Academic literature on the topic 'Modified Bohr model'
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Journal articles on the topic "Modified Bohr model"
1
Trippe, Sascha. "The “graviton picture”: a Bohr model for gravitation on galactic scales?" Canadian Journal of Physics 93, no. 2 (February 2015): 213–16. http://dx.doi.org/10.1139/cjp-2014-0158.
Full textAbstract:
Modified Newtonian dynamics (MOND) provides a successful description of stellar and galactic dynamics on almost all astronomical scales. A key feature of MOND is the transition function from Newtonian to modified dynamics, which corresponds to the empirical mass discrepancy–acceleration (MDA) relation. However, the functional form of the MDA relation does not follow from theory in a straightforward manner; in general, empirical MDA relations are inserted ad hoc into analyses of stellar dynamics. I revisit the possibility of gravity being mediated by massive virtual particles, gravitons. Under certain reasonable assumptions, the resulting “graviton picture” implies a MDA relation that is equivalent to the — empirical — “simple μ” function of MOND, which is in very good agreement with observations. I conclude that the “graviton picture” offers a simple description of gravitation on galactic scales, potentially playing a role for gravitation analogous to the role played by Bohr’s model for atomic physics.
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Alimohammadi, M., and H. Hassanabadi. "The X(3) model for the modified Davidson potential in a variational approach." International Journal of Modern Physics E 26, no. 09 (September 2017): 1750054. http://dx.doi.org/10.1142/s0218301317500549.
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In this work, we investigate the [Formula: see text]-rigid version of Bohr–Hamiltonian for the modified Davidson potential. Since the corresponding wave equation cannot be solved analytically, we apply the variational method. The related wave function, energy spectra and transition rates are determined. In order to evaluate our results, we fit the formula for the energy spectra to the available experimental data for some nuclei and compare the obtained standard error with the corresponding one in other similar work. Moreover, we study the collective behavior of these nuclei through the evolution of two quantities [Formula: see text] and [Formula: see text] in terms of number of valence nucleons.
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Freitas, Savana Dos Anjos, and Agostinho Serrano. "Use of different external mediating mechanisms of the Bohr atom model: Evidence of Meaningful Learning through verbal-gestural analysis in elementary school students." Acta Scientiae 21, no. 4 (September 4, 2019): 133–48. http://dx.doi.org/10.17648/acta.scientiae.v21iss4id5253.
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The present article sought to investigate if the use of different external mediation mechanisms to teach the Bohr Atom model in elementary education with the didactic methodology of the Potentially Significant Teaching Units (PSTU) can result in Meaningful learning. Therefore, we naturally use the theoretical contribution of the Ausubelian Meaningful Learning Theory, in particular by discussing elements that indicate evidence of meaningful learning. This theory was adopted with the purpose of understanding and analyzing whether or not there is evidence of meaningful learning with elementary level students after about a year of using the didactic methodology. The didactic methodology used was the application of didactic sequences inspired by the PSTU model, modified to be applied in Elementary School. We also use different external mediation mechanisms that independently reproduce the Bohr atom model, such as model building (psychophysical mediation), teacher explanation on a blackboard (social mediation), use of textbooks (cultural mediation) and computer simulations (hypercultural mediation). Data analysis was carried out through two semi-structured interviews according to the Report Aloud protocol followed by the depictive gestural analysis, performed with an interval of almost one year, both interviews were carried out after the application of the didactic methodology, in order to assess the retention of the learning residue. We argue that the students' verbal-gestural production indicates that there was meaningful learning of the Bohr Atom model, especially related to social and hypercultural mediations.
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Soheibi, Nahid, Majid Hamzavi, Mahdi Eshghi, and Sameer M. Ikhdair. "Calculations of the decay transitions of the modified Pöschl–Teller potential model via Bohr Hamiltonian technique." International Journal of Modern Physics E 26, no. 11 (November 2017): 1750073. http://dx.doi.org/10.1142/s0218301317500732.
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We calculate the eigenvalues and their corresponding eigenfunctions of the Bohr’s collective Hamiltonian with the help of the modified Pöschl–Teller (MPT) potential model within [Formula: see text]-unstable structure. Our numerical results for the ground state (g.s.) [Formula: see text] and [Formula: see text] band heads, together with the electric quadrupole [Formula: see text] transition rates, are displayed and compared with the available experimental data.
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Abou-Salem, L. I., K. E. Abdelmageed, I. A. Elmashad, and R. Al Allam. "Testing the core-cluster model calculations for some heavy deformed nuclei." International Journal of Modern Physics E 28, no. 07 (July 2019): 1950049. http://dx.doi.org/10.1142/s0218301319500496.
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In this work, the spectra of some even–even isotopes are studied by selecting core-cluster decomposition of the parent nucleus. The considered nuclei lie in the rare-earth and the transition metal regions. The Schrödinger equation can be solved using Bohr–Sommerfeld relation and the modified Woods–Saxon beside Coulomb potentials to reproduce the spectra of these isotopes with mass number [Formula: see text]. The theoretical calculations of the excitation energies of the ground state rotational band are compared to the experimental data. The cluster model calculations show a good agreement with the experimental data for the transitional and rotational nuclei more than the vibrational nuclei. Some negative parity bands of the chosen nuclei are studied. The core-cluster charge products are correlated with the transition probability [Formula: see text].
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PIIPER, JOHANNES, PETER SCHEID, STEVEN F. PERRY, and GEORGE M. HUGHES. "Effective and Morphometric Oxygen-Diffusing Capacity of the Gills of the Elasmobranch Scyliorhinus Stellaris." Journal of Experimental Biology 123, no. 1 (July 1, 1986): 27–41. http://dx.doi.org/10.1242/jeb.123.1.27.
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Calculations of the effective O2 conductance (diffusing capacity or transfer factor, Dcff) of fish gills, obtained from experimental data on gill O2 exchange, were compared with the predicted CVexchange properties of gill models based on morphometric measurements of the elasmobranch, Scyliorhinus stellaris. Deff was calculated from O2 uptake and POO2 in gill water and blood, using a modified Bohr integration technique. In the morphometric gill model, O2 conductance was considered for both the water-blood tissue barrier (Dm) and the interlamellar water (Dw). Dm was calculated from the total secondary lamellar surface area, the harmonic mean water-blood barrier thickness, and an assumed Krogh 02-diffusionconstant for gill tissue. Dw was estimated from the dimensions of the interlamellar spaces, the mean respiratory water flow velocity, and the diffusion coefficient of O2 in water. The ratio Dm/Dw was 1.84 in quiescently resting, 1.68 in resting alert, and 1.47 in swimming fish, showing that diffusion across interlamellar water was somewhat more important than that across the water-blood barrier in limiting the diffusive O2 transfer between water and blood. The total morphometric diffusing capacity, Dmorph estimated by the combined membrane-and-water diffusing capacity, Dm+w, which is defined as 1/Dm+w= 1/Dm+1/Dw, was similar to Deff, the ratio Dm+w/Deff being 1.64 for quiescently resting, 1.02 for resting alert, and 0.92 for swimming fish. The good agreement between the effective and morphometric D estimates validates the approach, and leaves, at least for the alert and swimming fish, little space for functional inhomogeneities, which are expected to reduce Deff as compared to Dm+w.
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Karunanithy, C., K. Muthukumarappan, and A. Donepudi. "Moisture Sorption Characteristics of Corn Stover and Big Bluestem." Journal of Renewable Energy 2013 (2013): 1–12. http://dx.doi.org/10.1155/2013/939504.
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Moisture content is an important feedstock quality in converting it into energy through biochemical or thermochemical platforms. Knowledge of moisture sorption relationship is useful in drying and storage to preserve the quality of feedstocks. Moisture sorption isotherms for potential feedstocks such as corn stover and big bluestem are missing. EMC values of corn stover and big bluestem were determined using static gravimetric technique with saturated salt solutions (ERH 0.12–0.89) at different temperatures (20, 30, and 40°C). Depending upon the ERH values, EMC values were ranged from 8.0 to 19.6 and 8.8 to 19.2% db for corn stover and big bluestem, respectively, and they followed typical type II isotherm found in food materials. Nonlinear regression was used to fit five commonly used three-parameter isotherm models (i.e., modified Oswin model, modified Halsey model, modified Chung-Pfost model, modified Henderson model, and the modified Guggenheim-Anderson-de Boer (GAB) model) to the experimental data. Modified Halsey emerged as the best model with highF-statistic andR2values with lowEmandEsand fairly random scattered residual plot for corn stover and big bluestem. These models can be used to predict the equilibrium moisture content of these feedstocks starting from harvesting, drying, preprocessing, transportation, storage, and conversion.
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Jiang, Xiuping, Xiuping Jiang, Huanhuan Li, Hosahalli S. Ramaswamy, Songming Zhu, Yong Yu, Huanhuan Li, Hosahalli S. Ramaswamy, Songming Zhu, and Yong Yu. "Moisture Sorption Isotherms and Isosteric Heats of Sorption of High-Pressure Treated Paulownia Wood under Different Storage Conditions." Transactions of the ASABE 62, no. 1 (2019): 105–14. http://dx.doi.org/10.13031/trans.12899.
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Abstract. Understanding of moisture sorption isotherms (MSI) is critical for predicting the stability of wood during handling, transport, and storage. The aim of this study was to evaluate the adsorption and desorption isotherm characteristics of high-pressure (HP) treated paulownia wood and to identify the best-fitting model to describe its sorption behavior. The equilibrium moisture contents (EMCs) of HP-treated paulownia wood were obtained using a static gravimetric method under different storage conditions: three temperatures (20°C, 30°C, and 40°C) and five water activity (aw) levels (0.32 to 0.95). Results showed that HP parameters did not significantly affect the MSI trend of treated groups. Eight modified models (modified Chung-Pfost, modified Henderson, modified Oswin, modified Halsey, Chen-Clayton, Guggenheim-Anderson-de Boer (GAB), simply modified GAB, and Peleg) were fitted to the experimental data. The Chen-Clayton model (temperature-dependent) produced randomized residuals and the best prediction performance for both adsorption and desorption among all models. Net isosteric heat of adsorption and desorption decreased from 7.55 to 4.84 kJ mol-1 and from 18.1 to 12.2 kJ mol-1, respectively, with an increase in EMC from 7.5% to 10%. The isosteric temperature (Tß) was 352 K for adsorption and 335 K for desorption, between which all the adsorption and desorption reactions proceeded at the same rate. All thermodynamic functions were adequately characterized by a power law model. Keywords: Equilibrium moisture content, High-pressure treatment, Modeling, Moisture sorption isotherm, Paulownia wood, Temperature, Thermodynamic analysis.
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Cho, Min Gyoung, Gwanyong Jung, and Hong-Gye Sung. "Performance Parameter Analysis of a Hall Effect Thruster With Modified Bohm Parameter Model." International Journal of Aeronautical and Space Sciences 21, no. 4 (April 2, 2020): 1028–36. http://dx.doi.org/10.1007/s42405-020-00263-w.
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Ocieczek, Aneta, Magdalena Skotnicka, and Kinga Baranowska. "Sorptive properties of modified maize starch as indicators of their quality." International Agrophysics 31, no. 3 (July 1, 2017): 383–92. http://dx.doi.org/10.1515/intag-2016-0061.
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AbstractThe physical and adsorptive properties of three products of modified maize starch in terms of the susceptibility of starch granules to surface processes as affected by their physicochemical diversity was compared in this study, using five mathematical models. It was assumed that modification of native starch is an important factor affecting its adsorptive properties. The products under study differed significantly in terms of the distribution of the size and shape parameters of their granules. The Guggenheim, Anderson and de Boer equation, characterised by relatively low sums of square deviations and low and similar errors of their different parameters, was the most useful in the description of empirically determined isotherms of adsorption. Parameters of the Guggenheim, Anderson and de Boer equation were used to estimate the parameters of the product surface microstructure. Modification of native maize starch differentiated the size of the monolayer, specific surface of sorption, and characteristics of capillaries.
Dissertations / Theses on the topic "Modified Bohr model"
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Kim, Moochan. "Problems on Non-Equilibrium Statistical Physics." Thesis, 2010. http://hdl.handle.net/1969.1/ETD-TAMU-2010-05-8007.
Full textAbstract:
Four problems in non-equilibrium statistical physics are investigated: 1. The
thermodynamics of single-photon gas; 2. Energy of the ground state in Multi-electron
atoms; 3. Energy state of the H2 molecule; and 4. The Condensation behavior in N
weakly interacting Boson gas.
In the single-photon heat engine, we have derived the equation of state similar
to that in classical ideal gas and applied it to construct the Carnot cycle with a single
photon, and showed the Carnot efficiency in this single-photon heat engine.
The energies of the ground state of multi-electron atoms are calculated using the
modi ed Bohr model with a shell structure of the bound electrons. The di erential
Schrodinger equation is simpli ed into the minimization problem of a simple energy
functional, similar to the problem in dimensional scaling in the H-atom. For the
C-atom, we got the ground state energy -37:82 eV with a relative error less than 6
%.
The simplest molecular ion, H+
2 , has been investigated by the quasi-classical
method and two-center molecular orbit. Using the two-center molecular orbit derived
from the exact treatment of the H+
2 molecular ion problem, we can reduce the number
of terms in wavefunction to get the binding energy of the H2 molecule, without using
the conventional wavefunction with over-thousand terms. We get the binding energy
for the H2 with Hylleraas correlation factor 1 + kr12 as 4:7eV, which is comparable
to the experimental value of 4:74 eV.
Condensation in the ground state of a weakly interacting Bose gas in equilibrium
is investigated using a partial partition function in canonical ensemble. The recursive
relation for the partition function developed for an ideal gas has been modi ed to
be applicable in the interacting case, and the statistics of the occupation number in
condensate states was examined. The well-known behavior of the Bose-Einstein Condensate
for a weakly interacting Bose Gas are shown: Depletion of the condensate
state, even at zero temperature, and a maximum
uctuation near transition temperature.
Furthermore, the use of the partition function in canonical ensemble leads to
the smooth cross-over between low temperatures and higher temperatures, which has
enlarged the applicable range of the Bogoliubov transformation. During the calculation,
we also developed the formula to calculate the correlations among the excited
states.
Conference papers on the topic "Modified Bohr model"
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Kroniger, Daniel, Philipp Vinnemeier, Christian Rudolf, and Manfred Wirsum. "High Pressure Combustion Test Rig for 10 MW Full Scale Gas Turbine Combustors." In ASME Turbo Expo 2014: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/gt2014-26736.
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This paper reports about a high pressure combustion test rig which was designed and erected inside the laboratory of the Institute of Steam and Gas Turbine (IDG, RWTH Aachen University, Univ.-Prof. Dr.-Ing. Dieter Bohn) in the time period from 1992. The first cold start-up was done to test and adjust the complex infrastructure including monitoring and control. The first hot start-up followed in May 2009 with a can-type combustor for a 7 MWel gas turbine. Thereafter, different gas turbine combustors have been tested and optimized with regard to NOx emission and combustor stability (see Tanaka et al. [1]). This test rig is designed to conduct combustion tests with unscaled gas turbine combustors with a thermal power of up to 10 MW and exhaust gas temperatures of up to 1350°C. The test rig is capable of achieving air inlet conditions of up to 24 bar, 550°C and 12 kg/s. After a successful phase of operation, the test rig has been continuously modified and upgraded at the Institute for Power Plant Technology, Steam and Gas Turbines (IKDG, RWTH Aachen University, Univ.-Prof. Dr.-Ing. habil. Manfred Wirsum). This paper introduces the current test rig. First, the test rig is classified in relation to similar test rigs by relevant literature. Thereafter, the test rig design and operation mode is presented in detail including a quality evaluation of the combustor inlet conditions. Furthermore, a steady-state simulation is set up. Based on its results, the theoretical operating ranges and limitations are identified and discussed.