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MEMS Wireless Sensor Networks for Spacecraft and Vacuum TechnologyAndrew Strongrich (10691970) 06 May 2021 (has links)
<div>Wireless sensor networks are highly integrated across numerous industries from industrial</div><div>manufacturing to personal health monitoring. They provide several key benefits over</div><div>traditional wired systems including positioning flexibility, modularity, interconnectivity, and</div><div>robust data routing schemes. However, their adoption into certain sectors such as vacuum</div><div>and aerospace has been slow due to tight regulation, data security concerns, and device</div><div>reliability.</div><div>Lyophilization is a desiccation technique used to stabilize sensitive food and drug products</div><div>using vacuum sublimation. A series of wireless devices based on the Pirani architecture are</div><div>developed to quantify the spatial variations in pressure and temperature throughout this</div><div>process. The data is coupled to computational fluid dynamics simulations to estimate the</div><div>sublimation rate over time. This information is then used to quantify the heat and mass</div><div>transfer characteristics of the product, allowing estimates of product temperature and mass</div><div>flux to be obtained for an arbitrary cycle. This capability is significant, having the ability</div><div>to accelerate process development and reduce manufacturing time.</div><div>Drying performance during lyophilization is highly sensitive to the dynamics of the freezing</div><div>process. This work therefore also develops a wireless network to monitor both gas</div><div>pressure and temperature throughout the controlled ice nucleation process, a technique used</div><div>to improve batch uniformity by inducing simultaneous and widespread ice nucleation via</div><div>adiabatic decompression. The effects of initial charge pressure, ballast composition, and vial</div><div>size are investigated. Experimental data is supported by numerical modeling to describe the</div><div>evolution of the true gas temperature during the discharge event.</div><div>Finally, The mechanisms governing the lyophilization process are directly applied to the</div><div>aerospace industry in the form of a novel milliNewton-class evaporation-based thruster concept.</div><div>The device was tested under vacuum using a torsional balance and demonstrated peak</div><div>thrust magnitudes on the order of 0.5 mN. A state observer model was then implemented</div><div>to decouple the dynamics of the balance with the time-dependent thrust input. With this</div><div>model the true time-dependent thrust output and corresponding thruster performance are</div><div>analyzed.</div>
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Gully Erosion and Freeze-Thaw Processes in Clay-Rich Soils, Northeast Tennessee, USABarnes, Nicolas, Luffman, Ingrid, Nandi, Arpita 01 December 2016 (has links)
This study examines gully erosion in northeast Tennessee hillslopes in the Southern Appalachian Valley and Ridge physiographic province, where a thick sequence of red clay Ultisols (Acrisol, according to the World Reference Base for Soil) overlies dolomite and limestone bedrock. The role of freeze-thaw processes in gully erosion was examined weekly from 6/3/2012 to 9/17/2014 using a network of n = 78 erosion pins in three geomorphic areas: channels, interfluves, and sidewalls. Freeze-thaw days were identified using meteorological data collected on site. When freeze-thaw days occurred, erosion and deposition increased and gully conditions were more dynamic. When daily temperature did not plunge below freezing, more stable gully conditions persisted. Ordinary Least Square regression models of erosion pin length using freeze-thaw events explained significant portions of variability in channels (R² = 0.113, p < 0.01), interfluves (R² = 0.141, p < 0.01), and sidewalls (R² = 0.263, p < 0.01). Repeat analysis on only the winter-spring months minimally improved the sidewall model (R² = 0.272, p < 0.01). Erosion in interfluves exhibited a lagged effect, and was best correlated to freeze-thaw events during the prior period while erosion in channels and sidewalls was related to freeze-thaw events in the current week. Of the three geomorphic areas studied, sidewall erosion was best modeled by freeze-thaw events which contribute to widening of gullies through mobilization of sediment and mass wasting. This research demonstrates that freeze-thaw processes are a significant contributor to erosion in gully channels, interfluves, and especially sidewalls, and therefore temperature variability should be considered in erosion studies in similar climates.
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Anthocyanins of Fresh and Stored Freeze-Dried Sour Cherries in Compressed FormPotewiratananond, Suwan 01 May 1975 (has links)
A total of seven anthocyanin pigments were observed in both paper and thin layer chromatograms of the fresh and freeze-dried compressed samples stored for O month whereas the freeze-dried compressed samples stored at 70 F and 100 F for 6 months showed the retention of three to six pigments. All of those seven pigments were unstable and cyanidin-3- (2G- xylosylrutinoside) was the least stable pigment. The separation of anthocyanina by disc gel electrophoresis was studied for the first time. Disc electropherograms of fresh and freeze-dried com-pressed sour cherries stored at O month revealed the presence of eight bands whereas the freeze-dried compressed sour cherries stored at 70 F and 100 F for 6 months showed the retention of three to four bands. In further study, this technique could be helpful for the separation of anthocyanins in other fruits. The study indicated that the fresh samples had anthocyanin content higher than those of the freeze-dried compressed samples stored at 70 F and 100 F for 6 months and also showed that the degradation of anthocyanins is greater at the higher storage temperature with longer storage periods.
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Compression of foods during vacuum freeze dehydration.Emami, Seid-Hossein January 1979 (has links)
Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Nutrition and Food Science, 1979. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND SCIENCE. / Bibliography: leaves 153-157. / Ph.D.
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Freeze tolerance and cryoprotection of erythrocytes from Dryophytes chrysoscelisGeiss, Loren V. 28 August 2018 (has links)
No description available.
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Managing risks of soft red winter wheat production: evaluation of spring freeze damage and harvest date to improve grain qualityAlt, Douglas S., Alt January 2018 (has links)
No description available.
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Mitigation of Undesirable Flavor in Kefir Intended for Adjuvant Treatment of <i>Clostridioides difficile</i> InfectionKesler, Megan Kathleen January 2019 (has links)
No description available.
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Formulace lyofilizovaných tablet pro bukální aplikaci vakcín. / Formulation of freeze dried tablets for buccal application of vaccinesVuová, Ngoc Lien January 2021 (has links)
Charles University, Faculty of Pharmacy in Hradec Králové Department of: Pharmaceutical Technology Mentor: Doc. PharmDr. Zdeňka Šklubalová, Ph.D. Student: Ngoc Lien Vuová Title of Thesis: Formulation of freeze dried tablets for buccal application of vaccines Mucosal vaccines represent an attractive way of vaccination with an advantage of inducing both systemic and local immunity. The aim of this diploma thesis was designing a composition of freeze-dried tablets for buccal administration of a model Bordetella pertusis vaccine. The easy removal from blister, firmness and aesthetic appearance as well as the appropriate taste and mucoadhesivity were the required product quality parameters. The excipients were characterised by differential scanning calorimetry, osmolality and pH measurement; the mechanical properties and disintegration time of freeze-dried tablets were evaluated. Among the variety of studied excipients and their combinations, dextran 40 as the main component of the preparation provided the best results. For the further modification of properties, the addition of fish gelatin, iota carrageenan and macrogol 300 is suitable. Freeze-dried tablets containing trehalose, mannitol and povidon 25 did not achieve the desirable quality parameters. Freeze- dried tablets containing iota carrageenan...
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Freeze-Thaw Durability of Pervious ConcreteDemille, Carson B. 15 July 2008 (has links) (PDF)
Although the use of pervious concrete is expanding, only a limited number of scholarly papers have been published on the resistance of pervious concrete to deterioration under frost action. Based on this need for additional research on the durability of pervious concrete in cold regions, the objective of this research was to evaluate the resistance of pervious concrete to degradation during freeze-thaw cycling under different soil clogging and water saturation conditions. The laboratory research associated with this project involved three primary measures of pervious concrete performance, including freeze-thaw durability, compressive strength, and permeability. Testing associated with freeze-thaw durability involved two levels of soil clogging, two water saturation conditions, and two curing durations in a full-factorial experimental design. Field testing involved measurements of stiffness, permeability, and compressive strength at a single site in Orem, Utah. The factor of water saturation and the interaction between the factors of curing condition and clogging condition played significant roles in testing throughout the entire course of freeze-thaw testing. Regarding the factor of water saturation, specimens that were completely submerged in water during freeze-thaw testing were damaged at a notably faster rate than those specimens that were tested in a moist but unsaturated condition for both curing conditions. Regarding the interaction between the factors of curing condition and clogging condition, the effect of clogging on the number of freeze-thaw cycles to failure depended upon the curing condition. A comparison of in situ modulus values, core modulus values, and core compressive strengths associated with clogged locations and unclogged locations in the field indicated no significant differences in structural properties in the clogged and unclogged locations. Although the results of this research suggest that pervious concrete similar to that evaluated in this study can be successfully used in cold regions under essentially ideal conditions, further laboratory and field research should be performed to more carefully examine the effect of moisture content on the freeze-thaw durability of moist but unsaturated specimens. Also, given that clogging can reduce the freeze-thaw durability of pervious concrete, the efficacy of maintenance procedures available for cleaning partially clogged pervious concrete slabs should be investigated. Long-term monitoring of and supplementary experimentation on the pervious concrete slab tested in this research should be considered for these purposes. More conclusive data about the performance of pervious concrete in cold regions will be derived from such field tests.
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Flexural Performance of Steel Reinforced ECC-Concrete Composite Beams Subjected to Freeze–Thaw CyclesGe, W., Ashour, Ashraf, Lu, W., Cao, D. 11 December 2019 (has links)
Yes / Experimental and theoretical investigations on the flexural performance of steel reinforced ECC-concrete composite beams subjected to freeze–thaw cycles are presented in this paper. Four groups of reinforced composite beams with different ECC height replacement ratios subject to 0, 50, 100 and 150 cycles of freeze–thaw were physically tested to failure. Experimental results show that the bending capacity decreases with the increase of freeze–thaw cycles regardless of ECC height replacement ratios. However, the ultimate moment, stiffness and durability of ECC specimens and ECC-concrete composite specimens are greater than those of traditional concrete specimens, owing to the excellent tensile performance of ECC materials. With the increase of ECC height, the crack width and average crack spacing gradually decrease. According to materials’ constitutive models, compatibility and equilibrium conditions, three failure modes with two boundary failure conditions are proposed. Simplified formulas for the moment capacity are also developed. The results predicted by the simplified formulas show good agreement with the experimental moment capacity and failure modes. A parametric analysis is conducted to study the influence of strength and height of ECC, amount of reinforcement, concrete strength and cycles of freeze–thaw on moment capacity and curvature ductility of ECC-concrete composite beams.
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