title: High power linear AC Electronic Load for testing UPS Systems

authors: Jinadasa, Muthunacharige Damayanthi Chandani Srimathi Kumari

subjects: Electronic load

abstract: Concept of a series bipolar transistor array for AC power control is already developed. However non-linearity issues, high power capability with load sharing at high voltages and digital control with better transient performance were not adequately adopted in early-developed stages.

This thesis is a description of the design approach of digitally controllable linear 230V/50 Hz AC line voltage capable electronic load with predictable characteristics based on spice simulation. The BJT array used in this project provides high power dissipation capability and uniform voltage and power distribution across the individual transistors. A set of optoisolators are used to have electrical isolation between power stage and digital control circuits. A Zilog Z8Encore! 64K series development kit is used in controlling the circuit.

text: High power linear AC Electronic Load for testing UPS Systems Concept of a series bipolar transistor array for AC power control is already developed. However non-linearity issues, high power capability with load sharing at high voltages and digital control with better transient performance were not adequately adopted in early-developed stages.

This thesis is a description of the design approach of digitally controllable linear 230V/50 Hz AC line voltage capable electronic load with predictable characteristics based on spice simulation. The BJT array used in this project provides high power dissipation capability and uniform voltage and power distribution across the individual transistors. A set of optoisolators are used to have electrical isolation between power stage and digital control circuits. A Zilog Z8Encore! 64K series development kit is used in controlling the circuit.

year: 2007

title: An investigation into the persistence-strengthening effects of differential reinforcement of alternative (DRA) behaviour

authors: Layton, Karen Lorraine

subjects: differential reinforcement of alternative (DRA) behaviour

abstract: Ten experiments used hens to investigate the effects of different disruptive events and ways of introducing differential reinforcement of alternative behaviour (DRA), on the persistence of responding. Of interest was the persistencestrengthening effects of DRA on the target, or problem, behaviour, and whether this could be reduced by training an alternative behaviour in a separate context to that of the target behaviour. A DRA was compared to the effects of a procedure where the alternative and target behaviours were trained in the same context (traditional DRA). The different behaviours were pecking at different coloured keys, and responding was maintained by food reinforcement.
Baseline training involved a three-component multiple schedule; one component with two yellow keys available (DRA analogue using VI 37.5 s and 150 s) and the other two with one key available in each (analogous to target (blue and VI 150 s) and alternative (green and VI 37.5 s) behaviours trained separately). A disruptor test followed, also using three-component multiple schedules. This disruptor test included a component with the two yellow keys (Concurrent/DRA Component) and one which combined the, previously single, green and blue keys (Combined Component). In each experiment, the sequence of baseline followed by a disruptor test was repeated with different components in each test. Persistence was measured as the responses in the test as a proportion of baseline responses for that behaviour.
In Experiment 1 the disruptor was extinction and this showed that separate training reduced persistence of the target behaviour and extinction burst, as in previous research. Experiments 2 and 3 used the same procedures but the hens were exposed to a centre key alone (associated with one of VI 150 s (red centre key), 75 s (white centre key) or 37.5 s (pink centre key) schedule) prior to each baseline and this centre key then acted as the disruptor. Reinforcement was available on all keys in the tests. These found that the red key worked as a disruptor, and there were similar effects on persistence as in Experiment 1, regardless of the red key schedule. Experiment 4, using the same procedures but with no formal disruptor, also found the separate training gave reduced persistence of the target but not the alternative behaviour in the tests. Experiment 5 to 7 examined different disruptors (flashing light, sound, and a separate chamber), all with reinforcement continuing in tests. Target response persistence was reduced as a result of the separate training. Experiment 8 compared the effects on target persistence of separate training with the training schedule thinned prior combining and after combining. This found there was reduced target behaviour persistence when the schedules were thinned prior to being combined. Experiment 9 added a baseline with the target behaviour alone, prior to the previous procedure, and showed the same reduced target persistence even when both the target keys were initially presented alone. Experiment 10 showed the results were robust when each component was associated with a physically separate context. All experiments showed that training a target behaviour in a separate context to the alternative behaviour was successful at reducing the persistence-strengthening effects of DRA.

text: An investigation into the persistence-strengthening effects of differential reinforcement of alternative (DRA) behaviour Ten experiments used hens to investigate the effects of different disruptive events and ways of introducing differential reinforcement of alternative behaviour (DRA), on the persistence of responding. Of interest was the persistencestrengthening effects of DRA on the target, or problem, behaviour, and whether this could be reduced by training an alternative behaviour in a separate context to that of the target behaviour. A DRA was compared to the effects of a procedure where the alternative and target behaviours were trained in the same context (traditional DRA). The different behaviours were pecking at different coloured keys, and responding was maintained by food reinforcement.
Baseline training involved a three-component multiple schedule; one component with two yellow keys available (DRA analogue using VI 37.5 s and 150 s) and the other two with one key available in each (analogous to target (blue and VI 150 s) and alternative (green and VI 37.5 s) behaviours trained separately). A disruptor test followed, also using three-component multiple schedules. This disruptor test included a component with the two yellow keys (Concurrent/DRA Component) and one which combined the, previously single, green and blue keys (Combined Component). In each experiment, the sequence of baseline followed by a disruptor test was repeated with different components in each test. Persistence was measured as the responses in the test as a proportion of baseline responses for that behaviour.
In Experiment 1 the disruptor was extinction and this showed that separate training reduced persistence of the target behaviour and extinction burst, as in previous research. Experiments 2 and 3 used the same procedures but the hens were exposed to a centre key alone (associated with one of VI 150 s (red centre key), 75 s (white centre key) or 37.5 s (pink centre key) schedule) prior to each baseline and this centre key then acted as the disruptor. Reinforcement was available on all keys in the tests. These found that the red key worked as a disruptor, and there were similar effects on persistence as in Experiment 1, regardless of the red key schedule. Experiment 4, using the same procedures but with no formal disruptor, also found the separate training gave reduced persistence of the target but not the alternative behaviour in the tests. Experiment 5 to 7 examined different disruptors (flashing light, sound, and a separate chamber), all with reinforcement continuing in tests. Target response persistence was reduced as a result of the separate training. Experiment 8 compared the effects on target persistence of separate training with the training schedule thinned prior combining and after combining. This found there was reduced target behaviour persistence when the schedules were thinned prior to being combined. Experiment 9 added a baseline with the target behaviour alone, prior to the previous procedure, and showed the same reduced target persistence even when both the target keys were initially presented alone. Experiment 10 showed the results were robust when each component was associated with a physically separate context. All experiments showed that training a target behaviour in a separate context to the alternative behaviour was successful at reducing the persistence-strengthening effects of DRA.

year: 2018

title: Effects of industry on Maori cultural values: The case of the Tarawera River

authors: Dodd, Materoa

subjects: New Zealand

abstract: The research is a case study of the relationship between three tribes; Te Arawa, Tuwharetoa ki Kawerau and Ngāti Awa and the Tarawera River during the second half of the 20th century when the river was polluted with effluent from pulp and paper mills. It involves the cultural story of the Tarawera River as told by the iwi (tribes) of the river informed by Maori epistemologies and what has come to be known as a ‗kaupapa Maori research' approach. Reference is made to the history, legends, customs and lifestyle that have arisen from the relationship between iwi and the river. It includes comments on the pollution of the river from members of each iwi. The world views, experiences, and perceptions reported on here have forced a fundamental change on the iwi, a change that has affected their cultural and social relationship to the river. The price of economic development on the river has been cultural and ecological genocide. 
The cultural voice echoes a familiar story in indigenous communities. In the Maori context the research provides opportunities for further inquiry into determining the socio-cultural, economic and political future of the iwi of the river.

text: Effects of industry on Maori cultural values: The case of the Tarawera River The research is a case study of the relationship between three tribes; Te Arawa, Tuwharetoa ki Kawerau and Ngāti Awa and the Tarawera River during the second half of the 20th century when the river was polluted with effluent from pulp and paper mills. It involves the cultural story of the Tarawera River as told by the iwi (tribes) of the river informed by Maori epistemologies and what has come to be known as a ‗kaupapa Maori research' approach. Reference is made to the history, legends, customs and lifestyle that have arisen from the relationship between iwi and the river. It includes comments on the pollution of the river from members of each iwi. The world views, experiences, and perceptions reported on here have forced a fundamental change on the iwi, a change that has affected their cultural and social relationship to the river. The price of economic development on the river has been cultural and ecological genocide. 
The cultural voice echoes a familiar story in indigenous communities. In the Maori context the research provides opportunities for further inquiry into determining the socio-cultural, economic and political future of the iwi of the river.

year: 2010