title: Optimal task scheduling in a flexible manufacturing system using model checking

authors: Malik, Robi

subjects: computer science

abstract: This paper demonstrates the use of model checking to solve the problem of optimal task scheduling in a flexible manufacturing system. The system is modelled as a discrete event system, for which the least restrictive safe behaviour is synthesised according to supervisory control theory. Then timing constraints are added to the model in the form of extended finitestate machines, and time-optimal schedules are computed using the discrete event systems and model checking tool Supremica. In the case study considered in this paper, which previously was only solved heuristically, the method successfully produces optimal schedules to manufacture up to 30 products of two different types. The method is furthermore used to find an optimal cycle, solving the scheduling problem of the case study for an arbitrary number of products in optimal or asymptotically close to optimal time.

text: Optimal task scheduling in a flexible manufacturing system using model checking This paper demonstrates the use of model checking to solve the problem of optimal task scheduling in a flexible manufacturing system. The system is modelled as a discrete event system, for which the least restrictive safe behaviour is synthesised according to supervisory control theory. Then timing constraints are added to the model in the form of extended finitestate machines, and time-optimal schedules are computed using the discrete event systems and model checking tool Supremica. In the case study considered in this paper, which previously was only solved heuristically, the method successfully produces optimal schedules to manufacture up to 30 products of two different types. The method is furthermore used to find an optimal cycle, solving the scheduling problem of the case study for an arbitrary number of products in optimal or asymptotically close to optimal time.

year: 2018

title: Using a tephrostratigraphic framework to determine the past 40,000 yrs of fault rupture and paleohydrothermal activity on the east strand of the Whirinaki Fault, Ngakuru Graben, central Taupo Volcanic Zone

authors: Loame, Remedy Charlotte

subjects: seismology

abstract: The Ngakuru Graben in the central Taupo Volcanic Zone, North Island, New Zealand, is largely thermally inactive, but several fossil geothermal systems have been mapped throughout the area parallel to the Whirinaki Fault (WF). A fossil geothermal system was identified on the northeast section of the east strand of the WF at a location on Hossack Road hereafter referred to as the Meade-Hossack site. The aim of this study was to establish a history of fault rupture and sinter development at the Meade-Hossack site, and to relate the observed faulting and paleogeothermal activity to that at other locations on the WF. The objectives were to (i) describe the stratigraphy exposed in a trench and outcrop, (ii) identify (correlate) tephras using stratigraphic principles, ferromagnesian mineralogical assemblages, and electron microprobe-determined major-element compositions of glass shards, and (iii) restore tectonic deformation at the site using tephrochronology to date the timing of fault movement and the development of sinter formation.

A paleoseismic trench was excavated across the northeast section of the east strand of the WF. The stratigraphy and deformation in the trench were logged. Samples of tephras were taken for mineral and glass shard analysis by microscope petrography and electron microprobe analysis, respectively. Eight tephras were identified, namely the Kaharoa (AD 1314 ± 12 or 636 ± 12 cal. yr. BP) (95% probability age range), Taupo (AD 232 ± 10 or 1718 ± 10 cal. yr. BP), Rotoma (9423 ± 120 cal. yr. BP), Rotorua (15635 ± 412 cal. yr. BP), Okareka (21858 ± 290 cal. yr. BP), Kawakawa (25358 ± 162 cal. yr. BP), Poihipi (28446 ± 670 cal. yr. BP), and Tahuna (c. 40 ka), as well as the Ohakuri Ignimbrite (c. 240 ka).

Five fault rupture events were identified in the trench (MH1–5). The trench logs were used to reconstruct earlier stages of the stratigraphic succession at the site prior to deformation by each rupture events. The tephra ages were used to constrain the timing of fault movement. The slip rates and the vertical displacement measurements were also calculated using tephrochronology, and correlated with trends (fast-slow-fast) for events of similar ages observed in other trenches on the WF.

Rupture event MH1 occurred between the Taupo and Kaharoa eruption episodes at a slip rate of 0.87 ± 0.37 mm/yr, MH2 between the Rotoma and Taupo eruptions at a rate of 0.11 ± 0.20 mm/yr, MH3 between the Rotorua and Rotoma eruptions at a rate of 0.20 ± 0.22 mm/yr, MH4 between the Okareka and Rotorua eruptions at a rate of 0.13 ± 0.27 mm/yr, and MH5 between the Ohakuri and Okareka eruptions at a rate of 0.53 ± 0.24 mm/yr. The recurrence interval during the last 21.8 kyrs was calculated to be 1.8–5.4 kyrs, which fits within recurrence intervals calculated for other trenches on the WF.

The rupture events at the Meade-Hossack site show evidence of stress transfer from the southeast section of the east strand as well as the northwest section of the west strand of the WF, indicating that the strands are connected at depth. Sinter deposition mirrors that on the west strand from ~40–10 ka, indicating that the paleogeothermal fields were fed by the same source at depth.Sinter deposition mirrors that on the west strand from ~40–10 ka, indicating that the paleogeothermal fields were fed by the same source at depth. Fault rupture MH3 at the Meade-Hossack site altered the local fluid flow regime, leading to the cessation of sinter development on the east strand by 9423 ± 120 cal. yr. BP.

text: Using a tephrostratigraphic framework to determine the past 40,000 yrs of fault rupture and paleohydrothermal activity on the east strand of the Whirinaki Fault, Ngakuru Graben, central Taupo Volcanic Zone The Ngakuru Graben in the central Taupo Volcanic Zone, North Island, New Zealand, is largely thermally inactive, but several fossil geothermal systems have been mapped throughout the area parallel to the Whirinaki Fault (WF). A fossil geothermal system was identified on the northeast section of the east strand of the WF at a location on Hossack Road hereafter referred to as the Meade-Hossack site. The aim of this study was to establish a history of fault rupture and sinter development at the Meade-Hossack site, and to relate the observed faulting and paleogeothermal activity to that at other locations on the WF. The objectives were to (i) describe the stratigraphy exposed in a trench and outcrop, (ii) identify (correlate) tephras using stratigraphic principles, ferromagnesian mineralogical assemblages, and electron microprobe-determined major-element compositions of glass shards, and (iii) restore tectonic deformation at the site using tephrochronology to date the timing of fault movement and the development of sinter formation.

A paleoseismic trench was excavated across the northeast section of the east strand of the WF. The stratigraphy and deformation in the trench were logged. Samples of tephras were taken for mineral and glass shard analysis by microscope petrography and electron microprobe analysis, respectively. Eight tephras were identified, namely the Kaharoa (AD 1314 ± 12 or 636 ± 12 cal. yr. BP) (95% probability age range), Taupo (AD 232 ± 10 or 1718 ± 10 cal. yr. BP), Rotoma (9423 ± 120 cal. yr. BP), Rotorua (15635 ± 412 cal. yr. BP), Okareka (21858 ± 290 cal. yr. BP), Kawakawa (25358 ± 162 cal. yr. BP), Poihipi (28446 ± 670 cal. yr. BP), and Tahuna (c. 40 ka), as well as the Ohakuri Ignimbrite (c. 240 ka).

Five fault rupture events were identified in the trench (MH1–5). The trench logs were used to reconstruct earlier stages of the stratigraphic succession at the site prior to deformation by each rupture events. The tephra ages were used to constrain the timing of fault movement. The slip rates and the vertical displacement measurements were also calculated using tephrochronology, and correlated with trends (fast-slow-fast) for events of similar ages observed in other trenches on the WF.

Rupture event MH1 occurred between the Taupo and Kaharoa eruption episodes at a slip rate of 0.87 ± 0.37 mm/yr, MH2 between the Rotoma and Taupo eruptions at a rate of 0.11 ± 0.20 mm/yr, MH3 between the Rotorua and Rotoma eruptions at a rate of 0.20 ± 0.22 mm/yr, MH4 between the Okareka and Rotorua eruptions at a rate of 0.13 ± 0.27 mm/yr, and MH5 between the Ohakuri and Okareka eruptions at a rate of 0.53 ± 0.24 mm/yr. The recurrence interval during the last 21.8 kyrs was calculated to be 1.8–5.4 kyrs, which fits within recurrence intervals calculated for other trenches on the WF.

The rupture events at the Meade-Hossack site show evidence of stress transfer from the southeast section of the east strand as well as the northwest section of the west strand of the WF, indicating that the strands are connected at depth. Sinter deposition mirrors that on the west strand from ~40–10 ka, indicating that the paleogeothermal fields were fed by the same source at depth.Sinter deposition mirrors that on the west strand from ~40–10 ka, indicating that the paleogeothermal fields were fed by the same source at depth. Fault rupture MH3 at the Meade-Hossack site altered the local fluid flow regime, leading to the cessation of sinter development on the east strand by 9423 ± 120 cal. yr. BP.

year: 2016

title: Te tukuihotanga o te reo Māori: He aronga motuhake – ngā mokopuna a Te Kapunga

authors: Dewes, Te Kuru o te Marama

subjects: Reo Māori

abstract: Ko te tāhū o tēnei rangahau ko te reo Māori. Ko te ariā matua ko te tukuihotanga o te reo Māori, arā, ko te tuku iho o te reo ki rō whānau mai i ngā mātua ki ngā tamariki, ā, tae rawa iho ki ngā mokopuna. Kia whakawhāiti i te kaupapa, he aronga motuhake tēnei kei te titiro hāngai atu ki ngā whānau e whā ki ngā tāone e toru o Te Whanganui-a-Tara, Tāmakimakaurau me Te Rotorua-Nui-a-Kahumatamomoe. Nā te hurahura i ngā āhuatanga reo i roto i ngā kāenga o ngā whānau e whā i kitea mehemea kei te tutuki tēnei tūāhua te tukuihotanga o te reo Māori. Tuia, he aha ngā momo āhuatanga kei te taunaki i tēnei mahi, ā, he aha hoki ngā ārai e whakahōtaetae ana i a ia.  piti atu, i noho ki te ketuketu i ngā whakaaro o ngā mātua e pā ana ki tēnei kaupapa te tuku iho i te reo ki ngā tamariki mokopuna. Kāre i aro ki te kounga o te reo, he kaute noa i ngā whakamahinga reo Māori me whakamahinga reo Pākehā. Kia whakaritea ngā āhuatanga reo o ngā whānau me ngā tamariki, i tū ngā mahi whakarongo ki ngā wāhi e toru, arā, ki rō kāenga, ki rō kura, ka mutu, i tū ki wāhi kē atu hoki. Nā runga i te whakaaro kei te mōrearea tonu te reo Māori, kua herea tēnei kaupapa ki te ahurea me te tuakiri Māori, te mana motuhake me te tino rangatiratanga.

text: Te tukuihotanga o te reo Māori: He aronga motuhake – ngā mokopuna a Te Kapunga Ko te tāhū o tēnei rangahau ko te reo Māori. Ko te ariā matua ko te tukuihotanga o te reo Māori, arā, ko te tuku iho o te reo ki rō whānau mai i ngā mātua ki ngā tamariki, ā, tae rawa iho ki ngā mokopuna. Kia whakawhāiti i te kaupapa, he aronga motuhake tēnei kei te titiro hāngai atu ki ngā whānau e whā ki ngā tāone e toru o Te Whanganui-a-Tara, Tāmakimakaurau me Te Rotorua-Nui-a-Kahumatamomoe. Nā te hurahura i ngā āhuatanga reo i roto i ngā kāenga o ngā whānau e whā i kitea mehemea kei te tutuki tēnei tūāhua te tukuihotanga o te reo Māori. Tuia, he aha ngā momo āhuatanga kei te taunaki i tēnei mahi, ā, he aha hoki ngā ārai e whakahōtaetae ana i a ia.  piti atu, i noho ki te ketuketu i ngā whakaaro o ngā mātua e pā ana ki tēnei kaupapa te tuku iho i te reo ki ngā tamariki mokopuna. Kāre i aro ki te kounga o te reo, he kaute noa i ngā whakamahinga reo Māori me whakamahinga reo Pākehā. Kia whakaritea ngā āhuatanga reo o ngā whānau me ngā tamariki, i tū ngā mahi whakarongo ki ngā wāhi e toru, arā, ki rō kāenga, ki rō kura, ka mutu, i tū ki wāhi kē atu hoki. Nā runga i te whakaaro kei te mōrearea tonu te reo Māori, kua herea tēnei kaupapa ki te ahurea me te tuakiri Māori, te mana motuhake me te tino rangatiratanga.

year: 2017