In November 2000, the 4th Workshop on Measurement Techniques for Stationary and Transient Multiphase Flows took place in Rossendorf. Three previous workshops of this series were national meetings; this time participants from different countries took part. The programme comprised 14 oral presentations, 9 of which are included in these proceedings in full length. A special highlight of the meeting was the main lecture "Ultrasonic doppler method for bubbly flow measurement" of Professor Masanori Aritomi, Dr. Hiroshige Kikura and Dr. Yumiko Suzuki, which was read by Dr. Hiroshige Kikura. The workshop again dealt with high-resolution phase distribution and phase velocity measurement techniques based on electrical conductivity, ultrasound, laser light and high-speed cinematography. A number of presentations were dedicated to the application of wire-mesh sensors developed by FZR for different applications used by the Technical Universities of Delft and Munich and the Tokyo Institute of Technology. The presentations were in particular: M. Aritomi, H. Kikura, Y. Suzuki (Tokyo Institute of Technology): Ultrasonic doppler method for bubbly flow measurement V. V. Kontelev, V. I. Melnikov (TU Nishny Novgorod): An ultrasonic mesh sensor for two-phase flow visualisation A. V. Duncev (TU Nishny Novgorod): Waveguide ultrasonic liquid level transducers for power generating equipment H.-M. Prasser, E. Krepper, D. Lucas, J. Zschau (FZR), D. Peters, G. Pietzsch, W. Taubert, M. Trepte (Teletronic Ingenieurbüro GmbH), Fast wire-mesh sensors for gas-liquid flows and decomposition of gas fraction profiles according to bubble size classes D. Scholz, C. Zippe (FZR): Validation of bubble size measurements with wire-mesh sensors by high-speed video observation A. Manera, H. Hartmann, W.J.M. de Kruijf, T.H.J.J. van der Hagen, R.F. Mudde, (TU Delft, IRI): Low-pressure dynamics of a natural-circulation two-phase flow loop H. Schmidt, O. Herbst, W. Kastner, W. Köhler (Siemens AG KWU): Measuring methods for the investigation of the flow phenomena during external pressure vessel cooling of the boiling water reactor SWR1000 A. Traichel, W. Kästner, S. Schefter, V. Schneider, S. Fleischer, T. Gocht, R. Hampel (HTWS Zittau/Görlitz - IPM): Verification of simulation results of mixture level transients and evaporation processes in level measurement systems using needle-shaped probes S. Richter, M. Aritomi (Tokyo Institute of Technology): Methods for studies on bubbly flow characteristics applying a new electrode-mesh tomograph

Thesis advisor: Matthias M. Waegele / Studying the visible light-driven photoredox catalysis coupled with transition-metal complexes is of overriding importance in the development of synthetic strategy. Comparing to conventional thermal catalysis, reactions catalyzed and/ or initiated by photon energy are not only attractive for establishing a more sustainable system, but also for their unique reactivity that has previously been inaccessible. However, one issue draws our attention is that such photoredox catalytic schemes often suffer from a limited substrate scope. To develop more efficient and effective synthetic strategies applicable to broader range of substrates, it is of our interest to construct an functional and reliable instrument to identify the critical mechanistic steps that lead to low product yield. To this end, we designed a time-resolved visible-pump/ infrared-probe spectroscopic measurement technique to monitor reaction dynamics in-situ. Using our transmission infrared setup, we effectively demonstrated in-situ photoexcitation and decay process of Tris(2,2′-bipyridyl)dichlororuthenium(II) hexahydrate in deuterated acetonitrile. In addition, to optimize signal resolution, an electronic filter was installed in one of the data-collecting channels to allow for concurrent AC-coupled and DC-coupled signal recording. A series of chopper wheel experiments was conducted to assure the functionality of the system and reliability of obtained data. / Thesis (MS) — Boston College, 2020. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Chemistry.

No description available.

Compliant electronics are an emerging class of electronics which offer physical flexibility in their structure. Such mechanical flexibility opens up opportunities for wide ranging applications. Nonetheless, compliant electronics which can be functional in unusual environments are yet to be explored. Unusual environment can constitute a harsh environment where temperature and/or pressure is much higher or lower than the usual room temperature and/or pressure. Unusual environment can be an aquatic environment, such as ocean/sea/river/pond, industrial processing related liquid and bodily fluid environment, external or internal for implantable electronics. Finally, unusual environment can also be conditions when extreme physical deformation is anomalously applied to compliant electronics in order to understand their performance and reliability under such extraordinary mechanical deformations. Therefore, in this thesis, three different aspects of compliant electronics are thoroughly studied, addressing challenges of material selection/optimization for unusual environment applications, focusing on electrical performance and mechanical flexible behavior. In the first part, performance of silicon-based high-performance complementary metal oxide semiconductor (CMOS) devices are studied under severe mechanical deformation. Next, a high-volume manufacturing compatible solution is offered to reduce the usage of toxic chemicals in semiconductor device fabrication. To accomplish this, Germanium Dioxide (GeO2) is simultaneously used as transient material and dielectric layer to realize a dissolvable/bioresorbable transient electronic system which can be potentially used for implantable electronics. Finally, wide bandgap semiconductor Gallium Nitride is studied to understand its mechanical flexibility under high temperature conditions. In summary, this research contributes to the advancement of material selection, optimization and process development towards achieving compliant and transient devices for novel applications in unusual environments.

No description available.

Today’s energy infrastructure will need to rapidly expand in terms of reliability and flexibility due to aging infrastructure, changing energy market conditions, projected load increases, and system reliability requirements. Over the few decades, several states in the U.S. are now requiring an increase in wind penetration. These requirements will have impacts on grid reliability given the inherent intermittency of wind generation and much research has been completed on the impact of wind on grid reliability. Energy storage has been proposed as a tool to provide greater levels of reliability; however, little research has occurred in the area of wind with storage and its impact on stability given different possible scenarios. This thesis addresses the impact of wind farm penetration on transient stability when energy storage is added. The results show that battery energy storage located at the wind energy site can improve the stability response of the system.

Abstract available through the Journal of Investigative Medicine.

Thermal switch is very important in today’s world and it has varies of applications including heat dissipation and engine efficiency improving. The commercial thermal switch based on mechanical design is very slow and the structure is too complicated to make them smaller. To enable fast thermal switch as well as to make thermal switch more compact, I try to use second-order phase transition material to enable our thermal switch. Noticing the transition properties of thermoresponsive polymer for drug delivery, its potential in thermal switch can be expected. I used Poly(N-isopropylacrylamide) (PNIPAM) as an example to show the abrupt thermal conductivity change of thermoresponsive polymer solutions below and above their phase transition temperature. A novel technique, transition grating method, is used to measure the thermal conductivity. The ratio of thermal switch up to 1.15 in transparent PNIPAM solutions after the transition is observed. This work will demonstrate the new design of using second-order phase transition material to enable fast and efficient thermal switch. / Master of Science / Controllable thermal conductivity (thermal switching) is very important to thermal management area and useful in a wide area of applications. Nowadays, mechanical thermal conductivity controller device suffers from large scale and slow transition speeds. To solve these problems, I tired the phase transition thermoresponsive polymers to create quick thermal switching because the thermal conductivity will change with the phase. Thermoresponsive polymers show sharp phase changes upon small changes in temperature. Such polymers are already widely used in biomedical-like applications, the thermal switch applications are not well-studied. In this work, I tested Poly(N-isopropylacrylamide) (the abbreviation is PNIPAM) as an example to show the quick thermal conductivity changing ability of thermoresponsive polymer when the transition was happened .I used a novel approach, called the TTG, transient thermal grating. It has easy setup and high sensitivity. The thermal conductivity switching ratio as high as 1.15 in transparent PNIPAM solutions after transition is observed. This work will give new opportunities to control thermal switches using the phase change of thermoresponsive material or abrupt other phase change material in general.

<p> 1,1-Bis(4-(trifluoromethyl)phenyl)germacyclobutane and 1,1-bis(3,5-bis(trifluoromethyl)phenyl)germacyclobutane have been prepared, and their photochemistry studied by steady state and nanosecond laser flash photolysis (NLFP) techniques. Photolysis of the two compounds in the presence of methanol leads to the formation of products resulting from reaction of the alcohol with two germanium-containing reactive intermediates, the germenes and germylenes.</p> <p> The reactivities of the two germenes with nucleophiles such as alcohols, carboxylic acids, and amines have been examined by NLFP techniques, and the results are compared to analogous data for 1,1-diphenylgermene and 1,1-diphenylsilene. Germene reactivity is shown to increase with increasing electron-withdrawing power of the substituents, consistent with a mechanism initiated by nucleophilic attack at germanium. The increased electrophilicity of the substituted 1,1-diarylgermenes results in kinetic behavior indistinguishable from that of 1,1-diphenylsilene, indicating that germenes and silenes form a mechanistic continuum in their reactions with nucleophiles.</p> / Thesis / Master of Science (MSc)

In many Resistance-Capacitance Oscillators the oscillation amplitude is controlled by the use of a temperature-dependent resistor incorporated in the negative feedback loop. The use of thermistors and tungsten lamps is discussed and an approximate analysis is presented for the behaviour of the tungsten lamp. The result is applied in an analysis of the familiar Wien Bridge Oscillator both for the presence of a linear circuit and a cubic nonlinearity. The linear analysis leads to a highly unstable transient response which is uncommon to most oscillators. The inclusion of the slight cubic nonlinearity, however, leads to a result which is in close agreement to the observed response. / Thesis / Master of Engineering (MEngr)