Optimal setpoint chasing in dynamic positioning of deep‐water drilling and intervention vessels

Conventional controller designs for dynamic positioning of ships and floating marine structures have so far been based on the principle on automatic positioning in the horizontal‐plane about desired position and heading co‐ordinates defined by the operator. A three degrees‐of‐freedom multivariable controller either of linear or nonlinear type, normally with feedback signals from surge, sway and yaw position and velocities, has been regarded as adequate for the control objective. For floating structures with small waterplane area such as semi‐submersibles, feedback from roll and pitch angular rotation velocity may also be included to avoid thrust‐induced roll and pitch motions that are caused by the hydrodynamic and the geometrical couplings between the horizontal and vertical planes. However, for certain marine operations this control philosophy may not be the most appropriate approach ensuring safety and cost effectiveness. For drilling and work‐over operations the main positioning objective is to minimize the bending stresses along the riser and the riser angle magnitudes at the well head on the subsea structure, and at the top joint as well. A positioning control strategy solely based on manual setting of the desired position co‐ordinates may not be the most optimal solution for these applications. In this paper a new hybrid dynamic positioning controller, that also accounts for riser angle offsets and bending stresses is proposed. It is shown that a significant reduction in riser angle magnitude can be achieved. Simulations with a drilling semi‐submersible demonstrate the effect of the proposed control strategy. Copyright © 2001 John Wiley & Sons, Ltd.     

Polarized light imaging of white matter architecture

Polarized light imaging (PLI) is a method to image fiber orientation in gross histological brain sections based on the birefringent properties of the myelin sheaths. The method uses the transmission of polarized light to quantitatively estimate the fiber orientation and inclination angles at every point of the imaged section. Multiple sections can be assembled into a 3D volume, from which the 3D extent of fiber tracts can be extracted. This article describes the physical principles of PLI and describes two major applications of the method: the imaging of white matter orientation of the rat brain and the generation of fiber orientation maps of the human brain in white and gray matter. The strengths and weaknesses of the method are set out.     

Molecular dynamics simulations of oscillatory flows in microfluidic channels

In this paper we apply the direct non-equilibrium molecular dynamics technique to oscillatory flows of fluids in microscopic channels. Initially, we show that the microscopic simulations resemble the macroscopic predictions based on the Navier–Stokes equation very well for large channel width, high density and low temperature. Further simulations for high temperature and low density show that the non-slip boundary condition traditionally used in the macroscopic equation is greatly compromised when the fluid–wall interactions are the same as the fluid–fluid interactions. Simulations of a system with very narrow channel width confirm earlier findings of Poiseuille flow, namely, that the velocity profiles are modulated. We find that these modulations cannot be explained by the local area density model.

Oxygen transmission rates of packages at ambient,chill and freezing temperatures measured by the AOIR method

The ambient oxygen ingress rate (AOIR) method is an alternative or supplementary method to Ox‐Tran for measuring the oxygen transmission rate (OTR) of packages. The method has high capacity, requires relatively inexpensive equipment and measures OTR at different temperatures and humidity conditions. The aim of this study was, on the one hand, to study the effect of temperature on the OTR for packages produced from different polymer materials and laminates, and on the other hand to evaluate the suitability of the AOIR method at freezing temperature conditions. The OTR for 10 packages with different polymer compositions was measured at 23°C, 6°C and ?25°C. The AOIR method was shown to be a reliable test method for measuring OTR of packages at all the applied test conditions, also at frozen storage temperature. The OTR for the packages decreased with lower temperatures, especially for the packages with the highest OTR values at 23°C. In order to avoid higher packaging expenses than necessary to obtain the required shelf‐life for different food products, the OTR for alternative packages should be measured at the temperature and humidity conditions of intended use. Copyright © 2004 John Wiley & Sons, Ltd.     

Designing on-site: Facilitating participatory contextual architecture with mobile phones

Some movements within modern architecture particularly emphasise the importance of matching buildings to their surroundings. However, practicing such “contextual architecture” is highly challenging and typically not something the future inhabitants of a building are well equipped for participating in. This paper explores the potentials of using mobile phone technology for facilitating such client participation in the parts of an architecture process that take place on the building site. For this we introduce ArchiLens, a mobile system for interactive on-site 3D visualisation of houses, and findings from a field study with 40 participants in the process of building or modifying their home. The study showed that using the system helped evoke people’s imagination of the look and feel of their future house, and envision it in context. This enabled them to participate more closely in the design process on-site by iteratively reviewing design alternatives and exploring, for example, other placements and materials.     

Effects of level of social contact on dairy calf behavior and health

Housing preweaned dairy calves in pairs rather than individually has been found to positively affect behavioral responses in novel social and environmental situations, but concerns have been raised that close contact among very young animals may impair their health. In previous studies, the level of social contact permitted in individual housing has been auditory, visual, or physical contact. It is unclear how these various levels of social contact compare with each other and to pair housing, when their effects on behavior and health are considered, and whether the timing of pair housing has an effect. To investigate this, 110 Holstein calves (50 males, 60 females) in 11 blocks were paired according to birth date. Within 60 h of birth, each pair of calves was allocated to 1 of 5 treatments: individual housing with auditory contact (I), individual housing with auditory and visual contact (V), individual housing with auditory, visual, and tactile contact (T), pair housing (P), or individual housing with auditory and visual contact the first 2 wk followed by pair housing (VP). At 6 wk of age, calves were subjected to a social test and a novel environment test. In the social test, all pair-housed calves (P and VP) had a shorter latency to sniff an unfamiliar calf than did individually housed calves (I, V, and T), whereas calves with physical contact (T, P, and VP) sniffed the unfamiliar calf for longer than calves on the remaining treatments (I and V). In the novel environment test, calves with physical contact (T, P, and VP) had a lower heart rate, and more of these calves vocalized during the test compared with calves without physical contact (I and V). No effect of treatment was found for clinical scores, levels of the 5 most common pathogens in feces, or in development of serum antibodies against the 3 most common respiratory pathogens. Calves housed individually are more fearful of unfamiliar calves than are pair-housed calves. Contrary to common belief, the allowance of physical contact and pair housing had no effects on the health of the calves.     

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International Journal on Software Tools for Technology Transfer - User interfaces for interactive proof assistants have always lagged behind those for mainstream programming languages. Whereas...     

Comparison of the performance of masterbatch and liquid color concentrates for mass coloration of polypropylene

The properties of polypropylene (PP) mixed with masterbatch (MB) and liquid color concentrates (LCC), respectively, were compared by preparing samples of PP with MB and PP with LCC and neat PP as a reference material using 1–4 extrusion cycles. Two colors were examined, i.e., a white color consisting of pigment white 6, and a green color consisting of pigment white 6, pigment blue 15:3, and pigment green 7. The color difference between PP prepared with MB and LCC was determined and the mechanical, rheological, and crystalline properties of PP prepared with MB and LCC were found to be generic. The color of PP obtained from MB and LCC were comparable. Further, it was found that the tensile strength, the viscosity, and the crystal structure obtained were similar when using LCC instead of MB. The viscosity of the treated PP generally decreased with increasing extruder retention time due to thermal degradation. The tensile strength and the crystal structure were independent of increased extruder retention time. © 2015 Wiley Periodicals, Inc. Col Res Appl, 41, 484–492, 2016     

A GIS-based management and publication framework for data handling of numerical model results

There has been an increasing awareness that large-scale datasets of earth-system model results would be produced and accumulated rapidly within the next few decades with extensive usage of numerical models. The successful exploration of these data for scientific research and engineering applications requires the capability of efficient storage, retrieval, integration and visualization of these large datasets. Robust publication methods are also needed to enable data exchange through the web to increase global research collaborations. In this study, a comprehensive GIS-based data management and publication framework (GMPF) was developed and applied to the use, representation, and analysis of hydrodynamic modeling results of Hamburg Port, Germany. Linking with GIS, a desktop- and a web-based model-results data atlas were developed to provide an interactive environment for various cartography and time series plots. The implementation of the framework was based on modular software design, open specifications and reuse of open source projects. The study results showed that the project life-cycle was shortened and development efforts were reduced through applying GMPF. The developed system could be integrated into commercial hydrodynamics software platforms to enhance the capability of model-results management and publication.