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Cerebrovascular diseases, such as stroke, constitute the most common life-threatening neurological disease in the United States. To support normal brain function, maintaining adequate brain perfusion (i.e., cerebral blood flow (CBF)) is important. Therefore, it is crucial to assess the brain perfusion so that early intervention in cerebrovascular diseases can be applied if abnormal perfusion is observed. The goal of my study is to develop metrics to measure the brain perfusion through modeling brain physiology using resting-state and task-based blood-oxygenation-level- dependent (BOLD) functional MRI (fMRI). My first and second chapters focused on deriving the blood arrival time using the resting-state BOLD signal. In the first chapters, we extracted the systemic low-frequency oscillations (sLFOs) in the fMRI signal from the internal carotid arteries (ICA) and the superior sagittal sinus (SSS). Consistent and robust results were obtained across 400 scans showing the ICA signals leading the SSS signals by about 5 seconds. This delay time could be considered as an effective perfusion biomarker that is associate with the cerebral circulation time (CCT). To further explore sLFOs in assessing dynamic blood flow changes during the scan, in my second chapter, a “carpet plot” (a 2-dimensional plot time vs. voxel) of scaled fMRI signal intensity was reconstructed and paired with a developed slope-detection algorithm. Tilted vertical edges across which a sudden signal intensity change took place were successfully detected by the algorithm and the averaged propagation time derived from the carpet plot matches the cerebral circulation time. Given that CO2 is a vasodilator, controlling of inhaled CO2 is able to modulate the BOLD signal, therefore, as a follow-up study, we focused on investigating the feasibility of using a CO2 modulated sLFO signal as a “natural” bolus to track CBF with the tool developed from the second chapter. Meaningful transit times were derived from the CO2-MRI carpet plots. Not only the timing, the BOLD signal deformation (the waveform change) under CO2 challenge also reveals very useful perfusion information, representing how the brain react to stimulus. Therefore, my fourth chapter focused on characterizing the brain reaction to the CO2 stimulus to better measure the brain health using BOLD fMRI. Overall, these studies deepen our understanding of fMRI signal and the derived perfusion parameters can potentially be used to assess some cerebrovascular diseases, such as stroke, ischemic brain damage, and steno-occlusive arterial disease in addition to functional activations.

Supplemental material, sj-pdf-1-jcb-10.1177_0271678X221074639 for Coupling between cerebrovascular oscillations and CSF flow fluctuations during wakefulness: An fMRI study by Ho-Ching (Shawn) Yang, Ben Inglis, Thomas M Talavage, Vidhya Vijayakrishnan Nair, Jinxia (Fiona) Yao, Bradley Fitzgerald, Amy J Schwichtenberg and Yunjie Tong in Journal of Cerebral Blood Flow & Metabolism

The transmission line grounding device is an important electrical equipment to avoid accidents of lightning. A new type intelligent detection system of transmission line grounding device is designed for the transmission line and tower of multi-lead line grounding, the detection method of transmission line integrated grounding devices and the fault identification method are proposed, and the practical application is also deployed. The system integrates GPS and remote communication function, can recognize the name of transmission lines and the number of tower, and report the measurement data automatically and remotely. The system provides a kind of new equipment and system platform for the daily maintenance and management of transmission line grounding device.

Perfusion MRI is a promising tool used in assessing stroke, brain tumors, and patients with neurodegenerative diseases. However, common perfusion MRI techniques have several disadvantages, such as using exogenous contrast agents, low signal-to-noise ratio and long acquisition time. In this study, we used a computer-controlled gas delivery system RespirAct TM. This system provides a reliable carbon dioxide based vasoactive stimulus. This stimulus will immediately generate large and reliable functional magnetic resonance imaging (fMRI) signals, which can be used for perfusion imaging. Each subject was required to have three sequential magnetic resonance imaging (MRI) scans, which are structural scan, resting state fMRI scan while breathing room air, and fMRI scan while breathing a sequence of gases. Crucial perfusion parameters such as cerebrovascular reactivity (CVR) maps and time of arrival (TOA) maps were derived. CVR is defined as the change in cerebral blood flow in response to vasoactive stimuli. TOA maps reflect the blood arrival time at each voxel. It has been demonstrated that many cerebral vascular diseases can alter the CVR and TOA maps. By using accurate gas delivery system in perfusion MRI study, accurate CVR and TOA maps are derived, which will be applied for the early detection and diagnosis of various brain diseases.

Based on the demand for deep-sea submarine cable salvage in Northeast Asia, a mathematical model of Sub Marine Tracked Vehicle-Cable Salvage (SMT-CS) was designed in this study. Considering the slip characteristics of the submarine track, the mechanical model of the SMT-CS during steady-state steering was simplified to obtain the kinetic equation of the vehicle body during steady-state steering. According to the steering geometrical relationship, the arbitrary shear rate and shear displacement of the ground plane during the steering process were solved. Combined with the empirical shear model of bottom sediments, the longitudinal driving force, lateral resistance and resistance moment of the larboard and starboard were derived during steady-state steering. The functional relationship between the lateral shift of instantaneous center of the conventional steering rate and the turning radius and angular velocity of the vehicle body as well as that between the slipping rate and the turning radius and angular velocity of the vehicle body was derived according to the geometrical relationship of steering motion. These are of great reference value to the design, performance prediction and maritime application of SMT-CS in the future.

The submarine cable salvage robot needs energy storage device as power supply or backup power supply when working underwater. The optimal control strategy of load distribution can realize the reasonable distribution of electric load among multiple energy storage devices according to the different residual capacity of energy storage devices, thus improving the energy utilization efficiency of energy storage devices and prolonging the operation time of salvage robots.