Journal articles: 'Polar parameters'

1

J K Pendharkar, J. K. Pendharkar, and Veena Khilnani. "Acoustic Parameters of Polar- Non polar Chemicals at Variable Frequencies." Indian Journal of Applied Research 3, no. 7 (October 1, 2011): 588–90. http://dx.doi.org/10.15373/2249555x/july2013/186.

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2

Dierer, Silke, and Katharina Heinke Schluenzen. "In fluence parameters for a polar mesocyclone development." Meteorologische Zeitschrift 14, no. 6 (December 19, 2005): 781–92. http://dx.doi.org/10.1127/0941-2948/2005/0077.

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3

Giese, Bernd, and Wolf Mehl. "Polar parameters for radical substituents." Tetrahedron Letters 32, no. 34 (January 1991): 4275–78. http://dx.doi.org/10.1016/s0040-4039(00)92147-6.

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4

McCarthy, Dennis D. "Requirements for Earth Rotation Parameters." Highlights of Astronomy 7 (1986): 63–64. http://dx.doi.org/10.1017/s1539299600006183.

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AbstractObservations of Earth orientation parameters (polar motion and Universal Time) have reached a level of accuracy which challenges the definition of the reference systems which these observations seek to relate. Observational accuracies of better than in polar motion and in Universal Time are now routinely available. Urgent requirements therefore exist now for the IAU to take a fresh look at the concepts and definitions of the reference systems as well as reference frames. Of particular concern are the definitons of the equinox, the terrestrial reference pole, the zero of longitude and sidereal time.

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5

Zhao, Chen-Yang, Chi-Fai Cheung, and Wen-Peng Fu. "An Investigation of the Cutting Strategy for the Machining of Polar Microstructures Used in Ultra-Precision Machining Optical Precision Measurement." Micromachines 12, no. 7 (June 27, 2021): 755. http://dx.doi.org/10.3390/mi12070755.

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In this paper, an investigation of cutting strategy is presented for the optimization of machining parameters in the ultra-precision machining of polar microstructures, which are used for optical precision measurement. The critical machining parameters affecting the surface generation and surface quality in the machining of polar microstructures are studied. Hence, the critical ranges of machining parameters have been determined through a series of cutting simulations, as well as cutting experiments. First of all, the influence of field of view (FOV) is investigated. After that, theoretical modeling of polar microstructures is built to generate the simulated surface topography of polar microstructures. A feature point detection algorithm is built for image processing of polar microstructures. Hence, an experimental investigation of the influence of cutting tool geometry, depth of cut, and groove spacing of polar microstructures was conducted. There are transition points from which the patterns of surface generation of polar microstructures vary with the machining parameters. The optimization of machining parameters and determination of the optimized cutting strategy are undertaken in the ultra-precision machining of polar microstructures.

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Ou, Shui-Ping, Sen Wang, Xu-Mei Zhou, and Ling Chen. "Solubility Behaviour of Baicalin in Polar and Non-Polar Solvents: Solubility Parameters Approach." Asian Journal of Chemistry 27, no. 7 (2015): 2401–5. http://dx.doi.org/10.14233/ajchem.2015.17854.

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7

Golubkin, Pavel, Julia Smirnova, and Leonid Bobylev. "Satellite-Derived Spatio-Temporal Distribution and Parameters of North Atlantic Polar Lows for 2015–2017." Atmosphere 12, no. 2 (February 6, 2021): 224. http://dx.doi.org/10.3390/atmos12020224.

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A list of North Atlantic polar lows was compiled for 2015–2017. A total of 131 polar lows were found by analyzing the Moderate Resolution Imaging Spectroradiometer (MODIS) infrared imagery and auxiliary information. The study region was additionally divided by the 20° W meridian to assess possible differences in the polar lows occurring in the western and eastern parts of the region. The highest polar low activity was found over the Barents Sea and the northern Norwegian Sea. A large number of polar lows over this region were dual or multiple. When considering such systems as a single event, more polar lows were found in 2015 over the Labrador Sea and southern Davis Strait, which is the region with the second highest number of polar lows. High interannual variability of polar low frequency was noted, which was more pronounced in the western part of the region. During the analyzed period, the largest number of polar lows occurred in January for the western part of the region and in February for the eastern part. The main polar low parameters were similar within the region, with the mean values slightly higher in the western part of the region, but all extreme high values were observed in the eastern part.

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8

Sobia, Iren. "Fluctuations of Solar Wind Parameters During Polar Reversal." American Journal of Astronomy and Astrophysics 3, no. 3 (2015): 56. http://dx.doi.org/10.11648/j.ajaa.20150303.15.

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9

van Leeuwen, M. E. "Derivation of Stockmayer potential parameters for polar fluids." Fluid Phase Equilibria 99 (August 1994): 1–18. http://dx.doi.org/10.1016/0378-3812(94)80018-9.

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10

Dudev, T., and B. Galabov. "Relationship between infrared intensity theories: Electro-optical parameters and bond polar parameters." Spectrochimica Acta Part A: Molecular Spectroscopy 48, no. 8 (August 1992): 1153–63. http://dx.doi.org/10.1016/0584-8539(92)80126-h.

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11

Guthrie, J. Peter. "Concerning the distant polar interaction in free energies of transfer. An explanation and an estimation procedure." Canadian Journal of Chemistry 69, no. 12 (December 1, 1991): 1893–903. http://dx.doi.org/10.1139/v91-274.

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For polyfunctional compounds, free energies of transfer from gas to aqueous solution require corrections for the interactions of polar groups (Distant Polar Interactions). These corrections can be made with very few adjustable parameters by using a model of the solvation process assuming hydrogen bonding is the major source of the effect on free energy of transfer for polar groups, and that hydrogen bonding is perturbed by polar effects, measured by Taft σ*. Parameters evaluated for polyfluoro, polychloro, and polybromo compounds successfully predicted the free energies of transfer for mixed polyhalogen compounds. Preliminary parameters have been evaluated for ethers, amines, phenyl groups, nitriles, and esters. Key words: free energy of transfer, distant polar interaction, hydrogen bonding, solvation.

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12

Tian, Zhuxin, and Yu Huang. "Transformation between polar and rectangular coordinates of stiffness and dampness parameters in hydrodynamic journal bearings." Friction 9, no. 1 (January 18, 2020): 201–6. http://dx.doi.org/10.1007/s40544-019-0328-9.

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Abstract The stiffness and dampness parameters of journal bearings are required in rectangular coordinates for analyzing the stability boundary and threshold speed of oil film bearings. On solving the Reynolds equation, the oil film force is always obtained in polar coordinates; thus, the stiffness and dampness parameters can be easily obtained in polar coordinates. Therefore, the transformation between the polar and rectangular coordinates of journal bearing stiffness and dampness parameters is discussed in this study.

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13

Samantaray, B., M. K. Praharaj, B. R. Das, and S. P. Das. "Comparative Study of Molecular Interaction in Ternary Liquid Mixtures of Polar and Non-Polar Solvents." Journal of Scientific Research 14, no. 3 (September 1, 2022): 917–29. http://dx.doi.org/10.3329/jsr.v14i3.57587.

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Ultrasonic velocity measurements, density measurements, and viscometric studies were conducted for the ternary mixture of pyridine and toluene separately with N, N-dimethylformamide (DMF) in butanol, at different temperatures and for different concentrations of component liquids. Using these basic experimental data, various acoustic and thermodynamic parameters, such as adiabatic compressibility (β), free length (Lf,), free volume (Vf), etc. were calculated. Also, Excess thermo-acoustical parameters were calculated from the experimentally measured data. The outcomes were expressed in terms of the molecular interactions and the variations in parameters under varying solute concentrations. A comparative study is discussed. Variation in the above parameters for the different mixtures is indicative of the nature of the interactions between the components in the liquid mixture. Concluding remarks regarding intermolecular interactions are provided.

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14

Banachowicz, Andrzej, and Adam Wolski. "Determination of Ship Approach Parameters in the Polar Coordinates System." Reports on Geodesy and Geoinformatics 96, no. 1 (June 1, 2014): 1–8. http://dx.doi.org/10.2478/rgg-2014-0001.

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Abstract An essential aspect of the safety of navigation is avoiding collisions with other vessels and natural or man made navigational obstructions. To solve this kind of problem the navigator relies on automatic anti-collision ARPA systems, or uses a geometric method and makes radar plots. In both cases radar measurements are made: bearing (or relative bearing) on the target position and distance, both naturally expressed in the polar coordinates system originating at the radar antenna. We first convert original measurements to an ortho-Cartesian coordinate system. Then we solve collision avoiding problems in rectangular planar coordinates, and the results are transformed to the polar coordinate system. This article presents a method for an analysis of a collision situation at sea performed directly in the polar coordinate system. This approach enables a simpler geometric interpretation of a collision situation

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15

Pytela, Oldřich. "A new classification of solvents based on chemometric empirical scale of parameters." Collection of Czechoslovak Chemical Communications 55, no. 3 (1990): 644–52. http://dx.doi.org/10.1135/cccc19900644.

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The paper presents a classification of 51 solvents based on clustering in three-dimensional space formed by the empirical scale of PAC, PBC, and PPC parameters designed for interpretation of solvent effect on a model with cross-terms. For the classification used are the clustering methods of the nearest neighbour, of the furthest neighbour, of average bond, and the centroid method. As a result, the solvents have been divided into 8 classes denoted as: I - nonpolar-inert solvents (aliphatic hydrocarbons), IIp - nonpolar-polarizable (aromatic hydrocarbons, tetrachloromethane, carbon disulphide), IIb - nonpolar-basic (ethers, triethylamine), IIIp - little polar-polarizable (aliphatic halogen derivatives, substituted benzenes with heteroatom-containing substituents), IIIb - little polar-basic (cyclic ethers, ketones, esters, pyridine), IVa - polar-aprotic (acetanhydride, dialkylamides, acetonitrile, nitromethane, dimethyl sulfoxide, sulfolane), IVp - polar-protic (alcohols, acetic acid), and V - exceptional solvents (water, formamide, glycol, hexamethylphosphoric triamide). The information content of the individual parameters used for the classification has been determined. The classification is based primarily on solvent polarity/acidity (PAC), less on polarity/basicity (PBC), and the least on polarity/polarizability (PPC). Causal relation between chemical structure of solvent and its effect on the process taking place therein has been established.

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16

Hanif, Muhammad, and Masoud Ardakani. "Polar Codes: Bounds on Bhattacharyya Parameters and Their Applications." IEEE Transactions on Communications 66, no. 12 (December 2018): 5927–37. http://dx.doi.org/10.1109/tcomm.2018.2867475.

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17

Szumilin, Krystyna, and Jacek J. Milczarek. "Physical Interpretation of Polar Order Parameters in Liquid Crystals." Molecular Crystals and Liquid Crystals Science and Technology. Section A. Molecular Crystals and Liquid Crystals 262, no. 1 (March 1995): 499–506. http://dx.doi.org/10.1080/10587259508033552.

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18

Staude, A., A. D. Schwope, and R. Schwarz. "System parameters of the long-period polar V1309 Ori." Astronomy & Astrophysics 374, no. 2 (August 2001): 588–98. http://dx.doi.org/10.1051/0004-6361:20010695.

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19

Fedosov, S. N., and A. E. Sergeeva. "Measuring of electrical relaxation parameters in polar polymer dielectrics." Journal of Electrostatics 30 (May 1993): 327–33. http://dx.doi.org/10.1016/0304-3886(93)90086-m.

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20

Panettieri, Enrico, Marco Montemurro, and Anita Catapano. "Blending constraints for composite laminates in polar parameters space." Composites Part B: Engineering 168 (July 2019): 448–57. http://dx.doi.org/10.1016/j.compositesb.2019.03.040.

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21

Saynisch, J., M. Wenzel, and J. Schröter. "Assimilation of Earth rotation parameters into a global ocean model: excitation of polar motion." Nonlinear Processes in Geophysics 18, no. 5 (September 8, 2011): 581–85. http://dx.doi.org/10.5194/npg-18-581-2011.

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Abstract. The oceanic contribution to Earth rotation anomalies can be manifold. Possible causes are a change of total ocean mass, changes in current speed or location and changes in mass distribution. To derive the governing physical mechanisms of oceanic Earth rotation excitation we assimilate Earth rotation observations with a global circulation ocean model. Before assimilation, observations of length of day and polar motion were transformed into estimates of ocean angular momentum. By using the adjoint 4D-VAR assimilation method we were able to reproduce these estimated time series. Although length of day was assimilated simultaneously the analysis in this paper focuses on the oceanic polar motion generation. Our results show that changes in mass distribution and currents contribute to oceanic polar motion generation. Both contributions are highly correlated and show similar amplitudes. The changes in the model done by the assimilation procedure could be related to changes in the atmospheric forcing. Since for geometrical reasons the change of total ocean mass does not project on polar motion, we conclude that the polar motion is mainly generated by a geostrophic response to atmospheric momentum forcing. In geostrophic currents mass displacement and current speed entail each other. This way the large similarity of mass and current generated ocean angular momentum can be explained.

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22

Formella, K., T. Braumann, and H. Elmenhorst. "The Influence of Different Filter Parameters on the Semivolatile Composition of Mainstream Smoke." Beiträge zur Tabakforschung International/Contributions to Tobacco Research 15, no. 3 (November 1, 1992): 123–28. http://dx.doi.org/10.2478/cttr-2013-0627.

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AbstractThe semivolatile fraction of cigarette smoke contains the most important aroma and taste compounds which contribute to the smoker's enjoyment. Obviously, the semivolatile composition is strongly affected by cigarette filters and consequently by the material which is used for filter manufacturing. We have studied the effect of cellulose acetate and polypropylene as filter material on the smoke semivolatiles. Further, the effect of other parameters like pressure drop and the use of additives has been investigated. Smoke condensate was collected on a Cambridge filter pad, the semivolatiles were evaporated using a headspace apparatus and subsequently collected in a cold trap. Semivolatile analyses were performed by high-resolution GC/MS. The cellulose acetate filter, due to its polar structure, selectively retains polar compounds such as phenols and furans while the non-polar polypropylene filter shows a non-selective retention behaviour. The addition to polypropylene filters of a polar compound such as triacetin, which is used as plasticiser in the manufacturing of cellulose acetate filters, does not affect the retention behaviour towards the semivolatiles.

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23

Nitta, Tohru. "Learning Dynamics of a Single Polar Variable Complex-Valued Neuron." Neural Computation 27, no. 5 (May 2015): 1120–41. http://dx.doi.org/10.1162/neco_a_00729.

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This letter investigates the characteristics of the complex-valued neuron model with parameters represented by polar coordinates (called polar variable complex-valued neuron). The parameters of the polar variable complex-valued neuron are unidentifiable. The plateau phenomenon can occur during learning of the polar variable complex-valued neuron. Furthermore, computer simulations suggest that a single polar variable complex-valued neuron has the following characteristics in the case of using the steepest gradient-descent method with square error: (1) unidentifiable parameters (singular points) degrade the learning speed and (2) a plateau can occur during learning. When the weight is attracted to the singular point, the learning tends to become stuck. However, computer simulations also show that the steepest gradient-descent method with amplitude-phase error and the complex-valued natural gradient method could reduce the effects of the singular points. The learning dynamics near singular points depends on the error functions and the training algorithms used.

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24

Castillo, Oscar Daniel Garibaldi, and Ana Beltrán. "Identificación de Parámetros de Desempeño de un UAV a Través de Vuelos de Prueba." KnE Engineering 3, no. 1 (February 11, 2018): 482. http://dx.doi.org/10.18502/keg.v3i1.1452.

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The design and implementation of a autonomous navigation and control system for UAV, mandates simulating the system before in-flight testing. These simulations require a computational model of the aircraft, that can be obtained from the computation of aerodynamic parameters such as the drag polar. In this paper we present the identification of these parameters using two methods: one by flight testing techniques; the other by a combination of semi-empirical methods and computational fluid dynamics, dubbed the hybrid method. The hybrid method, which produces a parabolic polar drag, had the same qualitative trend compared to experiments. However, a detailed analysis of the parameters that shapes the polar drag, had significant differences, particularly in the parasite drag. This is probably due to propeller effects, low Reynolds Number and limitations of the piloting technique.Keywords: Drag polar, flight testing, parasite drag, UAV, VLM

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Bruna, M., and C. J. W. Breward. "The influence of non-polar lipids on tear film dynamics." Journal of Fluid Mechanics 746 (April 4, 2014): 565–605. http://dx.doi.org/10.1017/jfm.2014.106.

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AbstractIn this paper we examine the effect that physiological non-polar lipids, residing on the surface of an aqueous tear film, have on the film evolution. In our model we track the evolution of the thickness of the non-polar lipid layer, the thickness of the aqueous layer and the concentration of polar lipids which reside at the interface between the two. We also utilise a force balance in the non-polar lipid layer in order to determine its velocity. We show how to obtain previous models in the literature from our model by making particular choices of the parameters. We see the formation of boundary layers in some of these submodels, across which the concentration of polar lipid and the non-polar lipid velocity and film thickness vary. We solve our model numerically for physically realistic parameter values, and we find that the evolution of the aqueous layer and the polar lipid layer are similar to that described by previous authors. However, there are interesting dynamics for the non-polar lipid layer. The effects of altering the key parameters are highlighted and discussed. In particular, we see that the Marangoni number plays a key role in determining how far over the eye the non-polar lipid spreads.

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Aniceto, José P. S., Bruno Zêzere, and Carlos M. Silva. "Predictive Models for the Binary Diffusion Coefficient at Infinite Dilution in Polar and Nonpolar Fluids." Materials 14, no. 3 (January 23, 2021): 542. http://dx.doi.org/10.3390/ma14030542.

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Experimental diffusivities are scarcely available, though their knowledge is essential to model rate-controlled processes. In this work various machine learning models to estimate diffusivities in polar and nonpolar solvents (except water and supercritical CO2) were developed. Such models were trained on a database of 90 polar systems (1431 points) and 154 nonpolar systems (1129 points) with data on 20 properties. Five machine learning algorithms were evaluated: multilinear regression, k-nearest neighbors, decision tree, and two ensemble methods (random forest and gradient boosted). For both polar and nonpolar data, the best results were found using the gradient boosted algorithm. The model for polar systems contains 6 variables/parameters (temperature, solvent viscosity, solute molar mass, solute critical pressure, solvent molar mass, and solvent Lennard-Jones energy constant) and showed an average deviation (AARD) of 5.07%. The nonpolar model requires five variables/parameters (the same of polar systems except the Lennard-Jones constant) and presents AARD = 5.86%. These results were compared with four classic models, including the 2-parameter correlation of Magalhães et al. (AARD = 5.19/6.19% for polar/nonpolar) and the predictive Wilke-Chang equation (AARD = 40.92/29.19%). Nonetheless Magalhães et al. requires two parameters per system that must be previously fitted to data. The developed models are coded and provided as command line program.

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Puķīte, Jānis, Christian Borger, Steffen Dörner, Myojeong Gu, and Thomas Wagner. "OClO as observed by TROPOMI: a comparison with meteorological parameters and polar stratospheric cloud observations." Atmospheric Chemistry and Physics 22, no. 1 (January 7, 2022): 245–72. http://dx.doi.org/10.5194/acp-22-245-2022.

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Abstract. Chlorine dioxide (OClO) is a by-product of the ozone-depleting halogen chemistry in the stratosphere. Although it is rapidly photolysed at low solar zenith angles (SZAs), it plays an important role as an indicator of the chlorine activation in polar regions during polar winter and spring at twilight conditions because of the nearly linear dependence of its formation on chlorine oxide (ClO). Here, we compare slant column densities (SCDs) of chlorine dioxide (OClO) retrieved by means of differential optical absorption spectroscopy (DOAS) from spectra measured by the TROPOspheric Monitoring Instrument (TROPOMI) with meteorological data for both Antarctic and Arctic regions for the first three winters in each of the hemispheres (November 2017–October 2020). TROPOMI, a UV–Vis–NIR–SWIR instrument on board of the Sentinel-5P satellite, monitors the Earth's atmosphere in a near-polar orbit at an unprecedented spatial resolution and signal-to-noise ratio and provides daily global coverage at the Equator and thus even more frequent observations at polar regions. The observed OClO SCDs are generally well correlated with the meteorological conditions in the polar winter stratosphere; for example, the chlorine activation signal appears as a sharp gradient in the time series of the OClO SCDs once the temperature drops to values well below the nitric acid trihydrate (NAT) existence temperature (TNAT). Also a relation of enhanced OClO values at lee sides of mountains can be observed at the beginning of the winters, indicating a possible effect of lee waves on chlorine activation. The dataset is also compared with CALIPSO Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) polar stratospheric cloud (PSC) observations. In general, OClO SCDs coincide well with CALIOP measurements for which PSCs are detected. Very high OClO levels are observed for the northern hemispheric winter 2019/20, with an extraordinarily long period with a stable polar vortex being even close to the values found for southern hemispheric winters. An extraordinary winter in the Southern Hemisphere was also observed in 2019, with a minor sudden stratospheric warming at the beginning of September. In this winter, similar OClO values were measured in comparison to the previous (usual) winter till that event but with a OClO deactivation that was 1–2 weeks earlier.

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Weltrowski, Marek, and Patricia I. Dolez. "Compatibilizer Polarity Parameters as Tools for Predicting Organoclay Dispersion in Polyolefin Nanocomposites." Journal of Nanotechnology 2019 (March 3, 2019): 1–9. http://dx.doi.org/10.1155/2019/1404196.

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Nanocomposites give an innovative method to increase the mechanical, thermal, and barrier performance of polymers. However, properly dispersing the nanoparticles in the polymer matrix is often key in achieving high performance, especially in the case of hydrophilic nanoparticles and hydrophobic polymers. For that purpose, nanoparticles may be functionalized with organic groups to increase their affinity with the polymer matrix. Compatibilizing agents may also be included in the nanocomposite formulation. This paper aims at identifying parameters relative to the compatibilizer polarity that would allow predicting nanoparticle dispersion in the polymer nanocomposite. The analysis used published data on nanocomposite samples combining clay nanoparticles, polyolefins, and various compatibilizing agents. We studied the correlations between the nanoclay exfoliation ratio and five different parameters describing the compatibilizer hydrophilic-lipophilic balance: the acid value, the mole, and weight fraction of polar groups, the number of polymer chain units per polar group, and the number of moles of polar groups per mole of compatibilizer. The best correlation was observed with the number of polymer chain units per polar group in the compatibilizer. This parameter could be used as a tool to predict the dispersion of organoclay nanoparticles in polyolefins. Another important result of the study is that, among the compatibilizers investigated, those with a low acid value provided a better nanoclay exfoliation compared to those with a high acid value. This may indicate the existence of a maximum in the nanoclay exfoliation/compatibilizer polarity curve, which would open new perspectives for nanocomposite performance optimization.

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Sakwe, Sakwe Aloysius, Yeon Suk Jang, and Peter J. Wellmann. "Defect Etching of Non-Polar and Semi-Polar Faces in SiC." Materials Science Forum 556-557 (September 2007): 243–46. http://dx.doi.org/10.4028/www.scientific.net/msf.556-557.243.

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Wet chemical etching using molten KOH is the most frequently applied method to reveal structural defects in SiC. Until now etching kinetics of SiC in planes different from the polar cplane has not been reported. In this paper we report on defect etching of SiC in non-polar faces. Using a calibrated KOH defect-etching furnace with possibilities to set accurate etching temperatures we have etched SiC samples of various orientations to (i) study defect occurrence and their morphologies (ii) set KOH defect etching parameters for SiC for these orientations and (iii) investigate etching kinetics in relation to anisotropy/surface polarity. For non-polar planes of the same orientations a comparison in etching kinetics and defect morphologies in crystals grown in different directions is presented.

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Kolmachikhina, E. B., E. A. Ryzhkova, and D. V. Dmitrieva. "Influence of Zinc Sulfide Wetting in Surfactants Presence on Leaching Parameters." Solid State Phenomena 284 (October 2018): 737–42. http://dx.doi.org/10.4028/www.scientific.net/ssp.284.737.

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This paper is describing an investigation of surfactants influence on zinc sulfide wetting by non-polar liquids and sphalerite concentrates pressure leaching parameters. Zinc sulfide preferential wettability by oil was tested in presence anionic surfactants with different chemical structures. Interfacial tension was determinated by the maximum liquid drop volume method. It allows to determine surfactant potential effectivity on pressure leaching of sphalerite concentrate. It is found that SDBS decreases zinc sulfide wettability by non-polar liquids in a greater degree than SDS and Ls. Combined addition of Ls and SDBS allowed to receive residues with optimal coarseness, eliminate pellet formation and increase zinc extraction.

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Misra, Rajni, Amar Singh, J. P. Shukla, and M. C. Saxena. "Complex Formation and Associated Parameters in Various Non-Polar Solvents." Physics and Chemistry of Liquids 15, no. 1 (September 1985): 49–58. http://dx.doi.org/10.1080/00319108508081003.

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32

Morita, Terumitsu, Branka M. Ladanyi, and James T. Hynes. "Polar solvent contributions to activation parameters for model ionic reactions." Journal of Physical Chemistry 93, no. 4 (February 1989): 1386–92. http://dx.doi.org/10.1021/j100341a041.

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García-Haro, Francisco Javier, Manuel Campos-Taberner, Jordi Muñoz-Marí, Valero Laparra, Fernando Camacho, Jorge Sánchez-Zapero, and Gustau Camps-Valls. "Derivation of global vegetation biophysical parameters from EUMETSAT Polar System." ISPRS Journal of Photogrammetry and Remote Sensing 139 (May 2018): 57–74. http://dx.doi.org/10.1016/j.isprsjprs.2018.03.005.

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34

Troshichev, O. A., N. A. Podorozhkina, and A. S. Janzhura. "Invariability of relationship between the polar cap magnetic activity and geoeffective interplanetary electric field." Annales Geophysicae 29, no. 8 (August 31, 2011): 1479–89. http://dx.doi.org/10.5194/angeo-29-1479-2011.

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Abstract. The PC (polar cap) index characterizing the solar wind energy input into the magnetosphere is calculated with use of parameters α, β, and φ, determining the relationship between the interplanetary electric field (EKL) and the value of magnetic activity δF in the polar caps. These parameters were noted as valid for large and small EKL values, and as a result the suggestion was made (Troshichev et al., 2006) that the parameters should remain invariant irrespective of solar activity. To verify this suggestion, the independent sets of calibration parameters α, β, and φ were derived separately for the solar maximum (1998–2001) and solar minimum (1997, 2007–2009) epochs, with a proper choice of a quiet daily variation (QDC) as a level of reference for the polar cap magnetic activity value. The results presented in this paper demonstrate that parameters α, β, and φ, derived under conditions of solar maximum and solar minimum, are indeed in general conformity and provide consistent (within 10 % uncertainty) estimations of the PC index. It means that relationship between the geoeffective solar wind variations and the polar cap magnetic activity responding to these variations remains invariant irrespective of solar activity. The conclusion is made that parameters α, β, and φ derived in AARI#3 version for complete cycle of solar activity (1995–2005) can be regarded as forever valid.

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Mason, Paul A., Natalie K. Wells, Mokhine Motsoaledi, Paula Szkody, and Emmanuel Gonzalez. "CRTS J035010.7 + 323230, a new eclipsing polar in the cataclysmic variable period gap." Monthly Notices of the Royal Astronomical Society 488, no. 2 (July 25, 2019): 2881–91. http://dx.doi.org/10.1093/mnras/stz1863.

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ABSTRACT We report the discovery of a new eclipsing polar, CRTS J035010.7+323230 (hereafter CRTS J0350+3232). We identified this cataclysmic variable (CV) candidate as a possible polar from its multiyear Catalina Real-Time Transient Survey (CRTS) optical light curve. Photometric monitoring of 22 eclipses in 2015 and 2017 was performed with the 2.1-m Otto Struve Telescope at McDonald Observatory. We derive an unambiguous high-precision ephemeris. Strong evidence that CRTS J0350 + 3232 is a polar comes from optical spectroscopy obtained over a complete orbital cycle using the Apache Point Observatory 3.5-m telescope. High velocity Balmer and He ii λ4686Å emission-line equivalent width ratios, structures, and variations are typical of polars and are modulated at the same period, 2.37 h (142.3 min), as the eclipse to within uncertainties. The spectral energy distribution and luminosity is found to be comparable to that of AM Herculis. Pre-eclipse dips in the light curve show evidence for stream accretion. We derive the following tentative binary and stellar parameters assuming a helium composition white dwarf and a companion mass of 0.2 M⊙: inclination i = 74.68° ± 0.03°, semimajor axis a = 0.942 ± 0.024 R⊙, and masses and radii of the white dwarf and companion, respectively: M1 = 0.948 $^{+0.006}_{-0.012}$ M⊙, R1 = 0.00830 $^{+0.00012}_{-0.00006}$ R⊙, and R2 = 0.249 ± 0.002 R⊙. As a relatively bright (V ∼ 17–19 mag), eclipsing, period-gap polar, CRTS J0350 + 3232 will remain an important laboratory for the study of accretion and angular momentum evolution in polars.

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Li, Xiuhong, Xuejie Hao, Lizeyan Yin, Lu Liu, Yushuang Ma, Rongjin Yang, and Qiao Song. "Validation of GPS-Based Monitoring and Remote Sensing of Ice-Shelf and Ice-Sheet Movement Changes." Sensors 21, no. 23 (November 24, 2021): 7822. http://dx.doi.org/10.3390/s21237822.

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The north and south poles of the earth (hereinafter referred to as the polar regions) are important components of the earth system. Changes in the material balance and movement of the polar ice shelf reflect the influence of the polar regions on global climate change and are also a response to global climate change. Through a comprehensive investigation of ice-shelf kinematics, with sufficient accuracy, it is possible to obtain ice-shelf elevation, movement-state data, ice-shelf material balance state, and the ice-shelf movement dynamics mechanism. Due to the extremely harsh environment in polar regions, remote sensing is currently widely used. Manual and equipment monitoring methods show insufficient accuracy or discontinuous time series. There is an urgent need to obtain continuous real-time ice-shelf kinematics-related parameters on the ground to verify the reliability of the parameters obtained by satellite remote sensing. These parameters should be combined with remote sensing monitoring to provide data support. In this paper, a monitoring system for the movement of polar ice and shelf ice cover is developed, and it is proposed that various data can be acquired by integrating high-precision GPS (global positioning system) and other sensors. Solutions to the problem of low-temperature power supply in the polar regions, data acquisition and storage strategies, and remote communication methods are proposed. Testing and remote sensing validation verified that the developed acquisition system can fulfill the requirements for monitoring the movement of the polar unmanned ice shelves and ice sheets.

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Yagova, Nadezda, Natalia Nosikova, Lisa Baddeley, Olga Kozyreva, Dag A. Lorentzen, Vyacheslav Pilipenko, and Magnar G. Johnsen. "Non-triggered auroral substorms and long-period (1–4 mHz) geomagnetic and auroral luminosity pulsations in the polar cap." Annales Geophysicae 35, no. 3 (March 8, 2017): 365–76. http://dx.doi.org/10.5194/angeo-35-365-2017.

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Abstract. A study is undertaken into parameters of the polar auroral and geomagnetic pulsations in the frequency range 1–4 mHz (Pc5∕Pi3) during quiet geomagnetic intervals preceding auroral substorms and non-substorm background variations. Special attention is paid to substorms that occur under parameters of the interplanetary magnetic field (IMF) conditions typical for undisturbed days (non-triggered substorms). The spectral parameters of pulsations observed in auroral luminosity as measured by a meridian scanning photometer (Svalbard) in the polar cap and near the polar boundary of the auroral oval are studied and compared with those for the geomagnetic pulsations measured by the magnetometer network IMAGE in the same frequency range. It is found that Pc5∕Pi3 power spectral density (PSD) is higher during pre-substorm time intervals than for non-substorm days and that specific variations of pulsation parameters (substorm precursors) occur during the last 2–4 pre-substorm hours.

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Monder, Hila, Leo Bielenki, Hanna Dodiuk, Anna Dotan, and Samuel Kenig. "Poly (Dimethylsiloxane) Coating for Repellency of Polar and Non-Polar Liquids." Polymers 12, no. 10 (October 21, 2020): 2423. http://dx.doi.org/10.3390/polym12102423.

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The wettability of poly (dimethylsiloxane) (PDMS) coating on plasma-treated glass was studied at room temperature using polar and non-polar liquids. The wettability was investigated regarding the liquids’ surface tensions (STs), dielectric constants (DCs) and solubility parameters (SPs). For polar liquids, the contact angle (CA) and contact angle hysteresis (CAH) are controlled by the DCs and non-polar liquids by the liquids’ STs. Solubility parameter difference between the PDMS and the liquids demonstrated that non-polar liquids possessed lower CAH. An empirical model that integrates the interfacial properties of liquid/PDMS has been composed. Accordingly, the difference between the SPs of PDMS and the liquid is the decisive factor affecting CAH, followed by the differences in DCs and STs. Moreover, the interaction between the DCs and the SPs is of importance to minimize CAH. It has been concluded that CAH, and not CA, is the decisive attribute for liquid repellency of PDMS coating.

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Munoz, V. A., R. J. Mikula, C. Payette, and W. W. Lam. "Microscopic versus process parameters in heavy-oil upgrading." Proceedings, annual meeting, Electron Microscopy Society of America 50, no. 1 (August 1992): 366–67. http://dx.doi.org/10.1017/s042482010012223x.

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The transformation of high molecular weight components present in heavy oils into useable liquid fuels requires their decomposition by means of a variety of processes. The low molecular weight species produced recombine under controlled conditions to generate synthetic fuels. However, an important fraction undergo further recombination into higher molecular weight components, leading to the formation of coke. The optical texture of the coke can be related to its originating components. Those with high sulfur and oxygen content tend to produce cokes with small optical texture or fine mosaic, whereas compounds with relatively high hydrogen content are likely to produce large optical texture or domains. In addition, the structure of the parent chemical components, planar or nonplanar, determines the isotropic or anisotropic character of the coke. Planar molecules have a tendency to align in an approximately parallel arrangement to initiate the formation of the nematic mesophase leading to the formation of anisotropic coke. Nonplanar highly alkylated compounds and/or those rich in polar groups form isotropic coke. The aliphatic branches produce steric hindrance to alignment, whereas the polar groups participate in cross-linking reactions.

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Bilgiç, Ceyda. "Determination of the surface properties of kaolinite by inverse gas chromatography." Water Science and Technology 2017, no. 2 (March 27, 2018): 319–28. http://dx.doi.org/10.2166/wst.2018.136.

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Abstract Inverse gas chromatography (IGC) was applied to characterize the surface of kaolinite. The adsorption thermodynamic parameters (the standard enthalpy (∆H0), entropy (∆S0) and free energy of adsorption (∆G0), the dispersive component of the surface energy (γsd), and the acid/base character of kaolinite surface were estimated by using the retention time of different non-polar and polar probes at infinite dilution region. The specific free energy of adsorption (∆Gsp), the specific enthalpy of adsorption (∆Hsp), and the specific entropy of adsorption (∆Ssp) of polar probes on kaolinite were determined. (∆Gsp) values were correlated with the donor and modified acceptor numbers of the probes to quantify the acidic (KA) and the basic (KD) parameters of the kaolinite surface. The values obtained for the parameters KA and KD indicated a basic character for kaolinite surface.

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Saeteaw, Akarachai, Nuttawat Sawang, and Thana Sutthibutpong. "van der Waals parameters of inert, polar and non-polar gas molecules obtained from atomistic molecular dynamics simulations." Journal of Physics: Conference Series 1380 (November 2019): 012094. http://dx.doi.org/10.1088/1742-6596/1380/1/012094.

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Zhu, Wei-Hong, Shao-Tang Zhang, and Zheng-Biao Li. "An analysis of heat conduction in polar bear hairs using one-dimensional fractional model." Thermal Science 20, no. 3 (2016): 785–88. http://dx.doi.org/10.2298/tsci1603785z.

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Hairs of a polar bear are of superior properties such as the excellent thermal protection. The polar bears can perennially live in an extremely cold environment and can maintain body temperature at around 37 ?C. Why do polar bears can resist such cold environment? Its membrane-pore structure plays an important role. In the previous work, we established a 1-D fractional heat conduction equation to reveal the hidden mechanism for the hairs. In this paper, we further discuss solutions and parameters of the equation established and analyze heat conduction in polar bear hairs.

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Zhang, Yu, Jing Li, and Libo Zhou. "The Relationship between Polar Vortex and Ozone Depletion in the Antarctic Stratosphere during the Period 1979–2016." Advances in Meteorology 2017 (2017): 1–12. http://dx.doi.org/10.1155/2017/3078079.

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As the most prominent feature of the polar stratosphere, polar vortex results in widespread changes in the climate system, especially in the ozone variation. In this study, the linkage between polar vortex and ozone depletion in Antarctic stratosphere during the period 1979–2016 is investigated; we calculated the averaged total column ozone within the polar vortex based on the vortex edge (−28.8 PVU PV contour) instead of the geographical region defined by latitude and longitude. Results from the spatial patterns of ozone and polar vortex suggest that the morphological changes of polar vortex can impact the horizontal distribution of ozone and the ozone within the polar vortex experiences a severe depletion in spring. The negative relationship between ozone and polar vortex in terms of vortex area, strength, and breakup time is significant with the correlation coefficients of −0.57, −0.68, and −0.76, respectively. The breakup time of polar vortex plays an important role in the relation between polar vortex and ozone depletion with the highest-value correlation coefficient among three polar vortex parameters. Furthermore, the possible mechanism for this relationship is also discussed in this article.

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Zhang, Yin Yong, Jian Guo Zhao, Lu Ping Ma, Yue Jin Ma, and Jian Jun Hao. "Process Optimization of Reaction Nitrogen Arc Welding Cladding TiCN/Fe Metal Ceramic Composite Coating." Applied Mechanics and Materials 217-219 (November 2012): 1279–82. http://dx.doi.org/10.4028/www.scientific.net/amm.217-219.1279.

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In order to research the technique of reaction nitrogen arc cladding, the 5 factors 4 levels orthogonal experiments have been designed, and the effects of process parameters (such as cladding current, tungsten polar diameter, nitrogen flow, cladding speed and precoated thickness) on coating wear resistance performance were discussed. The process parameters were optimized as follows: cladding current 200 A, tungsten polar diameter 1.6 mm, nitrogen flow 12L. min-1, cladding speed 2 mm.s-1, precoated thickness 1.5 mm.

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Ohshima, Hiroyuki, and Shin-ichi Takeda. "A New Method for Calculating the Hamaker Constant Based on the Hansen Solubility Parameters for Non-Polar Liquids." Colloids and Interfaces 8, no. 2 (February 22, 2024): 14. http://dx.doi.org/10.3390/colloids8020014.

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A simple relationship between the Hamaker constant and the Hansen solubility parameters for non-polar liquids is derived by combining a Hamaker constant/surface tension relationship derived by Israelachvili and a Hansen solubility parameters/surface tension relationship derived by Abbott. With this relationship, one can easily estimate the Hamaker constant of non-polar liquids on the basis of the database of the Hansen solubility parameters. This is an entirely new method for calculating the Hamaker constant without recourse to data on the frequency-dependent dielectric permittivity of those substances (which are required for the rigorous Lifshitz theory) and laborious numerical calculations.

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Avanesov, G. A., B. S. Zhukov, M. V. Mikhailov, and B. G. Sherstyukov. "Cosmic Regulators of the Earth’s Climate." Астрономический вестник 57, no. 6 (November 1, 2023): 521–31. http://dx.doi.org/10.31857/s0320930x23060014.

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A discussion is presented of the effects generated by the imbalance between the insolation energy of polar-day zones and the radiation energy of polar-night zones on multicentennial changes in the Earth’s climate. The dependence of this imbalance on the Earth’s orbital parameters is determined. The energy imbalance curves are compared with the known temperature curves for the polar regions, which have been estimated from the results of an analysis of ice cores taken in Antarctica and Greenland. The curves clearly reveal a difference between the contributions of cosmic and terrestrial factors to the temperature profiles for the regions in question and demonstrate a synchronicity of these factors. Algorithms are obtained for calculating the magnitude of fluctuations in the size of the Earth’s polar caps relative to their averages. The results obtained within the assumptions taken in this work enable predictions to be made about the development of the current global warming and about changes in the size of the Arctic and Antarctic polar caps. It is predicted that over the next three millennia, changes in the Earth’s orbital parameters will contribute to the slow melting of the northern polar cap. Then, the trend for a new growth of the northern polar cap will again manifest itself. In the Southern Hemisphere, a trend towards increased glaciation has already formed. Influenced by the cosmic factor, it will intensify over the next 20 000 years.

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Zêzere, Bruno, Inês Portugal, José R. B. Gomes, and Carlos M. Silva. "Modeling Tracer Diffusion Coefficients of Any Type of Solutes in Polar and Non-Polar Dense Solvents." Materials 15, no. 18 (September 15, 2022): 6416. http://dx.doi.org/10.3390/ma15186416.

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In this work, a simple two-parameters correlation based on the Rice and Gray, Lennard-Jones, and Stockmayer theories was devised for the calculation of binary diffusion coefficients (D12) of any type of solutes at infinite dilution in polar and non-polar solvents. This equation can be relevant for systems with polar solvents, since most models in the literature fail when strong intermolecular forces predominate in solution. The new correlation embodies the Stockmayer potential without requiring the dipole moments of any component, which significantly enlarges its application. It was validated with the largest D12 database of polar and non-polar dense systems, with 8812 data points (NDP) spanning 553 systems, of which 133 have water as solvent (NDP = 1266), 89 contain polar solvents excluding water (NDP = 1405), 177 have supercritical carbon dioxide (SC-CO2) as solvent (NDP = 5028), and 154 have non-polar or weakly polar solvents excluding SC-CO2 (NDP = 1113). Overall, the model achieved an average deviation of only 3.43%, with accurate and unbiased behavior even for polar systems.

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Tabassum, Shagufta, and V. P. Pawar. "Complex permittivity spectra of binary polar liquids using time domain reflectometry." Journal of Advanced Dielectrics 08, no. 03 (June 2018): 1850019. http://dx.doi.org/10.1142/s2010135x18500194.

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The study of complex properties in a binary mixture of polar liquids has been carried out in the frequency range of 10[Formula: see text]MHz to 30 GHz at 293[Formula: see text]K and 298[Formula: see text]K temperatures using time domain reflectometry. The complex properties of polar liquids in binary mixture give information about the frequency dispersion in the dielectric permittivity ([Formula: see text]) and dielectric loss ([Formula: see text]). The information regarding the orientation of electric dipoles in a polar liquid mixture is given by Kirkwood parameters. The Bruggeman parameters are used as the indicator of liquid1 and liquid2 interaction. Molar entropy ([Formula: see text]) and molar enthalpy ([Formula: see text]) are also discussed at the end of the paper.

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Daemen, Jannes, Arvid Martens, Mathias Kersemans, Erik Verboven, Steven Delrue, Wim Van Paepegem, and Koen Van Den Abeele. "Optimal Design Parameters for a Phased-Array-Based Ultrasonic Polar Scan." IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control 68, no. 8 (August 2021): 2781–93. http://dx.doi.org/10.1109/tuffc.2021.3070736.

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Cartwright, Jessica, Alexander D. Fraser, and Richard Porter-Smith. "Polar maps of C-band backscatter parameters from the Advanced Scatterometer." Earth System Science Data 14, no. 2 (February 4, 2022): 479–90. http://dx.doi.org/10.5194/essd-14-479-2022.

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Abstract. Maps of backscatter anisotropy parameters from the European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT) Advanced Scatterometer (ASCAT), a C-band fan-beam scatterometer, contain unique and valuable data characterising the surface and subsurface of various cryospheric elements, including sea ice and ice sheets. The computational expense and considerable complexity required to produce parameter maps from the raw backscatter data inhibits the wider adoption of ASCAT data. Here, backscatter anisotropy parameter maps gridded at a resolution of 12.5 km per pixel are made available to the community in order to facilitate the exploitation of these parameters for cryospheric applications. These maps have been calculated from the EUMETSAT Level 1B Sigma0 product acquired from ASCAT on board MetOp-A, MetOp-B and MetOp-C. The dataset is unique in that it prioritises anisotropy characterisation over temporal resolution and combines ASCAT data from multiple platforms. The parameterisation chosen assumes a linear falloff of backscatter with incidence angle and a fourth-order Fourier series parameterisation of azimuth angle anisotropy. The product (Fraser and Cartwright, 2022) is available at https://doi.org/10.26179/91c9-4783 presented on three timescales depending on orbital platform availability: 5 d (2007 to 2020 – MetOp-A only – suitable for users requiring a long time series), 2 d (2013 to 2020 – MetOp-A and MetOp-B) and 1 d resolution (2019–2020 – MetOp -A, MetOp-B and MetOp-C – suitable for users needing both high temporal resolution and detailed anisotropy characterisation). Datasets will be updated annually.

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Journal articles on the topic 'Polar parameters'

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