In this work, we evaluate the feasibility of tracking-based interaction using a mobile phone's or tablet's camera in order to create and edit 3D objects in augmented reality applications. We present a feasibility study investigating if and how gestures made with your finger can be used to create such objects. A revised interface design is evaluated in a user study with 24 subjects that reveals a high usability and entertainment value, but also identifies issues such as ergonomic discomfort and imprecise input for complex tasks. Hence, our results suggest huge potential for this type of interaction in the entertainment, edutainment, and leisure domain, but limited usefulness for serious applications.

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Injection of silicate grouting materials is widely used to create temporary horizontal layers for reducing inflow of groundwater at construction sites, in regions with shallow water tables. The erosion of a grouting layer was investigated by means of analytical solutions for groundwater flow and transport within a pit after construction finished. Erosion is assumed to occur by dissolution of the temporary injection layer and subsequent advective transport. Thereby, the hydraulic conductivity changes with time. This paper presents novel analytical solutions and approximate solutions for the major fluxes in the construction pit as a function of the domain settings, aquifer gradient and hydraulic conductivity. In addition, the mass flux and the dilution ratio of erosion-related components leaving the construction pit and entering the aquifer are quantified. Derived solutions are verified against numerical simulations. A sensitivity study shows the impact of domain settings on fluxes and dilution ratio. The results confirm that mass flux of grout components increases with ongoing erosion. Thus, its effect on groundwater quality increases with time after construction ceased.

<p><span>Injection of grout material is widely used to create a temporary flow barrier at construction sites in the Netherlands. We investigate the long-term erosion behavior of a grout layer by means of semi-analytical expressions for groundwater flow and transport. </span></p><p><span>A typical grout injection contains sodium-meta silicate, water and solidifier forming a temporarily impermeable ‘waterglass’. The combination of a waterglass layer and vertical walls allow for dry excavations below the groundwater table. After construction is finished, the waterglass remains in the subsurface and erodes over time. A question concerning the potential risk to groundwater quality remains: How high is the concentration of dissolved waterglass in the groundwater leaving the site?</span></p><p><span>Numerical simulations allow to describe the flow and transport for site specific conditions. However, it’s missing an analytical expression to predict the transport behavior for arbitrary settings. We approximate the erosion behavior by a set of semi-analytical equations. The challenge here is the change in permeability of the waterglass layer from almost impermeable to fully permeable. We define a dilution ratio relating the flux into the construction site to the flux through the layer as a measure of dissolved waterglass concentration leaving the site. We also determine the impact of design parameters such as construction site aspect ratio, depth of the waterglass layer and its thickness. We checked our results against numerical simulations for a range of parameter settings. Preliminary results show that erosion is initially slow and accelerates until the temporary injection layer is completely gone. </span></p>