No description available.

Yes / In this paper, a performance enhancement scheme has been investigated for a class of stochastic nonlinear systems via set-point adjustment. Considering the practical industrial processes, the multi-layer systematic structure has been adopted to achieve the control design requirements subjected to random noise. The basic loop control is given by PID design while the parameters have been fixed after the design phase. Alternatively, we can consider that there exists an unadjustable loop control. Then, the additional loop is designed for performance enhancement in terms of the tracking accuracy. In particular, a novel approach has been presented to dynamically adjust the set-points using the estimated states of the systems through extended Kalman filter (EKF). Minimising the entropy criterion, the parameters of the set-point adjustment controller can be optimised which will enhance the performance of the entire closed-loop systems. Based upon the presented scheme, the stochastic stability analysis has been given to demonstrate that the closed-loop tracking errors are bounded in probability one. To indicate the effectiveness of the presented control scheme, the numerical examples have been given and the simulation results imply that the designed systems are bounded and the tracking performance can be enhanced simultaneously. In summary, a new framework for system performance enhancement has been presented even if the loop control is unadjustable which forms the main contribution of this paper.

With the advantage of modern high speed computers, there has been an increased interest in the use of first-principles based computational approaches for the aerodynamic modeling of horizontal axis wind turbine (HAWT). Since these approaches are based on the laws of conservation (mass, momentum, and energy), they can capture much of the physics in great detail. The ability to accurately predict the airloads and power output can greatly aid the designers in tailoring the aerodynamic and aeroelastic features of the configuration. First-principles based analyses are also valuable for developing active means (e.g., circulation control), and passive means (e.g., Gurney flaps) of reducing unsteady blade loads, mitigating stall, and for efficient capture of wind energy leading to more electrical power generation. In this present study, the aerodynamic performance of a wind turbine rotor equipped with circulation enhancement technology (trailing edge blowing or Gurney flaps) is investigated using a three-dimensional unsteady viscous flow analysis. The National Renewable Energy Laboratory (NREL) Phase VI horizontal axis wind turbine is chosen as the baseline configuration. Prior to its use in exploring these concepts, the flow solver is validated with the experimental data for the baseline case under yawed flow conditions. Results presented include radial distribution of normal and tangential forces, shaft torque, root flap moment, surface pressure distributions at selected radial locations, and power output. Results show that good agreement has been for a range of wind speeds and yaw angles, where the flow is attached. At high wind speeds, however, where the flow is fully separated, it was found that the fundamental assumptions behind this present methodology breaks down for the baseline turbulence model (Spalart-Allmaras model), giving less accurate results. With the implementation of advanced turbulence model, Spalart-Allmaras Detached Eddy Simulation (SA-DES), the accuracy of the results at high wind speeds are improved. Results of circulation enhancement concepts show that, at low wind speed (attached flow) conditions, a Coanda jet at the trailing edge of the rotor blade is effective at increasing circulation resulting in an increase of lift and the chordwise thrust force. This leads to an increased amount of net power generation compared to the baseline configuration for moderate blowing coefficients. The effects of jet slot height and pulsed jet are also investigated in this study. A passive Gurney flap was found to increase the bound circulation and produce increased power in a manner similar to the Coanda jet. At high wind speed where the flow is separated, both the Coanda jet and Gurney flap become ineffective. Results of leading edge blowing indicate that a leading edge blowing jet is found to be beneficial in increasing power generation at high wind speeds. The effect of Gurney flap angle is also studied. Gurney flap angle has significant influence in power generation. Higher power output is obtained at higher flap angles.

Introduction: Overload injuries are common among elite cross-country skiers. Screening tests are used in sports to prevent injuries. The tests are used extensively, however, the method has low validity. The knowledge from the current study may be used when developing new screening methods. Aim: To explore elite cross-country skiers’ own experiences, desires and needs for screening tests. Method: A qualitative method with an inductive approach was used and individual semi-structed interviews were analyzed using qualitative content analysis.. Seven elite cross-country skiers at the National Sport University in Umeå were strategically selected. Consisting of six men and one woman, the median age of the skiers was 24 years old. All had performed a Functional Movement Screen (FMS) within the last three years. Results: The result consist of one main theme, namely “Strivning for avoidence of injury and increased performance”. Within this main theme there were four categories “Insufficient challenge to improve performance”, “Physical check leading to exercise adjustments“,”Athletic posture and good technique improves skiing” and “Adapting and planning their exercise”. Each of the categories have 3-4 sub-categories respectively. The result represent the skiers’ desire to remain un-injured while increasing their performance. They request more tailor made and sport specific screening tests developed for cross-country skiing. This based on careful observations and meassurements of the specific requirements of the sport. The insights from the screening test would ideally result in suggested training schedules and individualized exercises. Conclusion: Elite cross-country skiers piont out the need for objective observations and analysis methods of the physical challenges of cross-country skiing. This in order to identify performance-enhancing measures, while at the same time avoiding overload injuries. The knowledge from this study can provide future researchers the direction in which they should focus when developing new sport-specific tests. / Introduktion: Inom längdskidåkning är överbelastning den vanligaste orsaken till skada. För att undvika skador används ofta screeningtester av idrottare men det har i litteraturen dock svag validitet. Kunskapen från aktuell studie kan användas vid utvecklande av nya anpassade screeningmetoder. Syfte: Att utforska elitlängdskidåkares egna erfarenheter, önskemål och behov av screeningtester. Metod: Metoden var kvalitativ med induktiv ansats och individuella semi-strukturerade intervjuer analyserades med kvalitativ innehållsanalys. Sju elitskidåkare vid Riksidrottsuniversitetet i Umeå valdes strategiskt ut, sex män och en kvinna deltog, medianålder var 24 år. Alla hade utfört Functional Movement Screen (FMS) inom senaste tre åren. Resultat: Resultatet består av ett tema ”Att sträva efter att undvika skador och öka sin prestation” och de fyra kategorierna ”Otillräcklig utmaning för förbättrad prestation”, ”Kroppslig check som leder till träningsjustering”, ”Atletisk hållning och god teknik förbättrar skidåkningen” och ”Anpassning och planering av sin träning” med 3-4 underkategorier var. Resultatet representerar längdskidåkarnas önskan om att hålla sig skadefria och öka sin prestation. De önskar att ett mer anpassat screeningtest bör utvecklas utifrån noggranna observationer och mätningar utefter de specifika kraven i idrotten. Det nya screeningtestet skulle kunna leda till råd om träningsupplägg och individanpassade övningar. Slutsats: Elitskidåkarna tycker det behövs objektiv observation av längdskidåkning och vilka krav som ställs på kroppen, för utvecklande av skadeförebyggande och prestationshöjande åtgärder. Kunskapen från denna studie ger riktning mot vad framtida forskning inom ämnet bör fokusera på vid utvecklandet av nytt idrottsspecifikt test.

In sports discourse, the relationship between athletics and technology is often paradoxical. On the one hand, modern sports rely on technology at every level, from training and tracking of players to the equipment and apparel used by athletes to the game strategies and playing fields themselves. Nearly all of these technologies are intended to increase athletic performance on some level. And yet, certain performance enhancement technologies can be criticized for being antithetical to the spirit of sports, which is framed as being a strictly natural and pure human endeavor. Using a rhetorical-cultural methodological approach, popular sports discourse is analyzed to investigate how arguments in contested spaces between sports and technologies get (re)negotiated and (re)articulated to fit within a sports social language that emphasizes "pure" and "natural" ideals of sport. This often results in a dichotomy where the sport/technology relationship is either black boxed, thus being subsumed in the sport social language and becoming transparent and the relationships unarticulated, or the technology is regulated out of the sport through rules and bans. The reason for this articulation is attributed in large part to the deep humanism embedded in the sport social language. How a shift to a posthuman perspective would effect sports discourse is explored. These conclusions about underlying values in sports discourse lead to the formation of a new theoretical framework called disciplinary mythologies. Building off of Foucault's disciplinary power, Scott's disciplinary rhetorics, and Barthe's mythologies, disciplinary mythologies are discrete units of persuasion that both construct and constitute claims by drawing upon layered narratives and shifting associations that lose their context when entering the realm of myth. Two specific disciplinary mythologies are discussed—the level-playing-field topos and the nostalgia enthymeme—and it is shown how sports discourse often draws upon them to shape arguments and actions.

Problem-solving ability is now the most sought-after trait in up-and-coming executives, according to a survey of 1 000 executives conducted by Caliper Associates, reported in the Wall Street Journal by Hal Lancaster (Hoenig, 2002:338). This trait would include the ability to solve human performance problems, something many people tend to steer clear of. According to Piskurich (2002:57-58) and Rothwell, Hohne and King (2000:67-71), the most common problem-solving tools that are used when solving human performance problems are brainstorming, cause-and-effect analysis, and the five why’s technique. Although techniques such as these have proven to be robust and useful, what is required to solve human performance problems is a logical and verifiable process that can establish a data point about which relevant information can be recognized and gathered, and against which the conclusion can be evaluated, to have confirmed knowledge of the root cause of the problems. Unfortunately, existing root cause analysis processes tend to focus on processes and systems, rather than on individual performance (Bowling, 2003). The main objective of this study was to develop a root cause analysis process that would uncover the root cause(s) of uncontrolled variation(s) in human performance and prevent the recurrence of events causing the variation. In addition to addressing individual human performance incidents, it is also necessary continually to manage people’s performance to detect and address any occurrences (or recurrences) of performance variations. Therefore, in addition to the main objective, the study also aimed to develop a Human Performance Management Model that incorporated the root cause analysis process as a problem-solving tool. Action research was used in this study, because of the cyclical iterative nature of this type of research, and because it is a rigorous, responsive and flexible process. The study consisted of three cycles. The end result was a structured root cause analysis process – the Human Performance Variation Analysis (HPVA) process – that enables the systematic collection of valid and reliable information, as is required to solve variation in human performance. The HPVA process is a three-part process that consists of 11 steps. The process is in turn a tool that forms part of a ten-step Human Performance Management Model. The study contributes to the body of knowledge on human performance management by presenting the following: • a systematic root cause analysis process that uncovers the root causes of human performance problems effectively and consistently and that controls these causes of problems in a way that prevents the problems from recurring; and • a Human Performance Management Model that will help to sustain the new, improved performance; prevent the same or similar performance problem(s) in other areas of the organisation; and ultimately, create an environment and culture of continuous human performance improvement. / Thesis (PhD)--University of Pretoria, 2009. / Human Resource Management / unrestricted

No description available.

Desire for low-power, high performance computing has been at core of the symbiotic union between digital circuits and CMOS scaling. While digital circuit performance improves with device scaling, analog circuits have not gained these benefits. As a result, it has become necessary to leverage increased digital circuit performance to mitigate analog circuit deficiencies in nanometer scale CMOS in order to realize world class analog solutions. In this thesis, both circuit and system enhancement techniques to improve performance of clock generators are discussed. The following techniques were developed: (1) A digital PLL that employs an adaptive and highly efficient way to cancel the effect of supply noise, (2) a supply regulated DPLL that uses low power regulator and improves supply noise rejection, (3) a digital multiplying DLL that obviates the need for high-resolution TDC while achieving sub-picosecond jitter and excellent supply noise immunity, and (4) a high resolution TDC based on a switched ring oscillator, are presented. Measured results obtained from the prototype chips are presented to illustrate the proposed design techniques. / Graduation date: 2013 / Access restricted to the OSU Community at author's request from July 16, 2012 - July 16, 2014