title: Work distribution of multiple Cartesian robot arms for kiwifruit harvesting

authors: Barnett, Josh

subjects: Science & Technology

abstract: Employing multiple robot arms for kiwifruit harvesting can raise the efficiency since the task completion time is shortened. However, task partitioning and reachability are two major concerns. It is found that the task completion time is minimized if task partitions for robot arms are uniform. However, the partition uniformity is influenced by the fruit indivisibility and fruit cluster growing style. It is also constrained by the fruit distribution across the canopy and the robot arm positions which affect the fruit reachability. This article investigates how to partition the tasks of kiwifruit harvesting so that the harvesting can be completed by multiple robot arms in the minimum time with an assumption that the fruits can be harvested by any robot arm. A parameter termed work distribution is introduced to measure how the task partitioning is different from the optimum. A research platform with two robot arms is implemented to show how to approximate the assumption. Ten field experiments of kiwifruit harvesting had been run by the research platform in two kiwifruit orchards in New Zealand with satisfactory outcomes.

text: Work distribution of multiple Cartesian robot arms for kiwifruit harvesting Employing multiple robot arms for kiwifruit harvesting can raise the efficiency since the task completion time is shortened. However, task partitioning and reachability are two major concerns. It is found that the task completion time is minimized if task partitions for robot arms are uniform. However, the partition uniformity is influenced by the fruit indivisibility and fruit cluster growing style. It is also constrained by the fruit distribution across the canopy and the robot arm positions which affect the fruit reachability. This article investigates how to partition the tasks of kiwifruit harvesting so that the harvesting can be completed by multiple robot arms in the minimum time with an assumption that the fruits can be harvested by any robot arm. A parameter termed work distribution is introduced to measure how the task partitioning is different from the optimum. A research platform with two robot arms is implemented to show how to approximate the assumption. Ten field experiments of kiwifruit harvesting had been run by the research platform in two kiwifruit orchards in New Zealand with satisfactory outcomes.

year: 2020-02-01

title: Studies of sludge collected from the anaerobic digester of a meat processing company

authors: Ma, Nanxin

subjects: anaerobic digestion

abstract: Anaerobic digestion is commonly used as a wastewater treatment step where complex biological substrates are progressively degraded in the absence of oxygen to produce methane and carbon dioxide with hydrogen and volatile acids occurring as intermediate products. These intermediate products are more valuable commodities than methane so there is interest in optimizing their production and recovery from the anaerobic digestion process. In previous work, a sludge sample collected from a local meat processing company was reported to produce significant amounts of hydrogen at ambient temperatures.

In the present study, eleven sludge samples were collected from the same meat processing company and characterized in terms of their solids content, pH, as-collected gas production profiles and gas production profiles and gas production rates, when repetitively batch fed with glucose at their original pH and also at pHs successively lowered to pH 4.5. Similar studies were performed using cellulose as the substrate.

In these studies, no hydrogen was produced by the as-collected sludges, but hydrogen was produced by two of the sludges when batch fed with glucose. Detailed studies of the effect of pH on one of the sludges revealed that hydrogen was produced when the pH was lowered to between 5.2 and 5.4 and batch fed with glucose. No hydrogen was formed when the sludges were batch fed with cellulose under the conditions investigated. Acid conditions severely inhibited gas production rates when both glucose and cellulose were used as substrates. Gas production rates with cellulose substrate were systematically slower than when glucose was used as the substrate.

text: Studies of sludge collected from the anaerobic digester of a meat processing company Anaerobic digestion is commonly used as a wastewater treatment step where complex biological substrates are progressively degraded in the absence of oxygen to produce methane and carbon dioxide with hydrogen and volatile acids occurring as intermediate products. These intermediate products are more valuable commodities than methane so there is interest in optimizing their production and recovery from the anaerobic digestion process. In previous work, a sludge sample collected from a local meat processing company was reported to produce significant amounts of hydrogen at ambient temperatures.

In the present study, eleven sludge samples were collected from the same meat processing company and characterized in terms of their solids content, pH, as-collected gas production profiles and gas production profiles and gas production rates, when repetitively batch fed with glucose at their original pH and also at pHs successively lowered to pH 4.5. Similar studies were performed using cellulose as the substrate.

In these studies, no hydrogen was produced by the as-collected sludges, but hydrogen was produced by two of the sludges when batch fed with glucose. Detailed studies of the effect of pH on one of the sludges revealed that hydrogen was produced when the pH was lowered to between 5.2 and 5.4 and batch fed with glucose. No hydrogen was formed when the sludges were batch fed with cellulose under the conditions investigated. Acid conditions severely inhibited gas production rates when both glucose and cellulose were used as substrates. Gas production rates with cellulose substrate were systematically slower than when glucose was used as the substrate.

year: 2010

title: Teaching Māori in English-medium schools in New Zealand: Teacher responses to aspects of the curriculum guidelines for te reo Māori in English-medium school settings

authors: Takurua, Nātana

subjects: New Zealand

abstract: Opinions are divided about how the content of language courses should be specified and whether educational authorities should include specifications/ suggestions about language content in national curriculum documents. Issues associated with language content are, however, not ones that can be avoided, particularly as teachers are expected to prepare students for national examinations at the upper levels of schooling and these examinations are necessarily predicated on general expectations about proficiency achievements and more specific expectations about the types of language with which students will be familiar. In this article, we explore the complex nature of some of the issues involved and the ways in which the New Zealand Ministry of Education has sought/ is seeking to resolve them in the case of the curriculum for Māori in English-medium schools. We also report on the responses of a sample of teachers of Māori in secondary schools in New Zealand to the omission of language examples from the final version of the curriculum guidelines document.

text: Teaching Māori in English-medium schools in New Zealand: Teacher responses to aspects of the curriculum guidelines for te reo Māori in English-medium school settings Opinions are divided about how the content of language courses should be specified and whether educational authorities should include specifications/ suggestions about language content in national curriculum documents. Issues associated with language content are, however, not ones that can be avoided, particularly as teachers are expected to prepare students for national examinations at the upper levels of schooling and these examinations are necessarily predicated on general expectations about proficiency achievements and more specific expectations about the types of language with which students will be familiar. In this article, we explore the complex nature of some of the issues involved and the ways in which the New Zealand Ministry of Education has sought/ is seeking to resolve them in the case of the curriculum for Māori in English-medium schools. We also report on the responses of a sample of teachers of Māori in secondary schools in New Zealand to the omission of language examples from the final version of the curriculum guidelines document.

year: 2009-09