Engineering geological investigations for a subsea tunnel for an oil pipeline across the hjeltefjorden strait

A subsea tunnel across the approx. 6-km-wide and 375-m-deep Hjeltefjorden strait was planned to be part of STATOIL's concept for transportation of crude oil to the Mongstad refinery (GULLPIPE). The planning and engineering geological investigations were carried out in three phases from May 1983 to May 1984. This article deals with the different engineering geological investigations made, the results obtained, the evaluation and the recommendations made in connection with this subsea tunnel. Of particular importance were refraction seismic investigations of the seabed at depths of more than 350 m. Also, core drilling at such depths was carried out for the first time.     

Spectral Approximation of Partial Differential Equations in Highly Distorted Domains

In this paper we discuss spectral approximations of the Poisson equation in deformed quadrilateral domains. High order polynomial approximations are used for both the solution and the representation of the geometry. Following an isoparametric approach, the four edges of the computational domain are first parametrized using high order polynomial interpolation. Transfinite interpolation is then used to construct the mapping from the square reference domain to the physical domain. Through a series of numerical examples we show the importance of representing the boundary of the domain in a careful way; the choice of interpolation points along the edges of the physical domain may significantly effect the overall discretization error. One way to ensure good interpolation points along an edge is based on the following criteria: (i)?the points should be on the exact curve; (ii)?the derivative of the exact curve and the interpolant should coincide at the internal points along the edge. Following this approach, we demonstrate that the discretization error for the Poisson problem may decay exponentially fast even when the boundary has low regularity.     

Investigating an “Internet of Hybrid Products”: Assembling Products, Interactions, Services, and Networks through Design

This article takes up the relations between products, people, and the Internet. Our investigation is set in the context of the emergence of networked and service-driven physical products. The article builds upon the curation and design of an exhibition that pulls together recent hybrids composed of physical objects as well as digital things and networked services. Through investigating this selection of both prototypical and widely available consumer products, we seek to understand how the previously-separate domains of product, interaction, and service design might be combined in order to design and research new hybrid products, services, and interactions. Taken together, these investigations point toward an “Internet of Hybrid Products” that draws heavily from social practices in networked media that is already highly branded and in urgent need of attention from design research.     

A piezoelectric energy harvester with a mechanical end stop on one side

Nonlinear effects as severe as proof mass impact on mechanical end stops are potentially useful for energy harvesting. In this paper, we present measurements and modeling of a piezoelectric energy harvester with a mechanical end stop on one side. At high acceleration levels we observe nonlinear effects related to impacts on the end stop such as an enlarged up-sweep bandwidth in frequency sweeps. Based on SPICE simulations of an electrical equivalent circuit for the device, we show that modeling of the end stop as a parallel spring-dashpot system is sufficient to recapture the energy harvester behavior.     

Direct simulation Monte Carlo for simultaneous nucleation, coagulation, and surface growth in dispersed systems

A Monte Carlo simulation technique is developed to describe dispersed phase systems. The method is formulated for simultaneous coagulation, nucleation and surface growth, but can be extended to include other processes. These processes are considered in an initially constant simulation volume. The changes in the particle ensemble are determined by a random choice procedure, while the particle number in the simulation volume changes according to the chosen events. Every time, when the particle number in the simulation volume increases or decreases by a factor of two of its initial value, the simulation volume is halved or doubled, respectively. Therefore, this method is called a stepwise constant-volume Monte Carlo simulation. It allows to use only several thousands simulation particles, even if the particle number concentration experiences changes of several orders of magnitude. The simulations are validated through a comparison with the exact mathematical solutions for several simple cases. An example of simultaneous nucleation and coagulation in the free-molecular region demonstrates, that the stepwise constant-volume Monte Carlo simulations lead to more accurate results than the constant-number Monte Carlo simulations.     

Comparison of geophysical methods for sub-surface mapping of faults and fracture zones in a section of the Viggja road tunnel, Norway

Results from site investigations, 2D resistivity, refraction seismic and VLF on a section of tunnel near Trondheim, show that 2D resistivity data are most valuable for interpreting geological structures in the sub-surface. VLF only identifies zones and does not indicate thickness, width or dip direction. The method is also sensitive to technical installations. Refraction seismic is valuable for mapping depth to bedrock, location and width of fracture zones but cannot indicate the depth or dip direction of such zones. With 2D resistivity, the position of a zone is well identified. This method may also provide information on the depth and width of the zone as well as the dip direction. In most cases 2D resistivity clearly identifies zones in the bedrock that can be observed as fault and/or fracture zones in the tunnel. The results described in this paper show a good correlation between the resistivity profiles, mapped structures on the surface and mapped zones in the tunnel.     

Verifying traits: an incremental proof system for fine-grained reuse

Traits have been proposed as a more flexible mechanism than class inheritance for structuring code in object-oriented programming, to achieve fine-grained code reuse. A trait originally developed for one purpose can be adapted and reused in a completely different context. Formalizations of traits have been extensively studied, and implementations of traits have started to appear in programming languages. So far, work on formally establishing properties of trait-based programs has mostly concentrated on type systems. This paper presents the first deductive proof system for a trait-based object-oriented language. If a specification of a trait can be given a priori, covering all actual usage of that trait, our proof system is modular as each trait is analyzed only once. However, imposing such a restriction may in many cases unnecessarily limit traits as a mechanism for flexible code reuse. In order to reflect the flexible reuse potential of traits, our proof system additionally allows new specifications to be added to a trait in an incremental way which does not violate established proofs. We formalize and show the soundness of the proof system.     

User-defined schedulers for real-time concurrent objects

Scheduling concerns the allocation of processors to processes, and is traditionally associated with low-level tasks in operating systems and embedded devices. However, modern software applications with soft real-time requirements need to control application-level performance. High-level scheduling control at the application level may complement general purpose OS level scheduling to fine-tune performance of a specific application, by allowing the application to adapt to changes in client traffic on the one hand and to low-level scheduling on the other hand. This paper presents an approach to express and analyze application-specific scheduling decisions during the software design stage. For this purpose, we integrate support for application-level scheduling control in a high-level object-oriented modeling language, Real-Time ABS, in which executable specifications of method calls are given deadlines and real-time computational constraints. In Real-Time ABS, flexible application-specific schedulers may be specified by the user, i.e., developer, at the abstraction level of the high-level modeling language itself and associated with concurrent objects at creation time. Tool support for Real-Time ABS is based on an abstract interpreter that supports simulations and measurements of systems at the design stage.