Advanced flaw production method for in-service inspection qualification mock-ups

One of the key issues in in-service inspection qualification is the representativeness of the defects used in qualification specimens. The best representativeness is achieved with realistic defects. However, present specimen production techniques have some significant weaknesses, such as unrealistic defects or additional alterations induced in the surrounding material. Specimens manufactured, for example, by weld implantation or with weld solidification defects always result in one or more extra weld interfaces. These interfaces can be detected by NDT. To overcome problems with the current specimens, a new defect manufacturing technique was developed. The new technique produces natural, representative defects without introducing additional weld metal or other unwanted alterations to the specimen.The new method enables artificial production of single, separate fatigue cracks by thermal loading. The method is based on a natural thermal fatigue damage mechanism and enables production of real cracks directly into the samples. Cracks are produced without welding or machining and without any preliminary surface treatment or artificial initiator such as a notch or a precrack. Single crack or a network of cracks can be induced into the base material, welded areas, HAZ, weld claddings, threaded areas, T-joints, etc. The location, orientation and size of produced cracks can be accurately controlled. Produced cracks can be used to simulate different types of service-induced cracks such as thermal fatigue, mechanical fatigue and stress corrosion cracks. It is shown that artificially produced thermal fatigue cracks correspond well with the real, service-induced cracks and overcome the problems of traditional qualification specimen manufacturing techniques.     

Simple and low-cost fabrication of PDMS microfluidic round channels by surface-wetting parameters optimization

Convenient for both biologists and MEMS designers, Polydimethylsiloxane (PDMS) polymer is intensively investigated for its biocompatibility, transparency, high resistance under plasma treatment, flexibility and resistance to high temperature. However, for microfluidic applications, the fabrication of PDMS circular channels is difficult to achieve except by wire moulding. In this article, we present a simple, fast and low-cost fabrication method which can be applied out of clean-room environment. It is based on the deposition of alginic acid sodium salt aqueous solution, enabling the formation of a liquid cylinder on the most hydrophilic part of a hydrophilic/hydrophobic patterned surface. We experimentally studied the interaction between liquid rivulets and surfaces presenting a contrast of wettability and/or a stepwise texture. Subsequent moulding of the half-cylinder of liquid produces round PDMS microfluidic channels. The optimal parameters for hydrophilic/hydrophobic patterns have then been applied to produce the roundest possible channels. The realisation of both straight channels 300–500 μm wide, 1 cm long and 75° tangent chord angle at best, and Y-shaped channels with the same dimensions and 55° TCA is demonstrated.     

UTILIZATION OF POPULATION BALANCES IN SIMULATION OF LIQUID-LIQUID SYSTEMS IN MIXED TANKS

A simulation model has been developed to model drop populations in a mixed tank. A multiblock mixed tank model has been used with the drop population balance equations developed in the literature. The drop breakage and coalescence functions used in the population balance model take into account the local turbulent energy dissipation values. The drop breakage and coalescence function parameters are fitted against drop size measurements from dense liquid-liquid dispersions, which were assumed fully turbulent. Since the local turbulence and flow values of a mixed tank are used in the present model, the fundamental breakage and coalescence phenomena can be taken into closer examination. Furthermore, the present model is capable of predicting inhomogeneities occurring in a mixed tank. It is also considered as an improved tool for process scale-up, compared to the simple vessel-averaged population balance approach, or use of correlations of dimensionless numbers only. The present model can use two sources of data for fitting parameters in the drop rate functions. One is the transient data of the measured drop size distribution as the impeller speed is changed. The other is the time-averaged data measured at different locations of the mixed tank. Different flow regions can be chosen from direct measurements or from the CFD simulations in a straightforward manner. CFD flow simulation results can be used when no experimentally obtained flow conditions are available. This is especially useful for nonstandard vessels, such as reactors containing cooling coils.     

Surfascan 3D — An industrial 3D surface texture characterisation instrument

2D profile analysis has often in the past been considered sufficient to control the geometrical features of a surface and to ensure that they are compatible with the required functionalities. Yet, experience shows that 3D surface texture analysis is now essential wherever a complete assessment of the surface is required to enable the selection of the most appropriate surface texture to achieve a required functionality.This paper introduces measurement strategies and features considered as essential by SOMICRONIC when designing or developing 3D surface texture measuring instruments, knowing that the pursued aim is to assess the measured surface in a way to reveal the real surface. This is achieved without losing sight of existing ISO standardized concepts concerning surface texture profile analysis.Indeed, essentially for economical reasons, we consider that 31) surface texture stylus instruments must be designed to achieve classical surface texture profiles measurements and characterisations and to fulfil conditions and characteristics listed and described in existing surface texture ISO standards.We propose to develop in the next paragraphs, the following points:

• - Design of the data acquisition unit of a 3D surface texture instrument

• - Strategy for the measurement of the surface

• - Application of these concepts - Examples.

     

‘Podracing’: experimenting with mobile TV content consumption and delivery methods

Recently, mobile TV has been launched in several countries. While mobile TV integrates television contents into mobile phones, the most personal of communication devices, it becomes interesting to know how this feature will be used throughout the day and in varying contexts of everyday life. This paper presents empirical results on the use of mobile TV with different delivery mechanisms and both quantitative and qualitative results on how end-users prefer to use mobile TV contents in different situations. The data is based on ongoing empirical research in Finland in 2006 and 2007. The mobile TV services under study included both news and entertainment contents, and were tested in 3G, DVB-H and Wi-Fi networks using different delivery paradigms: broadcast, on-demand and download. To explore the use of different delivery methods and content consumption, we have developed a mobile TV service protoype, called Podracing. The analysis shows that users appreciated up-to-date information and information-rich media forms and contents especially for mobile news delivery. There was high demand for only the latest news on mobiles. The real-time property was considered important. Most of the users looked at the headlines or followed the news several times a day – much more often than the traditional TV and news prime times would allow.     

Mixed preconditioners for harmonic balance Jacobians

Preconditioning is crucial for the convergence of GMRES iteration in the Harmonic Balance analysis of RF and microwave circuits. In this article, mixed frequency/time‐domain preconditioners for harmonic balance Jacobians are presented. The efficiency of mixed preconditioners is demonstrated with realistic simulation examples. © 2008 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2009.     

Managing the requirements flow from strategy to release in large-scale agile development: a case study at Ericsson

In a large organization, informal communication and simple backlogs are not sufficient for the management of requirements and development work. Many large organizations are struggling to successfully adopt agile methods, but there is still little scientific knowledge on requirements management in large-scale agile development organizations. We present an in-depth study of an Ericsson telecommunications node development organization which employs a large scale agile method to develop telecommunications system software. We describe how the requirements flow from strategy to release, and related benefits and problems. Data was collected by 43 interviews, which were analyzed qualitatively. The requirements management was done in three different processes, each of which had a different process model, purpose and planning horizon. The release project management process was plan-driven, feature development process was continuous and implementation management process was agile. The perceived benefits included reduced development lead time, increased flexibility, increased planning efficiency, increased developer motivation and improved communication effectiveness. The recognized problems included difficulties in balancing planning effort, overcommitment, insufficient understanding of the development team autonomy, defining the product owner role, balancing team specialization, organizing system-level work and growing technical debt. The study indicates that agile development methods can be successfully employed in organizations where the higher level planning processes are not agile. Combining agile methods with a flexible feature development process can bring many benefits, but large-scale software development seems to require specialist roles and significant coordination effort.     

The pedophilic offender with antisocial character

The purpose of the study was to clarify how pedophilic offenders with antisocial character (psychopathy) differ from "ordinary" pedophilic offenders, among whom there are many persons with immaturity and contact difficulties. For this purpose all pedophilia cases subjected to mental examination during a period of 25 years were investigated. Of these 81 cases, 38 could be regarded as antisocial characters on the basis of the current diagnostic criteria. The others were regarded as controls. The criminals with antisocial character had also been involved in other kinds of crimes and had had hyperactivity problems more often than controls. The controls were often immature, had a low intelligence, and were less able to have relations with adult people than were antisocial characters. However, according to the present results, these features might also make criminals with antisocial character more susceptible to pedophilia.