Modeling a DFIG-Based Wind Turbine Focusing on DFIG and Aerodynamic Models

The present study is an attempt to develop and implement mathematical models of variable speed wind turbines using Doubly-Fed Induction Generator (DFIG) including aerodynamic model and DFIG through newly developed Matlab/Simulink .The so called models are developed in order to investigate dynamic behavior of power networks as well as to design and evaluate the behavior of each wind turbine under normal and disturbance conditions. In the study, aerodynamic (rotor) model is based on torque coefficient Cq look up table which is according to BEM method. DFIG model is developed in two sub models including generator and power converters. In generator model, electrical dynamic equations of wound rotor induction generator are provided in two different models (fifth-order model and third-order model) by choosing synchronous rotating reference frame.  As the simulation result revealed, the stator power is limited at rated value at high wind speed but wind turbine is operated at optimum power efficiency at lower wind speed to gain optimal power output, indicating a good agreement with the real behavior of the system

Modeling a DFIG-Based Wind Turbine Focusing on DFIG and Aerodynamic Models

The present study is an attempt to develop and implement mathematical models of variable speed wind turbines using Doubly-Fed Induction Generator (DFIG) including aerodynamic model and DFIG through newly developed Matlab/Simulink .The so called models are developed in order to investigate dynamic behavior of power networks as well as to design and evaluate the behavior of each wind turbine under normal and disturbance conditions. In the study, aerodynamic (rotor) model is based on torque coefficient Cq look up table which is according to BEM method. DFIG model is developed in two sub models including generator and power converters. In generator model, electrical dynamic equations of wound rotor induction generator are provided in two different models (fifth-order model and third-order model) by choosing synchronous rotating reference frame.  As the simulation result revealed, the stator power is limited at rated value at high wind speed but wind turbine is operated at optimum power efficiency at lower wind speed to gain optimal power output, indicating a good agreement with the real behavior of the system

Does the use of volunteers and playbooks in pediatric primary care clinic waiting rooms influence patient experience?

The purpose of this secondary data analysis was (1) to understand the use of a playbook as a positive distraction technique and (2) to explore the use of volunteers in the waiting room of an outpatient pediatric clinic setting. Specifically, the study examined the impact on perceived wait time, overall quality of care, and patient experience in a convenience sample of patients. Data obtained for a pilot program for improving patient experience were aggregated for exploratory analysis. Although significant differences in perceived wait time or patient experience were not found, the cohort exposed to both the playbook and volunteer intervention reported a significantly higher perceived quality of care. This analysis suggests the use of a playbook as a distraction technique along with the support of a waiting room volunteer may contribute to an increase in perceived quality of care in outpatient pediatric clinics

The use of fuzzy real option valuation method to rank Giga Investment Projects on Iran's natural gas reserves

Giga investments are exposed to numerous systematic and unsystematic (or specific) risks that significantly influence their feasibility and value. In addition to the conventional issues and complexities in evaluating investment projects, factors such as long construction time, high amount of capital required and irreversibility of investment, increase uncertainty of cash flows in these types of projects. As a consequence, decision makers are usually not satisfied with the results of the most popular valuation methodology – discounted cash flow analysis – in valuation of Giga investments. The most promising methodology of valuing flexibility in such investment projects is the real options valuation which quantifies the value of embedded flexibilities through option pricing techniques.In this paper, fuzzy real options valuation techniques are used to rank Giga project proposals faced in Iran's gas industry. To this end, different scenarios of project payoff and future uncertainties are quantified, using fuzzy numbers based on findings from earlier real option valuation methods.Keywords: Giga Investment, Fuzzy Pay Off, Real options valuation, Natural Gas, Ira

Nanoparticles for Simultaneous Near-Infrared and Magnetic Biomolecular Imaging

Nanoparticle probes can unlock the potential for multimodal biomedical imaging (in vivo and in vitro) with enhanced spatial resolution and penetration depth and targeted visualization of complex organisms. This thesis demonstrates synthesis and characterization of magnetic upconversion Gd2O3 nanoparticles that can serve as bimodal probes for optical imaging in near infrared (NIR) biomedical window, where minimal tissue auto uorescence is expected, as well as magnetic resonance imaging. More speci cally, Gd2O3:Yb3+,Tm3+ and Gd2O3:Yb3+,Er3+ nanoparticles are synthesized using urea-based homogeneous precipitation method (UHP) as well as Y2O3:Yb3+/Er3+ micro and nanoparticles using conventional combustion and thermal synthesis methods. The morphological and compositional properties of nanoparticles as well as their photonic and magnetic responses are systematically analyzed to understand the role of synthesis methods and initial synthesis materials including the concentrations of Tm and Er dopants and urea solution on the properties of the synthesized particles. The upconversion nanoparticles synthesized using UHP method are spherical and monodisperse with a size distribution in the range of 60 to 150 nm and controllable dopant concentration through manipulation of initial synthesis chemistry. When excited with 975 nm NIR radiation, Gd2O3:Yb3+,Tm3+ nanoparticles show a pure near infrared emission centered at around 810 nm (i.e., NIR-to-NIR upconversion) in NIR biological window with potential for high depth optical imaging while Er3+ doped particles emit light mainly in visible red centred at around 661 nm. The photoluminescence and transient optical decay measurements demonstrate distinctly di erent energy transfer mechanisms for Er and Tm doped samples. While these measurements signify a dominant role for Yb3+ dopants in strong upconversion emission of Tm3+ samples with a double exponential decay behaviour, they show less important role of Yb3+ in Er3+ samples with a single exponential decay. Systematic magnetic characterization demonstrate strong paramagnetic behaviour for the optically active upconversion nanoparticles, demonstrating their potential for bimodal optical and magnetic resonant imaging

Beacon-based opportunistic scheduling in wireless body area network

Wireless Body Area Networks (WBANs) are one of the key technologies that support the development of digital health care, which has attracted increasing attention in recent years. Compared with general Wireless Sensor Networks (WSNs), WBANs have more stringent requirements on reliability and energy efficiency. Though WBANs are applied within limited transmission range, the on-body channel condition can be very challenging because of blocking or absorbing of signal. In this paper, we are looking into the design of Medium Access Control (MAC) protocols and propose an opportunistic scheduling scheme by applying heuristic scheduling and dynamic superframe length adjustment to improve the system performance. The simulations have been supplemented to show the advantages of the proposed solutions in outage rate performance, compared with existing solutions

Hardware Accelerated Text Display

Web browsers and e-book are some of the most dominant applications on mobile devices today. They spend a significant amount of time handling text in these documents. Based on the experimental results from different commercial web browsers, the majority of the time spent to display text is dedicated to layout design and painting the bitmaps of the character glyphs on the screen; the time needed to rasterize the bitmaps of these glyphs is negligible. Many efforts have been made in software to improve the performance of text layout and display and very few are trying to come up with parallel processing schemes for System-On-Chip (SoC) designs to better handle this graphic processing. This work introduces a new novel hardware-software hybrid algorithm which performs the layout design of text and displays it faster by using a small piece of hardware which can easily be added to the SoCs of today\u27s mobile devices. This work also introduces a novel method for applying kerning to layout design process. The performance of the algorithms are compared to WebKit, the most widely used web rendering framework, and has resulted in a 29X and 192X performance increases in layout design when kerning is both used and not used respectively

A philosophical context for methods to estimate origin-destination trip matrices using link counts.

This paper creates a philosophical structure for classifying methods which estimate origin-destination matrices using link counts. It is claimed that the motivation for doing so is to help real-life transport planners use matrix estimation methods effectively, especially in terms of trading-off observational data with prior subjective input (typically referred to as 'professional judgement'). The paper lists a number of applications that require such methods, differentiating between relatively simple and highly complex applications. It is argued that a sound philosophical perspective is particularly important for estimating trip matrices in the latter type of application. As a result of this argument, a classification structure is built up through using concepts of realism, subjectivity, empiricism and rationalism. Emphasis is put on the fact that, in typical transport planning applications, none of these concepts is useful in its extreme form. The structure is then used to make a review of methods for estimating trip matrices using link counts, covering material published over the past 30 years. The paper concludes by making recommendations, both philosophical and methodological, concerning both practical applications and further research

Die Rolle religiöser Intellektueller bei den politischen Veränderungen der Jahre 1960 bis 1997 im Iran

Der Widerspruch, der nach okzidentalem Verständnis im Begriff des religiösen Intellektuellen liegt, ist in den Werken der hier vorgestellten iranischen Theoretiker mit den Händen zu greifen. Ihr Versuch, aus der iranisch-islamischen Tradition heraus eine Antwort auf die kulturelle Moderne zu finden, mündet in religiösen Revitalisierungsversuchen. Keinem der namhaften Laien-Intellektuellen, nicht Jalal Al-e Ahmad und Mehdi Bazargan, nicht Ali Schariati, der Leitfigur der sozialrevolutionären Bewegung vor der islamischen Revolution, noch dem „modernen Theologen“ Abdolkarim Sorousch, dem eine Art religiöser Demokratie vorschwebt, gelingt der Schritt aus dem Bannkreis des Religiösen. Indem sie auf die Neuinterpretation der in ihrer Autorität unangetasteten religiösen Texte setzen, können sie keine Alternativen für den Iran entwickeln, um das Land langfristig von seinen postkolonialen Strukturen, der Unterentwicklung sowie der Gewalt und Bevormundung durch den politischen Islam zu befreien