Relevant bibliographies by topics / Variable temperature NMR

Academic literature on the topic 'Variable temperature NMR'

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Published: 4 June 2021
Last updated: 7 February 2022

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Journal articles on the topic "Variable temperature NMR"

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Blanz, Martin. "5530353 Variable temperature NMR probe." Magnetic Resonance Imaging 15, no. 3 (January 1997): XVI. http://dx.doi.org/10.1016/s0730-725x(97)82876-7.

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Haw, James F. "Variable-Temperature Solid-State NMR Spectroscopy." Analytical Chemistry 60, no. 9 (May 1988): 559A—570A. http://dx.doi.org/10.1021/ac00160a721.

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Bussian, D. A., and G. S. Harbison. "Variable temperature 207Pb NMR of PbTiO3." Solid State Communications 115, no. 2 (June 2000): 95–98. http://dx.doi.org/10.1016/s0038-1098(00)00128-9.

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Taylor, R. E., and C. Dybowski. "Variable temperature NMR characterization of α-glycine." Journal of Molecular Structure 889, no. 1-3 (October 2008): 376–82. http://dx.doi.org/10.1016/j.molstruc.2008.02.023.

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Gallagher, Margaret M., A. Denise Rooney, and John J. Rooney. "Variable temperature 1H NMR studies on Grubbs catalysts." Journal of Organometallic Chemistry 693, no. 7 (April 2008): 1252–60. http://dx.doi.org/10.1016/j.jorganchem.2008.01.020.

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Huggins, Michael T., Tanay Kesharwani, Jonathan Buttrick, and Christopher Nicholson. "Variable Temperature NMR Experiment Studying Restricted Bond Rotation." Journal of Chemical Education 97, no. 5 (April 27, 2020): 1425–29. http://dx.doi.org/10.1021/acs.jchemed.0c00057.

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Gale, Douglas J., David J. Craik, and Robert T. C. Brownlee. "Variable-temperature NMR studies of thyroid hormone conformations." Magnetic Resonance in Chemistry 26, no. 4 (April 1988): 275–80. http://dx.doi.org/10.1002/mrc.1260260402.

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Frank, Julia H., Yomica L. Powder-George, Russel S. Ramsewak, and William F. Reynolds. "Variable-Temperature 1H-NMR Studies on Two C-Glycosylflavones." Molecules 17, no. 7 (July 2, 2012): 7914–26. http://dx.doi.org/10.3390/molecules17077914.

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Lewis, K. C., A. R. Maxwell, S. McLean, W. F. Reynolds, and R. G. Enriquez. "Room-temperature (1H,13C) and variable-temperature (1H) NMR studies on spinosin." Magnetic Resonance in Chemistry 38, no. 9 (2000): 771–74. http://dx.doi.org/10.1002/1097-458x(200009)38:9<771::aid-mrc729>3.0.co;2-4.

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Hugi-Cleary, Deirdre, Lothar Helm, and Andr� E. Merbach. "Variable-Temperature and Variable-Pressure17O-NMR Study of Water Exchange of Hexaaquaaluminium(III)." Helvetica Chimica Acta 68, no. 3 (May 15, 1985): 545–54. http://dx.doi.org/10.1002/hlca.19850680302.

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Dissertations / Theses on the topic "Variable temperature NMR"

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Liu, Yang Glaser Rainer. "Variable-temperature ¹H-NMR and AB initio study of 5-amino-imidazole-4-carboxamide (AICA) competing paths for amide-H scrambling /." Diss., Columbia, Mo. : University of Missouri--Columbia, 2008. http://hdl.handle.net/10355/6281.

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Title from PDF of title page (University of Missouri--Columbia, viewed on Feb. 18, 2010). The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract appears in the public.pdf file. Dr. Rainer Glaser, Thesis Supervisor. Includes bibliographical references.
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Kasprzyk, Milena, and milena kasprzyk@freehills com. "Synthetic Studies Towards the Tridachione Family of Marine Natural Products." Flinders University. Chemistry, Physics and Earth Sciences, 2008. http://catalogue.flinders.edu.au./local/adt/public/adt-SFU20081107.085933.

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Since the middle of the 20th century, significant interest has evolved from the scientific community towards the polypropionate family of marine natural products. A number of these compounds have been shown to possess significant biological activity, and this property, as well as their structural complexity, has driven numerous efforts towards their synthesis. The first chapter provides an introduction into the world of polypropionates, with a discussion on synthetic studies into a number of members of the tridachiapyrone family. Fundamental synthetic concepts utilised in this thesis towards the preparation of polyketides are also described, with a focus on their application towards the synthesis of 9,10-deoxytridachione, anti tridachiahydropyrone and syn tridachiahydropyrone. Chapter 2 describes the work undertaken towards the total synthesis of 9,10-deoxytridachione. The novel tandem conjugate addition-Dieckmann condensation of complex enones developed previously in the Perkins group was used to generate anti methylated cyclohexenones as key synthetic intermediates. The conversion of the cyclohexenones into the corresponding cyclohexadienes via allylic alcohols was attempted, utilising a Grignard-mediated reaction to achieve the selective 1,2-reduction. Studies into the Grignard-mediated reduction were also undertaken on seven additional cyclohexenones, in order to investigate the utility and scope of the reaction. The extension of the methodology previously developed for the synthesis of cyclohexenones is the subject of Chapter 3. This section describes investigations into the synthesis of stereochemically-diverse cyclohexenones from complex enones. The conjugate addition-Dieckmann condensation strategy was extended successfully towards the synthesis of a syn methylated cyclohexenone, which allowed the synthesis of the proposed true structure of tridachiahydropyrone to be pursued. The methodology developed in Chapter 3 was utilised in Chapter 4 to synthesise a model system of syn tridachiahydropyrone. A comparative analysis of the NMR data of the syn model, an anti model and anti tridachiahydropyrone with the natural product indicated that the true structure of tridachiahydropyrone may indeed have syn stereochemistry. The synthesis of syn tridachiahydropyrone was attempted, and to this end a suitable cyclohexanone was successfully synthesised. However, the subsequent methylation-elimination cascade failed to furnish the desired syn methylated cyclohexenone, producing only an anti methylated cyclohexanone. The stereochemistry of the methylation was deduced using high and low variable temperature NMR coupled with selective irradiation NOESY.
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Manzanera, Esteve Isaac Vicente 1977. "Development of variable temperature NMR force microscopy : proton spin relaxation measurements in ammonium sulfate." Thesis, 2012. http://hdl.handle.net/2152/ETD-UT-2012-08-6046.

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Nuclear magnetic resonance force microscopy (NMRFM) of a micron size sample of ammonium sulfate was performed by measuring the cantilever deflection produced by coupling the magnetic force to a mechanical cantilever at its resonance frequency. Spin-lattice and spin-spin relaxation measurements were obtained with our newly developed NMRFM probe. A system with more advanced positioning, acquisition and analysis has been fabricated. A new device in which a semi-automatic system performs nanoposition control, spin manipulation, dynamical measurements, and data analysis has been demonstrated to be successful. The new system has proven to be an improvement with respect to other versions of NMRFM probes, thanks to its versatility for pulse sequence designs, faster data acquisition, and automatic analysis of the information. This thesis presents an explanation of the theoretical details of nuclear magnetic resonance force microscopy, and experiments are described in which dynamical measurements of proton spin interactions are obtained. Finally, relaxation time e ffects of the observed force signal are considered in detail. A novel spin manipulation technique which is being implemented for future measurements is described in detail, and magnet con figurations for larger magnetic field gradients and consequently larger signal-to-noise ratio, are also described.
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吳佳芳. "The intramolecular interaction and the fluxionality of (olefin) tetracarbonyliron derivatives:theoretical and �CC nmr variable temperature spectroscopic analysis." Thesis, 1992. http://ndltd.ncl.edu.tw/handle/53258739197231107140.

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Books on the topic "Variable temperature NMR"

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Wolf, Mark A. Conformational analysis of C1-oxygenated chiral alkenes, 4-tetrahydropyranone ring systems, and BFb3s aldehyde complexes using variable temperature NMR and computational techniques. 1994.

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Book chapters on the topic "Variable temperature NMR"

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Crosby, Richard C., James F. Haw, Shawn J. Maynard, and Ronnie Reese. "Variable-Temperature NMR Studies of Polyphosphazenes." In Functional Polymers, 206. Boston, MA: Springer US, 1989. http://dx.doi.org/10.1007/978-1-4613-0815-7_19.

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Haw, James F., and Richard C. Crosby. "Variable-Temperature Solid-State NMR of Polyphosphazenes." In Solid State NMR of Polymers, 321–30. Boston, MA: Springer US, 1991. http://dx.doi.org/10.1007/978-1-4899-2474-2_20.

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Guo, Mingming, Stephen Z. D. Cheng, and Roderic P. Quirk. "Variable Temperature, Solid-State13C NMR Study of Linear Low-Density Polyethylene." In ACS Symposium Series, 163–76. Washington, DC: American Chemical Society, 1999. http://dx.doi.org/10.1021/bk-2000-0749.ch011.

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Helluy, Xavier, Jörg Kümmerlen, Christoph Marschner, and Angelika Sebald. "Solid-State Molecular Dynamics of (Ph3Si)Si(SiMe3)3 Studied by Variable Temperature 13C and 29Si MAS NMR Spectroscopy." In Silicon Chemistry, 147–56. Vienna: Springer Vienna, 1999. http://dx.doi.org/10.1007/978-3-7091-6357-3_14.

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Athanassiou, Zafiria, Anastasios Troganis, and Ioannis P. Gerothanassis. "Thermodynamic Origin of Cis/Trans Isomers of N-substituted Amides and a Proline-Containing β-turn Model Dipeptide in Aqueous Solution: A Variable Temperature Gradient Enhanced 1H-NMR Study." In Spectroscopy of Biological Molecules: New Directions, 55–56. Dordrecht: Springer Netherlands, 1999. http://dx.doi.org/10.1007/978-94-011-4479-7_25.

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Roder, Heinrich, Gerhard Wagner, and Kurt Wüthrich. "Amide Proton Exchange in Proteins by EX1 Kinetics: Studies of the Basic Pancreatic Trypsin Inhibitor at Variable p2H and Temperature." In NMR in Structural Biology, 559–70. WORLD SCIENTIFIC, 1995. http://dx.doi.org/10.1142/9789812795830_0049.

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Baba, Toshihide, and Yoshio Ono. "Variable Temperature 1H MAS NMR: A Powerful Tool for the Investigation of Dynamic Properties of Acidic Protons in Zeolites and Heteropoly Compounds." In Annual Reports on NMR Spectroscopy, 355–90. Elsevier, 1999. http://dx.doi.org/10.1016/s0066-4103(08)60041-1.

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Jong, Sung-Jeng, Jin-Fu Wu, Ajit R. Pradhan, Hong-Ping Lin, Chung-Yuan Mou, and Shang-Bin Liu. "Variable temperature 129Xe NMR studies of xenon adsorbed on mesoporous MCM-41 molecular sieves." In Studies in Surface Science and Catalysis, 543–50. Elsevier, 1998. http://dx.doi.org/10.1016/s0167-2991(98)81036-7.

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Koch, M., E. Brunner, D. Fenzke, H. Pfeifer, and B. Staudte. "Variable-Temperature 1H MAS NMR Investigations on the Interaction Between Brønsted Acid Sites and Carbon Monoxide Adsorbed on H-ZSM-5 Zeolites." In Studies in Surface Science and Catalysis, 709–15. Elsevier, 1994. http://dx.doi.org/10.1016/s0167-2991(08)64177-4.

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Chen, Wen-Hua, Hong-Ping Lin, Jin-Fu Wu, Sung-Jeng Jong, DgChung-Yuan Mou, and Shang-Bin Liu. "Effect of pore size on the adsorption of xenon on mesoporous MCM-41 and on the 129Xe NMR chemical shifts: a variable temperature study." In Nanoporous Materials II, Proceedings of the 2nd Conference on Access in Nanoporous Materials, 517–24. Elsevier, 2000. http://dx.doi.org/10.1016/s0167-2991(00)80253-0.

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Conference papers on the topic "Variable temperature NMR"

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Jwad, Rasha Saad. "Synthesis and variable temperature NMR study of glucose based 1,2,3-triazole." In INTERNATIONAL CONFERENCE OF NUMERICAL ANALYSIS AND APPLIED MATHEMATICS ICNAAM 2019. AIP Publishing, 2020. http://dx.doi.org/10.1063/5.0027407.

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Montague, Joshua R., Kris A. Bertness, Norman A. Sanford, Victor M. Bright, and Charles T. Rogers. "Capacitive Readout Technique for Studies of Dissipation in GaN Nanowire Mechanical Resonators." In ASME 2011 International Mechanical Engineering Congress and Exposition. ASMEDC, 2011. http://dx.doi.org/10.1115/imece2011-65420.

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A variable-temperature homodyne reflectometry measurement technique for detecting nanoscale mechanical motion has recently been developed. We have extended this technique to make the first all-electrical measurements of an ensemble of as-grown, c-axis, single-crystal gallium nitride (GaN) nanowires. These nanowires are approximately 15 μm in length and 100 nm in diameter, and have fundamental resonance frequencies near 1 MHz, and mechanical quality factors, Q, (resonance frequency divided by resonance width) in excess of 104. These high-Q values are sensitive to surface conditions and offer the opportunity to study intrinsic damping mechanisms in the nanoscale resonators. The new microwave measurement technique has allowed us to study the ensemble behavior of nanowire resonances while varying extrinsic variables (e.g., temperature) and obtain statistics on nanowire resonance behavior. Our apparatus allows measurements to be made in either a two-phase lock-in mode, or in a power-spectrum mode, both of which have unique advantages. Our measurements demonstrate a position-spectral noise floor of 0.3 nm/ Hz, largely set by the dynamic range of our microwave readout system.
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Schuman, Thomas, Buddhabhushan Salunkhe, Ali Al Brahim, and Baojun Bai. "Development and Evaluation of Ultra-High Temperature Resistant Preformed Particle Gels for Conformance Control in North Sea Reservoirs." In SPE Annual Technical Conference and Exhibition. SPE, 2021. http://dx.doi.org/10.2118/206007-ms.

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Abstract Preformed particle gels (PPGs), a type of hydrogel, have been widely applied to control the conformance of reservoirs owing to their robust gel chemistries. Traditional PPGs are polyacrylamide-based hydrogel compositions which can withstand neither higher temperatures nor high salinity conditions. There are many deep oilfield reservoirs worldwide which demand PPG products with a long term hydrolytic and thermal stability at the temperatures of higher than 120 °C. Current PPGs neither remain hydrated nor retain polymer integrity at these temperatures. A unique high temperature-resistant hydrogel composition (HT-PPG) was developed with exceptional thermal stability for greater than 18 months in North Sea formation temperature (~130 °C) and formation water environments. HT-PPG described herein can swell up to 30 times its initial volume in brines of different salinity for North Sea. The effects of salinity and temperature on swelling, swelling rate, and rheological behavior was studied. These HT-PPGs exhibit excellent strength with storage modulus (G’) of over 3,000 Pa at the swelling ratio of 10. Thermostability evaluations were performed in North Sea brines with variable salinity at temperatures of 130 °C and 150 °C and found to be stable for 18 months with no loss of molecular integrity at the higher temperature. Laboratory core flooding tests were conducted to test its plugging efficiency to fracture. HT-PPGs showed good plugging efficiency by reducing the permeability of open fracture and did not wash out during waterflooding. Overall, HT-PPG is a novel product with excellent hydrothermal stability that make it an ideal candidate for conformance problems associated with reservoirs of high temperature and salinity conditions.
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Li, Yue-Rong, Gavin Pereira, Masoud Kasrai, and Peter R. Norton. "Studies on ZDDP Anti-Wear Films Formed Under the Different Conditions by XANES Spectroscopy, Atomic Force Microscopy and 31P NMR." In ASME/STLE 2007 International Joint Tribology Conference. ASMEDC, 2007. http://dx.doi.org/10.1115/ijtc2007-44218.

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Antiwear (AW) films, generated from a mineral base oil containing zinc dialkyl dithiophosphate (ZDDP) additive, were extensively studied. These films were formed at various conditions such as different temperatures, various loads and rubbing times. The surface morphology of these films was investigated using atomic force microscopy (AFM) and the surface roughness of these films has been calculated from the images. X-ray absorption near edge structure (XANES) spectroscopy has been used to characterize the chemistry of these films. The intensity of phosphorus K-edge was also used to monitor the thickness of these films. Phosphorus L-edge spectra show that these films have slightly variable chemical natures. 31P Nuclear magnetic resonance (31P NMR) was used to study the ZDDP components in the residue oils. The spectra show that the primary and secondary ZDDP decompose quite differently at the various conditions. Tribological characteristics of these AW films were probed by measuring the coefficients of friction and the wear scar width of the counter faces.
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Guo, Li, Desong Fan, Qiang Li, and Yimin Xuan. "Thermal Radiative Properties of (La,Sr)MnO3 Thermochromic Coating Prepared by Sol-Gel Process." In ASME 2016 5th International Conference on Micro/Nanoscale Heat and Mass Transfer. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/mnhmt2016-6420.

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Thermochromic coating on yttria stabilized zirconia (YSZ) substrate was prepared by the sol-gel La0.825Sr0.175MnO3 nanoparticles and the binder composed of terpineol and ethyl cellulose. The surface morphology and the variable emittance properties of coating in the infrared range was evaluated from infrared reflectance spectra at various temperatures. LSMO nanoparticles with size 200 nm are obtained by the sol-gel process. The coating sample shows a thermochromic behavior with the rise of temperature. The emittance of coating increases from 0.62 at 173 K to 0.88 at 373 K. When the sample surface root-mean-square roughness is 122 nm, its emittance variation increases from 0.43 at 173 K to 0.73 at 373 K.
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Rajaram, Gukan, Salil Desai, Zhigang Xu, Devdas M. Pai, and Jag Sankar. "Process Optimization Studies on Ni-YSZ Anode Material for Solid Oxide Fuel Cell Applications." In ASME 2007 International Mechanical Engineering Congress and Exposition. ASMEDC, 2007. http://dx.doi.org/10.1115/imece2007-43592.

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The characteristics of the Ni/YSZ anode material for the solid oxide fuel cells (SOFCs) were investigated in order to study the relation between the porosity and the conductivity of the cell. The nano-sized Yittria Stabilized Zirconia (YSZ) (∼ 60 nm), Nickel Oxide (NiO) (∼ 40 nm) and graphite (∼ 40 nm) particles were used as the raw materials. The graphite particles act as a pore former. The experiments were planned based on a response surface design (central composite design matrix). The graphite content and the sintering temperatures were varied based on the design chart, while the other variables like NiO/YSZ ratio, ball milling time, powder compaction pressure and reduction temperature values were fixed. Porosity and conductivity measurements were performed on the sintered and reduced anode material. The results indicated that the porosity values got decreased by increasing sintering temperature values, while the conductivity values were on the reverse scale. The conductivity values increase with increasing temperature. The scanning electron microscope (SEM) images showed that the sintering temperature had a visible impact on the microstructure. At elevated temperature, the microstructure showed visible particle growth and it formed a better Ni-network along the structure, compared to samples sintered at lower temperature. It is believed that the enhanced Ni-network at elevated temperature helps to increase the electrical conductivity of the Ni-YSZ anode cermet.
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Serrano, José Ramón, Francisco José Arnau, Luis Miguel García-Cuevas, Alejandro Gómez-Vilanova, Stephane Guilain, and Samuel Batard. "A Methodology for Measuring Turbocharger Adiabatic Maps in a Gas-Stand and its Usage for Calibrating Control Oriented and 1D Models at Early ICE Design Stages." In ASME 2019 Internal Combustion Engine Division Fall Technical Conference. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/icef2019-7125.

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Abstract Turbocharged engines are the standard architecture for designing efficient spark ignition and compression ignition reciprocating internal combustion engines (ICE). Turbochargers characterization and modeling are basic tasks for the analysis and prediction of the whole engine system performance and this information is needed in quite early stages of the engine design. Turbocharger characteristics (efficiency, pressure ratio, mass flow rates...) traditionally rely in maps of pseudo non-dimensional variables called reduced variables. These maps must be used by reciprocating ICE designer and modeler not only for benchmarking of the turbocharger, but for a multiplicity of purposes, i.e: assessing engine back-pressure, boost pressure, load transient response, after-treatment inlet temperature, intercooler inlet temperature, low pressure EGR temperature, ... Maps of reduced variables are measured in gas-stands with steady flow but non-standardized fluids conditioning; neither temperatures nor flows. In concrete: turbine inlet gas temperature; lubrication-oil flow and temperature; water-cooling flow and turbo-machinery external heat transfer are non-standardized variables which have a big impact in assessing said multiplicity of purposes. Moreover, adiabatic efficiency, heat losses and friction losses are important data, hidden in the maps of reduced variables, which depend on the testing conditions as much as on the auxiliary fluids temperature and flow rate. In this work it is proposed a methodology to standardize turbochargers testing based in measuring the maps twice: in close to adiabatic and in diathermal conditions. Along the paper it is discussed with special detail the impact of the procedure followed to achieve said quasi-adiabatic conditions in both the energy balance of the turbocharger and the testing complexity. As a conclusion, the paper proposes a methodology which combines quasi-adiabatic tests (cold and hot gas flow) with diathermal tests (hot gas flow) in order to extract from a turbocharger gas-stand all information needed by engine designers interested in controlling or 1D-modelling the ICE. The methodology is completed with a guide for calibrating said control-oriented turbocharger models in order to separate aerodynamic efficiency (adiabatic) from heat transfer losses and from friction losses in the analysis of the turbocharger performance. The outsourced calibration of the turbocharger model allows avoiding uncertainties in the global ICE model calibration, what is very interesting for turbochargers benchmarking at early ICE-turbo matching stages or for global system analysis at early control design stages.
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Nayeb-Hashemi, Hamid, Yue Zheng, Ashkan Vaziri, and Masoud Olia. "Thermoelastic Response of Functionally Graded Fiber-Reinforced Rotating Disk With Non-Uniform Thickness Profile Under Variable Angular Velocity." In ASME 2019 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/imece2019-10213.

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Abstract Displacement and stress fields in a functionally graded (FG) fiber-reinforced rotating annular disk with a non-uniform thickness profile, subjected to angular deceleration and a temperature profile were investigated. Unidirectional fibers were considered to be circumferentially distributed within the disk with fiber volume fraction changing radially. The governing equations for displacement, stress, and temperature fields were solved using finite difference method. The results indicated that thermal induced stresses were more dominate than the rotational induced stresses. Disks which were fiber rich at the inner radius, the fibers made negligible difference on the displacement and stress fields when compared to a homogenous disk made from the matrix material. In addition, it was found that the deceleration magnitude had no effect on the radial and hoop stresses, nor the temperature on the developed shear stress. The shear stress was only affected by the disk deceleration. Tsai-Wu failure criterion was applied for decelerating disks to ascertain their failure behavior. The results show that Tsai-Wu failure index is dominated by the thermal stresses.
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Chang, Ruxia, Desong Fan, and Qiang Li. "Research on Thermal Properties of Insulator-Metal Transition at Room Temperature in Sm1-xCaxMnO3." In ASME 2019 6th International Conference on Micro/Nanoscale Heat and Mass Transfer. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/mnhmt2019-3963.

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Abstract The high-purity electron-doped manganites Sm1-xCaxMnO3 nanopowder were prepared by the solid-state reaction method, then the bulk material were obtained through granulation, molding, calcining, grinding and polishing. SCMO nanoparticles with 200 nm were obtained by the sol-gal process. The phase and surface morphology of these materials were characterized by X-ray diffraction and Scanning electron microscope and other experiments. The variable resistivity of the bulk materials were measured by two-wire method in the temperature range of 100–420K. The thermal conductivity was measured by the Laser Flash method. The results show that different doping ratios can change the phase transition temperature of the metal-insulation state. The temperature changed from 0 to 50 °C. The TMI could be regulated to room temperature. When the temperature is high than the TMI, it performs as metal state, on the contrary, it performs as an insulating state.
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Gusev, Sergei, and Martijn van den Broek. "Analysis and Comparison Between Fixed and Variable Volume Ratio Expander for Micro-Scale ORC." In ASME 2015 Power Conference collocated with the ASME 2015 9th International Conference on Energy Sustainability, the ASME 2015 13th International Conference on Fuel Cell Science, Engineering and Technology, and the ASME 2015 Nuclear Forum. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/power2015-49271.

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Waste heat recovery has become very important in the last decennia. The Organic Rankine Cycle is the most popular technology to transform waste heat into mechanical work or electricity. While large and medium scale installations are widely available on the market for various temperature and power levels, small scale ORCs are still in a pre-commercial phase because of a relatively high specific price. To make small scale ORCs more attractive for potential customers, the price has to be drastically reduced which means reducing the manufacturing and assembling operations, the number of parts in assemblies and unification of these assemblies. In addition, the performance has to be increased by using advanced cycle architectures and the right fluids. Not only the right choice of the working fluid is important but also the expander built-in volume ratio (BVR) has to be optimal or improved. Neither a fixed volume ratio expander, nor a turbine can provide an optimal expansion of a working fluid in a wide range of operating conditions [1]. In automotive applications, for instance, a strongly fluctuating heat input will be introduced to an ORC unit. To estimate losses caused by non-optimal operation, a model of a volumetric expander has been developed and verified using the result of extensive test campaigns with a screw expander. The volume ratio of the expander mentioned cannot be physically changed, so under widely changing pressure ratio, caused by varying inlet waste heat and ambient temperatures, it operates mostly far from its design point. The model gives a possibility to vary the BVR in order to compare a fixed-volume ratio expander with a variable one. Benefits from replacement of this expander by an adaptive one are studied. Only steady states are taken into account since there is no dynamic model of this expander developed yet. As a consequence of the results obtained, a concept of a variable volume ratio expander is proposed.
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Reports on the topic "Variable temperature NMR"

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Ziegeweid, Marcia A. I: Low Frequency NMR and NQR Using a dc SQUID. II: Variable-temperature 13C CP/MAS of Organometallics. Office of Scientific and Technical Information (OSTI), November 1995. http://dx.doi.org/10.2172/970015.

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