Spelling suggestions: "subject:"ehe 1aster"" "subject:"ehe 1master""
261 |
Security in SOA-Based Healthcare SystemsSassoon, Richard January 2009 (has links)
Healthcare organizations need to handle many kinds of information and integrate different support systems, which may be accessed from external corporations. Service Oriented Architecture (SOA) provides the means to achieve a common platform to deploy services that can be used across the organization and its boundaries, but introduces new security concerns that need to be evaluated in order to implement a secure system, while still suffering from standard threats. Web Services are the common way to implement SOA applications, having several standards related to security (such as XML Encryption, XML Signature and WS-Security). Still, other security mechanisms such as input validation and SSL/TLS need to be thought of as well. A penetration test based on recognized methodologies and guidelines, such as the NIST Technical Guide to Information Security Testing and Assessment, OWASP Testing Guide and SIFT Web Services Security Testing Framework, was performed on a case study system. A proof of concept application making use of a set of middleware (web) services, the MPOWER platform, was audited in order to expose vulnerabilities. After conducting the penetration test on the system, 10 out of 15 scenarios presented security issues. The vulnerabilities found were described, demonstrating several risks from misusing, or not implementing at all, security mechanisms. As a consequence, countermeasures and recommendations were proposed in an attempt to improve the overall security of SOA-based (healthcare) systems. The results of the assessment show us how important is to validate the security of a system before putting it into production environment. We also come to the conclusion that security testing should be an inherent part of a secure software development life cycle. Moreover, not only healthcare systems may benefit from this study, and also not only SOA-based ones.
|
262 |
Dielectric Spectroscopy of Bisphenol A Epoxy Resin Aged in Wet and Dry ConditionsVaishampayan, Deep January 2009 (has links)
This thesis presents the laboratory test data on Bisphenol A epoxy insulation.This thesis work deals with electrical, mechanical and thermal analysis of Bisphenol A epoxy resin. The main aim of this thesis work was to examine if dry and wet aging changes the glass transition temperature (Tg) of the epoxies and measure the impact on the complex permittivity under different ageing conditions namely dry and wet. During ageing the samples (epoxy discs and dog bones) were kept in water at 20°C, 45°C and 80°C both in dry and wet conditions for a period of one month. After the samples were removed from ageing they were conditioned in a vacuum oven for one week. The effect of temperature and relative humidity on unaged epoxy i.e. dry characterization was determined by keeping the samples in climate chamber with 15%RH (Relative Humidity) and temperatures 20°C, 45°C and 80°C. The wet characterization was carried out with 90%RH and temperatures 20°C, 45°C and 80°C. The surface of these samples was painted with silver paint (electrodes). Two circular discs were used for dielectric response measurement and 2 rectangular pieces for water sorption measurement. The dielectric response was measured when equilibrium/saturation condition was achieved. The dielectric response was measured in the frequency range from 0.01 Hz to 1000 Hz at 200 volts (peak). The wet characterization showed increases with aging temperature. The dielectric loss was also increasing with the temperature. It can be deduced that the water uptake by the epoxy increases with increase in humidity and temperature. The dry characterization showed and has steady growth with aging temperature. Therefore it can be deduced that characterization done in dry condition didnt significantly affect the complex permittivity as compared with wet characterization. The glass transition temperature (Tg) of the samples were found using DSC (Differential Scanning Calorimetry) with a heating rate 20°C/min. The Tg was measured in the samples in dry condition before the water absorption process, then in samples after the water absorption process with moisture in the sample, and then in sample after the desorption. The effect of water on the Tg of the epoxy polymer was studied. Tg was increasing with aging temperature, for both dry as well as wet samples. The increase in the value can be mainly attributed to post curing process of the epoxy. The mechanical strength of the epoxy was studied by applying a tensile force to the dog bone shaped samples till breakdown and the stress versus strain curve was detected. This test was also performed on the dry aged sample before water absorption, then in sample which was kept under water at 20°C ,45°C and 80°C for absorption, and in sample which has undergone absorption and desorption at 20°C ,45°C and 80°C. The difference between the stress-strain curves was documented and discussed. The ageing temperature plays a significant role in reducing the value of stress and percentage strain at max. For dry aged epoxy, stress reduces around 14% from 200C to 800C. However for wet aged epoxy samples tensile strength reduces around 25%. For dry aged samples % strain reduces around 0,3 %. and for wet aged samples it reduces around 0,5%.
|
263 |
An Investigation of Spam Filter Optimaltiy : based on Signal Detection TheorySingh, Kuldeep January 2009 (has links)
Unsolicited bulk email, commonly known as spam, represents a significant problem on the Internet. The seriousness of the situation is reflected by the fact that approximately 97% of the total e-mail traffic currently (2009) is spam. To fight this problem, various anti-spam methods have been proposed and are implemented to filter out spam before it gets delivered to recipients, but none of these methods are entirely satisfactory. This thesis analyzes the properties of spam filters from the viewpoint of Signal Detection Theory (SDT). The Bayesian approach of Signal Detection Theory provides a basis for determining the tuning of spam filters from the particular user's point of view and helps in determining the utility which the spam filter provides to the user.
|
264 |
Investigation of the Doubly Fed Permanent Magnet Synchronous MachineFeilberg, Espen January 2009 (has links)
This master thesis treats the research of a novel generator with converter design called Doubly Fed Permanent Magnet Synchronous Machine, DF-PMSM, patented by SmartMotor. The thesis includes an introduction to the machine, a state-of-the-art survey, a hydro power case, simulations and a laboratory experiment. The DF-PMSM concept adds an important feature to fixed speed PMSM systems; the reactive power can be regulated. Compared to a direct coupled PMSM the DF-PMSM concept can add voltage control (by controlling the reactive power) in addition to active power control. The concept is based on a 6-phase Permanent Magnet Synchronous Machine where the windings are grouped into two sets of 3-phase, both situated in the stator. These winding sets are named control and power winding, named after their purpose in the design. The control winding is routed through a converter with active-front-end rectifier. It will be used to control the reactive power and the active power from the control winding. The power winding will carry most of the generated power, directly coupled and in sync with the voltages of the connected grid. The state-of-the-art survey includes constant speed and variable speed generators utilized in hydro power generation today. It also includes some general info about doubly fed and multiphase machines. The grid regulations for Norway are also investigated to give a pointer to what requirements that the DF-PMSM needs to fulfill to be connected to the grid. The machine simulations are done in LTspice where machine simulation models are developed for this purpose. Simulation of machine startup and changes is load is done. The simulation models are developed as hierarchical sub blocks that can be re used in later simulation cases. The laboratory is done with two machines in back-to-back configuration with industry standard converters. The DF-PMSM is made from a 3-phase permanent magnet machine that is rewired to a 6-phase configuration. The laboratory exercise includes start up, synchronization of the power winding to the grid, machine loading and reactive power compensation by the active front end converter. The DF-PMSM is confirmed working and design considerations are given based experience gained from working with this design. All of this information is included in this report and the further work needed before this machine is constructed and sold is sketched in the conclusion.
|
265 |
Secure Context-Aware Mobile SIP User AgentMerha, Bemnet Tesfaye January 2009 (has links)
Context awareness is an important aspect of pervasive and ubiquitous computing. By utilizing contextual information gathered from the environment, applications can adapt to the users specific situation. In this thesis, user context is used to automatically discover multimedia devices and services that can be used by a mobile Session Initiation Protocol (SIP) user agent. The location of the user is captured using various sensing technologies to allow users of our SIP user agent to interact with network attached projectors, speakers, and cameras in a home and office environment. In order to determine the location of the user, we have developed and evaluated a context aggregation framework that gathers and analyzes contextual information from various sources such as passive infrared sensors, infrared beacons, light intensity, and temperature sensors. Once the location of the user is determined, the Service Location Protocol (SLP) is used to search for services. For this purpose, we have implemented a mobile SLP user agent and integrated it with an existing SIP user agent. The resulting mobile SIP user agent is able to dynamically utilize multimedia devices around it without requiring the user to do any manual configuration. This thesis also addressed the challenge of building trust relationship between the user agent and the multimedia services. We propose a mechanism which enables the user agent authenticate service advertisements before starting to redirect media streams. The measurements we have performed indicate that the proposed context aggregation framework provides more accurate location determination when additional sensors are incorporated. Furthermore, the performance measurements indicate that the delay incurred by introducing context awareness to the SIP user agent is acceptable for a small deployment such as home and office environment. In order to realize large scale deployments, future investigations are recommended to further improve the performance of the framework. Keywords: SIP, context-awareness, service discovery, trust establishment
|
266 |
Losses and Inductive Parameters in Subsea Power CablesStølan, Ronny January 2009 (has links)
Four samples of galvanized steel armour for sub sea power cables are tested with an electric steel tester. The samples exhibit different remanence magnetization and permeability. The effects of permeability on loss in sub sea cables is found to be insignificant. Slight increase of conductor inductance due to increase in permeability of armour wires is observed. Mutual cancellation of inductance between circuits that are twisted opposite to each other, or with respect to one circuit, is confirmed with laboratory tests and measurements on full scale sub sea power cables. The parameters of one cable is calculated using IECs analytical approach and found to be inaccurate for conductor resistance. The Calculations places 22% of total cable loss in the armour. Measurements on two sub sea cables and analysis using finite element method contradict the calculated armour loss. Parameters for two sub sea power cables are calculated based on measurements performed on the actual cables. The calculated values are compared with values computed using finite element analysis. Derived physics from laboratory experiments and measurements on the cables is applied in finite element analysis and found to be accurate compared with calculated values from measurements and computed values using Flux 2.5D.
|
267 |
Optimal Operation of a Distributed System with High Share of Power Electronic LoadsJelani, Nadeem January 2010 (has links)
The tendency of connecting the loads to the three phase AC system through power electronic interfaces is increasing with time. These interfaces greatly affect the performance of the power system when properly operated. The injection of reactive power by these interfaces provides the possibility to support the voltage, increase the stability margins and decrease the power losses in the power system. The power electronic loads when tightly regulated consume constant power from the grid and therefore exhibit negative resistance instability behavior. A fast control system with high stability margins is desirable for the converters. This thesis deals with the control of power electronic loads and the stability of the AC distribution system. One of the objectives of the work is to understand the basic control structure of the converters and establish the tuning rules for the PI regulators of the converter controllers. A basic power electronic converter is considered and vector control method is implemented. A mathematical model of the control system for the converter is described and transfer functions are analyzed in frequency domain for different values of grid voltage. The simulations in time domain are performed in PSCAD/EMTDC software. The simulation results validate the results from the frequency domain analysis. The simulation analysis also shows that the stability of the converter in generation mode is higher as compared to when it acts as a load. A larger model of AC distribution system with different shares of loads is investigated for the transient stability. It has been observed through simulations that the injection of reactive power during contingency greatly improve the stability limits of the system. However this increase in the stability margins comes at the cost of an increase in converter current rating. A comparison between the distributed injection by parallel converter and centralized injection through STATCOM confirms the advantages of the distributed injection.
|
268 |
Fremstilling og karakterisering av potensielle virkestoffer mot sopp og protozoer / Synthesis and characterisation of substrates with potential antifungal activityElgen, Marianne January 2008 (has links)
Det er syntetisert fire potensielle virkestoffer mot sopp. To av disse er fluorerte forbindelser.
|
269 |
Atmosfærisk kvikksølvspesiering i Ny-Ålesund : Hvor pålitelig er den nåværende metoden? / Atmospheric mercury speciation in Ny-Ålesund : How reliable is the present Method?Valved, Hilde January 2008 (has links)
Detekterte maksimumsverdier av RGM og PHg var henholdsvis 38 og 47 pg/m3. Dette var lave konsentrasjoner i forhold til tidligere rapporterte data fra polare områder. Hovedårsaken til de lave konsentrasjonene av RGM og PHg antas å ikke skyldes instrumentelle svakheter med spesieringsenheten, men andre parametere som vindstyrke og isfri fjord. Det ble vurdert at ekskludering av en hel syklus etter oppstart av instrumentet bør være tilstrekkelig etter skifte av denuder og RPF. Det anbefales å skifte denuder etter to ukers bruk for å styrke påliteligheten av deteksjonene. Det trengs datasett for flere år slik at det kan bli utført vurderinger av instrumentet på et større grunnlag. Utvikling av kalibreringsmetode for spesieringsenheten ville økt påliteligheten.
|
270 |
Parametrisering av kraftfelt for ReaxFF med H, C, Si og Ge / Force Field Paramatres for ReaxFF with H, C, Si og GeSøby, Magne Inderberg January 2008 (has links)
Sammenligning av DFT og ReaxFF beregninger for å kunne validere gjorte beregninger som input til paramtreisering av kraftfelt i ReaXFF for C, Si og Ge.
|
Page generated in 0.0725 seconds