In this work we present the first implementation of the incremental scheme for coupled cluster linear-response frequency-dependent dipole polarizabilities. The implementation is fully automated and makes use of the domain-specific basis set approach. The accuracy of the approach is determined on the basis of a test suite of 47 molecules and small clusters. The local approximation in the coupled cluster singles and doubles polarizability exhibits a mean error of 0.02% and a standard deviation of 0.32% when using a third-order incremental expansion. With the proposed approach, it is possible to compute polarizabilities with larger basis sets compared to the canonical implementation and thus it is possible to obtain higher total accuracy. The incremental scheme yields the smallest errors for weakly-bound and quasi-linear systems, while two- and three-dimensional (cage-like) structures exhibit somewhat larger errors as compared to the full test set. / Dieser Beitrag ist aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich.

Personality, as a frequently used predictor of job performance, has often been criticized for its low criterion-related validity when compared to cognitive tests and some other predictors. The present study investigated incremental validity of narrow-trait personality to distinguish predictive from non-predictive facets of Conscientiousness and Extraversion dimensions. In addition, some intermediate mechanisms that may link the two personality dimensions with the criterion, such as different types of person-environment (P-E) fit and job involvement variables, were tested as well. The institution's job performance scale, NEO-PI-3 personality scale, person-organization (P-O) fit, needs-supplies (N-S) fit, demands-abilities (D-A) fit, job involvement questionnaire (JIQ), and demographic measures were administered in an online survey to 295 professional and civil service employees of a midsize Midwestern university. The sample was predominantly female and Caucasian with a mean age of 45.8 years and a median length of current employment of 5.1 years. Both personality dimensions were positively related to overall job performance. Conscientiousness was a stronger predictor of task performance, whereas Extraversion was related more consistently to contextual performance. In stepwise multiple regression analyses containing facets of personality dimensions as predictors of overall job performance, Competence emerged as the only facet of Conscientiousness, and Warmth and Assertiveness as the only facets of Extraversion that accounted for a meaningful amount of variance in the criterion. The use of narrow-trait personality to predict overall job performance enhances criterion-related validity of the construct and renders it a more efficient predictor of job performance than global-trait personality. Among the potential mediators, P-O and D-A fit partially mediated the personality-performance relationship providing evidence for the importance of perceptions of congruence in values and the ability to meet demands of the job. Current results are considered in light of limitations. Implications for theory, research, and practice, as well as future research directions are discussed.

The combination of machine learning on embedded systems has quickly increased throughout the years. Subsets like TinyML have become an integral part of how embedded systems implement machine learning. The field has evolved quickly, and TinyOL is an emerging subset that redefines what is possible with embedded systems. This report presents a comparison of how a neural network that implements incremental online learning learns and adapts how to do simple tasks in home automation. The comparison is done with another system, mainly a proportional-integral-derivative (PID). The systems were tasked with controlling an LED lightning threshold based on feedback from the user. The systems were evaluated based on their mean absolute error (MAE) and accuracy in predicting the output of the LED lighting system. The MAE values of both systems were compared for different target outputs and threshold values, and the accuracy was calculated by comparing the number of successful iterations to the total number of iterations. The results show that the neural network has an accuracy of 50\% when a learning rate of 0.2 is used, 97.5\% when a learning rate of 0.5 is used, and 47.5\% when a learning rate of 1.0 is used. The PID control system had accuracy values of 45\% when using an adaption rate of 0.2, 47.5\% when using an adaption rate of 0.5, and 90\% when using an adaption rate of 1.0. The neural network also showcased a lower median MAE for every test conducted. The study provides insights into the effectiveness of different control systems and can inform the development of similar systems in the future. / Kombinationen av maskininlärning på inbygga system har snabbt ökat under åren. Tekniker som TinyML har snabbt blivit en integrerad del av hur inbyggda system implementerar maskininlärning. Teknikerna har snabbt utvecklats och TinyOL är en framväxande delmängd av TinyML som omdefinierar vad som är möjligt med inbyggda system. Denna rapport presenterar en jämförelse av hur ett neuralt nätverk som implementerar inkrementell online-inlärning lär och anpassar sig för att utföra enklare uppgifter inom hemautomation. Jämförelsen görs med ett annat system, huvudsakligen en proportional-integral-derivative (PID). Systemen fick i uppgift att kontrollera en LED-lampa baserat på användarens feedback. Systemet utvärderas baserat på deras mean absolute error (MAE) och noggrannhet i att förutsäga börvärdet för LED-belysningen. MAE-värderna för båda systemen jämfördes för de olika målen och börvärdena, och noggrannheten beräknades genom att jämföra antalet lyckade iterationer med det totala antalet iterationer. Resultaten visar att neurala nätverket har en  noggrannhet på  50\% när en learning rate på 0.2 användes, 97.5\% när en learning rate på 0.5 användes och 47.5\% när en learning rate på 1.0 användes. PID kontroll system hade en noggranhet på 45\% när en adaption rate på 0.2 användes, 47.5\% när en adaption rate på 0.5 användes och 90\% när en adaption rate på 1.0 användes. Det neurala nätverket visade också ett lägre MAE-värde på alla de testerna som utfördes. Studien ger insikter i effektiviteten hos olika kontrollsystem och kan hjälpa utvecklingen av liknande system i framtiden.

This thesis focuses on the design of linear precoding schemes for downlink multiple-input multiple-output (MIMO) networks. These schemes are designed to be amenable to implementation in wireless networks that allow rate-limited feedback of channel state information (CSI). In the first half of this thesis, memoryless quantization codebooks are designed and incremental vector quantization techniques are developed for the representation of CSI in MIMO point-to-point links and isolated (single-cell) downlink networks. The second half of the thesis seeks to design linear precoding schemes for the multi-cell downlink networks that can achieve improved performance without requiring significantly more communication resources for CSI feedback than those required in the case of an isolated single-cell. For the quantization problem, smooth optimization algorithms are developed for the design of codebooks that possess attractive features that facilitate their implementation in practice in the addition to having good quantization properties. As one example, the proposed approach is used to design rank-2 codebooks that have a nested structure and elements from a phase-shift keying (PSK) alphabet. The designed codebooks have larger minimum distances than some existing codebooks, and provide tangible performance gains. To take advantage of temporal correlation that may exist in the wireless channel, an incremental approach to the Grassmannian quantization problem is proposed. This approach leverages existing codebooks for memoryless quantization schemes and employs a quantized form of geodesic interpolation. Two schemes that implement the principles of the proposed approach are presented. A distinguishing feature of the proposed approach is that the direction of the geodesic interpolation is specified implicitly using a point in a conventional codebook. As a result, the approach has an inherent ability to recover autonomously from errors in the feedback path. In addition to the development of the Grassmannian quantization techniques and codebooks, this thesis studies linear precoder design for the downlink MIMO networks in the cases of small networks of arbitrary topology and unbounded networks that have typical architectures. In particular, a linear precoding scheme for the isolated 2-cell network that achieves the optimal spatial degrees of freedom of the network is proposed. The implementation of a limited feedback model for the proposed linear precoding scheme is developed as well. Based on insight from that model, other linear precoding schemes that can be implemented in larger networks, but with finite size, are developed. For unbounded networks of typical architecture, such as the hexagonal arrangement of cells, linear precoding schemes that exploit the partial connectivity of the network are presented under a class of precoding schemes that is referred to as spatial reuse precoding. These precoding schemes provide substantial gains in the achievable rates of users in the network, and require only local feedback. / Thesis / Doctor of Philosophy (PhD)

Decision diagrams have recently emerged as a promising approach for difficult scheduling problems, along with other challenging discrete optimization problems. Decision diagrams can offer a compact representation of the solution space, and has the ability to capture complex constraints that are hard to model or express in other techniques. This thesis explores two standard construction methods for relaxed decision diagrams, top-down construction and incremental refinement. The techniques are compared on their ability to handle scheduling problems with multiple time windows and precedence constraints. The construction methods are evaluated on several metrics, including generated bound, execution time, and the size of the diagram, on instances of the problem with up to 200 tasks. The results show that incremental refinement generates smaller diagrams with good bounds when compared to the top-down compilation algorithm; the reduction in diagram size and increase in bounds for incremental refinement comes at the expense of execution time compared to top-down compilation.

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The first purpose of this research is to investigate the effect of added viscous fluid dampers on a nine story special steel moment frame designed for strength in Seattle. At the initial stages of the work, knowing the fact that moment frames are almost always controlled by drift, it was thought that two different moment frames, controlled by strength or controlled by drift (stiffness), could be designed in Seattle and the effect of additional dampers on the structural behavior of the strength controlled design could be studied. However, since ASCE 7 permits determining the elastic drifts by using the seismic design forces based on the computed fundamental period of the structure, without the upper limit (CuTa), the strength controlled design satisfied the drift limit requirements of ASCE 7. Although the strength controlled design meets the drift requirements, the stability checks of both ASCE 7 and the AISC Seismic Design Manual were not satisfied. Thus, the strength controlled frame was redesigned to meet the stability requirements, and the process is called stability controlled design. By adding supplemental dampers to the strength controlled design, it was expected that the seismic drift would be controlled and a better structural behavior would be obtained in terms of dynamic stability. Incremental Dynamic Analysis (IDA) was implemented to investigate the benefits of the dampers on the structural behavior. Using ten different earthquakes scaled up to a maximum target multiplier two, with ten increments, damage measures such as interstory drift, residual displacement, IDA dispersion, base shear, and roof displacement were studied. Using IDA dispersion, the effect of dampers on dynamic instability was also investigated in this study. As a result, it was found that as the damping of the structure increases with the help of added dampers, the structural response gets better. Maximum and residual roof displacements, interstory drifts, and IDA dispersion decreases with increasing damping. In addition, by using supplemental damping, most of the collapses that occur for the inherently damped frames are prevented. The second purpose of this research is to develop an improved "Hybrid" moment frame without added damping but by controlling the inelastic behavior. Hybrid Frames were designed as the combination of three different moment frames: Special, Intermediate and Ordinary Moment Frames (SMF, IMF, OMF). The design procedure of each bay, which corresponds to different moment frame systems, follows the rules of the related moment frame for that bay. By varying the plastic hinge capacities across the same level stories, four different Hybrid Frame designs were obtained. Nonlinear static pushover analysis was applied to these frames, and as expected, the more reduction in the plastic capacity of the Hybrid Frame, the earlier the pushover curve starts yielding and the later the negative post yield stiffness of the pushover curve was reached. It was observed that the effect of early plastic hinge forming in the frame, which caused inelastic hysteretic damping, and the relatively late formation of negative post yield stiffness resulted in a better dynamic behavior. As a result of the IDA studies, as the frames become more "hybrid", the residual displacements decrease significantly and then collapses are even prevented. This is considered as the positive effect of reaching the negative post yield stiffness late. The residual displacement was reduced for low intensity gentle earthquakes. The ductility demand IDA study proves that as the frames become more hybrid, the ductility demand increases for the special detailing frame, where plastic capacity was reduced, and decreases for the ordinary detailing frame, where the plastic capacity was increased. The Hybrid Frame system is expected to perform better than the traditional special moment frame, and to be more economical than the special moment frame because of the limited amount of special detailing. / Master of Science

This thesis presents the results of a study that uses Incremental Dynamic Analysis to assess the seismic performance of steel moment-resisting frames with fluid viscous dampers subjected to earthquake ground motions. The study systematically investigated the effects of linear and nonlinear dampers on the response of steel moment-resisting frames to earthquakes that varied in intensity and type. Both near-field and far-field motions were considered. Two different types of nonlinear dampers were investigated; one had a hardening and the other had a softening force-velocity relationship. The nonlinear dampers were calibrated to the linear dampers so that there was a basis of comparison. Maximum damper displacement is one of the parameters of the calibration, and it was varied to investigate its effect on structural response. Several nonlinear inelastic time history analyses were performed to obtain responses, such as peak base shear, peak interstory drift, or residual displacement index, which were plotted versus earthquake intensity to create individual IDA curves. Sets of related IDA curves provide a useful summary of the structural behavior for a wide range of variables. IDA curves for the tests with different damping types are presented. The results show that for both near-field and far-field ground motions the nonlinear dampers with a hardening force-velocity relationship are best suited to reduce undesirable drifts and residual displacements; however, these reductions come at the cost of high base shear forces. / Master of Science

This thesis presents the details of a study regarding both the use of linear viscous fluid dampers in controlling the interstory drift in steel moment frames, and the use of incremental dynamic analysis as a method of visualizing the behavior of these moment frames when subjected to seismic load effects. Models of three story and nine story steel moment frames were designed to meet typical strength requirements for office buildings in Seattle, Washington. These models were intentionally designed to violate seismic interstory drift restrictions to test the ability of the linear viscous fluid dampers to reduce these drifts to the point of code compliance. Dampers were included in one bay of every story in each model. These devices were used to produce total structural damping ratios of 5%, 10%, 20%, and 30% of critical. Undamped, traditional stiffness controlled models of both three stories and nine stories were also created for comparison purposes. Incremental dynamic analysis was used to subject these models to ten ground motions, each scaled to twenty incremental levels. Two new computer applications were written to facilitate this process. The results of these analyses were studied to determine if the linear viscous fluid dampers were able to cause compliance with codified drift limits. Also, incremental dynamic analysis plots were created to examine the effects of the dampers on structural behavior as damping increased from inherent to 30% of critical. It was found that including linear viscous fluid dampers in steel moment frame design can satisfactorily control interstory drift, and incremental dynamic analysis is a beneficial tool in visualizing dynamic structural behavior. / Master of Science

During the months I have been at Virginia Tech, I have experienced the most exciting time of my life. There are many persons who helped me to pursue my Master's degree. I would like to take this opportunity to express my appreciations to them. I would like to thank my advisor and committee chairman, Dr Finley A. Charney. He has supported me for the entire duration of this project with all of his efforts. Without his assistance, it would have been very difficult for me to learn so many concepts in the field of nonlinear dynamic analysis and practical earthquake engineering. I would also like to acknowledge my other committee members, Dr. Raymond Plaut and Dr. W. Samuel Easterling, for taking the time to review the thesis and providing valuable insights and feedback on this thesis. I would like to thank my father, Chan Kwok Fung, who encouraged me to pursue my Master Degree, and my mother, Yu Yuk Ping, who brought me to life. I would like to thank my sister, Doris Chan, and my girlfriend, Ka Man Chan, for supporting and encouraging me during the past two years at Virginia Tech. Finally, I would like to give thanks to the rest of my family, friends, professors, and fellow graduate students for their help and encouragement during my stay at Virginia Tech. / Master of Science