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Indiana University-Purdue University Indianapolis (IUPUI) / In this work we have designed and simulated a thermal bi-directional integrated circuit mass flow sensor. The approach used here was an extension to the gas flow model given by Mayer and Lechner. The design features high precision response received from analog integrated circuits. A computational fluid dynamic (CFD) model was designed for simulations with air and water Using COMSOL Multiphysics. Established mathematical models for the heat flow equations including CFD parameters were used within COMSOL simulation(COMSOL Multiphysics, Sweden). Heat pulses of 55 °C for a period of nearly 120 seconds and 50% duty cycles were applied as thermal sources to the flowstream. The boundary conditions of the heat equations at the solid (heating element) fluid interface were set up in the software for the thermal response. The hardware design included one heating element and two sensing elements to detect the bi-directional mass flow. Platinum sensors were used due to their linear characteristics within 0 ºC to 100 ºC range, and their high temperature coefficient(0.00385 Ω/Ω/ºC). Polyimide thinfilm heater was used as the heating element due to its high throughput and good thermal efficiency. Two bridge circuits were used to sense the temperature distribution in the vicinity of the sensing elements. Three high precision instrumentation low power amplifiers with offset voltage ~2.5μV (50μV max) were used for bridge signal amplification and the difference circuit. The difference circuit was used to indicate the flow direction. A LM555 timer chip was utilized to provide the heat pulse period. Simulation and experimental measurements for heat pulses with different amplitude (temperature) were in good agreement. Also, the sensitivity of the flow sensor was observed to remain unaffected with the change in the duty cycle of the heat operation mode.

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Electrostatic Discharge (ESD), as a subset of Electrical Overstress (EOS), was reported to be in charge of more than 35% of failure in integrated circuits (ICs). Especially in the manufacturing process, the silicon wafer turns out to be a functional ICs after numerous physical, chemical and mechanical processes, each of which expose the sensitive and fragile ICs to ESD environment. In normal end-user applications, ESD from human and machine handling, surge and spike signals in the power supply, and wrong supplying signals, will probably cause severe damage to the ICs and even the whole systems. Generally, ESD protections are evaluated after wafer and even system fabrication, increasing the development period and cost if the protections cannot meet customer's requirements. Therefore, it is important to design and customize robust and area-efficient ESD protections for the ICs at the early development stage. As the technologies generally scaling down, however, ESD protection clamps remain comparable area consumption in the recent years because they provide the discharging path for the ESD energy which rarely scales down. Diode is the most simple and effective device for ESD protection in ICs, but the usage is significantly limited by its low turn-on voltage. MOS devices can be triggered by a dynamic-triggered RC circuit for IOs operating at low voltage, while the one triggered by a static-triggered network, e.g., zener-resistor circuit or grounded-gate configuration, provides a high trigger voltage for high-voltage applications. However, the relatively low current discharging capability makes MOS devices as the secondary choice. Silicon-controlled rectifier (SCR) has become famous due to its high robustness and area efficiency, compared to diode and MOS. In this dissertation, a comprehensive design methodology for SCR based on simulation and measurement are presented for different advanced commercial technologies. Furthermore, an ESD clamp is designed and verified for the first time for the emerging GaN technology. For the SCR, no matter what modification is going to be made, the first concern when drawing the layout is to determine the layout geometrical style, finger width and finger number. This problem for diode and MOS device were studied in detail, so the same method was usually used in SCR. The research in this dissertation provides a closer look into the metal layout effect to the SCR, finding out the optimized robustness and minimized side-effect can be obtained by using specific layout geometry. Another concern about SCR is the relatively low turn-on speed when the IOs under protection is stressed by ESD pulses having very fast rising time, e.g., CDM and IEC 61000-4-2 pulses. On this occasion a large overshoot voltage is generated and cause damage to internal circuit component like gate oxides of MOS devices. The key determination of turn-on speed of SCR is physically investigated, followed by a novel design on SCR by directly connecting the Anode Gate and Cathode Gate to form internal trigger (DCSCR), with improved performance verified experimentally in this dissertation. The overshoot voltage and trigger voltage of the DCSCR will be significantly reduced, in return a better protection for internal circuit component is offered without scarifying neither area or robustness. Even though two SCR's with single direction of ESD current path can be constructed in reverse parallel to form bidirectional protection to pins, stand-alone bidirectional SCR (BSCR) is always desirable for sake of smaller area. The inherent high trigger voltage of BSCR that only fit in high-voltage technologies is overcome by embedding a PMOS transistor as trigger element, making it highly suitable for low-voltage ESD protection applications. More than that, this modification simultaneously introduces benefits including high robustness and low overshoot voltage. For high voltage pins, however, it presents another story for ESD designs. The high operation voltages require that a high trigger voltage and high holding voltage, so as to reduce the false trigger and latch-up risk. For several capacitive pins, the displacement current induced by a large snapback will cause severe damage to internal circuits. A novel design on SCR is proposed to minimize the snapback with adjustable trigger and holding voltage. Thanks to the additional a PIN diode, the similar high robustness and stable thermal leakage performance to SCR is maintained. For academic purpose of ESD design, it is always difficult to obtain the complete process deck in TCAD simulation because those information are highly confidential to the companies. Another challenge of using TCAD is the difficulty of maintaining the accuracy of physics models and predicting the performance of the other structures. In this dissertation a TCAD-aid ESD design methodology is used to evaluate ESD performance before the silicon shuttle. GaN is a promising material for high-voltage high-power RF application compared to the GaAs. However, distinct from GaAs, the leaky problem of the schottky junction and the lack of choice of passive/active components in GaN technology limit the ESD protection design, which will be discussed in this dissertation. However, a promising ESD protection clamp is finally developed based on depletion-mode pHEMT with adjustable trigger voltage, reasonable leakage current and high robustness.

Intracellular transport is fundamental to many cellular processes- from capturing and destroying pathogens to the propagation of nerve impulses. This transport is mediated by specialized enzymes that convert the free energy of ATP hydrolysis to ‘walk’ on polymeric filaments. The microtubule filament and its associated motors- dynein and kinesin - are responsible for the long-range transport of various cellular cargoes. While these two motors move in the opposite directions, they are often simultaneously present on individual cargoes leading to bidirectional motility characterized by frequency directional reversals. How this process is regulated and what determines the direction of cargo transport remains poorly understood. Addressing these questions requires a systematic analysis where the contribution of various factors in regulating/determining the transport direction of a well-defined cargo can be elucidated. This project establishes an in vitro assay where we reconstitute bidirectional motility of large unilamellar vesicles driven by purified dynein and kinesin-3 motors. Vesicles exhibit fast runs in either direction, with a subset exhibiting directional reversals. The transport features of these vesicles are remarkably similar to that of cargoes in vivo and do not require any additional regulatory proteins/complexes. The simultaneous opposing activity of dynein and kinesin-3 leads to tugs-of-war for a finite period. Finally, we use this assay to determine how microtubule-associated proteins that have differential activity towards dynein and kinesin affect the transport direction of vesicles. MAP9 biases the direction of vesicles towards the plus-end by limiting the ability of dynein to land on microtubules. Our approach can be extended to investigate the potential biasing activities of cellular factors such as posttranslational modifications of tubulin, motor-adaptors, etc. and physical factors, such as fluidity and tension of the vesicle membrane.:1 Introduction 1.1 Microtubules, dynein, kinesin, and microtubule-associated proteins (MAPs) 1.2 Bidirectional transport: In vivo observations and models 1.3 Bidirectional transport: In vitro reconstitution 1.4 Role of membranes in modulating motor activities 1.5 Aims of the thesis 2 Purification of dynein and dynactin 2.1 Purification of dynein and dynactin from adherent mammalian cell cultures 2.2 Purification of dynein and dynactin from suspension cultures using BacMam system 2.3 Validation of dynein and dynactin function using single-molecule motility assays 3 Reconstitution and characterization of bidirectional vesicle motility 3.1 DDB-KIF16B-vesicles exhibit directional reversals in vitro 3.2 Transport direction of vesicles is dependent on the relative concentration of DDB and KIF16B 3.3 Opposing motors do not affect the velocity of the driving motor 3.4 DDB and KIF16B engage in a tug-of-war before directional reversals 3.5 Discussion 4 Characterization of bidirectional motility in the presence of MAPs 4.1 Tau does not differentially affect DDB versus KIF16B at the single-molecule level 4.2 MAP9 affects landing of DDB but not KIF16B 4.3 Motor ensembles can circumnavigate the inhibitory effects of MAPs 4.4 Tau does not bias the transport direction of DDB-KIF16B-vesicles 4.5 MAP9 biases the transport direction of DDB-KIF16B-vesicles towards the plus-end 4.6 Discussion 5 Conclusion and outlook 6 Materials and Methods 6.1 Molecular Biology 6.2 Culture of Flp-In 293 cells 6.3 Protein biochemistry 6.4 In vitro motility assays 6.5 Data processing and analysis

In this study, onboard chargers for EVs are investigated and a design of bi-directional onboard chargers is proposed and simulated. The goal of the charger is to be built in the future to be used in the test setup at Uppsala University. The charger consists of two stages: a power factor correction (PFC) converter, which converts AC voltages and currents from the grid side to DC while maintaining a unity power factor, and a bi-directional buck-boost converter, which regulates the charging and discharging current of the battery. The model was built using MATLAB/SIMULINK and the d-q synchronous reference frame was utilized to implement the current controller of the PFC converter, while the bi-directional buck-boost current controller was constructed using DC pulse width modulation. The Proportional and Integral gains were tuned using the MATLAB single input and single output tool (sisotool). The converter's topologies, structure, and corresponding mathematical model were investigated, and the charger was simulated and tested for charging and discharging modes. The battery voltage, current, and state of charge were monitored during all modes of operation to evaluate the performance of the buck-boost controller, and the functionality of the PFC controller and filter was tested by measuring the currents and voltages on the AC side. The charging and discharging efficiencies were mapped under various battery voltages and current sets to determine the performance of the charger under different operating conditions. The charger demonstrated excellent performance during charging and discharging modes and recommendations for future work to improve the efficiency and performance of bi-directional charging systems were provided.

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Yes / In nearshore regions, bidirectional tidal flow is the main hydrodynamic factor, which induces local scour around submarine pipelines. So far, most studies on scour around submarine pipelines only consider the action of unidirectional, steady currents and little attention has been paid to the situation of bidirectional tidal currents. To deeply understand scour characteristics and produce a more accurate prediction method in bidirectional tidal currents for engineering application, a series of laboratory scale experiments were conducted in a bidirectional current flume. The experiments were carried out at a length scale of 1:20 and the tidal currents were scaled with field measurements from Cezhen pipeline in Hangzhou Bay, China. The experimental results showed that under bidirectional tidal currents, the scour depth increased significantly during the first half of the tidal cycle and it only increased slightly when the flow of the tidal velocity was near maximum flood or ebb in the following tidal cycle. Compared with scour under a unidirectional steady current, the scour profile under a bidirectional tidal current was more symmetrical, and the scour depth in a bidirectional tidal current was on average 80% of that under a unidirectional, steady current based on maximum peak velocity. Based on previous research and the present experimental data, a more accurate fitted equation to predict the tidally induced live-bed scour depth around submarine pipelines was proposed and has been verified using field data from the Cezhen pipeline.

Electric vehicles (EVs) and plug-in hybrid electric vehicles (PHEVs) are gaining popularity because they are more environmentally friendly, less noisy and more efficient. These vehicles have batteries can be charged by on-board battery chargers that can be conductive or inductive. In conductive chargers, the charger is physically connected to the grid by a connector. With the inductive chargers, energy can be transferred wirelessly over a large air-gap through inductive coupling, eliminating the physical connection between the charger and the grid. A typical on-board battery charger consists of a boost power factor correction (PFC) converter followed by a dc-dc converter. This dissertation focuses on the design, modeling and control of a bidirectional dc-dc converter for conductive battery charging application. In this dissertation, a detailed design procedure is presented for a bidirectional CLLLC-type resonant converter for a battery charging application. This converter is similar to an LLC-type resonant converter with an extra inductor and capacitor in the secondary side. Soft-switching can be ensured in all switches without additional snubber or clamp circuitry. Because of soft-switching in all switches, very high-frequency operation is possible, thus the size of the magnetics and the filter capacitors can be made small. To further reduce the size and cost of the converter, a CLLC-type resonant network with fewer magnetics is derived from the original CLLLC-type resonant network. First, an equivalent model for the bidirectional converter is derived for the steady-state analysis. Then, the design methodology is presented for the CLLLC-type resonant converter. Design of this converter includes determining the transformer turns ratio, design of the magnetizing inductance based on ZVS condition, design of the resonant inductances and capacitances. Then, the CLLC-type resonant network is derived from the CLLLC-type resonant network. To validate the proposed design procedure, a 3.5 kW converter was designed following the guidelines in the proposed methodology. A prototype was built and tested in the lab. Experimental results verified the design procedure presented. The dynamics analysis of any converter is necessary to design the control loop. The bandwidth, phase margin and gain margin of the control loops should be properly designed to guarantee a robust system. The dynamic analysis of the resonant converters have not been extensively studied, with the previous work mainly concentrated on the steady-state models. In this dissertation, the continuous-time large-signal model, the steady-state operating point, and the small-signal model are derived in an analytical closed-form. This model includes both the frequency and the phase-shift control. Simulation and experimental verification of the derived models are presented to validate the presented analysis. A detailed controller design methodology is proposed in this dissertation for the bidirectional CLLLC-type resonant converter for battery charging application. The dynamic characteristics of this converter change significantly as the battery charges or discharges. And, at some operating points, there is a high-Q resonant peaking in the open-loop bode-plot for any transfer functions in this converter. So, if the controller is not properly designed, the closed-loop system might become unstable at some operating points. In this paper, a controller design methodology is proposed that will guarantee a stable operation during the entire operating frequency range in both battery charging mode (BCM) and regeneration mode (RM). To validate the proposed controller design methodology, the output current and voltage loop controllers are designed for a 3.5 kW converter. The step response showed a stable system with good transient performance thus validating the proposed controller design methodology. / Ph. D.