Bubble Movement in Downward-Inclined Pipes

An experimental investigation with large-scale model tests of bubbles moving upward and downward in downward-inclined pipes is presented. The shape, velocity, and drag coefficient of single nonspherical air bubbles in continuous air-water flows are discussed. The bubble height depends mainly on the approach flow water velocity and the pipe slope. For stagnant bubbles, the bubble height is determined depending on these two parameters. Equilibrium of the drag and buoyancy forces is applied on single air bubbles in downward-inclined pipes. In pipes with pipe slope ranging from 0.052–0.087, the bubble drag coefficient is independent of the bubble Reynolds number. However, the bubble drag coefficient depends on the pipe slope and the approach flow water velocity. Using the approach of the equilibrium of the main forces the volume of stagnant bubbles can be predicted.     

Effect of Wet–Dry Cycles and Cation Exchange on Gas Permeability of Geosynthetic Clay Liners

A series of gas permeability tests were performed on a partially hydrated needle punched geosynthetic clay liner (GCL) after exposure to wet–dry cycles and ion exchange. To be able to evaluate the effect of wetting and drying cycles combined with the effect of cation exchange, three sets of GCL samples were prepared with different types of hydrating liquid. The first set of GCL samples was hydrated with de-ionized water, which formed a baseline test series. The second and third sets were hydrated with 0.0125 and 0.125?M calcium chloride (CaCl2) solutions, respectively. All three sets of GCL samples were subjected to multiple wetting and drying cycles before undergoing gas permeability tests. Gas permeability of the GCL, hydrated with 0.0125?M calcium chloride solution, was found to be approximately one order of magnitude higher than that of the GCL hydrated with de-ionized water, whereas gas breakthrough flow was observed for all but the first wetting cycle on GCLs hydrated with the stronger 0.125?M calcium chloride solution.     

The elements of probabilistic time geography

Time geography uses space–time volumes to represent the possible locations of a mobile agent over time in a x–y–t space. A volume is a qualitative representation of the fact that the agent is at a particular time t _i inside of the volume’s base at t _i . Space–time volumes enable qualitative analysis such as potential encounters between agents. In this paper the qualitative statements of time geography will be quantified. For this purpose an agent’s possible locations are modeled from a stochastic perspective. It is shown that probability is not equally distributed in a space–time volume, i.e., a quantitative analysis cannot be based simply on proportions of intersections. The actual probability distribution depends on the degree of a priori knowledge about the agent’s behavior. This paper starts with the standard assumption of time geography (no further knowledge), and develops the appropriate probability distribution by three equivalent approaches. With such a model any analysis of the location of an agent, or relations between the locations of two agents, can be improved in expressiveness as well as accuracy.     

Age-dependent gene expression profile and protein expression in a transgenic rat model of Huntington's disease

Polyglutamine‐induced changes in gene expression have been demonstrated by using several mouse models of Huntington's disease (HD), which express extreme numbers of CAG repeats. We have recently developed a transgenic rat model of HD carrying a truncated huntingtin fragment with 51 CAG repeats, which is in the range seen in adult HD patients. For further evaluation, we have performed microarray analyses on whole brains of transgenic rats at 3 and 12 months of age and correlated it with protein expression by Western blot analysis. We found that genes functionally associated with gene expression and behavior were differently regulated already at 3 months of age, whereas at 12 months of age especially genes related to neurological diseases and cell‐to‐cell signaling and interaction were dysregulated. A detailed analysis of canonical pathways revealed that at 3 months of age genes in calcium signaling and synaptic long term potentation pathways were altered, while at 12 months of age, additionally, expression level of many genes implicated in Huntington's disease signaling, were changed.     

Quantifying low back peak and cumulative loads in open and senior sheep shearers in New Zealand: examining the effects of a trunk harness

Sheep shearing requires shearers to adopt sustained flexed postures for prolonged periods of time and has been associated with an increased risk of developing low back pain (LBP). However, these postures do not generally result in acute compressive values at L4/L5 exceeding the action limit proposed by the National Institute for Occupational Safety and Health, despite the high prevalence of LBP in this occupation. Therefore, it may not be peak loading that is responsible for LBP in this occupation but instead it may be the effect of cumulative loading over the course of a workday. The primary purpose of this research was to quantify the low back cumulative load exposure in 12 sheep shearers with and without the aid of a commercial trunk harness. Results revealed a significant reduction in the magnitude of cumulative compression with the use of the trunk harness and therefore its use may potentially reduce the risk of injury. The use of the trunk harness also reduced the time spent in axially twisted postures, which have been associated with LBP. However, using the trunk harness also resulted in increased time spent in laterally bent postures, which has been associated with increased risk for pain and injury.     

Learning a subclass of regular patterns in polynomial time

An algorithm for learning a subclass of erasing regular pattern languages is presented. On extended regular pattern languages generated by patterns π$\pi$ of the form _x0α1x1…_αmxm$x_0{\alpha }_1{x}_1\dots {\alpha }_m{x}_m$, where _x0,…,_xm$x_0,\dots ,x_m$ are variables and _α1,...,_αm${\alpha }_1,...,{\alpha }_m$ strings of terminals of length c each, it runs with arbitrarily high probability of success using a number of examples polynomial in m (and exponential in c). It is assumed that m is unknown, but c is known and that samples are randomly drawn according to some distribution, for which we only require that it has certain natural and plausible properties.     

Knowledge transfer in offshore outsourcing software development projects: an analysis of the challenges and solutions from German clients

Knowledge transfer is a critical factor in ensuring the success of offshore outsourcing software development projects and is, in many cases, neglected. Compared to in‐house or co‐located projects, however, such globally distributed projects feature far greater complexity. In addition to language barriers, factors such as cultural differences, time zone variance, distinct methods and practices, as well as unique equipment and infrastructure can all lead to problems that negatively impact knowledge transfer, and as a result, a project's overall success. In order to help minimise such risks to knowledge transfer, we conducted a research study based on expert interviews in six projects. Our study used German clients and focused on offshore outsourcing software development projects. We first identified known problems in knowledge transfer that can occur with offshore outsourcing projects. Then we collected best‐practice solutions proven to overcome the types of problems described. Afterward, we conducted a follow‐up study to evaluate our findings. In this subsequent stage, we presented our findings to a different group of experts in five projects and asked them to evaluate these solutions and recommendations in terms of our original goal, namely to find ways to minimise knowledge‐transfer problems in offshore outsourcing software development projects. Thus, the result of our study is a catalog of evaluated solutions and associated recommendations mapped to the identified problem areas.