High-power widely tunable Raman fiber laser

Tunable Raman fiber lasers have attracted great interest owing to their high efficiency and reliability important for applications, such as optical fiber communications and sensing, spectroscopy, and instrument testing. Their tuning range is defined by the Raman gain bandwidth amounting to about 40 nm in telecom spectral range (∼1550 nm) for conventional silica single mode fibers (SMF). To increase the range, highly nonlinear fibers which broaden pump spectrum may be incorporated in the cavity of Raman fiber lasers, see e.g. [1]. Another approach is to involve Rayleigh scattering forming random distributed feedback in a relatively long fiber resulting in prominent flattening of the tuning curve [2]. In this paper we report on combination of these two techniques in tunable Raman fiber lasers thus providing great improvement of their output characteristics. © 2013 IEEE.

A coordinated control scheme for power demand changes in a PMSG based multi-terminal DC wind farm

Although maximum power point tracking (MPPT) is crucial in the design of a wind power generation system, the necessary control strategies should also be considered for conditions that require a power reduction, called de-loading in this paper. A coordinated control scheme for a proposed current source converter (CSC) based DC wind energy conversion system is presented in this paper. This scheme combines coordinated control of the pitch angle, a DC load dumping chopper and the DC/DC converter, to quickly achieve wind farm de-loading. MATLAB/Simulink simulations and experiments are used to validate the purpose and effectiveness of the control scheme, both at the same power level. © 2013 IEEE.

Wireless power and data transfer via a common inductive link using frequency division multiplexing

For wireless power transfer (WPT) systems, communication between the primary side and the pickup side is a challenge because of the large air gap and magnetic interferences. A novel method, which integrates bidirectional data communication into a high-power WPT system, is proposed in this paper. The power and data transfer share the same inductive link between coreless coils. Power/data frequency division multiplexing technique is applied, and the power and data are transmitted by employing different frequency carriers and controlled independently. The circuit model of the multiband system is provided to analyze the transmission gain of the communication channel, as well as the power delivery performance. The crosstalk interference between two carriers is discussed. In addition, the signal-to-noise ratios of the channels are also estimated, which gives a guideline for the design of mod/demod circuits. Finally, a 500-W WPT prototype has been built to demonstrate the effectiveness of the proposed WPT system.

Design of a modular, high step-up ratio DC–DC converter for HVDC applications integrating offshore wind power

High-power and high-voltage gain dc-dc converters are key to high-voltage direct current (HVDC) power transmission for offshore wind power. This paper presents an isolated ultra-high step-up dc-dc converter in matrix transformer configuration. A flyback-forward converter is adopted as the power cell and the secondary side matrix connection is introduced to increase the power level and to improve fault tolerance. Because of the modular structure of the converter, the stress on the switching devices is decreased and so is the transformer size. The proposed topology can be operated in column interleaved modes, row interleaved modes, and hybrid working modes in order to deal with the varying energy from the wind farm. Furthermore, fault-tolerant operation is also realized in several fault scenarios. A 400-W dc-dc converter with four cells is developed and experimentally tested to validate the proposed technique, which can be applied to high-power high-voltage dc power transmission.

Hatalmi távolság és intézményi kollektivizmus – a versenyképesség előrejelzése szövegelemzéssel (Power distance and institutional collectivism – Forecast of competitiveness by text analysis)

A tárgyalófelek elé kitett mobiltelefon alkalmazása előrejelzi a beszélgetőpartnerek versenyképességét a versenyképesség-mutatók alapján, javaslatokat adva a tárgyalás további menetére. Ez a vízió nyilván még futurisztikus, ám a csúcsvezetői nyilatkozatok rejtett szövegtartalma alapján következtetéseket levonni a képviselt szervezetek versenyképességi orientációira – ez már ma lehetőség. A GLOBE-projekt kultúrakutatási módszertanával, valamint szövegelemzési módszerekkel sikerült kimutatni a versenyképességet előrejelző hatalmi távolság és az intézményi kollektivizmus szövegbeli jeleit. Mindez eszközt jelenthet egyebek mellett a szervezetfejlesztéssel, hírszerzéssel, HR-gazdálkodással foglalkozó szakembereknek is. _______ The use of the mobile telephones laid in front of the negotiators during their conversations forecasts their indicators of competitiveness and gives suggestions for the further course of negotiation. This is obviously a futuristic vision, but drawing conclusions from the hidden content of top management narratives concerning the competitive cultural orientations of the represented organizations is a possibility that is already available. Using the culture research methodology of the GLOBE project as well as text analysis methods, it was possible to reveal narrative patterns both of the power distance, forecasting competitiveness, and of institutional collectivism. These findings may be useful tools for professionals, among others of organizational development, intelligence service and HR management.

Power and thermal aware scheduling for real-time computing systems

Over the past few decades, we have been enjoying tremendous benefits thanks to the revolutionary advancement of computing systems, driven mainly by the remarkable semiconductor technology scaling and the increasingly complicated processor architecture. However, the exponentially increased transistor density has directly led to exponentially increased power consumption and dramatically elevated system temperature, which not only adversely impacts the system's cost, performance and reliability, but also increases the leakage and thus the overall power consumption. Today, the power and thermal issues have posed enormous challenges and threaten to slow down the continuous evolvement of computer technology. Effective power/thermal-aware design techniques are urgently demanded, at all design abstraction levels, from the circuit-level, the logic-level, to the architectural-level and the system-level. ^ In this dissertation, we present our research efforts to employ real-time scheduling techniques to solve the resource-constrained power/thermal-aware, design-optimization problems. In our research, we developed a set of simple yet accurate system-level models to capture the processor's thermal dynamic as well as the interdependency of leakage power consumption, temperature, and supply voltage. Based on these models, we investigated the fundamental principles in power/thermal-aware scheduling, and developed real-time scheduling techniques targeting at a variety of design objectives, including peak temperature minimization, overall energy reduction, and performance maximization. ^ The novelty of this work is that we integrate the cutting-edge research on power and thermal at the circuit and architectural-level into a set of accurate yet simplified system-level models, and are able to conduct system-level analysis and design based on these models. The theoretical study in this work serves as a solid foundation for the guidance of the power/thermal-aware scheduling algorithms development in practical computing systems.^

Leakage temperature dependency aware real-time scheduling for power and thermal optimization

Catering to society's demand for high performance computing, billions of transistors are now integrated on IC chips to deliver unprecedented performances. With increasing transistor density, the power consumption/density is growing exponentially. The increasing power consumption directly translates to the high chip temperature, which not only raises the packaging/cooling costs, but also degrades the performance/reliability and life span of the computing systems. Moreover, high chip temperature also greatly increases the leakage power consumption, which is becoming more and more significant with the continuous scaling of the transistor size. As the semiconductor industry continues to evolve, power and thermal challenges have become the most critical challenges in the design of new generations of computing systems. ^ In this dissertation, we addressed the power/thermal issues from the system-level perspective. Specifically, we sought to employ real-time scheduling methods to optimize the power/thermal efficiency of the real-time computing systems, with leakage/ temperature dependency taken into consideration. In our research, we first explored the fundamental principles on how to employ dynamic voltage scaling (DVS) techniques to reduce the peak operating temperature when running a real-time application on a single core platform. We further proposed a novel real-time scheduling method, “M-Oscillations” to reduce the peak temperature when scheduling a hard real-time periodic task set. We also developed three checking methods to guarantee the feasibility of a periodic real-time schedule under peak temperature constraint. We further extended our research from single core platform to multi-core platform. We investigated the energy estimation problem on the multi-core platforms and developed a light weight and accurate method to calculate the energy consumption for a given voltage schedule on a multi-core platform. Finally, we concluded the dissertation with elaborated discussions of future extensions of our research. ^

Student Independent Projects Environmental Studies: Energizing the Future: Meeting Future Power Needs of Grenfell College

In this paper I pose the Questions: Is it feasible to install a large wind turbine(S) at Grenfell College as a pilot project, and what will the benefits of the installation be to Grenfell if the project goes ahead? My answers are based on a literature review, data analysis from previous experiments, and a SWOT analysis. I will conclude by recommending a course of action for Grenfell that will move it toward using more renewable energy, and becoming a local resource for alternative energy solutions.

Enhancing Cloud Security and Privacy: The Power and the Weakness of the Audit Trail

Winner of best paper award.

Race, Power and Economic Extraction in Benton Harbor, MI

My dissertation investigates twin financial interventions—urban development and emergency management—in a single small town. Once a thriving city drawing blacks as blue-collar workers during the Great Migration, Benton Harbor, Michigan has suffered from waves of out-migration, debt, and alleged poor management. Benton Harbor’s emphasis on high-end economic development to attract white-collar workers and tourism, amidst the poverty, unemployment, and disenfranchisement of black residents, highlights an extreme case of American urban inequality. At the same time, many bystanders and representative observers argue that this urban redevelopment scheme and the city’s takeover by the state represent Benton Harbor residents’ only hope for a better life. I interviewed 44 key players and observers in local politics and development, attended 20 public meetings, conducted three months of observations, and collected extensive archival data. Examining Benton Harbor’s time under emergency management and its luxury golf course development as two exemplars of a larger relationship, I find that the top-down processes allegedly intended to alleviate Benton Harbor’s inequality actually reproduce and deepen the city’s problems. I propose that the beneficiaries of both plans constitute a white urban regime active in Benton Harbor. I show how the white urban regime serves its interests by operating an extraction machine in the city, which serves to reproduce local poverty and wealth by directing resources toward the white urban regime and away from the city.

The Resurgence of Gaelic power in Ireland and Scotland and its wider impact, c.1350-1513

Over the course of the later Middle Ages nearly half the landmass of the British Isles fell under the control of a handful of Gaelic dynasties in Ireland and Scotland. The impact of this profound geopolitical recasting of much of the Atlantic Archipelago has however, received very little scholarly attention. Instead, historians have tended to view events within this expanding Gaelic world, or Gàidhealtachd, as peripheral to the political development of the British Isles and the course of Anglo-Scottish relations during the later Medieval period. Drawing upon a comprehensive range of sources from Ireland, Scotland, and England, as well as significant archival research, this thesis challenges the concept of the so-called 'Celtic fringe' and illustrates how developments within the Gàidhealtachd impacted upon the course of 'British' politics during the period c.1350-1513. The thesis centres on an examination of how two competing Gaelic alliance systems came to dominate much of the Gàidhealtachd from the late fourteenth century through to the early 1500s. The first of these alliance blocs was controlled chiefly by the O'Neills of Tyrone, the O'Briens of Thomond, and MacDonalds of the Hebrides; in the other network the O'Donnells of Tyrconnell, the Burkes of Mayo and the Campbells of Argyll held sway. By tracing the interconnectivity of the lordships in each respective network, the thesis investigates how these alliance systems became a durable force not only within the Gàidhealtachd but also on the broader 'British' stage. The thesis is structured in a manner that makes the intricate, lineage-based world of the Gàidhealtachd more accessible. Each chapter shifts between the various regions of the Gaelic world and examines how developments in one region impacted upon corresponding territory. Ultimately, this provides historians with a new model for exploring what has previously been a majorly neglected area of Irish and British history.

Joint Power Amplifiers and I/Q Modulator Impairments Modelling and Compensation for LTE Transmitters Using Artificial Neural Networks

This work introduces joint power amplifier (PA) and I/Q modulator modelling and compensation for LongTerm Evolution (LTE) transmitters using artificial neural networks (ANNs). The proposed solution util-izes a powerful nonlinear autoregressive with exogenous inputs (NARX) ANN architecture, which yieldsnoticeable results for high peak to average power ratio (PAPR) LTE signals. Given the ANNs learning capa-bilities, this one-step solution, which includes the mitigation of both PA nonlinearity and I/Q modulatorimpairments, is both accurate and adaptable