High Lundquist Number Simulations of Parker\u27s Model of Coronal Heating: Scaling and Current Sheet Statistics Using Heterogeneous Computing Architectures

Parker\u27s model [Parker, Astrophys. J., 174, 499 (1972)] is one of the most discussed mechanisms for coronal heating and has generated much debate. We have recently obtained new scaling results for a 2D version of this problem suggesting that the heating rate becomes independent of resistivity in a statistical steady state [Ng and Bhattacharjee, Astrophys. J., 675, 899 (2008)]. Our numerical work has now been extended to 3D using high resolution MHD numerical simulations. Random photospheric footpoint motion is applied for a time much longer than the correlation time of the motion to obtain converged average coronal heating rates. Simulations are done for different values of the Lundquist number to determine scaling. In the high-Lundquist number limit (S \u3e 1000), the coronal heating rate obtained is consistent with a trend that is independent of the Lundquist number, as predicted by previous analysis and 2D simulations. We will present scaling analysis showing that when the dissipation time is comparable or larger than the correlation time of the random footpoint motion, the heating rate tends to become independent of Lundquist number, and that the magnetic energy production is also reduced significantly. We also present a comprehensive reprogramming of our simulation code to run on NVidia graphics processing units using the Compute Unified Device Architecture (CUDA) and report code performance on several large scale heterogenous machines

Privacy, security, and trust issues in smart environments

Recent advances in networking, handheld computing and sensor technologies have driven forward research towards the realisation of Mark Weiser's dream of calm and ubiquitous computing (variously called pervasive computing, ambient computing, active spaces, the disappearing computer or context-aware computing). In turn, this has led to the emergence of smart environments as one significant facet of research in this domain. A smart environment, or space, is a region of the real world that is extensively equipped with sensors, actuators and computing components [1]. In effect the smart space becomes a part of a larger information system: with all actions within the space potentially affecting the underlying computer applications, which may themselves affect the space through the actuators. Such smart environments have tremendous potential within many application areas to improve the utility of a space. Consider the potential offered by a smart environment that prolongs the time an elderly or infirm person can live an independent life or the potential offered by a smart environment that supports vicarious learning

Energy Harvesting in Wireless Applications

The objective of this thesis has been to study how extensive current research has gone within energy harvesting and to investigate a solution for making the OLP425 (a sensor module developed by ConnectBlue AB) independent of a conventional battery as energy source, whilst staying wireless. This has been done by investigating the amounts of energy that is available from our surroundings (e.g. solar´radiation, thermal gradients, and radio waves) and how suitable the methods are for supplying the OLP425. A solution based on a photovoltaic cell was chosen and an electrical circuit was designed around it, powering the OLP425 and recharging a Li-ion rechargeable battery. It was successful in powering the OLP425 but limited by the sensor module’s duty cycle. Whilst being a successful solution there is still more to investigate in the field that includes other energy harvesting methods where some require a larger business model to implement

Beyond capital ideals : restoring banking stability

The authors examine why emerging markets, in particular, are susceptible to and affected by financial difficulties. They show that these difficulties have a richer, more complex structure than they are sometimes believed to have - with marked information asymmetries and substantial volatility. The sources of heightened regulatory failure in emerging markets in recent years include the volatility of real and nominal shocks, the difficulty of operating in uncharted territory after financial liberalization and other changes in regime, and the political pressures that can inhibit the enforcement of prudential regulation. The authors discuss what stronger regulation can and cannot accomplish, as well as options to improve the incentive structure for bankers, regulators, and other market participants. They probe the shortcomings of a regulatory paradigm that relies mainly on supervised capital adequacy and discuss the possible intermittent application of supplementary"blunt instruments"as an interim solution while longer-term reforms are being put in place. Certain well-worn messages remain valid, but are respected more in theory than in practice. There would be fewer problems, the authors say, if there were: 1) more diversification; 2) more balanced financial structures (for example, as between debt and equity); 3) more foreign banks in emerging markets'financial systems; and 4) better enforcement of both contracts and regulations. Participants in the financial sector will constantly try to get around rules that limit their profitability, so regulation must be seen as an evolutionary struggle. Prevention of financial failure is not costless, and a heavy repressive hand is not warranted. But a richer regulatory palette can be used to protect financial systems more successfully against crisis while preserving the systems'growth-enhancing effectiveness.Environmental Economics&Policies,Payment Systems&Infrastructure,Financial Intermediation,Banks&Banking Reform,Financial Crisis Management&Restructuring,Economic Theory&Research,Banks&Banking Reform,Financial Intermediation,Financial Crisis Management&Restructuring,Environmental Economics&Policies

ENABLING MOBILE DEVICES TO HOST CONSUMERS AND PROVIDERS OF RESTFUL WEB SERVICES

The strong growth in the use of mobile devices such as smartphones and tablets in Enterprise Information Systems has led to growing research in the area of mobile Web services. Web services are applications that are developed based on network standards such as Services Oriented Architecture and Representational State Transfer (REST). The mobile research community mostly focused on facilitating the mobile devices as client consumers especially in heterogeneous Web services. However, with the advancement in mobile device capabilities in terms of processing power and storage, this thesis seeks to utilize these devices as hosts of REST Web services. In order to host services on mobile devices, some key challenges have to be addressed. Since data and services accessibility is facilitated by the mobile devices which communicate via unstable wireless networks, the challenges of network latency and synchronization of data (i.e. the Web resources) among the mobile participants must be addressed. To address these challenges, this thesis proposes a cloud-based middleware that enables reliable communication between the mobile hosts in unreliable Wi-Fi networks. The middleware employs techniques such as message routing and Web resources state changes detection in order to push data to the mobile participants in real time. Additionally, to ensure high availability of data, the proposed middleware has a cache component which stores the replicas of the mobile hosts’ Web resources. As a result, in case a mobile host is disconnected, the Web resources of the host can be accessed on the middleware. The key contributions of this thesis are the identification of mobile devices as hosts of RESTful Web services and the implementation of middleware frameworks that support mobile communication in unreliable networks

Beyond information: factors in participation in networks of practice, a case study of web management in UK Higher Education

Purpose To explore the pattern and significance of cross-organizational ties in an emergent professional field, web production in UK Higher Education. Methodology/Approach The research is based on in-depth interviews with 21 practitioners and analysis of activity in cross-organizational spaces, such as an online community and a series of annual practitioner conferences on the web in HE (1997-). Findings The cross organizational spaces have support and symbolic roles as well as informational ones. They have overlapping but different membership and agendas. Key factors that govern individual participation and so the shape of cross-organizational spaces are differential involvement in technical innovation, degree of organizational embedding or marginality, differences in organizational position and role, orientation towards centralisation or decentralisation and orientation towards marketing or IT. There is some sense of occupational community among web managers, but within that also diversity and a significant fracture line between marketing and IT perspectives on the role. This may explain the lack of formal professionalization. As a more natural boundary practice between organizations than marketing, IT has more public visibility, possibly influencing the course jurisdictional struggles over who should control the web. Research limitations/implications As a heavily contextualised study, its detail reflects particular features of HE in the UK at one period as well as specific aspects of the web as a technology. Nevertheless, underlying factors which seem to influence participation and non-participation in cross-organizational networks may be generalisable to many occupations, particularly where knowledge is rapidly changing. Practical implications Some suggestions about how cross-organizational knowledge sharing is most effectively supported can be derived from the analysis. IT is a natural focus for cooperation, but there is a risk of this masking the importance of other professional practices. Efforts at formal professionalization may be devisive because people have different professional ambitions and there are individual and organizational benefits in not professionalizing the role formally. New practitioners may be the most active in using extra-organizational networks to assist them to become more embedded locally. Old hands, though they have high prestige and centrality, may increasingly take their own path away from the community. Aspects of local roles such as involvement in innovation or decentralist strategies favour participation in cross-organizational networks. Originality/value of paper Most studies of knowledge sharing have focussed on the factors which influence it within an organization, yet cross-organizational sharing is also of importance, even for established professions as the boundaries of organizations become more open. For new occupations cross-organizational ties may be a critical resource, and not only for sharing information or support, but for making sense of what the job is about at the deepest level. The research is also original in analysing a relatively little researched occupational group, those producing web sites for a living. It will be relevant to those interested in online and people centred information seeking, in professionalization and occupational identity

A framework and methods for on-board network level fault diagnostics in automobiles

A significant number of electronic control units (ECUs) are nowadays networked in automotive vehicles to help achieve advanced vehicle control and eliminate bulky electrical wiring. This, however, inevitably leads to increased complexity in vehicle fault diagnostics. Traditional off-board fault diagnostics and repair at service centres, by using only diagnostic trouble codes logged by conventional onboard diagnostics, can become unwieldy especially when dealing with intermittent faults in complex networked electronic systems. This can result in inaccurate and time consuming diagnostics due to lack of real-time fault information of the interaction among ECUs in the network-wide perspective. This thesis proposes a new framework for on-board knowledge-based diagnostics focusing on network level faults, and presents an implementation of a real-time in-vehicle network diagnostic system, using case-based reasoning. A newly developed fault detection technique and the results from several practical experiments with the diagnostic system using a network simulation tool, a hardware- in-the- loop simulator, a disturbance simulator, simulated ECUs and real ECUs networked on a test rig are also presented. The results show that the new vehicle diagnostics scheme, based on the proposed new framework, can provide more real-time network level diagnostic data, and more detailed and self-explanatory diagnostic outcomes. This new system can provide increased diagnostic capability when compared with conventional diagnostic methods in terms of detecting message communication faults. In particular, the underlying incipient network problems that are ignored by the conventional on-board diagnostics are picked up for thorough fault diagnostics and prognostics which can be carried out by a whole-vehicle fault management system, contributing to the further development of intelligent and fault-tolerant vehicles

Cloud Computing

In the recent years, Cloud Computing has become very popular and an interesting subject in the field of science and technology. The research efforts in the Cloud Computing have led to a number of applications used for the convenience in daily life. Cloud Computing is not only providing solutions at the enterprise level but it is also suitable in organizing a centralized database which is accessible from every corner of the world. It is said that, 10 to 15 years later when all the enterprises have adopted the Cloud Computing, there will be no more perception for the data center in the company. The aim of this Master’s thesis “Cloud Computing: Server Configuration and Software Implementation for the Data Collection with Wireless Sensor Nodes” was to integrate the Wireless Sensor Network with Cloud Computing in a such a way that the data received from the Sensor node can be access able from anywhere in the world. To accomplish this task, a Wireless Sensor Network was deployed to measure the environmental conditions such as Temperature, Light and the Sensor’s battery information and the measured values are sent to a web server from where the data can be accessed. The project also includes the software implementation to collect the sensor’s measurements and a Graphical User Interface (GUI) application which reads the values from the sensor network and stores it to the database.fi=Opinnäytetyö kokotekstinä PDF-muodossa.|en=Thesis fulltext in PDF format.|sv=Lärdomsprov tillgängligt som fulltext i PDF-format