SCANNING ACOUSTIC MICROSCOPE FOR CHARACTERIZATION OF ARTERIAL PLAQUE

Unstable arterial plaque is likely the key component of atherosclerosis, a disease which is responsible for two-thirds of heart attacks and strokes, leading to approximately 1 million deaths in the United States. Ultrasound imaging is able to detect plaque but as of yet is not able to distinguish unstable plaque from stable plaque. In this work a scanning acoustic microscope (SAM) was implemented and validated as tool to measure the acoustic properties of a sample. The goal for the SAM is to be able to provide quantitative measurements of the acoustic properties of different plaque types, to understand the physical basis by which plaque may be identified acoustically. The SAM consists of a spherically focused transducer which operates in pulse-echo mode and is scanned in a 2D raster pattern over a sample. A plane wave analysis is presented which allows the impedance, attenuation and phase velocity of a sample to be de- termined from measurements of the echoes from the front and back of the sample. After the measurements, the attenuation and phase velocity were analysed to ensure that they were consistent with causality. The backscatter coefficient of the samples was obtained using the technique outlined by Chen et al [8]. The transducer used here was able to determine acoustic properties from 10-40 MHz. The results for the impedance, attenuation and phase velocity were validated for high and low-density polyethylene against published results. The plane wave approximation was validated by measuring the properties throughout the focal region and throughout a range of incidence angles from the transducer. The SAM was used to characterize a set of recipes for tissue-mimicking phantoms which demonstrate indepen- dent control over the impedance, attenuation, phase velocity and backscatter coefficient. An initial feasibility study on a human artery was performed.This work was supported in part by CenSSIS the Center for Subsurface Sensing and Imaging Systems under the Engineering Research Centers Program of the National Science Foundation (Award EEC- 9986821

IDENTIFYING AND MONITORING THE ROLES OF CAVITATION IN HEATING FROM HIGH-INTENSITY FOCUSED ULTRASOUND

For high-intensity focused ultrasound (HIFU) to continue to gain acceptance for cancer treatment it is necessary to understand how the applied ultrasound interacts with gas trapped in the tissue. The presence of bubbles in the target location have been thought to be responsible for shielding the incoming pressure and increasing local heat deposition due to the bubble dynamics. We lack adequate tools for monitoring the cavitation process, due to both limited visualization methods and understanding of the underlying physics. The goal of this project was to elucidate the role of inertial cavitation in HIFU exposures in the hope of applying noise diagnostics to monitor cavitation activity and control HIFU-induced cavitation in a beneficial manner. A number of approaches were taken to understand the relationship between inertial cavitation signals, bubble heating, and bubble shielding in agar-graphite tissue phantoms. Passive cavitation detection (PCD) techniques were employed to detect inertial bubble collapses while the temperature was monitored with an embedded thermocouple. Results indicate that the broadband noise amplitude is correlated to bubble-enhanced heating. Monitoring inertial cavitation at multiple positions throughout the focal region demonstrated that bubble activity increased prefocally as it diminished near the focus. Lowering the HIFU duty cycle had the effect of maintaining a more or less constant cavitation signal, suggesting the shielding effect diminished when the bubbles had a chance to dissolve during the HIFU off-time. Modeling the effect of increasing the ambient temperature showed that bubbles do not collapse as violently at higher temperatures due to increased vapor pressure inside the bubble. Our conclusion is that inertial cavitation heating is less effective at higher temperatures and bubble shielding is involved in shifting energy deposition at the focus. The use of a diagnostic ultrasound imaging system as a PCD array was explored. Filtering out the scattered harmonics from the received RF signals resulted in a spatially- resolved inertial cavitation signal, while the amplitude of the harmonics showed a correlation with temperatures approaching the onset of boiling. The result is a new tool for detecting a broader spectrum of bubble activity and thus enhancing HIFU treatment visualization and feedback.Gordon Center for Subsurface Sensing and Imaging Systems via NSF ERC Award Number EEC-9986821 and the U.S. Army, award number DAMD17-02-2-0014

Utility Coordination on LPA Project

Utility coordination can make or break a local public agency’s project budget and schedule. The session will educate local public agency (LPA) employees in responsible charge (ERCs) and designers on the utility coordination process, the utility coordinator’s responsibilities, the project manager’s responsibilities, and the LPA ERC’s responsibilities and how they work collectively to remediate utility conflicts during design and avoid conflicts in the field, while maintaining the design and construction schedules and overall project budget

PENINGKATAN KEMAMPUAN BERHITUNG 1-20 MELALUI PERMAINAN PUZZLE DI TK TUNAS MUDA KOTA BANGUN

Untuk mengetahui peningkatkan kemampuan berhitung 1-20 melalui permainan puzzle di TK Tunas Muda Kota Bangun. Penelitian ini dilaksanakan di TK Tunas Muda Kota Banguan semester 2 tahun 2016/2017. Subjek dalam penelitian adalah anak di TK Tunas Muda Kota Bangun. Pelaksanaan pembelajaran adalah penelitian, Teknik pengumpulan data di lakukan melaui dokumentasi dan lembar observasi. Observasi di lakukan padasaat proses pembelajaran, penelitian ini dilaksanakan dalam 3 siklus, yaitu siklus I, siklus II, dan siklus III, setiap siklusnya sebanyak 2 kali pertemuan. Hasil penelitian menunjukan pada siklus I diperoleh nilai rata-rata yaitu 49,65% (Kurang), pada siklus II nilai rata-rata 61,45% (Cukup), pada siklus III niali rata-rata 77,08% (Baik). karean kriteria sudah baik dan nilai yang diperoleh adalah 70% sesuai target sehingga pada siklus III dikatakan berhasil. Dengan demikian dapat disimpulkan bahwa peningkatan kemampuan berhitung melalui permainan puzzle di TK Tunas Muda mengalami peningkatan

Modeling and control design of a contact-based, electrostatically actuated rotating sphere

The performance of micromirrors in terms of their maximum deflection is often limited due to mechanical constraints in the design. To increase the range of achievable deflection angles, we present a novel concept in which a free-lying sphere with a flat side as reflector can be rotated. Due to the large forces needed to move the sphere, multiple electrostatic actuators are used to cooperatively rotate the sphere in iterative steps by impacts and friction. A parameterized system-level model of the configuration is derived, which considers arbitrary multi-contact scenarios and can be used for simulation, analysis, and control design purposes. Due to the complex, indirect relation between the actuator voltages and the sphere motion, model-based numerical optimization is applied to obtain suitable system inputs. This results in rotation sequences, which can be understood as a sequence of motion primitives, thus transforming the continuous time model into an abstract discrete time model. Based on this, we propose a feedback control strategy for trajectory following, considering model uncertainties by a learning scheme. High precision is achieved by an extension controlling the angular change of each rotation step. The suitability of the overall approach is demonstrated in simulation for maximum angles of 40°, achieving angular velocities of approximately 10°/s