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The Evolution of Star Formation Rate Density of Galaxies
Issue:
Volume 10, Issue 1, January 2021
Pages:
1-6
Received:
30 October 2020
Accepted:
5 January 2021
Published:
20 February 2021
Abstract: We present a semi-analytical calculation of the global star formation density (SFD) by using the well constrained cold dark matter (CDM) halo mass function. Both, halo masses MH(z) and stellar masses M*(z) are taken from observations of Lyα emitter (LAEs) and/or Lyman break galaxies (LBGs). Most of them, spectroscopically selected, are characterized by high star formation rates. The view of galaxy formation is mainly based on the hierarchical (“botton-up”) cold dark matter model for structure formation. We have used the connection between the halo mass and the star formation rate in galaxies of the halo mass MH at redshift z. Our model has the advantage that we are able to calculate the global star formation rate ρ*(z) (in Mʘy-1Mpc-3) by a closed equation. All parameters (MH; M* and n) have a well-defined physical meaning. From the CDM spectrum, the power law index of the halo mass function is well constrained. Our results are compiled in Table 1 and Figure 1. Here our results are compared with observations and hydrodynamical simulations. The physical meaning of the evolution of comoving cosmic star density as a function of redshift with three epochs is discussed. We find a good agreement between the SFD inferred from observations and our model in the range of redshifts z = 0 - 7.
Abstract: We present a semi-analytical calculation of the global star formation density (SFD) by using the well constrained cold dark matter (CDM) halo mass function. Both, halo masses MH(z) and stellar masses M*(z) are taken from observations of Lyα emitter (LAEs) and/or Lyman break galaxies (LBGs). Most of them, spectroscopically selected, are characterize...
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A Sectional Control Method to Decrease the Accumulated Survey Error of Tunnel Installation Control Network
Ying-gang Guo,
Zong-chun Li
Issue:
Volume 10, Issue 1, January 2021
Pages:
7-15
Received:
1 March 2021
Accepted:
12 March 2021
Published:
17 March 2021
Abstract: The location reference for the precision installation of components of particle accelerator is provided by tunnel installation control network. The long and narrow control network has big accumulated error with increasing distance. In order to decrease the accumulated survey error of tunnel installation control network of particle accelerator, a sectional control method is proposed. Firstly, the accumulation rule of positional error with the length of control network is obtained by simulation calculation according to the shape of tunnel installation control network. Then, the RMS of horizontal positional precision of tunnel backbone control network is taken as the threshold. When the accumulated error is bigger than the threshold, tunnel installation control network should be divided into subsections reasonably. On each segment, the middle survey station is taken as the datum for independent adjustment calculation. Finally, by taking the backbone control points as faint datums, the weighted partial parameters adjustment is performed with the adjustment results of each segment and the coordinates of backbone control points. The subsections are jointed and unified into the global coordinate system in the adjustment process. An installation control network of linac with a length of 1.6 km is simulated. The RMS of positional deviation of the proposed method is 2.583 mm, and the RMS of the difference of positional deviation between adjacent points reaches 0.035 mm. Experimental results show that the proposed sectional control method can not only effectively decrease the accumulated survey error, but also guarantee the relative positional precision of installation control network. So it can be applied in the data processing of tunnel installation control network, especially for large particle accelerators.
Abstract: The location reference for the precision installation of components of particle accelerator is provided by tunnel installation control network. The long and narrow control network has big accumulated error with increasing distance. In order to decrease the accumulated survey error of tunnel installation control network of particle accelerator, a se...
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Dynamics of Dusty Pair-Ion-Electron Plasma Modeled by the Cylindrical Kadomtsev-Petviashvili Equations
Bertrand Noel Tagne Wafo,
François Marie Moukam Kakmeni
Issue:
Volume 10, Issue 1, January 2021
Pages:
16-25
Received:
26 November 2020
Accepted:
16 January 2021
Published:
17 March 2021
Abstract: The nonlinear propagation and stability of dust ion-waves in plasma is analytically and numerically investigated. By using the the standard reductive perturbation method, the electrostatic potential in dusty pair-ion-electron plasma is modelled by cylindrical Kadomtsev-Petviashvili (CKP) equation. The soliton solutions are obtained using the direct integration for single soliton solution and the Hirota bilinear method to find multisoliton solution of the system. It is noticed that the Hirota method better illustrate the physical reality of dust pair-ion plasma since it generalizes different forms of solutions. From the numerical simulations, it is obseved that, the plasma parameters strongly influence the properties of the soliton solution, namely, the amplitude and the width. The analysis of the stability of the soliton solutions revels that the stable solution co-propagates with seven other solutions, eigenmodes of the Legendre equation. These modes contain basic symmetry and axisymmetric configuration consistent with relevant experimental observations in existing experiments.
Abstract: The nonlinear propagation and stability of dust ion-waves in plasma is analytically and numerically investigated. By using the the standard reductive perturbation method, the electrostatic potential in dusty pair-ion-electron plasma is modelled by cylindrical Kadomtsev-Petviashvili (CKP) equation. The soliton solutions are obtained using the direct...
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