title: Tensile behaviour of radiata pine with different moisture contents at elevated temperatures

authors: Pearson, Hamish

subjects: Drying

abstract: The aim of this study was to obtain tensile elastic modulus (EM) information for radiata pine (Pinus radiata D. Don) sapwood in tangential grain direction, over a temperature range of 70 degrees C to 150 degrees C for a wide range of moisture contents. Such information is scarce, probably because of difficulties with research equipment design and process control strategies to perform accurate tests. As expected, EM dramatically decreased with increasing temperature and moisture content. The results were modelled to yield a relationship between stress and strain. The results were also successfully transposed into a mastercurve based on temperature-moisture equivalence through a modified form of the Williams, Landel, and Ferry equation for amorphous polymers. This result is consistent with the view that wood is visco-plastic around the glass transition zone of the ligno-hemicellulosic matrix. It is demonstrated that moisture and temperature can play a significant role in reducing stress during drying, regardless of the drying time. Properties of wood, such as tensile elastic information at elevated temperatures, are important for mechanical design, distortion modelling and understanding the fundamental behaviour of wood in general.

text: Tensile behaviour of radiata pine with different moisture contents at elevated temperatures The aim of this study was to obtain tensile elastic modulus (EM) information for radiata pine (Pinus radiata D. Don) sapwood in tangential grain direction, over a temperature range of 70 degrees C to 150 degrees C for a wide range of moisture contents. Such information is scarce, probably because of difficulties with research equipment design and process control strategies to perform accurate tests. As expected, EM dramatically decreased with increasing temperature and moisture content. The results were modelled to yield a relationship between stress and strain. The results were also successfully transposed into a mastercurve based on temperature-moisture equivalence through a modified form of the Williams, Landel, and Ferry equation for amorphous polymers. This result is consistent with the view that wood is visco-plastic around the glass transition zone of the ligno-hemicellulosic matrix. It is demonstrated that moisture and temperature can play a significant role in reducing stress during drying, regardless of the drying time. Properties of wood, such as tensile elastic information at elevated temperatures, are important for mechanical design, distortion modelling and understanding the fundamental behaviour of wood in general.

year: 2012

title: Database systems as middleware- event, notifications, messages

authors: Schweppe, Heinz

subjects: computer science

abstract: Database systems have been traditionally used as integration tools. Data integration was the primary goal of first generation systems. After relational technology had become a mature base for application development, new architectures where developed for the tight integration of data, procedures and all kinds of processing. This phase of DBS research and development was dominated by object-oriented database management and specific architectures like Starburst [HaCH 1990], which had a strong impact on current object-relational technology. The ubiquitous computer network has added another facet to the usage of DBS as an integration tool. In distributed environment, middleware aims at making distribution transparent. Corba or RMI are well-known examples. The call-oriented style of communication has been complemented by message-oriented, event-driven interaction of independent programs. System processes use this type of communication for decades. However, it is not well known as a mechanism on the application level - despite the fact that it has been employed for quite some time, e.g. in workflow systems [LeRo 2000]. The event-driven message passing paradigm becomes more and more important for highly distributed applications. Many kinds of interactions between applications follow a common pattern: n inde-pendent providers submit their output as messages, which in turn will be consumed asynchronously by m consumer applications. As opposed to call-level interaction, providers and consumers may or may not know each others identity. In a stock ticker application for example, there is no reason why providers should know the identity of consumers.

text: Database systems as middleware- event, notifications, messages Database systems have been traditionally used as integration tools. Data integration was the primary goal of first generation systems. After relational technology had become a mature base for application development, new architectures where developed for the tight integration of data, procedures and all kinds of processing. This phase of DBS research and development was dominated by object-oriented database management and specific architectures like Starburst [HaCH 1990], which had a strong impact on current object-relational technology. The ubiquitous computer network has added another facet to the usage of DBS as an integration tool. In distributed environment, middleware aims at making distribution transparent. Corba or RMI are well-known examples. The call-oriented style of communication has been complemented by message-oriented, event-driven interaction of independent programs. System processes use this type of communication for decades. However, it is not well known as a mechanism on the application level - despite the fact that it has been employed for quite some time, e.g. in workflow systems [LeRo 2000]. The event-driven message passing paradigm becomes more and more important for highly distributed applications. Many kinds of interactions between applications follow a common pattern: n inde-pendent providers submit their output as messages, which in turn will be consumed asynchronously by m consumer applications. As opposed to call-level interaction, providers and consumers may or may not know each others identity. In a stock ticker application for example, there is no reason why providers should know the identity of consumers.

year: 2000

title: Boat electrofishing survey of fish abundance in the Ohau Channel, Rotorua, in 2015

authors: Hicks, Brendan J.

abstract: The aim of the survey was to provide on-going monitoring of the fish communities and abundance by boat electrofishing in the Ohau Channel, especially fish species that are taonga to Maori (eels, goldfish, and koura). In the current study, we present the findings from the ninth year of sampling (2015) and a summary of previous surveys.
We used the University of Waikato's 4.5 m-long, aluminium-hulled electrofishing boat to catch a total of total of 1,198 fish and koura (18.9 kg) at 13 sites on 2 December 2015, which comprised 2,671 lineal m and 10,684 m² in area. Koura (freshwater crayfish) and 6 fish species were present, with common bully the most abundant species (up to 45.5 fish 100 m⁻² at the site 6, edge habitat). Goldfish (up to 4.85 100 m⁻²) was the next most abundant species, with most goldfish at sites 7 and 12-13 in and around the side channel. Rainbow trout densities were up to 0.28 fish 100 m⁻². Mean bully density (11.41 fish 100 m⁻²) was much higher than for smelt (0.29 fish 100 m⁻²). Koura had a patchy distribution; only 3 individuals were caught at one site.
Comparing catches over the 9 years of sampling, the mean abundance of common bullies in 2015 was consistent with densities in most post-wall years (after 2007), but lower than in 2007 before wall closure (ANOVA P = 0.001). The cause of fluctuating bully abundance is not known, and was not accounted for by changes in water clarity expressed as black disc distance (BDD), water temperature, or water conductivity. Poor water clarity can reduce the efficiency of electrofishing, but high BDD did not correspond with high common bully densities. In 2015, smelt abundance had recovered somewhat from the low catch in 2014.
Goldfish biomass increased initially (2009-2010) because of targeted fishing in the excavated side branch (site 11), which has dense macrophytes and offers good habitat for goldfish. The continued rise in density from 2012 on, however, suggests a real increase in goldfish numbers. In 2012 and 2013 shortfin eels were caught, but no eels were caught in 2014 and only a single longfin eel was caught in 2015.
Analysis of fish densities before and after wall closure is hampered by the single data point before closure. However, we now have 9 years of post-wall data, and comparison of means suggest that the number of bullies has been lower since 2007. An obvious cause could be interruption of bully migration into the Ohau Channel from Lake Rotoiti by the wall. This suggests that the bully population in the Ohau Channel before wall construction and closure was a mixture of fish from lakes Rotorua and Rotoiti, and that recruitment from Rotoiti is now restricted. This hypothesis is testable with otolith microchemistry.

text: Boat electrofishing survey of fish abundance in the Ohau Channel, Rotorua, in 2015 The aim of the survey was to provide on-going monitoring of the fish communities and abundance by boat electrofishing in the Ohau Channel, especially fish species that are taonga to Maori (eels, goldfish, and koura). In the current study, we present the findings from the ninth year of sampling (2015) and a summary of previous surveys.
We used the University of Waikato's 4.5 m-long, aluminium-hulled electrofishing boat to catch a total of total of 1,198 fish and koura (18.9 kg) at 13 sites on 2 December 2015, which comprised 2,671 lineal m and 10,684 m² in area. Koura (freshwater crayfish) and 6 fish species were present, with common bully the most abundant species (up to 45.5 fish 100 m⁻² at the site 6, edge habitat). Goldfish (up to 4.85 100 m⁻²) was the next most abundant species, with most goldfish at sites 7 and 12-13 in and around the side channel. Rainbow trout densities were up to 0.28 fish 100 m⁻². Mean bully density (11.41 fish 100 m⁻²) was much higher than for smelt (0.29 fish 100 m⁻²). Koura had a patchy distribution; only 3 individuals were caught at one site.
Comparing catches over the 9 years of sampling, the mean abundance of common bullies in 2015 was consistent with densities in most post-wall years (after 2007), but lower than in 2007 before wall closure (ANOVA P = 0.001). The cause of fluctuating bully abundance is not known, and was not accounted for by changes in water clarity expressed as black disc distance (BDD), water temperature, or water conductivity. Poor water clarity can reduce the efficiency of electrofishing, but high BDD did not correspond with high common bully densities. In 2015, smelt abundance had recovered somewhat from the low catch in 2014.
Goldfish biomass increased initially (2009-2010) because of targeted fishing in the excavated side branch (site 11), which has dense macrophytes and offers good habitat for goldfish. The continued rise in density from 2012 on, however, suggests a real increase in goldfish numbers. In 2012 and 2013 shortfin eels were caught, but no eels were caught in 2014 and only a single longfin eel was caught in 2015.
Analysis of fish densities before and after wall closure is hampered by the single data point before closure. However, we now have 9 years of post-wall data, and comparison of means suggest that the number of bullies has been lower since 2007. An obvious cause could be interruption of bully migration into the Ohau Channel from Lake Rotoiti by the wall. This suggests that the bully population in the Ohau Channel before wall construction and closure was a mixture of fish from lakes Rotorua and Rotoiti, and that recruitment from Rotoiti is now restricted. This hypothesis is testable with otolith microchemistry.

year: 2016