Testing butt joints in pipes made of VM12-SHC martensitic steel

VM12-SHC steel is the newest grade of 12% Cr steel developed by the V&M company. At the present moment, there are works being conducted in order to make use of this steel in steam superheaters. It is also planned to implement VM12-SHC steel to the fabrication of water-walls for prototype boilers operated at very high temperature and pressure parameters. In this article, test materials and welding consumbables are characterized and the process of preparation of pipes to be welded is discussed. The results of metallographic examination and mechanical testing of the test joints are presented.     

Video mediated social interaction between groups: System requirements and technology challenges

This paper discusses results from research related to the use of television as a device that supports social interaction between close-knit groups in settings that include more than two locations, each location being potentially equipped with more than one camera. The paper introduces the notion of a framing experience, as a specific scenario or situation within which social communication takes place. It reports on the evaluation of some of the key attributes of social communication through semi-structured interviews, with 16 families across four European countries. The inferences drawn from this study are reduced to four system capabilities including the ability to support: excitement, engagement and entertainment; high quality, reliable audiovisual communications; flexibility and adaptability sufficient to support the unpredictable and reactive nature of human interaction and discourse. These system requirements are, in turn, reduced to a number of technology challenges which if solved will help enable effective social communications between groups, mediated by the television. These technology challenges include: high quality reliable audio visual communication; interaction orchestration, multimedia interpretation and multimedia composition. Finally the paper reflects on the impact the use of framing experiences, such as those described here, could have on strategy and policy for service providers and regulators.     

Das Sperrmanagement im neuen deutschen Personalausweis

Dieser Artikel beschreibt im Detail die datenschutzfreundliche Ausgestaltung des Sperrmanagements, wie es im neuen deutschen Personalausweis zum Einsatz kommt.     

Cooperative transaction hierarchies: Transaction support for design applications

Traditional atomic and nested transactions are not always well-suited to cooperative applications, such as design applications. Cooperative applications place requirements on the database that may conflict with the serializability requirement. They require transactions to be long, possibly nested, and able to interact with each other in a structured way. We define a transaction framework, called acooperative transaction hierarchy, that allows us to relax the requirement for atomic, serializable transactions to better support cooperative applications. In cooperative transaction hierarchies, we allow the correctness specification for groups of designers to be tailored to the needs of the application. We usepatterns andconflicts to specify the constraints imposed on a group's history for it to be correct. We also provide some primitives to smooth the operation of the members. We characterize deadlocks in a cooperative transaction hierarchy, and provide mechanisms for deadlock detection and resolution. We examine issues associated with failure and recovery.     

Efficient parallel algorithms for path problems in directed graphs

In this paper we describe a technique for finding efficient parallel algorithms for problems on directed graphs that involve checking the existence of certain kinds of paths in the graph. This technique provides efficient algorithms for finding dominators in flow graphs, performing interval and loop analysis on reducible flow graphs, and finding the feedback vertices of a digraph. Each of these algorithms takesO(log² n) time using the same number of processors needed for fast matrix multiplication. All of these bounds are for an EREW PRAM.     

Case Study: Sediment Control at Water Intake for Large Thermal-Power Station on a Small River

A large thermal-power station drawing water from a small alluvial river had a chronic problem with alluvial-bed sediment buildup at the station’s river-water intake structure. The problem required expensive corrective dredging and adversely affected the station’s fuel-consumption efficiency. This case-study paper describes how the sediment problem was successfully controlled by means of modifications to the area in front of the intake and the upstream riverbank. The modifications comprised erosion-promoting vanes and a skimming wall, together with realignment of the riverbank upstream of the intake. A hydraulic model was used to aid the design of the modifications. Installation of the modifications required construction techniques that enabled the intake and power station to continue operating while the modifications were being installed.     

Polarization dynamics and non-equilibrium switching processes in ferroelectrics

Time- and temperature-dependent effects are critical for the operation of non-volatile memories based on ferroelectrics. In this paper, we assume a domain nucleation process of the polarization reversal and we discuss the polarization dynamics in the framework of a non-equilibrium statistical model. This approach yields analytical expressions which can be used to explain a wide range of time- and temperature-dependent effects in ferroelectrics. Domain wall velocity derived in this work is consistent with a domain wall creep behavior in ferroelectrics. In the limiting case of para-electric equilibrium, the model yields the well-known Curie law. We also present experimental P-E loops data obtained for soft ferroelectrics at various temperatures. The experimental coercive fields at various temperatures are well predicted by the coercive field formula derived in our theory.