Online learning has been widely adopted in higher education to reach students who typically would not have a chance to complete accredited courses (Kentnor, 2015). Massive open online courses (MOOC), which is a type of online learning, makes it easier for people to take university courses with internet access and a fraction of cost compared to traditional residential programs (Reich, 2020). MOOCs also become popular for those who want to increase their professional profile or advance their academic career (Pheatt, 2017). However, online learning has long been criticized for its universally low completion rates, high dropout rate and poor learning performance (Almeda et al., 2018). This phenomenon is more exacerbated in MOOC environments. Historical studies have attempted to support learner self-regulated learning (SRL) activities in order to enhance completion rates and academic outcomes. Prior studies have conducted pre-course questionnaires as inexpensive SRL interventions to prompt learners as SRL support(Kizilcec et al., 2017, Kizilcec & Cohen, 2017; Kizilcec et al., 2020; Yeomans & Reich, 2017). Yet, these one-time-only, short-term interventions only yield limited or no effects. This study implemented and evaluated the effectiveness of an alternative intervention, the self-regulated learning user interface (SRLUI), to support students' self-regulated learning (SRL) strategies in a MOOC environment. SRLUI is based on Zimmerman’s (2000) SRL model and develops learner’s SRL skills through longitudinal, recurring practice of multiple SRL dimensions activities (i.e., goal setting, self-evaluation, task planning, setting reminders) with content-specific information. The study utilized a randomized experimental design and implemented SRLUI in eight MOOCs with a total of 808 participants. The results indicated a higher usage rate of SRL support compared to the historical findings, which may be owing to the SRL support embedded into the learning activities throughout the course. Also, the study showed improved learning outcomes for a subgroup of participants, but there was no reduction in the number of dropouts. Based on the findings of this study, it is recommended that a personalized SRL tool featuring content-specific information should be embedded in online courses. The research design also recorded direct cognitive records of learners' SRL activities, which yield stronger validity compared to trace and survey data. The result suggested SRLUI might only benefit a subgroup of learners with passing grades. Thus, it is recommended that future research identify various subgroups of learner profiles in MOOC environments and to consider how to reach and support learners in different subgroups.

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This thesis aims at designing a solution to the comprehensive use of construction underlying documents for the CNC programming of turbine casings. The introductory part of the thesis contains a description of the CNC programming and CAD/CAM systems. The following is mapping of the current state of the construction underlying documents, and mapping of the situation in the department of technology in Siemens Industrial Turbomachinery, s.r.o., Brno. The further section presents an analysis of the problem that arose when processing and sharing the construction underlying documents with the aim of streamlining the CNC programming process. The closing part presents the evaluation and conclusions for implementation of the proposed solutions.

This thesis explores the possibility of using the Collective System Design Methodology to design systems that will improve the health of people. The focus of the thesis is on the reversal of type-2 diabetes.

Advanced power electronic techniques are crucial to enable high-performance energy conversion systems for the applications of various load and source interfaces, e.g., electric vehicle battery charger, solar power, wind power, motor traction, grid-connection. Also, the improvements on electrification for energy conversion contributes to the Carbon Neutrality with the reduction of fuel combustion. The control and design of the power conversion systems largely determine the efficiency, power density and system cost which typically need specialized design procedures. Since the types of interfaced energy sources may vary, the corresponding control algorithms and hardware configurations will be different. Thus, the power electronics system design is conventionally a specific routine based on the desired source and load requirements. Generally speaking, two main perspectives need to be considered when designing a power conversion system: (1) the power converter circuitry topology with the corresponding hardware components, e.g., low/high power circuits design, passive components design; (2) control algorithms and functions design, e.g., voltage/current control techniques, active/reactive power balancing and adjustment. However, the repetitive and specific power electronics design procedures for different load/source requirements are time-consuming and costly. This thesis proposes a software-defined power electronics concept to develop a generalized auto-converter module (ACM) by leveraging variable-frequency critical-soft-switching, model predictive control techniques and high-performance litz-PCB inductors. The software-defined power electronics techniques can be applied to various types of electrified load/source applications without the need of repetitive hardware components and software algorithms designing procedures. The fundamental unit for the generalized concept, auto-converter module, is a type of MPC-based power module. A hierarchical control architecture is designed to manage the local ACMs and satisfy different load/source energy conversion requirements with high efficiency, high power-density and high-reconfigurability. To achieve high-performance for the software-defined power electronics system, several advanced technologies are developed and integrated including variable-frequency critical-soft-switching, modular model predictive control, litz-PCB inductor design. Firstly, a variable-frequency critical-soft-switching technique is developed to adjust the switching frequency for the zero-voltage soft-switching. Doing so, the switching losses can be largely reduced with high efficiency. Secondly, the critical-soft-switching inductor is designed based on litz-PCB winding structure and neural network model to optimize the inductor losses and reduce the volume for the application of high frequency and large current ripple. Thirdly, a modular model predictive control method is designed for each of the local ACM to improve the dynamic performance and attenuate the oscillation caused by the variable frequency operation. Lastly, a hierarchical control architecture is developed to generalize the software-defined power electronics with multi-layer structure, central control layer, local module control layer and application layer. The hierarchical control architecture can be widely applied to different types of load/source interfaces, e.g., single/three-phase grid-connected inverters, motor traction inverter, battery charger, solar energy and so on. Leveraging the hierarchical control architecture and software-defined power electronics, the repetitive power converter hardware components and software algorithms design procedures can be simplified and standardized. Also, for different power converter applications, the efficiency and power density are both improved with better dynamic performance.

My dissertation examines the experiences of Teachers College faculty that transitioned to online teaching for the first time during the forced circumstances of COVID-19. More specifically, I explore: 1) the relationship between feeling prepared, supported, and connected with professional development; 2) the experiences of faculty making the transition to online teaching; and 3) how faculty described re-evaluating, as Boud describes it, their teaching experiences. To better understand this, I used the case-selection variant of the explanatory sequential, mixed-methods design (quan → QUAL). I surveyed 85 participants (Phase 1) that engaged in professional development opportunities provided by the institution to better understand their experiences preparing for this transition and then interviewed 10-participants (Phase 2) to better understand their unique experiences. I found that most participants that made this transition grew both in their ability to use technology and comfort with teaching online. Participants described the experience as a challenging transition, especially as there was little time to prepare; however, participants also learned (through consultations, intensive programs, colleagues, and students) from this experience. In Phase 2, 7 of 10 participants indicated that they will take their learnings from teaching online and integrate them into their face-to-face teaching.

The combination of silicon photonics and advanced heterogeneous integration is promising for next-generation disaggregated data centers that demand large scale, high throughput, and low power. In this dissertation, we discuss the design and theory of power-efficient optical transceivers with System-in-Package (SiP) 2.5D integration. Combining prior arts and proposed circuit techniques, a receiver chip and a transmitter chip including two 10 Gb/s data channels and one 2.5 GHz clocking channel are designed and implemented in 28 nm CMOS technology. An innovative transimpedance amplifier (TIA) and a single-ended to differential (S2D) converter are proposed and analyzed for a low-voltage high-sensitivity receiver; a four-to-one serializer, programmable output drivers, AC coupling units, and custom pads are implemented in a low-power transmitter; an improved quadrature locked loop (QLL) is employed to generate accurate quadrature clocks. In addition, we present an analysis for inverter-based shunt-feedback TIA to explicitly depict the trade-off among sensitivity, data rate, and power consumption. At last, the research on CDR-based​ clocking schemes for optical links is also discussed. We introduce prior arts and propose a power-efficient clocking scheme based on an injection-locked phase rotator. Next, we analyze injection-locked ring oscillators (ILROs) that have been widely used for quadrature clock generators (QCGs) in multi-lane optical or wireline transceivers due to their low power, low area, and technology scalability. The asymmetrical or partial injection locking from 2 phases to 4 phases results in imbalances in amplitude and phase. We propose a modified frequency-domain analysis to provide intuitive insight into the performance design trade-offs. The analysis is validated by comparing analytical predictions with simulations for an ILRO-based QCG in 28 nm CMOS technology. This dissertation also discusses the design of high-linearity wireless wideband receivers. An out-of-band (OB) IM3 cancellation technique is proposed and analyzed. By exploiting a baseband auxiliary path (AP) with a high-pass feature, the in-band (IB) desired signal and out-of-band interferers are split. OB third-order intermodulation products (IM3) are reconstructed in the AP and cancelled in the baseband (BB). A 0.5-2.5 GHz frequency-translational noise-cancelling (FTNC) receiver is implemented in 65nm CMOS to demonstrate the proposed approach. It consumes 36 mW without cancellation at 1 GHz LO frequency and 1.2 V supply, and it achieves 8.8 MHz baseband bandwidth, 40dB gain, 3.3dB NF, 5dBm OB IIP3, and −6.5dBm OB B1dB. After IM3 cancellation, the effective OB-IIP3 increases to 32.5 dBm with an extra 34 mW for narrow-band interferers (two tones). For wideband interferers, 18.8 dB cancellation is demonstrated over 10 MHz with two −15 dBm modulated interferers. The local oscillator (LO) leakage is −92 dBm and −88 dB at 1 GHz and 2 GHz LO respectively. In summary, this technique achieves both high OB linearity and good LO isolation.

The ever-increasing demand for wireless throughput requires modern handset receivers to aggregate signals from multiple non-contiguously allocated RF carriers. This poses significant receiver design challenges, including concurrent signal reception, RF input interface, out-of-band (OB) linearity, and suppression of spurious responses. Commercial solutions use external antenna switches and off-chip RF multiplexers to provide non-tunable, narrowband filtering and impedance matching. The RF signal is then divided into separate signal chains, each with a dedicated receiver for signal reception. Although this solution allows the selection of any carrier combinations supported by the available RF filters, as the number of aggregation band combinations increases, the scale of the passive front-end module grows rapidly, leading to increased system complexity, extra signal loss, and degraded performance. This thesis presents the design and implementation of two receiver architectures that support reconfigurable operations and flexible, concurrent reception from two inter-band carriers with a tuned RF interface. We first present a multi-branch receiver with modulated mixer clocks (MMC). It unifies the functions of single-carrier and dual-carrier reception, as well as compressive-sampling spectrum scanning into a single architecture. With continuous-wave-modulated mixer clocks, the receiver supports concurrent reception from two distinct bands and realizes tuned impedance matching that greatly improves the OB linearity. With pseudo-noise-modulated mixer clocks, the receiver supports spectrum scanning. Disabling modulation reverts the receiver into a single-carrier receiver with good OB linearity. The 65nm CMOS prototype is developed that operates from 300 to 1300MHz and offers 2.7dB minimum NF, -1.3dBm B1dB, and +8.0dBm IIP3 for single-carrier reception. Concurrent dual-carrier reception is demonstrated that offers -8.4dBm B1dB and sub-6dB NF with the two carriers separated from 200 to 600MHz apart. For spectrum scanning, the receiver achieves a 66dB dynamic range with -75dBm sensitivity over a 630MHz RF span. In addition, a discussion of the higher-order MMC technique is included to improve the receiver’s spurious and noise performance by suppressing the higher-order responses and mitigating the noise-folding effect. Next, we present an IF-filterless, double-conversion receiver. The concurrent, narrowband RF interface is realized with two layers of passive mixing in its mixer-first branches, which translate the low-pass, baseband impedance twice to two distinct bands and improve the OB linearity. Branches with DDS-modulated LNTAs for multi-phase, switched-Gm mixing offer rejection of spurious responses and improved noise performance. The 65nm CMOS prototype is developed that operates from 100 to 1200MHz. For single-carrier reception, the receiver delivers 4.8dB minimum NF, +7.9dBm B1dB, and +22.8dBm IIP3. For concurrent signal reception, two arbitrarily-allocated RF carriers, separated from 200 to 600MHz apart, can be received concurrently. The receiver delivers a +1.9dBm B1dB and supports 8-/16-phase DDS modulation with a 30dB spurious rejection across its operating range. In addition, a theoretical study of a modified, mixer-first branch is included. By re-arranging the connections of the baseband termination resistors, the baseband noise can be fully cancelled, thus improving the receiver’s noise performance.