Numerical modelling of erosion and sedimentation around offshore pipelines

In this paper a numerical model is presented for the description of the erosion and sedimentation near pipelines on the sea bottom. The model is based on the Navier-Stokes equations and the equation of motion and continuity of sediment.\ud \ud The results of the simulations have been compared with the results of tests in a large-scale facility. The agreement between the results of the simulations and the experimental results is good.\ud \ud The applicability of the method is twofold: firstly, the processes of erosion and sedimentation around bodies on the sea bottom can be simulated; secondly, the method can be used for the design of pipelines, including erosion stimulating elements, such as spoilers

Patterns of financial change in the OECD area

Financial Policy;Interest Rate;OECD;monetary economics

Combining expert knowledge and databases for risk management

Correctness, transparency and effectiveness are the principalattributes of knowledge derived from databases. In current data miningresearch there is a focus on efficiency improvement of algorithms forknowledge discovery. However important limitations of data mining canonly be dissolved by the integration of knowledge of experts in thefield, encoded in some accessible way, with knowledge derived formpatterns in the database. In this paper we will in particular discussmethods for combining expert knowledge and knowledge derived fromtransaction databases.The framework proposed is applicable to widevariety of risk management problems. We will illustrate the method ina case study on fraud discovery in an insurance company.risk management;datamining;knowledge discovery;knowledge based systems

Superconducting magnet system for an experimental disk MHD facility

A predesign of a split-pair magnet for a magnetohydrodynamic (MHD) facility for testing a 10-MW open-cycle disk or a 5-MW closed-cycle disk generator is presented. The magnet system consists of a NbTi and a Nb 3Sn section, which provide a magnetic field of 9 T in the active area of the MHD channel. The optimization process, which is based on minimum conductor costs is discussed, and the proposed conductor design is described. Basic solutions for the construction of the magnet, the cryostat and the cooling technique are also presente

Gate Delay Fault Test Generation for Non-Scan Circuits

This article presents a technique for the extension of delay fault test pattern generation to synchronous sequential circuits without making use of scan techniques. The technique relies on the coupling of TDgen, a robust combinational test pattern generator for delay faults, and SEMILET, a sequential test pattern generator for several static fault models. The approach uses a forward propagation-backward justification technique: The test pattern generation is started at the fault location, and after successful ¿local¿ test generation fault effect propagation is performed and finally a synchronising sequence to the required state is computed. The algorithm is complete for a robust gate delay fault model, which means that for every testable fault a test will be generated, assuming sufficient time. Experimental results for the ISCAS'89 benchmarks are presented in this pape

Damage-based fracture with electro-magnetic coupling

Acoupled elastic and electro-magnetic analysis is proposed including finite displacements and damage-based fracture. Piezo-electric terms are considered and resulting partial differential equations include a non-classical wave equation due to the specific constitutive law. The resulting wave equation is constrained and, in contrast with the traditional solutions of the decoupled classical electromagnetic wave equations, the constraint is directly included in the analysis. The absence of free current density allows the expression of the magnetic field rate as a function of the electric field and therefore, under specific circumstances, removal of the corresponding magnetic degrees-offreedom. A Lagrange multiplier field is introduced to exactly enforce the divergence constraint, forming a three-field variational formulation (required to include thewave constraint). No vector-potential is required or mentioned, eliminating the need for gauges. The classical boundary conditions of electromagnetism are specialized and a boundary condition involving the electric field is obtained. The spatial discretization makes use of mixed bubble-based (of the MINI type) finite elementswith displacement, electric field and Lagrange multiplier degrees-of-freedom. Three verification examples are presented with very good qualitative conclusions and mesh-independence

Some environmental aspects of grassland cultivation; the effects of ploughing depth, grassland age, and nitrogen demand of subsequent crops

The Netherlands has submitted a derogation under the Nitrate Directives to the European Union (EU) in 2000. In the final opinion by a group of experts about the Dutch derogation, recommendations on ploughing of grasslands were included dealing with i) the depth of ploughing of permanent grassland, ii) the age of temporary grassland and iii) the nitrogen demand of the subsequent crop of temporary grassland. A literature study was carried out in order to provide scientific information on these three issues. No studies were found in literature in which the effects of cultivation depth on nitrogen mineralisation and losses in reseeded grassland were assessed. The results of transformation of grassland into arable land show no clear effects of ploughing depth on N mineralisation. Differences in nitrogen mineralisation after 5 and 3 years temporary grassland are small. Italian and perennial ryegrass, potato, silage maize, winter wheat, and several vegetables have a high nitrogen demand (i.e. >250 kg N ha-1)