Download or read book Study of Phase Change Dynamics by a Frequency Response Technique written by Argyrios J Lygeros and published by . This book was released on 1967 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Dynamics and Rheology of Soft Phase change Materials written by Michela Geri and published by . This book was released on 2019 with total page 353 pages. Available in PDF, EPUB and Kindle. Book excerpt: Many industrial processes involve multicomponent or composite materials in which one component can undergo a phase transition leading to the appearance of a solid phase dispersed in a liquid-like continuous phase. Examples of soft phase-change materials can be found in a variety of applications from food products (e.g., organogels, casein gels and gelatin), pharmaceutical products (e.g., tissue mimicking phantoms and encapsulating agents), cosmetics (e.g., foundations and lipsticks), and in the oil and gas industry, where formation of paraffin waxes and clathrate hydrates represent major issues for upstream production and flow assurance. Historically, phase-changing materials have been exploited for their unique thermal properties in energy storage applications, however soft solids and complex fluids that undergo phase transformation have broader impact in industrial and biomedical applications because of the dramatic changes in mechanical properties that result from the conditions across the phase transition. Typically, these soft phase-change materials are part of the broader class of elasto-visco-plastic materials, showing both viscoelasticity at small deformations and plasticity at large deformations. However, their material properties are greatly influenced by the specific processing conditions during formation, such as temperature and applied deformation, leading to a thermo-rheological complexity that still poses major challenges for their experimental and theoretical characterization. In this Thesis, we develop novel experimental protocols and theoretical frameworks to characterize and describe the complex rheological behavior of soft phase-changing materials, under both linear and non-linear deformations. We focus mainly on two types of materials that are of major importance in the oil and gas industry: paraffin gels, as model waxy crude oils, and clathrate hydrate suspensions. In the limit of small deformations, we are usually interested in measuring the frequency response of the material as it evolves, or mutates, over time. Current state-of-the-art techniques have major limitations in providing both time- and frequency-resolution primarily due to the type of input signals used. To overcome this, we develop a robust excitation signal that allows us to perform time-resolved mechanical spectroscopy of fast mutating systems. Inspired by the biosonar signals of bats and dolphins, we introduce a joint frequency- and amplitude- modulated chirp signal. Combining experiments and numerical simulations, we show that there exists an optimized range of amplitude modulation that minimizes the estimation error while reducing the total acquisition time by almost two orders of magnitude. With this new technique, which we call the Optimally Windowed Chirp (or OWCh), we then explore the phase transition during gelation of a series of mutating, phase-changing materials, including casein gels, gelatin and paraffin gels. To address large, non-linear deformations, we start from a thorough investigation of the steady state and transient response of paraffin gels under shear. We develop a robust protocol that enables us to systematically extract the main rheological features including the thermokinematic memory (i.e. the effect of thermal and shear history on the rheological behavior of the gel) and thixotropy (i.e. the time-dependent behavior under constant applied deformation). We show that these features can be understood in terms of microstructural rearrangements of the underlying solid particle network, which can be quantified through differential scanning calorimetry, birefringence imaging and rheometry. Based on this understanding, we present a constitutive framework that captures all of the different features while respecting thermodynamic and objectivity constraints. We also investigate mechanical instabilities that may arise during rheological measurements. Combining ultrasonic image velocimetry and rheometry, we show that both shear banding and slip can take place during steady shear below a critical value of the shear rate. However, the thixotropic nature of these materials precludes the banding instability from growing in the sheared region of the gap, ensuring that the measured stress response corresponds to the real bulk behavior. Finally, we study the visco-plastic response of clathrate hydrate suspensions. To do so, we develop a novel method to robustly control their formation, which so far has been a major issue in experimental studies due to uncontrolled nucleation and growth of hydrate crystals. Our method, based on the use of "frozen emulsions", decreases the induction time by orders of magnitude while guaranteeing that all the water droplets initially frozen into ice particles are converted into hydrate particles. Rheological measurements for different water volume fractions and shear rates reveal that the macroscopic rheological response is again governed by rearrangements of the microstructure; however, due to the very strong interparticle forces (which are the result of a continuous sintering process) the microstructure evolves towards a fully connected network that behaves as a porous solid structure. Incorporating this limit into our theoretical model, we show that the framework developed for softer interparticle interaction can also capture the macroscopic plastic response of hydrate suspensions. The results from this Thesis have the potential to impact many industrial processes that involve soft phase-change materials, such as flow assurance and oil extraction, thermal energy storage, gas transport and storage, and other processes where the dynamics of gelation are used to control the rheological properties of the ultimate product.
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1995 with total page 704 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Dissertation Abstracts International written by and published by . This book was released on 1970 with total page 1090 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book University of Michigan Official Publication written by University of Michigan and published by UM Libraries. This book was released on 1984 with total page 274 pages. Available in PDF, EPUB and Kindle. Book excerpt: Each number is the catalogue of a specific school or college of the University.
Download or read book OAR written by and published by . This book was released on 1967 with total page 570 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Terahertz Biomedical Science and Technology written by Joo-Hiuk Son and published by CRC Press. This book was released on 2014-06-13 with total page 374 pages. Available in PDF, EPUB and Kindle. Book excerpt: A number of applications including scientific spectroscopy, security screening, and medical imaging have benefitted from the development and utilization of new and emerging terahertz (THz) generation and detection techniques. Exploring recent discoveries and the advancements of biological behaviors through THz spectroscopy and imaging and the devel
Download or read book Research and Technology Program Digest Flash Index written by and published by . This book was released on 1967 with total page 794 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Publications of the National Institute of Standards and Technology Catalog written by National Institute of Standards and Technology (U.S.) and published by . This book was released on 1994 with total page 1162 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Nuclear Science Abstracts written by and published by . This book was released on 1967 with total page 894 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Air Force Research Resum s written by and published by . This book was released on with total page 572 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Comprehensive Dissertation Index written by and published by . This book was released on 1973 with total page 976 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Science and Technology of High Pressure written by Murli H. Manghnani and published by Universities Press. This book was released on 2000 with total page 650 pages. Available in PDF, EPUB and Kindle. Book excerpt: These books presents a wide spectrum of research and development activities in the field of High Pressure Science and Technology. These book provide comprehensive and interdisciplinary descriptions of recent research accomplishments in the biological, chemical, Earth, materrals, physical, physiological and related sciences.
Download or read book Van Nostrand s Scientific Encyclopedia written by Douglas M. Considine and published by Springer Science & Business Media. This book was released on 2013-12-11 with total page 3529 pages. Available in PDF, EPUB and Kindle. Book excerpt: Advancements in science and engineering have occurred at a surprisingly rapid pace since the release of the seventh edition of this encyclopedia. Large portions of the reference have required comprehensive rewriting and new illustrations. Scores of new topics have been included to create this thoroughly updated eighth edition. The appearance of this new edition in 1994 marks the continuation of a tradition commenced well over a half-century ago in 1938 Van Nostrand's Scientific Encyclopedia, First Edition, was published and welcomed by educators worldwide at a time when what we know today as modern science was just getting underway. The early encyclopedia was well received by students and educators alike during a critical time span when science became established as a major factor in shaping the progress and economy of individual nations and at the global level. A vital need existed for a permanent science reference that could be updated periodically and made conveniently available to audiences that numbered in the millions. The pioneering VNSE met these criteria and continues today as a reliable technical information source for making private and public decisions that present a backdrop of technical alternatives.
Download or read book Proceedings of the Sixth Meeting on Ferroelectricity written by and published by . This book was released on 1985 with total page 1118 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Research and Technology written by Goddard Space Flight Center and published by . This book was released on 1985 with total page 156 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Energy Research Abstracts written by and published by . This book was released on 1990 with total page 712 pages. Available in PDF, EPUB and Kindle. Book excerpt:
