Rothbaum, Weisz, and Snyder's (1982) dual-process model of control proposed that in addition to attempts to change one's environment (primary control, PC) or psychologically adjust to one's circumstances (secondary control, SC), the higher-order capacity to alternate between these processes in congruence with performance (optimization) served to foster development in achievement settings. The present five-phase longitudinal study conducted over an academic year explored how college students (n = 568) shift between PC and SC over time in response to actual performance feedback, as well as the differential effectiveness of congruent emphasis shifts for development based on the perceived ability to shift in a strategic manner. Dependent measures included academic achievement (course test scores), motivation (achievement orientation, perceived success and value, expectations), emotions (enjoyment, anxiety, boredom), health status (global health, illness symptoms), and overall adjustment (perceived stress, self-esteem, depression). Hypotheses were evaluated using phase-specific and cross-lagged structural equation models assessing moderation effects for perceived congruence ability. Results showed that students shift toward PC after success and toward SC following failure, and suggest an elaborated theoretical model of how PC and SC contribute to beliefs and behaviour involving strategic and congruent emphasis shifts. These findings also demonstrate that some individuals better recognize when this behaviour is most effective for their performance and well-being and strategically make congruent emphasis shifts to improve their subsequent development. In sum, this study highlights the benefits of one's ability to make strategic emphasis shifts between PC and SC in an academic achievement setting, and provides empirical support for this effective yet relatively unexplored facet of Rothbaum et al.'s model. / May 2006

Rothbaum, Weisz, and Snyder's (1982) dual-process model of control proposed that in addition to attempts to change one's environment (primary control, PC) or psychologically adjust to one's circumstances (secondary control, SC), the higher-order capacity to alternate between these processes in congruence with performance (optimization) served to foster development in achievement settings. The present five-phase longitudinal study conducted over an academic year explored how college students (n = 568) shift between PC and SC over time in response to actual performance feedback, as well as the differential effectiveness of congruent emphasis shifts for development based on the perceived ability to shift in a strategic manner. Dependent measures included academic achievement (course test scores), motivation (achievement orientation, perceived success and value, expectations), emotions (enjoyment, anxiety, boredom), health status (global health, illness symptoms), and overall adjustment (perceived stress, self-esteem, depression). Hypotheses were evaluated using phase-specific and cross-lagged structural equation models assessing moderation effects for perceived congruence ability. Results showed that students shift toward PC after success and toward SC following failure, and suggest an elaborated theoretical model of how PC and SC contribute to beliefs and behaviour involving strategic and congruent emphasis shifts. These findings also demonstrate that some individuals better recognize when this behaviour is most effective for their performance and well-being and strategically make congruent emphasis shifts to improve their subsequent development. In sum, this study highlights the benefits of one's ability to make strategic emphasis shifts between PC and SC in an academic achievement setting, and provides empirical support for this effective yet relatively unexplored facet of Rothbaum et al.'s model.

Rothbaum, Weisz, and Snyder's (1982) dual-process model of control proposed that in addition to attempts to change one's environment (primary control, PC) or psychologically adjust to one's circumstances (secondary control, SC), the higher-order capacity to alternate between these processes in congruence with performance (optimization) served to foster development in achievement settings. The present five-phase longitudinal study conducted over an academic year explored how college students (n = 568) shift between PC and SC over time in response to actual performance feedback, as well as the differential effectiveness of congruent emphasis shifts for development based on the perceived ability to shift in a strategic manner. Dependent measures included academic achievement (course test scores), motivation (achievement orientation, perceived success and value, expectations), emotions (enjoyment, anxiety, boredom), health status (global health, illness symptoms), and overall adjustment (perceived stress, self-esteem, depression). Hypotheses were evaluated using phase-specific and cross-lagged structural equation models assessing moderation effects for perceived congruence ability. Results showed that students shift toward PC after success and toward SC following failure, and suggest an elaborated theoretical model of how PC and SC contribute to beliefs and behaviour involving strategic and congruent emphasis shifts. These findings also demonstrate that some individuals better recognize when this behaviour is most effective for their performance and well-being and strategically make congruent emphasis shifts to improve their subsequent development. In sum, this study highlights the benefits of one's ability to make strategic emphasis shifts between PC and SC in an academic achievement setting, and provides empirical support for this effective yet relatively unexplored facet of Rothbaum et al.'s model.

<p>The purpose of the thesis has been to design and simulate different concepts of a secondary controlled swing drive for a wheel excavator. Secondary control is a known technology in the field of hydraulics that offers precise positioning as well as the possibility of energy recuperation. Secondary control is today used in certain industrial applications and is rather unemployed in mobile machinery. An excavator moves high loads in cyclic motions which are ideal conditions for energy recuperating systems. A study of the potential of a secondary controlled swing drive is therefore interesting. The focus has been on testing different circuit architectures and emergency brake concepts.</p><p>The results of the design process have been three types of circuit architectures and two types of hydraulic safety concepts. The results of the simulation have shown that the open and closed circuit architecture have similar energy efficiency. The closed circuit with low pressure accumulator however offers the best controllability. At least 20% energy savings can be achieved by storing thekinetic energy when braking.</p><p>A hydraulic emergency brake must function, independent on the direction of rotation of the excavator during a failure. The first principle recognises the rotation direction and changes the swivel angle of the secondary unit so that a braking torque is created. In the second principle a pressure difference is built up over the secondary unit that always results in a braking torque. Simulationshave shown that the principle with recognition of the speed direction is the most effective safety concept.</p>

The purpose of the thesis has been to design and simulate different concepts of a secondary controlled swing drive for a wheel excavator. Secondary control is a known technology in the field of hydraulics that offers precise positioning as well as the possibility of energy recuperation. Secondary control is today used in certain industrial applications and is rather unemployed in mobile machinery. An excavator moves high loads in cyclic motions which are ideal conditions for energy recuperating systems. A study of the potential of a secondary controlled swing drive is therefore interesting. The focus has been on testing different circuit architectures and emergency brake concepts. The results of the design process have been three types of circuit architectures and two types of hydraulic safety concepts. The results of the simulation have shown that the open and closed circuit architecture have similar energy efficiency. The closed circuit with low pressure accumulator however offers the best controllability. At least 20% energy savings can be achieved by storing thekinetic energy when braking. A hydraulic emergency brake must function, independent on the direction of rotation of the excavator during a failure. The first principle recognises the rotation direction and changes the swivel angle of the secondary unit so that a braking torque is created. In the second principle a pressure difference is built up over the secondary unit that always results in a braking torque. Simulationshave shown that the principle with recognition of the speed direction is the most effective safety concept.

According to Morling and Evered’s (2006) Fit-Focused model of secondary control, an individual can adapt to adverse circumstances by accepting the situation and adjusting the self. The present study examined this theory in a competitive achievement setting to determine whether vulnerable students who relinquish academic control (high acceptance/low adjustment beliefs) benefit from an Attributional Retraining (AR) treatment intervention compared with a Stress Reduction (SR) treatment. Based on an 8-month quasi-experimental treatment study, a priori t-tests were used to test the hypotheses within an Adjustment (low, high) x Treatment (AR, SR) Analyses of Covariance experimental design for individuals high in failure acceptance. Findings revealed that AR (versus SR) facilitated higher long-term learning-related affects and academic performance for relinquished control students. The findings reveal AR’s strategic utility for assisting vulnerable individuals who lack Fit-Focused SC, as well as provide empirical support for Morling and Evered’s (2006) Fit-Focused model.

Researchers have struggled to define how to age well since the time of Roman philosopher Cicero in 44 BC, yet today it remains a mystery (Tate, Lah, & Cuddy, 2003). In the context of dealing with age-related declines that often accompany later life, it has recently been suggested that positive reinterpretation, a concept implicit to positive psychology, may be important (Ouwehand, de Ridder, & Bensing, 2007; Seligman & Csikszentmihalyi, 2000). Positive reinterpretation has at times been referred to as “secondary control” in the psychological literature. In their seminal article of 1982, Rothbaum, Weisz, and Snyder theorized that there were multiple ways in which people could positively reinterpret outcomes and gain feelings of secondary control, including believing in the power of others and nature, as well as downgrading importance. These belief patterns become especially important in later life, when faced with age-related challenges. In the present study, secondary control beliefs were examined cross-sectionally in 2003 (n = 223) and prospectively in 2006 (n = 117) in a sample of older adults (M age = 85 years, 62% women) using a variety of outcome measures including severity of chronic conditions score, recent health, self-rated health, positive emotion, life satisfaction, and perceived stress. The unique contributions of this study are twofold. First, the findings suggest that some older adults may emphasize certain secondary control beliefs in combination. Second, the combined beliefs were found to relate cross-sectionally to measures of physical and psychological well-being. These exploratory findings have important implications in applied and theoretical contexts. In applied contexts, they may help to enhance physical and psychological well-being in the very old. In theoretical contexts, they extend contemporary thinking on secondary control.

Researchers have struggled to define how to age well since the time of Roman philosopher Cicero in 44 BC, yet today it remains a mystery (Tate, Lah, & Cuddy, 2003). In the context of dealing with age-related declines that often accompany later life, it has recently been suggested that positive reinterpretation, a concept implicit to positive psychology, may be important (Ouwehand, de Ridder, & Bensing, 2007; Seligman & Csikszentmihalyi, 2000). Positive reinterpretation has at times been referred to as “secondary control” in the psychological literature. In their seminal article of 1982, Rothbaum, Weisz, and Snyder theorized that there were multiple ways in which people could positively reinterpret outcomes and gain feelings of secondary control, including believing in the power of others and nature, as well as downgrading importance. These belief patterns become especially important in later life, when faced with age-related challenges. In the present study, secondary control beliefs were examined cross-sectionally in 2003 (n = 223) and prospectively in 2006 (n = 117) in a sample of older adults (M age = 85 years, 62% women) using a variety of outcome measures including severity of chronic conditions score, recent health, self-rated health, positive emotion, life satisfaction, and perceived stress. The unique contributions of this study are twofold. First, the findings suggest that some older adults may emphasize certain secondary control beliefs in combination. Second, the combined beliefs were found to relate cross-sectionally to measures of physical and psychological well-being. These exploratory findings have important implications in applied and theoretical contexts. In applied contexts, they may help to enhance physical and psychological well-being in the very old. In theoretical contexts, they extend contemporary thinking on secondary control.

This research focuses on frequency control ancillary services in large interconnected systems. It analyses and assesses possible alternatives for optimal and innovative solutions of major frequency control issues in large interconnected systems within liberalised electricity markets. Possible improvements in the performance of frequency control are identified. A framework of frequency control ancillary services in large interconnected systems by including loads and wind generation is also proposed.The research has been motivated by the paucity of research in power system dynamics focusing on large interconnected systems such as the European synchronous system and the Eastern interconnection which experience important frequency control challenges. These challenges include:- Decline in frequency response in the Eastern interconnection - Deterministic frequency deviations observed at the top of the hours in the European synchronous systemFrequency control issues became critical when electricity markets were deregulated and frequency control became an ancillary service with a decidedly commercial focus. This commercial focus has spawned a lot of work on frequency control markets and economics whereas not much research has been devoted to dynamic simulation of large interconnected systems. Apart from this commercial focus, frequency control in large interconnected systems is still based on historical practices mainly because changes suggested in the literature can be barely applied in large interconnected systems. This is essentially because dynamic simulation studies are uncorrelated with frequency control markets and economics. More specifically, dynamic studies do not take into account the characteristics of each reserve activated and also the way the reserve is activated. With the deregulation of the electricity market, reserve is considered as a product and not necessarily a response provided by a unit. The main objectives of this research therefore are to solve critical frequency control issues in large interconnected deregulated electricity systems, which may present potential economic benefits. To achieve these objectives, frequency control in large interconnected systems is studied by considering on one hand frequency control theory and on the other hand its implementation in practice taking account of frequency control ancillary service markets as well as the economics and practical consequences of frequency control. This approach is necessary to accommodate the future evolution of frequency control in large interconnected systems. The proposed approach is illustrated through a model of frequency control in the European synchronous system, where practices are better known, are clearly standardised and also where frequency data has been obtained.

As a result of climate change, extreme events occur more frequently and at higher severity, causing catastrophic power outages with significant economic losses. Microgrids are deployed as a technology to enhance power system resilience. A microgrid may include one or more distributed energy resources (DERs), including synchronous generators, solar panels, wind turbines, and energy storage systems which are decentralized power sources primarily in a distribution system to enable system recovery from catastrophic events. Microgrids can be operated in a utility-connected mode or an islanded mode in separation with the hosting transmission or distribution system. As major disasters occur, intentional islanding of a microgrid is a strategy to serve critical loads, within or outside the microgrids, until the utility service is restored. To operate microgrids, dispatch and control capabilities are required that would significantly improve the dynamic performance of the microgrid. An islanded microgrid can be used to serve critical load as a resiliency source when a severe outage occurs. In an islanded mode, control of a microgrid relies on the communication system significantly. Hence, microgrids are cyber-physical systems and, therefore, the cyber system plays a crucial role in the performance of the cyber-power system. Improper parameters of the cyber system can result in instability of a microgrid system. Simplification of the networked control system model is needed to enhance the computational performance, making the analytical method practical for large-scale power systems. To reduce the emission of carbon dioxide and alleviate the impact of climate change, the electric power industry has been integrating renewable energy into the power grid. The high penetration of renewable energy at an unprecedented level also raises new issues for the power grid, e.g., low inertia, degraded power quality, and higher uncertainties. Power electronics technology is used for power conversion of renewable energy. As the level of penetration of renewable energy increases, the inverter-based resources (IBRs) are being installed at a fast pace on the power grid. Compared to conventional synchronous generators (SGs), a major technical challenge of IBRs is their low inertia which can lead to system instability. In this context, the work of this dissertation results in major contributions regarding control algorithms for microgrid resilience, stability, and cyber-physical systems. Specifically, three novel contributions are presented: 1) A coordinated control scheme is proposed to achieve the goals of power dispatch and system regulation for an islanded microgrid. The proposed control scheme improves system dynamics; 2) A method is developed for the determination of critical values for the data reporting period and communication delay. Based on the proposed method, a 2-dimensional stability region of a microgrid in the space of cyber parameters is derived and critical values of cyber parameters are identified based on the stability region; 3) A control scheme is proposed to improve system stability of a hybrid-DER microgrid. The analysis serves to illustrate the stability regions of the hybrid-DER microgrid. A control methodology based on two-time scale decomposition is developed to stabilize the system. / Doctor of Philosophy / Climate change is causing more frequent and severe weather events, resulting in catastrophic power outages and significant economic losses. To enhance power system resilience, microgrids are proposed as a solution. Microgrids consist of one or more distributed energy resources, such as solar panels, wind turbines, and energy storage systems, which can be operated in a utility-connected or islanded mode. Microgrids can operate in an islanded mode to serve critical loads when an extended outage of the utility grid occurs. Proper dispatch and control capabilities are necessary for the operation and control. However, the performance of a microgrid, especially in an islanded mode, is dependent on the communication system. Excessive cyber latencies can result in system instability of the microgrid. To reduce carbon dioxide emissions, the power industry is integrating an unprecedented level of renewable energy into the power grid. Power electronics technology is being used for power conversion of renewable energy, and inverter-based resources are being installed at a fast pace into the power grid. One major technical challenge of inverter-based resources is their low inertia, which can lead to system instability. To address these issues, this dissertation presents three novel contributions: a coordinated control scheme to improve the microgrid dynamics and perform power dispatch and system regulation functions, a method to determine critical values of cyber parameters based on stability regions, and a control scheme to improve system stability of a hybrid-DER microgrid. These contributions provide valuable concepts and methodologies for resilient and stable microgrids that are critical to meet the operational and control challenges of an electricity infrastructure with a high-level penetration of renewable energy.