Review of Summation-by-parts schemes for initial-boundary-value problems

High-order finite difference methods are efficient, easy to program, scales well in multiple dimensions and can be modified locally for various reasons (such as shock treatment for example). The main drawback have been the complicated and sometimes even mysterious stability treatment at boundaries and interfaces required for a stable scheme. The research on summation-by-parts operators and weak boundary conditions during the last 20 years have removed this drawback and now reached a mature state. It is now possible to construct stable and high order accurate multi-block finite difference schemes in a systematic building-block-like manner. In this paper we will review this development, point out the main contributions and speculate about the next lines of research in this area

Another Hurdle to Habeas: The Streamlined Procedures Act

This report describes how the system may be exposed to oscillations and how this can lead to resonance. Resonance is a phenomenon that occurs when a system is affected by external periodic oscillations with frequencies close to the system's natural frequencies. Structures subjected to resonance can risk great damage and destruction, why resonance is something that is important to take into account when designing structures. Alternative ways to counteract resonance is to supply damping in the system. Damping means that the resonance decreases instead of letting the amplitude increase.The report discusses some examples on constructions that have experienced the effect of resonance. The control tower in Stockholm's Arlanda Airport was swaying so much that water tanks had to be installed as resonance dampers, where the water swung in opposite phase compared to the tower. The oscillations probably started due to the fact that the tower was too lightweight in relation to its height. Tacoma Narrows Bridge in Washington, USA, oscillated in the amount that the bridge collapsed. The reason was that the bridge weighed too little to withstand the strong wind forces. The stadium Ullevi in Gothenburg had to be strengthened due to the fact that a jumping crowd during a concert caused resonance oscillations which endangered parts of the construction. After the concert, beams with decent damping attributes were installed against the rooftops to reduce the risk of damage to these. Broughtons Suspension Bridge in Britain fell apart when soldiers marched in step and in this way contributed to the oscillations of the bridge. The bridge also had structural parts whose strength was not sufficient

Hospital Service Plans: Their Contract Provisions and Administrative Procedures

We propose an FDI system for the wind turbine benchmark designed by the application of a generic automated method. No specific adaptation of the method for the wind turbine benchmark is needed, and the number of required human decisions, assumptions, as well as parameter choices is minimized. The method contains in essence three steps: generation of candidate residual generators, residual generator selection, and diagnostic test construction. The proposed FDI system performs well in spite of no specific adaptation or tuning to the benchmark. All faults in the predefined test sequence can be detected and all faults, except a double fault, can also be isolated shortly thereafter. In addition, there are no false or missed detections

Journal Staff

A time-dependent coordinate transformation of a constant coeffcient hyperbolic equation which results in a variable coeffcient problem is considered. By using the energy method, we derive well-posed boundary conditions for the continuous problem. It is shown that the number of boundary conditions depend on the coordinate transformation. By using Summation-by-Parts (SBP) operators for the space discretization and weak boundary conditions, an energy stable finite dieffrence scheme is obtained. We also show how to construct a time-dependent penalty formulation that automatically imposes the right number of boundary conditions. Numerical calculations corroborate the stability and accuracy of the approximations

Entropy solutions of the compressible Euler equations

We consider the three-dimensional Euler equations of gas dynamics on a bounded periodic domain and a bounded time interval. We prove that Lax-Friedrichs scheme can be used to produce a sequence of solutions with ever finer resolution for any appropriately bounded (but not necessarily small) initial data. Furthermore, we show that if the density remains strictly positive in the sequence of solutions at hand, a subsequence converges to an entropy solution. We provide numerical evidence for these results by computing a sensitive Kelvin-Helmholtz problem

The international community and post-war reconciliation in Africa: A case study of the Sierra Leone Truth and Reconciliation Commission

The decade-long armed conflict and political unrest in Sierra Leone deeply affected the civilian population. Since the end of the war in 2002, the government of Sierra Leone and the international community have been involved in peacebuilding activities, national reconciliation and reconstruction. The reconciliatory process necessitated the setting up of a Truth and Reconciliation Commission (TRC) which was also a product of the Lomé Peace Agreement between the Government of Sierra Leone and the now defunct Revolutionary United Front (RUF). The international community invested US$ 4,6 million in the Sierra Leone TRC mission. The TRC examined the causes of the war, human rights violations and the role played by foreign actors. This paper analyses the TRC as an internationally driven process to enhance reconciliation, peace, development and democracy in Sierra Leone. It also evaluates the impact of the implementation of the recommendations of the TRC. Beyond this, it makes some suggestions on how the international community can better promote transitional justice and the peacebuilding process by supporting local initiatives and promoting national ownership for sustainability

DYNAMIC PORTFOLIO STRATEGY - USING A MULTIVARIATE GARCH MODEL

This paper examines if it is possible to achieve a higher cumulative and risk adjusted return through an active portfolio strategy compared to a passive portfolio strategy. This is done through a mean-variance framework in which the variance is forecasted using two different models. The results show that it is possible achieve a higher cumulative and risk adjusted return by dynamically changing the weights of the assets in the portfolio. Especially if a simple market timing rule is used

Female Sages in Akkadian Literature

Peer reviewe