A survey of deep space communications

Zhang, Gengxin; Xie, Zhidong; Bian, Dongming; Sun, Qibo

doi:10.1007/s11767-011-0623-8

Cited by 3 publications

(4 citation statements)

References 24 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Zhang's formula (Zhang & Xie, 1993):

{c}_{e}={k}_{z}{\left[\frac{{\left({u}^{2}+{v}^{2}\right)}^{1.5}}{gh\omega }\right]}^{{m}_{z}}/{\rho }_{s}

{c}_{e}={k}_{z}{\left[\frac{\left({k}_{v}+1\right){\left({u}^{2}+{v}^{2}\right)}^{1.5}}{gh\omega }\right]}^{{m}_{z}}/{\rho }_{s}

…”

Section: Discussionmentioning

confidence: 99%

“…where 𝐴𝐴 𝐴𝐴 is an empirical parameter; 𝐴𝐴 𝐴𝐴𝑚𝑚 is the size-specific settling velocity calculated by Zhang formula (Zhang & Xie, 1993); 𝐴𝐴 𝐴𝐴 = 4.45Re𝑝𝑝 −0.1 , 𝐴𝐴 Re𝑝𝑝 = 𝜔𝜔𝑚𝑚𝑑𝑑𝑚𝑚∕𝜈𝜈 is the particle Reynolds number; 𝐴𝐴 𝐴𝐴𝑚𝑚 is the sediment diameter;…”

Section: Hydrodynamic-sediment Partmentioning

confidence: 99%

See 1 more Smart Citation

Fast Modeling of Vegetated Flow and Sediment Transport Over Mobile Beds Using Shallow Water Equations With Anisotropic Porosity

Liu

2023

Water Resources Research

View full text Add to dashboard Cite

A two‐dimensional shallow water model based on the anisotropic porosity method is developed for predictions of water flows, sediment transport and bed morphological changes through rigid vegetation. Effects of the vegetation resistance and the spatial occupation are accounted for by adding an extra vegetation drag force and introducing porosity parameters. By defining a cell‐based porosity for the volumetric occupation and an edge‐based porosity for the flux exchange, the anisotropic property of the preferential flow can be well captured. Based on the finite volume method, the model is solved explicitly with a hybrid local time step/global maximum time step method and is parallelized using the Open MP techniques. The numerical grid convergence and quantitative accuracy of the model have been tested against a series of flume experiments for various configurations of rigid emergent vegetation over fixed or mobile beds. It is shown that using shallow water equations with anisotropic porosity, a constant drag coefficient can lead to numerical solutions of comparable accuracy as those complex empirical relations. Moreover, appropriate quantification of the stem‐scale turbulence effects brings significant improvement in modeling of the vegetation‐affected sediment transport.

show abstract

“…Zhang's formula (Zhang & Xie, 1993):

{c}_{e}={k}_{z}{\left[\frac{{\left({u}^{2}+{v}^{2}\right)}^{1.5}}{gh\omega }\right]}^{{m}_{z}}/{\rho }_{s}

{c}_{e}={k}_{z}{\left[\frac{\left({k}_{v}+1\right){\left({u}^{2}+{v}^{2}\right)}^{1.5}}{gh\omega }\right]}^{{m}_{z}}/{\rho }_{s}

…”

Section: Discussionmentioning

confidence: 99%

Section: Hydrodynamic-sediment Partmentioning

confidence: 99%

Fast Modeling of Vegetated Flow and Sediment Transport Over Mobile Beds Using Shallow Water Equations With Anisotropic Porosity

Liu

2023

Water Resources Research

View full text Add to dashboard Cite

show abstract

“…where C v is the volumetric concentration of sediment and n is an empirical exponent set as 7 in the Yellow River (Jiang et al, 2004); ω 0,ks is the settling velocity of a single particle (m/s) calculated by Zhang's formula (Zhang & Xie, 1993):…”

Section: Sediment and Morphological Modulementioning

confidence: 99%

Cumulative sedimentation hazard map of urban areas subject to hyperconcentrated flash flood: A case study of Suide County in the Wuding River basin, China

Lai,

Li,

Wang

et al. 2024

J Flood Risk Management

View full text Add to dashboard Cite

Flash floods can carry substantial sediment, posing significant sedimentation hazards in hilly cities. The sedimentation hazard map can reproduce the sediment thickness and extent of an extreme events scenario, playing an important role in sediment risk management. However, current research primarily focuses on modeling the inundation area and depth of floods, while studying sedimentation hazard caused by flash floods in urban areas remains insufficient. This paper aims to address this gap by utilizing a numerical model that simulates hyperconcentrated flow in hilly urban areas using the two‐dimensional hydro‐sediment‐morphological model to compile the cumulative sedimentation hazard map. The model, built upon the open‐source TELEMAC‐MASCARET framework, incorporates Zhang Hongwu's formula to simulate sediment‐carrying capacity, particularly suitable for hyper‐sediment concentration near the riverbed. This paper uses the data of extreme flash flood events in the Wuding River basin in 2017 to simulate and compile the cumulative sedimentation hazard map. The hazard map delineates the sedimentation hazard extent and level attributable to overbank floodplain sedimentation. Notably, the sediment thickness is highest in areas near the levees on both sides of the Dali River. Moreover, the map illustrates the extent of channel erosion resulting from hyperconcentrated floods, which could jeopardize bank stability.

show abstract

“…Been compared with terrestrial communication systems and ordinary satellite communication systems, deep-space systems hold the following characteristic, such as long propagation distance, huge free space loss, low signal noise ratio, large and time-variant transmission delay, strict requirement for bit error rate (BER) performance, etc [1], [2]. On the other hand, with the development of spatial detection technology, space exploration missions have become increasingly complicated and various, and a mass of data and image information need to be transferred to the ground real-timely, which will set a higher demand on the speed of digital transmission system for spacecrafts.…”

Section: Introductionmentioning

confidence: 99%

A Joint Coded Modulation Scheme and Its Iterative Receiving for Deep-Space Communications

Xue

Chen

2012

2012 8th International Conference on Wireless Communications, Networking and Mobile Computing

View full text Add to dashboard Cite

Space exploration missions have become increasingly complicated and various, and the current deep-space communication schemes can't meet the demand of high-speed and real-time multimedia correspondence. Therefore, the design of a fast and efficient transmission scheme is one of the important ways to solve the conflict. With organic combination of LDPC codes, continuous phase modulation (CPM) and turbo iterative detection, a scheme of joint coded modulation based on turbo principle is presented. In this paper, the model of LDPC-CPM system is established firstly, then realization scheme of CPM is proposed, and the effect of main parameters on the performance of the system is studied finally, which can provide the reference basis for practical application. The research results show that the proposed scheme can not only improve power efficiency and BER performance in the background of extremely low SNR effectively, but also give consideration to validity of information transmission and improve the band efficiency, and partly solve the problem of failing to give attention to both high-speed transmission and reliable transmission. Meanwhile, the receiver whose implementation is achievable can reach a good compromise between performance and complexity.

show abstract

A survey of deep space communications

Cited by 3 publications

References 24 publications

Fast Modeling of Vegetated Flow and Sediment Transport Over Mobile Beds Using Shallow Water Equations With Anisotropic Porosity

Fast Modeling of Vegetated Flow and Sediment Transport Over Mobile Beds Using Shallow Water Equations With Anisotropic Porosity

Cumulative sedimentation hazard map of urban areas subject to hyperconcentrated flash flood: A case study of Suide County in the Wuding River basin, China

A Joint Coded Modulation Scheme and Its Iterative Receiving for Deep-Space Communications

Contact Info

Product

Resources

About