The current test methods that evaluate the liquid water resistance performance of a water resistive barrier (WRB) have various drawbacks. A Hydrostatic Pressure Test Apparatus (HPTA) provided by SMT Research Ltd. was used to develop a unique test method to detect liquid water penetration through WRBs. The sensor used in HPTA has 42 channels and each channel reads an individual electric resistance. Lower electric resistance indicates more liquid water penetrates the sensor, vice versa. The measurement system of the device was studied and tested. The results showed the measurement system works properly to detect amount change of the liquid water applied to the sensor while there is no proportional relationship between the amount of liquid water and electrical resistance. The change between two adjacent electrical readings was evaluated by a factor called Normalized Difference Vegetation Index (NDMI). The NDMI factor was determined to be a better measurement than the value of electrical resistance. Preliminary tests using HPTA with Membrane D and Membrane F were done and the apparatus was found to have water leaking through the joint. The clamping method of HPTA was then modified to solve the problem and further WRBs were tested using the modified device. Six WRB materials, Membrane A, Membrane B, Membrane C, Membrane D, Membrane E and Membrane F were tested and 83 tests were conducted in total. A colormap method was used to evaluate the water resistance ability of each material. Among all materials, Membrane E had the highest water resistive duration of long and a water resistance score (WRS) of 337.14. Membrane F had a lower duration of short and a WRS of 78.75. Membrane C and Membrane D have water resistance durations between very short and short and their WRS were 36.5 and 82.71. Membrane A and Membrane B had the lowest water resistance duration of very short and their WRS were 15.15 and 23.19. Plots of Log R vs. Time and NDMI vs. Time of the edge sensors and center sensors were plotted in MATLAB. The water movement behaviours in the two groups of sensors varied by materials. / Graduate / 2023-06-22

No description available.

A new resistive Geodesic Acoustic Mode (GAM) theory is developed by two-fluids analysis and resistive gyro-kinetic formulation in this thesis. An analytical expression is obtained for the resistive GAM frequency. This theory suggests a large collision frequency will prohibit the parallel current in tokamak, which establishes the cross-field charge neutrality condition ∇·J⊥= 0 for the existence of GAM at the edge plasma of tokamak. Therefore, the resistive GAM theory provides a more plausible explanation to edge GAM phenomena. Various probe arrays are designed and installed in the STOR-M tokamak to search for the poloidal GAM phenomena. A series of experiments were conducted in the L-mode and RMP discharges. The FFT and wavelet analyses indicate the existence of GAM phenomena in STOR-M, and the observed GAM frequencies match the theoretical predication using the resistive GAM model.

Resistive Random Access Memory (RRAM) is considered as the most promising candidate for the next-generation nonvolatile memories due to their superior properties such as low operation voltage, fast operation speed, non-destructive read, simple metal-insulator-metal (MIM) sandwich structure, good scale-down ability. The main targets of this research are to clarify the corresponding physical mechanism, develop the potential material and structure of RRAM and stabilize the resistive switching characteristics, in which clarifying the physical mechanism will be the key factor for RRAM into production in the future. Recent research has suggested that variation of the low and high resistance states in RRAM could be caused due to the by instability in the formation and /disruption of the filament. In addition, the endurance and stability of RRAM may be related to the dissipation of oxygen ions in the switching layer. In this study, new material (Si Introduced) and structure (oxygen confined layer) are employed to improve RRAM performance and to clarify the physical mechanism. Furthermore, constant switching energy results can be used to select the optimal materials and structures also can be used to correctly allocate voltage and time to control RRAM. The detail physical mechanism is studied by the stable RRAM device (Ti/HfO2/TiN) which is offered from Industrial Technology Research Institute (ITRI). The switching process is proved as the formation/disruption of the filament. Furthermore, the dynamic switching behaviors during reset procedure in RRAM were analyzed by the sequential experimental design to illustrate the procedure of atomic quantized reaction at the ultra-cryogenic temperature.

No description available.

This thesis is devoted in two associated topics: a unique laser facility for researches of gaseous detectors; the investigations of Resistive Plate Chamber (RPC) detectors and the measurement of gas parameters in a realistic condition of timing RPC. A pulsed UV laser test facility has been assembled in HZDR. The focus of pico-second laser pulses is placed in a specific position in a gaseous detector sample to produce laser plasma, where free electrons are generated in ionizations with well defined number, micro-meter spatial accuracy in a volume of micro-meter scale. It provides a method, independent from accelerators, to make investigations with gaseous detectors in a laboratory. Samples of RPC detectors are designed and assembled for experiments with the laser test facility. Methods are developed to acquire the waveforms of electron avalanches for different drift lengths and to obtain the key gas parameters: the effective Townsend coefficient and the electron drift velocity. We have succeeded in the direct measurement of gas parameters at the field strength of timing RPC under atmospheric pressure for the first time in experimental conditions. The research has obtained different achievements. The laser test facility is proven to be qualified for the measurement of gas parameters, and has a potential to contribute to the eco-gas research for future RPC. The possible measurement range of electric field of gas parameter at atmospheric pressure is extended by a factor of two, from the range of trigger RPC to timing RPC. The results of experiments have revealed some fundamental mechanisms, which will extend the understanding of RPC performance and electron avalanche process.

No description available.

In this work, the properties of the liposomes, the artificially created vesicles by various methods, are explored by a resistive pulse method using micropipettes. The fact that vesicles are fundamental in the wide range of functionalities they fulfill as organelles strengthen the desire of understanding the properties of them. The motivation of this work comes from the significant roles that liposomes play in the development of targeted drug delivery systems. Among other significant variables, the size of liposomes is found to be one of the dominating parameters in liposome based drug delivery, and the correlation between liposome size and delivery efficiency is discussed. To help improving the size evaluation ability, a few mainstream methods for liposome size detection and measurements are reviewed. As a reliable and accessible alternative method for liposomes detection, the resistive pulse method is introduced and the measurement on liposomes size change upon pH gradient was performed using this method. With our current liposome composition, we found the size increases as environmental pH increases. Further investigation is performed with vesicular pH=6, 7, and 8, respectively. Lastly, the stability of the small unilamellar vesicles (SUV) was studied via resistive pulse method, by monitoring the size change of 50nm liposomes as function of time. A significant size change in freshly prepared 50nm liposomes is recorded. This information will provide invaluable knowledge for targeting tumor with tight tissues, where small size liposomes are needed.

There is an increased interest in the Conductive Bridge Random Access Memory (CBRAM) and Resistive Random Access Memory (RRAM) because of their excellent scaling potential, low power consumption, high switching speed, good retention and endurance properties. Although, various mechanisms have been proposed to explain the switching behavior in CBRAM devices, i.e. metal ion migration and subsequent formation and rupture of conductive filament, formation of conductive path via oxygen ion transport etc, there are still many aspects of these mechanisms that are little understood or are being disputed. This work probes the details of the switching mechanisms on a new level and asks questions like: 1) How is the formation of nanofilament affected by various degrees of Cu diffusion stopping power of the inert electrode? To answer this question, resistive switches with very thin Cu layers covering the Pt electrode were fabricated and analyzed. 2) How does a limited source of active ions impact the formation and rupture of nanofilaments? To answer this question, new samples with limited Cu supply were fabricated and analyzed. 3) What is the mechanism of nanofilament formation in Pt/TaOx/Pt resistive switches where the active copper electrode is removed and replaced by inert Pt electrode. 4) What are the most suitable conditions (material structure of the device and operation conditions) to set and reset multi nanofilaments? This work summarizes the current status of analysis of the data obtained while attempting to explain interesting phenomena like volatile switching and multiple filament formation experienced by modifying the switch structures. / Master of Science

The use of inflatable, rigidizable structures in solar arrays and other space structures has the potential to drastically reduce the weight, volume, and cost of placing payloads into orbit. Inflatable components consist of ultra-lightweight, flexible materials that enable compact packaging prior to launch. These structures are then transformed from their initially flexible state to one that offers permanent shape-holding and structural integrity through a tailored rigidization process. Inflatable spacecraft must be impervious to the environmental conditions in space--such as ionizing radiation, UV and particle radiation, atomic oxygen, and impacts from space debris and meteoroids. They must also exhibit stable operation over a useful storage and mission life. Methods for causing rigidization in inflatable spacecraft include both passive and active techniques. Passive techniques rely on an uncontrolled, unprovoked reaction between the rigidizable materials in the structure and the surrounding space environment. The benefits of a passive system are offset by their inherent lack of control, which can lead to long curing times and weak spots due to uneven curing. This work presents internal resistive heating as an alternative approach for inducing matrix consolidation and curing of thermoset-coated carbon fiber tows. The ability to dictate this physical transformation through temperature-controlled resistive heating highlights the responsive nature of thermoset polymer composites and demonstrates the advantages of active rigidization. Feedback temperature control is implemented so as to provide a reliable, robust heating method for prescribing material-specific curing profiles. Resistive heating curing schedules developed from previous thermal analysis on two resins, U-Nyte Set 201A and 201B, are prescribed for samples of carbon fiber tow coated with each resin. The rigidization success of each curing profile is then evaluated with respect to both the increase in mechanical stiffness and the cure completion. These experiments indicate that rigidizing the coated fiber tow results in a composite material that is 20 times stronger in bending than prior to curing. The stiffening process requires roughly 1W-hr of energy with 5W peak power over the course of a 24-minute curing schedule. Curing temperature, curing time, and heating rate are also individually varied to determine their effect on rigidization as well as develop methods for reducing curing time and energy. The rigidization of an inflatable structure culminates this work and demonstrates the ability to achieve real strengthening through temperature-controlled internal resistive heating. / Master of Science