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Implementation of an in‐field CMOS frequency division multiplexer for 9.4 T magnetic resonance applications
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Mazin Jouda Oliver G. Gruschke Jan G. Korvink 《International Journal of Circuit Theory and Applications》2015,43(12):1861-1878
This paper introduces the implementation of an application‐specific complementary metal oxide semiconductor frequency division multiplexer as a novel solution to interface magnetic resonance (MR) phased arrays of micro‐detectors to an image‐processing unit, thus reducing the complexity and space issues associated with MR detector arrays. The frequency multiplexer, in a compact 3 × 4 mm silicon die, is designed to operate at 400 MHz, which is the Larmor frequency of 1H protons in a 9.4‐T MR imaging system. The system implements eight channels, where each channel consists of a low‐noise amplifier, a frequency mixer, and a band‐pass filter. The maximum gain of an individual channel after the band‐pass filter stage is 38 dB. The suppression of the local oscillator ranges from 40 to ?51 dB, and the maximum coupling between channels is ?39 dB. The input dynamic range of an individual channel is 8 mV. Each channel consumes 54 mA from a 3.3‐V source. The chip operates without errors within a high 9.4‐T magnetic field. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
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Christoph Ehlers Moritz Schröder Georg Fieg 《American Institute of Chemical Engineers》2015,61(5):1648-1662
The implementation of a vertical dividing wall (DW) into a distillation column is a well‐known concept which can result in considerable energy savings for the separation of multicomponent mixtures. It is commonly known that heat streams across the DW, which are present due to temperature differences between both sides, may either increase or decrease the energy demand for a certain separation task. However, no work has been published so far which explains the maximum influence on energy demand. This article derives the maximum extent to which the minimum energy demand for a given column design can change due to heat transfer across the DW. Additionally, it is illustrated how energy‐efficient column operation can be assured even if the total amount of transferred heat is unknown. These results show that the phenomenon of heat transfer across the DW can be handled very well with a suitable control strategy. © 2015 American Institute of Chemical Engineers AIChE J, 61: 1648–1662, 2015 相似文献
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Annegret Potthoff Robert Kratzsch Maria Barbosa Nick Kulissa Oliver Kunze Filofteia-Laura Toma 《Journal of Thermal Spray Technology》2018,27(4):710-717
Compositions in the system Cr2O3-TiO2-Al2O3 are among the most used ceramic materials for thermally sprayed coating solutions. Cr2O3 coatings present good sliding wear resistance; Al2O3 coatings show excellent insulation behavior and TiO2 striking corrosion properties. In order to combine these properties, coatings containing more than one oxide are highly interesting. The conventional spraying process is limited to the availability of binary feedstock powders with defined compositions. The use of suspensions offers the opportunity for tailor-made chemical compositions: within the triangle of Cr2O3-TiO2-Al2O3, each mixture of oxides can be created. Criteria for the selection of raw materials as well as the relevant aspects for the development of binary suspensions in the Cr2O3-TiO2-Al2O3 system to be used as feedstock for thermal spraying are presented. This formulation of binary suspensions required the development of water-based single-oxide suspensions with suitable behavior; otherwise, the interaction between the particles while mixing could lead up to a formation of agglomerates, which affect both the stability of the spray process and the coating properties. For the validation of this formulation procedure, binary Cr2O3-TiO2 and Al2O3-TiO2 suspensions were developed and sprayed using the S-HVOF process. The binary coatings were characterized and discussed in terms of microstructure and microhardness. 相似文献
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Compressive and thermal characterization of syntactic foams containing hollow silicon carbide particles with porous shell
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Matthew Labella Vasanth Chakravarthy Shunmugasamy Oliver M. Strbik III Nikhil Gupta 《应用聚合物科学杂志》2014,131(17)
Silicon carbide hollow particle (SiCHS) reinforced vinyl ester matrix syntactic foams are prepared and characterized for compressive properties and coefficient of thermal expansion (CTE). Two types of SiCHS were utilized in 60 vol % to prepare syntactic foams. These SiCHS had ratio of inner to outer radius of 0.91 and 0.84 for the thin and thick walled particles. The specific compressive strength values were 33.4 and 38.8 kPa/kg/m3 and the specific compressive modulus values were 0.8 MPa/kg/m3 and 0.6 MPa/kg/m3 for the thin and thick walled SiCHS‐filled syntactic foams, respectively. The shell of the hollow particles contained microporous voids, and the porosity was estimated as 16.6% and 24.8% in the walls of the thin and thick walled particles, respectively. The shell porosity adversely affected the specific compressive strength and the modulus of the syntactic foam. However, the SiCHS‐filled syntactic foams exhibited low CTE values (26.7 and 15.9 × 10?6/°C). These CTE values were 65.1% and 79.3% lower than the CTE of the neat resin. Such properties can be useful for applications where syntactic foams are exposed to high temperatures and dimensional stability is important. A theoretical model is used to estimate the porosity level in the SiC shells and estimate the effective mechanical properties of the porous SiC material that forms the particle shell. Such analysis can help in using the models as predictive tools to estimate the mechanical properties of syntactic foams. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40689. 相似文献
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Thomas Crouzier Kathrin Boettcher Anthony R. Geonnotti Nicole L. Kavanaugh Julie B. Hirsch Katharina Ribbeck Oliver Lieleg 《Advanced Materials Interfaces》2015,2(18)
A key property of mucin glycoproteins is their exceptional capacity to hydrate and lubricate surfaces. In vivo, mucins assemble into mucus hydrogels that cover the epithelium and protect it from dehydration and shear stress. A better understanding of the origin of these properties could lead to new treatment strategies for patients with poor mucus coverage, defective mucus production, or glycosylation as caused by Sjögren syndrome, dry eye, or in the case of certain bacterial infections. In this work, mucin coatings are used to show that mucin‐associated glycans are essential for the formation of such hydrated and lubricating layers. Native mucins are compared with deglycosylated mucins by analyzing their hydration and it is shown that their lubricative potential in the boundary and mixed lubrication regime is linked to the hydration. The removal of glycans from the mucin results in a 3.5‐fold decrease in hydration and an increase in friction by two orders of magnitude. This loss of function is countered by grafting polyethylene glycol (PEG) molecules to defective mucins through lectin–glycan interactions. This lectin‐PEG conjugation restores hydration and improves lubrication of the partially deglycosylated mucin coatings. Thus, local complementation of defective mucus layers could prove to be a useful new treatment strategy. 相似文献
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