title: Surface Reconstruction by Triangular Mesh of Models with Uneven Density and with Hole

authors: Ye, Chen

subjects: reverse engineering

abstract: With the fast development of computer software, 3D computer aided design (CAD) and computer aided manufacturing (CAM) are being improved rapidly and have been commonly used in industry, especially in medical area and moulding field. 3D CAD/ CAM has greatly shortened the mould development time, thus it plays an important role in product development and automatic production.

It has been a serious topic about how to get the product design and also being manufactured in a short time to grasp the market opportunities in the competition of the developing manufacturing techniques, diversification and complexification of product demand. But not all the products have the design draft, for example, some of them were made by the mould of clay which came from craftsman by their hands. In order to conquer those problems, reverse engineering came into being. Reverse engineering could achieve a faster product design and manufacture, it also could be used in the field of vehicle components, home appliances, medical supplies (like human body measurement such as for artificial leg bones, tooth, etc.,), and rapid prototyping (such as precision casting products, industrial design, etc.). The so-called reverse engineering now targets to the existing mould (samples or manual model). It starts with the existing model, sampling surface data by data acquisition equipment (DAE) then acquire an ordered or unordered could of points. After that by the use of discrete geometry processing technology to get the CAD model of solid entity which computer could recognize. The following procedures of the CAD model could be redesigned or improved as required.

text: Surface Reconstruction by Triangular Mesh of Models with Uneven Density and with Hole With the fast development of computer software, 3D computer aided design (CAD) and computer aided manufacturing (CAM) are being improved rapidly and have been commonly used in industry, especially in medical area and moulding field. 3D CAD/ CAM has greatly shortened the mould development time, thus it plays an important role in product development and automatic production.

It has been a serious topic about how to get the product design and also being manufactured in a short time to grasp the market opportunities in the competition of the developing manufacturing techniques, diversification and complexification of product demand. But not all the products have the design draft, for example, some of them were made by the mould of clay which came from craftsman by their hands. In order to conquer those problems, reverse engineering came into being. Reverse engineering could achieve a faster product design and manufacture, it also could be used in the field of vehicle components, home appliances, medical supplies (like human body measurement such as for artificial leg bones, tooth, etc.,), and rapid prototyping (such as precision casting products, industrial design, etc.). The so-called reverse engineering now targets to the existing mould (samples or manual model). It starts with the existing model, sampling surface data by data acquisition equipment (DAE) then acquire an ordered or unordered could of points. After that by the use of discrete geometry processing technology to get the CAD model of solid entity which computer could recognize. The following procedures of the CAD model could be redesigned or improved as required.

year: 2015

title: Effects of low tide rainfall on the erodibility of intertidal cohesive sediments

authors: Pilditch, Conrad A.

subjects: sediment transport

abstract: Low tide rainfall may represent an important but little studied process affecting sediment fluxes on intertidal mudflats. In this study, we simulated rainfall events on an intertidal mudflat (median grain size=18.4 μm) of low slope (1 in 300) then quantified effects on sediment erodibility. Treatments consisted of a high (4.1 mm min⁻¹ for 6 min) and low (0.36 mm min⁻¹ for 60 min) rain intensity, chosen to match naturally occurring events and experiments were conducted seasonally (May and August) to encompass variations in ambient sediment stability. Changes in bed elevation due to rainfall were estimated using marked rods and sediment erodibility parameters (mass of sediment eroded at a flow velocity of 0.3 m s⁻¹ (ME-30, g m⁻²) and critical erosion velocity (Ucrit, m s⁻¹)) were determined in annular flumes (bed area=0.17 m²). Ambient/control sediment erodibility in May (ME-30=211 g m⁻², Ucrit=0.18 m s⁻¹) was higher than in August (ME-30=30 g m⁻², Ucrit=0.26 m s⁻¹) and was correlated with changes in biological activity. In May, surface sediment was influenced by high densities of the bioturbating snail Hydrobia ulvae (1736 ind. m⁻²) and low biomass of the sediment stabilising microphytobenthos (5.7 μg chlorophyll a cm⁻²). In contrast, in August H. ulvae densities were low (52 ind. m⁻²) and microphytobenthic biomass higher (9.2 μg chlorophyll a cm⁻²). The high rain treatment caused a decrease in bed elevation of between 1.5 mm (May) and 4.4 mm (August) and significantly reduced sediment organic content and microphytobenthic biomass. Rainfall increased sediment erodibility; compared to ambient sediments ME-30 increased by a factor of 1.4× in May and 8.8× in August and caused a 10–30% decline in Ucrit. The seasonal difference in treatment effect was due to the change in ambient sediment stability. The low rain treatment in August had no effect on bed elevation, microphytobenthic biomass or sediment erodibility. In May, the same treatment caused a reduction in bed elevation (0.5 mm) and microphytobenthic biomass but counter-intuitively, a decrease in sediment erodibility (ME-30 was reduced by 40%, Ucrit increased by 5%) compared to controls. We attribute this result to removal by rainfall of easily eroded surface flocs and biogenic roughness which resulted in an underlying sediment with a smoother surface and greater resistant to erosion. Results suggest that high intensity rain events may destabilise intertidal sediments making them more susceptible to erosion by returning tidal currents and that the sediment eroded during such events may represent a considerable fraction (up to 25%) of the seasonal variation in shore elevation. The impact of natural rain events are likely to vary considerably due to variations in droplet size, intensity and duration and the interaction with ambient sediment stability

text: Effects of low tide rainfall on the erodibility of intertidal cohesive sediments Low tide rainfall may represent an important but little studied process affecting sediment fluxes on intertidal mudflats. In this study, we simulated rainfall events on an intertidal mudflat (median grain size=18.4 μm) of low slope (1 in 300) then quantified effects on sediment erodibility. Treatments consisted of a high (4.1 mm min⁻¹ for 6 min) and low (0.36 mm min⁻¹ for 60 min) rain intensity, chosen to match naturally occurring events and experiments were conducted seasonally (May and August) to encompass variations in ambient sediment stability. Changes in bed elevation due to rainfall were estimated using marked rods and sediment erodibility parameters (mass of sediment eroded at a flow velocity of 0.3 m s⁻¹ (ME-30, g m⁻²) and critical erosion velocity (Ucrit, m s⁻¹)) were determined in annular flumes (bed area=0.17 m²). Ambient/control sediment erodibility in May (ME-30=211 g m⁻², Ucrit=0.18 m s⁻¹) was higher than in August (ME-30=30 g m⁻², Ucrit=0.26 m s⁻¹) and was correlated with changes in biological activity. In May, surface sediment was influenced by high densities of the bioturbating snail Hydrobia ulvae (1736 ind. m⁻²) and low biomass of the sediment stabilising microphytobenthos (5.7 μg chlorophyll a cm⁻²). In contrast, in August H. ulvae densities were low (52 ind. m⁻²) and microphytobenthic biomass higher (9.2 μg chlorophyll a cm⁻²). The high rain treatment caused a decrease in bed elevation of between 1.5 mm (May) and 4.4 mm (August) and significantly reduced sediment organic content and microphytobenthic biomass. Rainfall increased sediment erodibility; compared to ambient sediments ME-30 increased by a factor of 1.4× in May and 8.8× in August and caused a 10–30% decline in Ucrit. The seasonal difference in treatment effect was due to the change in ambient sediment stability. The low rain treatment in August had no effect on bed elevation, microphytobenthic biomass or sediment erodibility. In May, the same treatment caused a reduction in bed elevation (0.5 mm) and microphytobenthic biomass but counter-intuitively, a decrease in sediment erodibility (ME-30 was reduced by 40%, Ucrit increased by 5%) compared to controls. We attribute this result to removal by rainfall of easily eroded surface flocs and biogenic roughness which resulted in an underlying sediment with a smoother surface and greater resistant to erosion. Results suggest that high intensity rain events may destabilise intertidal sediments making them more susceptible to erosion by returning tidal currents and that the sediment eroded during such events may represent a considerable fraction (up to 25%) of the seasonal variation in shore elevation. The impact of natural rain events are likely to vary considerably due to variations in droplet size, intensity and duration and the interaction with ambient sediment stability

year: 2008

title: Proposed changes to Te Ture Whenua Maori

authors: Te Aho, Linda

abstract: This presentation will look at the proposed changes to Te Ture Whenua and a timeline for the changes.
• Examining current issues surrounding land and problems with Te Ture Whenua 1993.
• Explaining changes to the Maori Land Court and the new Maori Land Service

text: Proposed changes to Te Ture Whenua Maori This presentation will look at the proposed changes to Te Ture Whenua and a timeline for the changes.
• Examining current issues surrounding land and problems with Te Ture Whenua 1993.
• Explaining changes to the Maori Land Court and the new Maori Land Service

year: 2016