Статті в журналах: "Coefficient of resistance"

1

赵, 振国. "Study on Resistance Coefficient." International Journal of Fluid Dynamics 04, no. 01 (2016): 8–18. http://dx.doi.org/10.12677/ijfd.2016.41002.

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2

Fox, John N. "Temperature coefficient of resistance." Physics Education 25, no. 3 (May 1, 1990): 167–69. http://dx.doi.org/10.1088/0031-9120/25/3/411.

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3

Zhang, Mei Jie, Hou Zhi Wang, Hua Zhi Gu, and Ao Huang. "Analysis on Resistance Coefficients and Optimization of Structure and Properties of Porous Permeable Refractory." Key Engineering Materials 368-372 (February 2008): 1155–57. http://dx.doi.org/10.4028/www.scientific.net/kem.368-372.1155.

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The resistance coefficients through which gas flow permeable refractory are important properties and have great effect on the gas blowing parameters and gas-liquid two phase flowing characteristics in the metallurgy furnace such as ladles, tundish. In this paper, the resistance coefficients were measured according to the Forchheimer’s law. The results show when the gas flow rate is fixed, the viscosity resistance coefficient and inertia resistance coefficient decrease as the apparent porosity and average pore diameter increase. The viscous resistance coefficient is more lager than the inertial resistance coefficient. The resistance coefficients were analyzed by dimensional analysis and the statistical correlations between the resistance coefficients and parameters of porous permeable refractory were got based on the experimental data. In order to get high strength at low resistance coefficients, the raw materials particle degree were adjusted.

4

Lhomme, J. P., N. Boudhina, and M. M. Masmoudi. "Technical Note: On the Matt–Shuttleworth approach to estimate crop water requirements." Hydrology and Earth System Sciences Discussions 11, no. 4 (April 14, 2014): 4217–33. http://dx.doi.org/10.5194/hessd-11-4217-2014.

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Abstract. The Matt–Shuttleworth method provides a way to make a one-step estimate of crop water requirements with the Penman–Monteith equation by translating the crop coefficients, commonly available in FAO publications, into equivalent surface resistances. The methodology is based upon the theoretical relationship linking crop surface resistance to crop coefficient and involves the simplifying assumption that the reference crop evapotranspiration (ET0) is equal to the Priestley–Taylor estimate with a fixed coefficient of 1.26. This assumption, used to eliminate the dependence of surface resistance on certain weather variables, is questionable: numerical simulations show that it can lead to substantial differences between the true value of surface resistance and its estimate. Consequently, the basic relationship between surface resistance and crop coefficient, without any assumption, appears to be more appropriate for inferring crop surface resistance, despite the interference of weather variables.

5

Lhomme, J. P., N. Boudhina, and M. M. Masmoudi. "Technical Note: On the Matt–Shuttleworth approach to estimate crop water requirements." Hydrology and Earth System Sciences 18, no. 11 (November 4, 2014): 4341–48. http://dx.doi.org/10.5194/hess-18-4341-2014.

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Abstract. The Matt–Shuttleworth method provides a way to make a one-step estimate of crop water requirements with the Penman–Monteith equation by translating the crop coefficients, commonly available in United Nations Food and Agriculture Organization (FAO) publications, into equivalent surface resistances. The methodology is based upon the theoretical relationship linking crop surface resistance to a crop coefficient and involves the simplifying assumption that the reference crop evapotranspiration (ET0) is equal to the Priestley–Taylor estimate with a fixed coefficient of 1.26. This assumption, used to eliminate the dependence of surface resistance on certain weather variables, is questionable; numerical simulations show that it can lead to substantial differences between the true value of surface resistance and its estimate. Consequently, the basic relationship between surface resistance and crop coefficient, without any assumption, appears to be more appropriate for inferring crop surface resistance, despite the interference of weather variables.

6

Wang, Xinran, Lizhen Ge, Dong Liu, Qin Zhu, and Bin Zheng. "Experimental Study on Influencing Factors of Resistance Coefficient and Residual Resistance Coefficient in Oilfield Z." World Journal of Engineering and Technology 07, no. 02 (2019): 270–81. http://dx.doi.org/10.4236/wjet.2019.72018.

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7

Aida-Zade, K. R., and S. Z. Kuliev. "Hydraulic resistance coefficient identification in pipelines." Automation and Remote Control 77, no. 7 (July 2016): 1225–39. http://dx.doi.org/10.1134/s0005117916070092.

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8

Bekibayev, Timur, Uzak Zhapbasbayev, Gaukhar Ramazanova, and Daniyar Bossinov. "Oil pipeline hydraulic resistance coefficient identification." Cogent Engineering 8, no. 1 (January 1, 2021): 1950303. http://dx.doi.org/10.1080/23311916.2021.1950303.

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9

Wrzecioniarz, Piotr, Wojciech Ambroszko, and Aleksandra Pindel. "Limitations of vehicle movement resistances: rolling resistance." AUTOBUSY – Technika, Eksploatacja, Systemy Transportowe 19, no. 12 (December 31, 2018): 256–59. http://dx.doi.org/10.24136/atest.2018.394.

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In the paper limitations and exemplary methods of rolling resistance minimization are described. Changes of value of rolling resistance coefficient during years and values for exemplary rolling pairs are presented. Conclusions about future progress are formulated.

10

Schindelwig, Kurt, Martin Mössner, Michael Hasler, and Werner Nachbauer. "Determination of the rolling resistance of roller skis." Proceedings of the Institution of Mechanical Engineers, Part P: Journal of Sports Engineering and Technology 231, no. 1 (August 1, 2016): 50–56. http://dx.doi.org/10.1177/1754337116628719.

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The rolling resistance of skis used in roller skiing competitions should resemble the gliding resistance of cross-country skis to allow specific training and moving patterns for cross-country skiing and to guarantee equal opportunities for athletes in roller ski races. Therefore, the purpose of this work was to develop a portable rolling resistance meter to precisely measure the rolling resistance of roller skis. Measurements were based on recordings of the angular deceleration of a flywheel due to the rolling resistance between a roller ski’s wheel and the flywheel’s steel surface. Rolling resistance coefficients of four roller ski types ranged between 0.019 and 0.025. Measurements of the rolling resistance coefficient showed a precision of 1.26%. Substantial rolling resistance coefficient variations (10%) were observed for wheels of the same type. Furthermore, the rolling resistance coefficient was found to be negatively correlated with normal load or ambient temperature. The proposed rolling resistance meter is appropriate to determine the rolling resistance coefficient of roller skis’ wheels precisely.

11

Wrzecioniarz, Piotr, Wojciech Ambroszko, and Aleksandra Pindel. "Limitations of vehicle movement resistances: aerodynamic resistance." AUTOBUSY – Technika, Eksploatacja, Systemy Transportowe 19, no. 12 (December 31, 2018): 252–55. http://dx.doi.org/10.24136/atest.2018.393.

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In the paper limitations and exemplary methods of aerodynamic drag force minimization in different kinds of vehicles are described. Changes of value of aerodynamic drag coefficient during years are present-ed. Conclusions about future possible new solutions in different kinds of vehicles are formulated.

12

Zhang, Qin, Manlai Zhang, Zhihong Zhou, and Shizhong Wei. "Numerical Calculation of the Tee Local Resistance Coefficient." Open Mechanical Engineering Journal 9, no. 1 (October 7, 2015): 876–81. http://dx.doi.org/10.2174/1874155x01509010876.

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The local head loss of tee could be calculated with the determination of local resistance coefficient by CFD simulation and test. Based on the mesh-independent feature identified, the flow field inner tee was numerically simulated by the standard k - ε turbulent model and SIMPLEC algorithms, which has revealed the mainstream was obliged to turn to the opposite side of tee junction, and a rise in pressure drop between upstream and downstream was caused as a result. Furthermore, the frictional resistance coefficient was calculated for eliminating the frictional head loss of model, which decreased from 0.0207 to 0.0133 when the inlet velocity increased from 1 m/s to 12 m/s. Additionally, the local resistance coefficients of tee at flow conditions were attained, and the quadratic polynomial between the local resistance coefficient and flux ratio was presented due to the influence of branch on mainstream. Through the test, the simulation result has been compared and the effectiveness of simulation has been verified.

13

Qi, Han-Bing, Dong-Hai Li, Wei Wei, Xin-Hao Hu, Dong Li, Guo-Zhong Wu, and Xiao-Yan Liu. "Lattice Boltzmann simulation of resistance coefficient of the oil and water migration in porous media." Thermal Science 22, Suppl. 2 (2018): 547–56. http://dx.doi.org/10.2298/tsci171011039q.

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The coefficients of oil and water transfer resistance in porous media are the basis of numerical study on the migration of contamination in the pipeline, soil cleaning, oilfield water flooding, and oilfield water treatment. Based on the quartet structure generation set, the porous media with random distribution are constructed. The lattice Boltzmann method is used to simulate the mesoscopic migration of oil and water in porous media. Then the distribution law of oil and water velocity and pressure in porous media is analyzed, and the fitting equations of oil and water resistance coefficients are obtained under different porosity. The results show that when the oil and water migrate in porous media, the viscous resistance coefficient is larger than the inertia resistance factor, and the viscosity resistance coefficient of water is obviously higher than that of oil, while the coefficient of inertia resistance of oil and water is nearly same.

14

Jablonská, Jana, and Milada Kozubková. "Diagnostics of Resistance Coefficients and Cavitation of Flow Control Valve." Applied Mechanics and Materials 752-753 (April 2015): 980–87. http://dx.doi.org/10.4028/www.scientific.net/amm.752-753.980.

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The paper deals with the determination of characteristic as dependence of the valve pressure drop on the flow rate, flow characteristic and cavitation conditions in case of water flow in the flow control valve. Emphasis is put on the utilization of simple, available relationships and measuring for identification of the basic valve coefficients, e.g. loss coefficient, flow rate coefficient and cavitation factor. These coefficients are used for designing of pipe circuits. In this paper there is defined methodology for determining those coefficients and is applied to the modified cone of flow control valve for verification the linear flow characteristic. It is necessary to consider the fact that in various countries the modifications of coefficients are preferred and it is therefore necessary to specify them.

15

Okutani, Chihiro, Tomoyuki Yokota, Ryotaro Matsukawa, and Takao Someya. "Suppressing the negative temperature coefficient effect of resistance in polymer composites with positive temperature coefficients of resistance by coating with parylene." Journal of Materials Chemistry C 8, no. 22 (2020): 7304–8. http://dx.doi.org/10.1039/d0tc00702a.

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16

Guttieri, Mary J., Charlotte V. Eberlein, and Edward J. Souza. "Inbreeding coefficients of field populations ofKochia scopariausing chlorsulfuron resistance as a phenotypic marker." Weed Science 46, no. 5 (October 1998): 521–25. http://dx.doi.org/10.1017/s0043174500091025.

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Inbreeding coefficients were determined for nine southeastern Idaho kochia populations using chlorsulfuron resistance as a phenotypic marker. Inbreeding coefficients in six of the populations approximated 0, indicating that these field populations were random mating. One population had an inbreeding coefficient of 0.32, indicating partial selfing. No susceptible genotypes were identified in one population, which suggested recent selection and skewed the inbreeding coefficient. One population had an inbreeding coefficient of −0.19, suggesting either heterozygote advantage or some recent selection in the population. Our results suggest that kochia populations generally approximate random mating. Therefore, unlinked alleles will be independently assorted in field populations of kochia.

17

Achour, Bachir. "Chezy’s Resistance Coefficient in a Circular Conduit." Open Civil Engineering Journal 9, no. 1 (April 24, 2015): 187–95. http://dx.doi.org/10.2174/1874149501509010187.

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In the literature, there is no explicit method for calculating the resistance coefficient of Chezy, especially for a circular conduit. Existing relationships are either implicit or do not take into account all parameters influencing the flow such as kinematic viscosity or the slope of the conduit. In many practical cases, one affects arbitrarily a constant value for Chezy’s coefficient. It is a physically unjustified approach, because Chezy’s coefficient varies with flow parameters, especially the filling rate of the conduit and the absolute roughness. In this paper, simple and explicit relationships are presented for the calculation of Chezy’s resistance coefficient in a circular conduit. These relationships have been established based on the rough model method. The Chezy’s resistance coefficient is expressed in terms of known hydraulic parameters of the flow in a referential rough model. For fast calculation of Chezy’s coefficient, the simplified method is the most appropriate since it requires only four parameters which are the discharge, the absolute roughness, the slope and the kinematic viscosity. The study also shows that the Chezy’s resistance coefficient reaches a maximum whose expression is well defined. Some examples are presented showing how to calculate Chezy's coefficient in a circular conduit with a minimum practical data.

18

Achour, Bachir. "Chezy’s Resistance Coefficient in a Rectangular Channel." Journal of Scientific Research and Reports 7, no. 5 (January 10, 2015): 338–47. http://dx.doi.org/10.9734/jsrr/2015/18385.

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19

Yang, Kejun, Shuyou Cao, and Xingnian Liu. "Study on resistance coefficient in compound channels." Acta Mechanica Sinica 21, no. 4 (July 25, 2005): 353–61. http://dx.doi.org/10.1007/s10409-005-0042-x.

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20

Tunyagi, A., K. Kandrai, Z. Fülöp, Z. Kapusi, and A. Simon. "Friction coefficient determination by electrical resistance measurements." Physics Education 53, no. 3 (March 23, 2018): 035028. http://dx.doi.org/10.1088/1361-6552/aab308.

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21

Bhat, Masroor Ahmad, Rayees A. Zargar, Anchit Modi, Manju Arora, and N. K. Gaur. "Giant magneto resistance and temperature coefficient of resistance in Sm0.55Sr0.30Ag0.15MnO3 perovskite." Progress in Natural Science: Materials International 26, no. 6 (December 2016): 579–83. http://dx.doi.org/10.1016/j.pnsc.2016.11.012.

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22

Sobieszuk, Paweł, Filip Ilnicki, and Ryszard Pohorecki. "Contribution of Liquid- and Gas-Side Mass Transfer Coefficients to Overall Mass Transfer Coefficient in Taylor Flow in a Microreactor." Chemical and Process Engineering 35, no. 1 (March 1, 2014): 35–45. http://dx.doi.org/10.2478/cpe-2014-0003.

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Abstract Gas-liquid microreactors find an increasing range of applications both in production, and for chemical analysis. The most often employed flow regime in these microreactors is Taylor flow. The rate of absorption of gases in liquids depends on gas-side and liquid-side resistances. There are several publications about liquid-side mass transfer coefficients in Taylor flow, but the data about gas-side mass transfer coefficients are practically non existent. We analysed the problem of gas-side mass transfer resistance in Taylor flow and determined conditions, in which it may influence the overall mass transfer rate. Investigations were performed using numerical simulations. The influence of the gas diffusivity, gas viscosity, channel diameter, bubble length and gas bubble velocity has been determined. It was found that in some case the mass transfer resistances in both phases are comparable and the gas-side resistance may be significant. In such cases, neglecting the gas-side coefficient may lead to errors in the experimental data interpretation.

23

Lee, Mi-Jai, Jong-Hee Hwang, Jin-Ho Kim, and Tae-Young Lim. "Electric Properties of the Laminate Type PTC(Positive Temperature Coefficient of Resistance) Thermistor According to Polymer Blowing Agent." Korean Journal of Materials Research 22, no. 12 (December 27, 2012): 658–63. http://dx.doi.org/10.3740/mrsk.2012.22.12.658.

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24

Zhang, Xiao Yan, Fang Fang Jiang, Shan Yuan Zhao, Wen Fei Tian, and Xiao Hang Chen. "Experimental Study on Heat Transfer Characteristics and Pressure Drops for Water Flowing in Spiral Coil Heat Exchanger." Advanced Materials Research 732-733 (August 2013): 593–99. http://dx.doi.org/10.4028/www.scientific.net/amr.732-733.593.

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The heat transfer and pressure drop characteristics for water flowing in four spiral coils with different shapes and different sizes were experimental studied. Reynolds number range from 4000 to 9000, volume flow rate range from 200 to 350 L/h and heating power range from 80-350 W. Based on the experimental results, the regularity of Reynolds number and heating power influencing on heat transfer and pressure drop characteristics was analyzed and discussed. The results indicate: the Nu increases with increasing Re, the greatest average heat transfer coefficient appears in the smaller circular spiral coil. The heat transfer coefficients increase with increasing heating power, the greatest average heat transfer coefficient also appears in the smaller circular spiral coil. The pressure drops increase with increasing Re, the pressure drop in big ellipse spiral coil is greatest. The resistance coefficients gradually decrease with increasing Re. The resistance coefficient of small circular spiral coil is always greatest, and the resistance coefficient of big circular spiral coil is smallest.

25

Tozaki, Ken-ichi, and Kalyan Sou. "Novel Determination of Peltier Coefficient, Seebeck Coefficient and Thermal Resistance of Thermoelectric Module." Japanese Journal of Applied Physics 45, no. 6A (June 8, 2006): 5272–73. http://dx.doi.org/10.1143/jjap.45.5272.

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26

Long, Chunxia, and Jianyu Guan. "A method for determining valve coefficient and resistance coefficient for predicting gas flowrate." Experimental Thermal and Fluid Science 35, no. 6 (September 2011): 1162–68. http://dx.doi.org/10.1016/j.expthermflusci.2011.04.001.

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27

Dao, Hoang, Bas Hofland, Marcel Stive, and Tri Mai. "Experimental Assessment of the Flow Resistance of Coastal Wooden Fences." Water 12, no. 7 (July 4, 2020): 1910. http://dx.doi.org/10.3390/w12071910.

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Wooden fences are applied as a nature-based solution to support mangrove restoration along mangrove coasts in general and the Mekong Delta coast in particular. The simple structure uses vertical bamboo poles as a frame to store horizontal bamboo and tree branches (brushwood). Fence resistance is quantitatively determined by the drag coefficient exerted by the fence material on the flow; however, the behaviour of drag is predictable only when the arrangement of the cylinders is homogeneous. Therefore, for more arbitrary arrangements, the Darcy–Forchheimer equations need to be considered. In this study, the law of fluid flow was applied by forcing a constant flow of water through the fence material and measuring the loss of hydraulic pressure over a fence thickness. Fences, mainly using bamboo sticks, were installed with model-scale and full-scale diameters applying two main arrangements, inhomogeneous and staggered. Our empirical findings led to several conclusions. The bulk drag coefficient ( C D ¯ ) is influenced by the flow regime represented by Reynolds number. The drag coefficient decreases with the increase of the porosity, which strongly depends on fence arrangements. Finally, the Forchheimer coefficients can be linked to the drag coefficient through a related porosity parameter at high turbulent conditions. The staggered arrangement is well-predicted by the Ergun-relations for the Darcy–Forchheimer coefficients when an inhomogeneous arrangement with equal porosity and diameter leads to a large drag and flow resistance.

28

Song, Li Hua, Zhi Guo Zhang, Xian Zhou Wang, and Da Kui Feng. "Prediction of Surface Ship's Residual Resistance Coefficient Using Neural Networks." Advanced Materials Research 756-759 (September 2013): 3141–44. http://dx.doi.org/10.4028/www.scientific.net/amr.756-759.3141.

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The Holtrop method, which provides a prediction of the components of surface ships total resistance, is widely used at ships initial design stage for estimating the resistance. In this paper a neural network model which performs the same role as the Holtrop method is presented to predict the residual resistance. A multilayer perceptron has been trained with the data generated by the Holtrop method to learn the relationship between the input (length-displacement ratio, prismatic coefficient, breadth-draft ratio and Froude number) and the target variable (the residual resistance coefficient). The results of this model have been compared against those provided by the Holtrop method and it is found that the quality of the prediction is improved over the entire range of data. The neural network provides an accurate estimation of the residual resistance with the Froude number and the hull geometry coefficients as variables.

29

Loukam, Imed, Bachir Achour, and Messaoud Djeddou. "Chezy’s resistance coefficient in a horseshoe-shaped tunnel." Revue des sciences de l'eau 32, no. 4 (2020): 379. http://dx.doi.org/10.7202/1069572ar.

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30

Lepikhin, A. P. "Estimation of hydraulic resistance coefficient in smooth pipes." Computational Continuum Mechanics 8, no. 4 (2015): 369–75. http://dx.doi.org/10.7242/1999-6691/2015.8.4.31.

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31

Loukam, Imed, Bachir Achour, and Lakhdar Djemili. "Chezy’s resistance coefficient in an egg-shaped conduit." Journal of Water and Land Development 37, no. 1 (June 1, 2018): 87–96. http://dx.doi.org/10.2478/jwld-2018-0028.

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Abstract When calculating uniform flows in open conduits and channels, Chezy’s resistance coefficient is not a problem data and its value is arbitrarily chosen. Such major disadvantage is met in all the geometric profiles of conduits and channels. Knowing the value of this coefficient is essential to both the design of the channel and normal depth calculation. The main objective of our research work is to focus upon the identification of the resistance coefficient relationship. On the basis of the rough model method (RMM) for the calculation of conduits and channels, a general explicit relation of the resistance coefficient in turbulent flow is established with different geometric profiles, particularly the egg-shaped conduit. Chezy’s resistance coefficient depends strongly on the filling rate, the discharge, the longitudinal slope, the absolute roughness of the internal walls of the conduit and the kinematic viscosity of the liquid. Moreover, in this work, a simplified method is presented to determine Chezy’s resistance coefficient with a limited number of data, namely the discharge, the slope of the conduit, the absolute roughness and the kinematic viscosity. Last but not least, after studying the variation of Chezy’s resistance coefficient as a function of the filling rate, an equally explicit expression is given for the easy calculation of this coefficient when its maximum value is reached. Examples of calculation are suggested in order to show how the Chezy’s coefficient can be calculated in the egg-shaped conduit.

32

Wiersma, D. S., R. Righini, M. Colocci, and F. M. Aliev. "The optical analog of negative temperature coefficient resistance." IEEE Journal of Quantum Electronics 38, no. 7 (July 2002): 934–37. http://dx.doi.org/10.1109/jqe.2002.1017610.

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33

Mossa, Michele. "Resistance coefficient in a smooth concentric annular pipe." Journal of Hydraulic Research 44, no. 6 (November 2006): 832–40. http://dx.doi.org/10.1080/00221686.2006.9521734.

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34

Bhattacharya, Sitangshu, and Ramesh Chandra Mallik. "Electrical Resistance and Seebeck Coefficient in PbTe Nanowires." Journal of Electronic Materials 41, no. 6 (February 24, 2012): 1421–28. http://dx.doi.org/10.1007/s11664-012-1930-z.

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35

Sonderegger, Walter, Manuele Vecellio, Pascal Zwicker, and Peter Niemz. "Combined bound water and water vapour diffusion of Norway spruce and European beech in and between the principal anatomical directions." Holzforschung 65, no. 6 (October 1, 2011): 819–28. http://dx.doi.org/10.1515/hf.2011.091.

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Abstract The combined bound water and water vapour diffusion of wood is of great interest in the field of building physics. Due to swelling stresses, the steady-state-determined diffusion coefficient clearly differs from the unsteady-state-determined diffusion coefficient. In this study, both diffusion coefficients and the water vapour resistance factor of Norway spruce (Picea abies [L.] Karst.) and European beech (Fagus sylvatica L.) were investigated for the principal anatomical directions (radial, tangential and longitudinal) and in 15° steps between these directions. The values were determined with the cup method as the basic principle. The unsteady-state-determined diffusion coefficient is, independent of the direction, about half that of the steady-state-determined diffusion coefficient. Both diffusion coefficients are about two to three times higher for spruce than for beech. They are up to 12 times higher in the longitudinal direction than perpendicular to the grain for spruce, and up to 15 times higher for beech. With increasing moisture content, the diffusion coefficients exponentially increase. The water vapour resistance factor shows converse values to the diffusion coefficients.

36

Gu, Kun Peng, and Cheng Qi Wang. "Study on Corrosion Resistance Coefficient Assessment Method for Sulfate Resistance of Cementitious Material." Applied Mechanics and Materials 174-177 (May 2012): 624–30. http://dx.doi.org/10.4028/www.scientific.net/amm.174-177.624.

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By means of testing corrosion resistance coefficient of different cementitious material under the sulfate corrosion experimental conditions, sulfate resistance of cementitious material and assessment method are studied. The results show that 90d is proper corroded age for assessment sulfate resistance of cementitious material by corrosion resistance coefficient method, and the assessment method is put forwarded. Sulfate resistance of cementitious material can be divided into five classes according to corrosion resistance coefficient assessment method as follows: “very low”, “low”, “moderate”, “high” and “very high”. The sulfate resistance of Portland cement is better than ordinary Portland cement, and both of them are low. Mineral admixture with proper content can improve sulfate resistance of cementitious materia largely, but do not always available to all content. Sulfate corrosion mechanism of different kinds of cementitious material is analyzed.

37

Oliva, A. I., J. M. Lugo, R. A. Gurubel-Gonzalez, R. J. Centeno, J. E. Corona, and F. Avilés. "Temperature coefficient of resistance and thermal expansion coefficient of 10-nm thick gold films." Thin Solid Films 623 (February 2017): 84–89. http://dx.doi.org/10.1016/j.tsf.2016.12.028.

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38

Ryabkov, Igor', and Al'bina Baranova. "THE THERMAL CONDUCTIVITY AND THE THERMAL RESISTANCE OF THE LAYER OF NON-AUTOCLAVED FOAM CONCRETE BASED ON MICROSILICA." Modern Technologies and Scientific and Technological Progress 2020, no. 1 (June 16, 2020): 185–86. http://dx.doi.org/10.36629/2686-9896-2020-1-185-186.

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The article presents the results of measurements of thermal conductivity coefficients and thermal resistances of non-autoclaved foam concretes based on microsilica depending on their average density. It is experimentally established that reducing the grade of non-autoclaved foam concrete from D800 to D400 by increasing the porosity of samples leads to a decrease in the thermal conductivity coefficient by 2.4 times and an increase in the thermal resistance of the layer by 2.5 times.

39

Nikolic, Dragan. "Components of variance and heritability of resistance to important fungal diseases agents in grapevine." Journal of Agricultural Sciences, Belgrade 51, no. 1 (2006): 47–54. http://dx.doi.org/10.2298/jas0601047n.

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In four interspecies crossing combinations of grapevine (Seedling 108 x Muscat Hamburg, Muscat Hamburg x Seedling 108, S.V.I8315 x Muscat Hamburg and Muscat Hamburg x S.V.I2375) during three years period, resistance to important fungal diseases agents (Plasmopara viticola and Botrytis cinerea) were examined. Based on results of analysis of variance, for investigated characteristics, components of variance, coefficients of genetic and phenotypic variation and coefficient of heritability in a broader sense were calculated. It was established that for both characteristics and in all crossing combinations, genetic variance took the biggest part in total variability. The lowest coefficients of genetic and phenotypic variation were established for both properties in crossing combination Seedling 108 x Muscat Hamburg. The highest coefficients of genetic and phenotypic variation were determined for leaf resistance to Plasmopara viticola in crossing combination Muscat Hamburg x S.V.I2375, and for bunch resistance to Botrytis cinerea in crossing combination Muscat Hamburg x Seedling 108. Considering all investigated crossing combinations, coefficient of heritability for leaf resistance to Plasmopara viticola was from 87.23% to 94.88%, and for bunch resistance to Botrytis cinerea from 88.04% to 93.32%. .

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Gong, Dong Jun, Yao Zhang, Xing Ru Li, Li De Fang, Zi Hui Wei, and Ning Zhao. "Study on the Resistance Characteristics of Heat Metering System Based on Electric Valve." Applied Mechanics and Materials 492 (January 2014): 507–10. http://dx.doi.org/10.4028/www.scientific.net/amm.492.507.

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Through theoretical calculations and derivation, the paper obtained the relationship between resistance coefficient and pressure difference, as well as flow rate. For the series pipeline, the flow in the series pipeline is the same, as a result, all the resistance in the series pipeline is the total resistance. For the parallel pipeline, the pressure difference is same, and the all the flow in parallel pipeline is the total flow. According to the real example, the paper identified the inlet pressure difference of the indoor system, the most unfavorable ring and the ratio frictional resistance. Based on the room heat load calculation, the paper determined the most unfavorable loop diameter of each pipe section. By calculating the resistance coefficients of the electric valve at opening, the resistance coefficients of the electric valve at closing were obtained. In the experiment system, the resistance coefficient average value when the electric valve is off was 101831.65, which is basically in line with the calculable value 10719.6, indicating that the existing parameters are much more reasonable.

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Wang, Xiuyu, Zhisheng Zhang, Tian Bai, and Zhonge Liu. "Thin film chip resistors with high resistance and low temperature coefficient of resistance." Transactions of Tianjin University 16, no. 5 (October 2010): 348–53. http://dx.doi.org/10.1007/s12209-010-1473-4.

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Wright, S. W., C. P. Judge, M. J. Lee, D. F. Bowers, M. Dunbar, and C. D. Wilson. "High sheet resistance, low temperature coefficient of resistance resistor films for integrated circuits." Journal of Vacuum Science & Technology B, Nanotechnology and Microelectronics: Materials, Processing, Measurement, and Phenomena 28, no. 4 (July 2010): 834–40. http://dx.doi.org/10.1116/1.3466531.

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Yaohua, Li, Fan Jikang, He Jie, Nan Youfei, and Feng Qianlong. "Novel electric power steering control strategies of commercial vehicles considering adhesion coefficient." Advances in Mechanical Engineering 12, no. 12 (December 2020): 168781402098305. http://dx.doi.org/10.1177/1687814020983059.

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The steering resistance torque of commercial vehicles on low adhesion pavement is greatly reduced. Therefore, while driving on low adhesion pavement, the use of traditional EPS control strategies without considering adhesion coefficient will lead to driver’s road feeling being reduced or even lost, endangering driving safety. In this paper, the relationship between adhesion coefficient and steering resistance torque is researched through theoretical analysis and simulation. Two novel EPS control strategies of commercial vehicles considering adhesion coefficient are designed. The first control strategy calculates assist coefficient through steering resistance torque under different working conditions, and assist coefficient is used to adjust the assist torque on the pavements with different adhesion coefficients. The second control strategy applies a compensation current related to adhesion coefficient on the basis of traditional EPS control strategy to improve the road feeling of low adhesion roads. Finally, a joint simulation model of TruckSim/Simulink is established, the two novel control strategies are simulated and verified. The simulation results show that both the two novel control strategies can improve the road feeling of the driver and improve the driving safety on low-adhesion road while ensuring the steering portability.

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Lhomme, J. P., N. Boudhina, M. M. Masmoudi, and A. Chehbouni. "Estimation of crop water requirements: extending the one-step approach to dual crop coefficients." Hydrology and Earth System Sciences 19, no. 7 (July 30, 2015): 3287–99. http://dx.doi.org/10.5194/hess-19-3287-2015.

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Abstract. Crop water requirements are commonly estimated with the FAO-56 methodology based upon a two-step approach: first a reference evapotranspiration (ET0) is calculated from weather variables with the Penman–Monteith equation, then ET0 is multiplied by a tabulated crop-specific coefficient (Kc) to determine the water requirement (ETc) of a given crop under standard conditions. This method has been challenged to the benefit of a one-step approach, where crop evapotranspiration is directly calculated from a Penman–Monteith equation, its surface resistance replacing the crop coefficient. Whereas the transformation of the two-step approach into a one-step approach has been well documented when a single crop coefficient (Kc) is used, the case of dual crop coefficients (Kcb for the crop and Ke for the soil) has not been treated yet. The present paper examines this specific case. Using a full two-layer model as a reference, it is shown that the FAO-56 dual crop coefficient approach can be translated into a one-step approach based upon a modified combination equation. This equation has the basic form of the Penman–Monteith equation but its surface resistance is calculated as the parallel sum of a foliage resistance (replacing Kcb) and a soil surface resistance (replacing Ke). We also show that the foliage resistance, which depends on leaf stomatal resistance and leaf area, can be inferred from the basal crop coefficient (Kcb) in a way similar to the Matt–Shuttleworth method.

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Lhomme, J. P., N. Boudhina, M. M. Masmoudi, and A. Chehbouni. "Estimation of crop water requirements: extending the one-step approach to dual crop coefficients." Hydrology and Earth System Sciences Discussions 12, no. 5 (May 13, 2015): 4933–63. http://dx.doi.org/10.5194/hessd-12-4933-2015.

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Abstract. Crop water requirements are commonly estimated with the FAO-56 methodology based upon a "two-step" approach: first a reference evapotranspiration (ET0) is calculated from weather variables with the Penman–Monteith equation; then ET0 is multiplied by a tabulated crop-specific coefficient (Kc) to determine the water requirement (ETc) of a given crop under standard conditions. This method has been challenged to the benefit of a "one-step" approach, where crop evapotranspiration is directly calculated from a Penman–Monteith equation, its surface resistance replacing the crop coefficient. Whereas the transformation of the two-step approach into a one-step approach has been well documented when a single crop coefficient (Kc) is used, the case of dual crop coefficients (Kcb for the crop and Ke for the soil) has not been treated yet. The present paper examines this specific case. Using a full two-layer model as a reference, it is shown that the FAO-56 dual crop coefficient approach can be translated into a one-step approach based upon a modified combination equation. This equation has the basic form of the Penman–Monteith equation, but its surface resistance is calculated as the parallel sum of a foliage resistance (replacing Kcb) and a soil surface resistance (replacing Ke). We also show that the foliage resistance, which depends on leaf stomatal resistance and leaf area, can be inferred from the basal crop coefficient (Kcb) in a way similar to the Matt–Shuttleworth method.

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Lin, Hong Liang, Qiang Yu, and Xue Li Zhang. "A New Computational Model about Vehicle’s Sliding Resistance Coefficients." Advanced Materials Research 228-229 (April 2011): 60–65. http://dx.doi.org/10.4028/www.scientific.net/amr.228-229.60.

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Vehicle’s sliding resistance mainly includes rolling resistance, air drag resistance and friction within the transmission, wheel bearings and other related components. Among those, rolling resistance and air drag always exist whenever vehicle is running, so they have great influence on vehicle’s dynamic performance and fuel economy. Therefore, it is important to determine vehicle’s rolling resistance coefficient and air drag coefficient quickly and accurately in order to operate vehicle properly and reduce the vehicle’s fuel consumption. Combining theoretical analysis with experimental verification, calculation model based on road coasting test was given by means of least squares principle. And through which vehicle rolling resistance coefficient and air drag coefficient were determined easily. Then by using the test data from some Minibus, the vehicle's rolling resistance coefficient and air drag coefficient are calculated according to established model. The computation result shows that rolling resistance coefficient is a linear function of the speed and the air drag coefficient is constant. Finally, the analysis shows that the calculation model is simple, precise and useful.

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Iyere, Sunday F., Bernard O. A. Ozigi, and Joseph K. Yeboah. "Response characteristics of a negative temperature coefficient thermistor." Journal of Electrical, Control and Telecommunication Research 1 (July 29, 2020): 17–22. http://dx.doi.org/10.37121/jectr.vol1.113.

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This article focuses on the thermistor as a device that is widely used for temperature measurement and control in most electrical and electronic devices and appliances. The research is based on the type of thermistor used in photocopiers with particular reference to Minolta Bizhub (model-210) photocopier. The resistance and temperature were recorded by the application of conventional heat to deduce the response curves of resistance versus temperature and resistance/time. Results obtained from the characteristics show that the thermistor employed in the photocopier is a negative temperature coefficient (NTC) device. Also, there was a time variation in the response of the thermistor resistance to temperature changes, which indicates that the thermistor under test functions as a temperature control device. The shape of resistance versus temperature curve appeared to be similar to that of a typical NTC thermistor characteristics.

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Laukaitis, Antanas, and Vytautas Lasauskas. "AKYTOJO BETONO GARSO ABSORBCIJOS TYRIMAI/POROUS CONCRETE SOUND ABSORPTION INVESTIGATION." JOURNAL OF CIVIL ENGINEERING AND MANAGEMENT 2, no. 8 (December 31, 1996): 67–72. http://dx.doi.org/10.3846/13921525.1996.10590174.

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Low-density porous concrete can be used as a sound absorbing material. This paper generalizes porous concrete sound absorption investigations. Porous concrete relative wave resistance modulus is longer than air wave resistance W=1 and that is why this material can be ascribed to materials with a high resistance to air flows, i.e. materials with a satisfactory sound absorption. Various thickness porous concrete sample sound absorption coefficients can be calculated according to equations (1), (2), (3), when wave parameter values are determinated (Table 1). Normal sound absorption coefficient measurement results (Fig. 1) show that for 35 mm and thicker samples the coefficient does not vary. It means that the samples apparent resistance (impleance) coincides with the materials wave resistance. The sound absorption coefficient increases (Fig. 2) with a decrease in porous concrete density. The asymmetric average dependency is expressed by a rectilinear curve (Fig. 3). The sound absorption coefficient depends not only on porous concrete density, but also on its nature (Fig. 4). The different sound absorption coefficient values for uniform density porous concrete can be explained by the various structure of porous concrete products, i.e. a change in pore dimensions, their amount and distribution (Fig. 5, Table 2). The production of acoustical slabs has shown that 280350 kg/m3 density porous concrete products are not sufficiently strong. It was therefore decided to increase their density to 460 kg/m3, with the purpose of increasing the sound absorption coefficient by using various special form resonators (cavity-type accelerators). The influence of the cuts on sound absorption is given in Fig. 6 (cut step is 22 mm). Measurements in a reverberation chamber have shown that the sound absorption coefficient value in porous concrete slabs with deeper or complex cuts increases, but it is harder to produce slabs with complex form cuts. It is easier to make a simple form resonator. Reverberated sound absorption for regular form resonators is given in Fig. 7. Porous concrete slab surface acoustical resistance decreases due to cuts and that is why there is an increase in sound absorption coefficients (Fig. 7, 2 and 3 curves).Porous concrete slabs with resonator cuts on both sides can be used in spacious constructions, for noise absorption in industrial premises. In this case, the construction sound absorption coefficient depends on the lay-out of these slabs. Three types of special lay-outs were investigated (Fig. 8, Table 3). Most of the investigated constructions have revertible sound absorption coefficients higher than 1. This is explained by sound diffraction phenomena on the slab edges. The most effective of all the investigated constructions are those where porous concrete slabs with two-sided perforations are hung jointly (Fig. 8, curves 6 and 10). They are effective in the entire distance between the slabs. The reverberation absorption coefficient decreases for all types of constructions (Fig. 8, curves 1 and 2, 5 and 6, 7–10). The special construction sound absorption coefficient can be changed by selecting porous concrete slab lay-out.

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Zhang, S., Y. Liu, J. Zhang, and Y. Liu. "Simulation study of anisotropic flow resistance of farmland vegetation." Soil and Water Research 12, No. 4 (October 9, 2017): 220–28. http://dx.doi.org/10.17221/50/2016-swr.

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Farmland vegetation is commonly cultivated with uniform planting spacing and heights. The effect of these features on resistance to hydraulic erosion is unclear. Hydraulic model experiments with the angle between the crop rows and the water flow direction set at 15°, 30°, 45° or 90° were conducted to analyze variation in the law of water flow resistance under partial or complete submergence of the crop. Cultivation can impact the flow resistance on slopes and this effect was greater when the crop was partially submerged. When planting spacing, slope, and water depth were constant, the change of the water flow Darcy-Weisbach resistance coefficient f with crop row-water flow angle was f15° > f30° > f45° > f90°. This suggests that flow resistance of farmland vegetation is anisotropic. The water flow resistance coefficient of crops that were partly submerged increased with water depth, but decreased with water depth when the crop was completely submerged. At the critical change from partial submergence to complete submergence, the water flow resistance coefficient was the highest when water depth was equal to crop height. These results may be useful for optimizing farmland planting and soil and water conservation.

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Wang, Hai Ying, Chun Fang Li, Song Tao Hu, and Lin Song. "Resistance Coefficient Research of the Train Air Supply Orifice." Advanced Materials Research 614-615 (December 2012): 475–79. http://dx.doi.org/10.4028/www.scientific.net/amr.614-615.475.

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High-speed train air-conditioning systems put forward higher request on the aspect of air uniformity and comfort. The use of orifice which can form a more uniform velocity and temperature field in the car can be widely applied to high-speed train air-conditioning system. The experimental study of the influence of several different factors (such as the opening rate, aperture, orifice plate thickness, etc.) in the research may provide a reference for the design choices of the orifice type.

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