C) PPO. Cycling performance was similar between trials (PLA;336 ± 45 W vs NIT;337 ± 50 W, CV±95%CL; 0.2 ± 2.5%). Outcomes for heart rate, and perceptual measures were unclear across the majority of time-points.

Conclusions:
Three days of NO₃⁻ supplementation, resulted in small increases in Tᵣₑ during low- to moderate-intensity exercise, however this did not appear to influence 4 km cycling time-trial performance in hot climates.

text: The Effect of Nitrate Supplementation on Cycling Performance in the Heat in Well-Trained Cyclists Purpose:
The aim of this study was to determine the effect of NO₃⁻ consumption on measures of perception, thermoregulation and cycling performance in hot conditions.

Methods:
Using a randomised, double-blind, crossover-design, 8 well-trained cyclists (mean ± SD: age: 25 ± 8 y, V̇O2peak: 64 ± 5 ml·kg⁻¹·min⁻¹) performed 2 separate trials, in hot (35°C, 60% relative humidity) environments, having ingested either 140 ml NO3--rich beetroot juice ~8 mmol NO₃⁻ (NIT), or placebo (PLA), daily for 3-days with a 7-day washout period separating trials. Trials consisted of 2 × 10 min bouts at 40 and 60% peak power output (PPO) to determine physiological and perceptual responses in the heat, followed by a 4 km cycling time-trial.

Results:
Basal [nitrite] was substantially elevated in NIT (2.70 ± 0.98 μM) vs PLA (1.10 ± 0.61 μM) resulting in a most likely (ES = 1.58 ± 0.93) increase after 3-days. There was a very likely trivial increase in rectal temperature [Tᵣₑ] in NIT at 40% (PLA;37.4 ± 0.2°C vs NIT;37.5 ± 0.3°C, 0.1 ± 0.2°C) and 60% (PLA;37.8 ± 0.2°C vs NIT;37.9 ± 0.3°C, 0.1 ± 0.2°C) PPO. Cycling performance was similar between trials (PLA;336 ± 45 W vs NIT;337 ± 50 W, CV±95%CL; 0.2 ± 2.5%). Outcomes for heart rate, and perceptual measures were unclear across the majority of time-points.

Conclusions:
Three days of NO₃⁻ supplementation, resulted in small increases in Tᵣₑ during low- to moderate-intensity exercise, however this did not appear to influence 4 km cycling time-trial performance in hot climates.

year: 2017

title: Changing patterns of Otitis Media in the Waikato region during the Covid Pandemic

authors: Becker, Andre

subjects: COVID-19 pandemic

abstract: Introduction. Acute otitis media (AOM) is a common condition of children encountered in general practice. A proportion of children develop otitis media with effusion (OME), which may require tympanostomy and ventilation tube insertion. Aim. The aim of the study was to compare the incidence of AOM in Māori and New Zealand (NZ) European children in general practice and the referral practices to secondary care for tympanostomy and ventilation tube insertion. Methods. The study was conducted in two parts: (1) an analysis of the incidence of AOM and OME in a rural Waikato general practice (Ōtorohanga) with a high Māori population over a 2-year period; and (2) an analysis of all referrals to the otorhinolaryngology (ORL) department at Waikato District Health Board and tympanostomy and ventilation tube insertion by this service over the same period. Results. The incidence of AOM was similar in Māori compared with NZ European children. The incidence declined significantly between 2019 and 2020 and 50% of children with AOM were treated with antibiotics. Referral rates to the ORL department were greater for Māori compared with NZ European children as were tympanostomy and ventilation tube insertion rates. Discussion. Although AOM is common, OME was rarely diagnosed. The clinical guidelines regarding antibiotic use for common conditions are not being readily adopted and further research is needed into this matter. The COVID-19 pandemic had a substantial effect on demand both in general practice and in the hospital sector. This may have been due to a reduction in the incidence of AOM or due to system changes caused by the pandemic.

text: Changing patterns of Otitis Media in the Waikato region during the Covid Pandemic Introduction. Acute otitis media (AOM) is a common condition of children encountered in general practice. A proportion of children develop otitis media with effusion (OME), which may require tympanostomy and ventilation tube insertion. Aim. The aim of the study was to compare the incidence of AOM in Māori and New Zealand (NZ) European children in general practice and the referral practices to secondary care for tympanostomy and ventilation tube insertion. Methods. The study was conducted in two parts: (1) an analysis of the incidence of AOM and OME in a rural Waikato general practice (Ōtorohanga) with a high Māori population over a 2-year period; and (2) an analysis of all referrals to the otorhinolaryngology (ORL) department at Waikato District Health Board and tympanostomy and ventilation tube insertion by this service over the same period. Results. The incidence of AOM was similar in Māori compared with NZ European children. The incidence declined significantly between 2019 and 2020 and 50% of children with AOM were treated with antibiotics. Referral rates to the ORL department were greater for Māori compared with NZ European children as were tympanostomy and ventilation tube insertion rates. Discussion. Although AOM is common, OME was rarely diagnosed. The clinical guidelines regarding antibiotic use for common conditions are not being readily adopted and further research is needed into this matter. The COVID-19 pandemic had a substantial effect on demand both in general practice and in the hospital sector. This may have been due to a reduction in the incidence of AOM or due to system changes caused by the pandemic.

year: 2023