Wyniki wyszukiwania - Biblioteka Nauki

1

Adaptive control of nonlinear pressure tanks using grey box modeling with neural networks

100%

Ma Z. , Jutan A.

Journal of Applied Computer Science

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2000

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tom Vol. 8, nr 2

45-63

EN

In this work, a nonlinear process is modeled in a so called 'grey box' format. This format divides the model into a known linear part and an unknown nonlinear part. The linear part is modeled using simple linear discrete dynamics whereas the nonlinear pan is modeled using a neural network with some weights. An adaptive controller is designed to incorporate the unknown nonlinear dynamics into the overall process dynamics. A smaller number of neural network weights can be used in this format so that the controller can be used adoptively for on-line control. The effectiveness of this approach is demonstrated using simulation and finally is used for real time control of a pressure tank process with excellent results.

2

Efficiency optimization of a closed indirectly fired gas turbine cycle working under two variable-temperature heat reservoirs

100%

Ma Z. , Wu J.

Archives of Thermodynamics

|

2011

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tom Vol. 32, no. 2

3-20

EN

Indirectly or externally fired gas turbines (IFGT or EFGT) are interesting technologies under development for small and medium scale combined heat and power (CHP) supplies in combination with micro gas turbine technologies. The emphasis is primarily on the utilization of the waste heat from the turbine in a recuperative process and the possibility of burning biomass even "dirty" fuel by employing a high temperature heat exchanger (HTHE) to avoid the combustion gases passing through the turbine. In this paper, finite time thermodynamics is employed in the performance analysis of a class of irreversible closed IFGT cycles coupled to variable temperature heat reservoirs. Based on the derived analytical formulae for the dimensionless power output and efficiency, the efficiency optimization is performed in two aspects. The first is to search the optimum heat conductance distribution corresponding to the efficiency optimization among the hot- and cold-side of the heat reservoirs and the high temperature heat exchangers for a fixed total heat exchanger inventory. The second is to search the optimum thermal capacitance rate matching corresponding to the maximum efficiency between the working fluid and the high-temperature heat reservoir for a fixed ratio of the thermal capacitance rates of the two heat reservoirs. The influences of some design parameters on the optimum heat conductance distribution, the optimum thermal capacitance rate matching and the maximum power output, which include the inlet temperature ratio of the two heat reservoirs, the efficiencies of the compressor and the gas turbine, and the total pressure recovery coefficient, are provided by numerical examples. The power plant configuration under optimized operation condition leads to a smaller size, including the compressor, turbine, two heat reservoirs and the HTHE.

3

Numerical simulation of heat transfer and two-phase flow in a novel heat pipe cold plate

100%

Ma Z. , Yao S.

Archives of Thermodynamics

|

2009

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tom Vol. 30, no. 1

45-62

EN

To solve high heat flux cooling problems in case of modern electronic appliances, a novel heat pipe cold plate is designed and developed. The heat pipe cold plate is uniquely-different from normal thermosyphons, in which the acetone-aluminum heat pipe construction is composed of eight vertical heat pipe branches with their upper ends and lower ends connected with each other by two horizontal heat pipe branches, respectively, which make the working vapour and liquid flow smooth within the internal flow space of the heat pipe cold plate. In this paper, based on previous experimental and theoretical studies, a mathematical model for numerical simulations of the vapour-liquid two-phase flow and heat transfer phenomena in the heat pipe cold plate is presented. Two-fluid-model is employed to describe flow characteristics and phase interaction between vapour and liquid phases. Differential equations are solved by finite volume method and IPSA algorithm is employed to consider the vapour-liquid coupling effect. Effects of the total heating power and the cooling water flow rate on wall temperature distribution and two-phase flow heat transfer characteristics are numerically simulated. Computation results well agree with experimental results. The novel heat pipe cold plate possesses excellent heat transfer characteristics and temperature uniformity performance; it can provide a much better cooling solution for multi-heat-source and high heat-flux cooling problems than forced-convection cooling techniques. Also, numerical solution established and realized in this paper can be used as a reference.

4

Flotation behavior of nickel sulfide ore in a cyclonic flotation column

80%

Deng L. , Li G. , Cao Y. , Ma Z.

Physicochemical Problems of Mineral Processing

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2017

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tom Vol. 53, iss. 2

770--780

EN

This study aimed to show the flotation behavior of a nickel sulfide ore in a cyclonic flotation column. The flotation experiments were carried out using a sample of nickel sulfide ore obtained from a mineral processing plant of China. Representative samples collected from the feed, concentrate, tailing, and circulation middling were sieved using a cyclonic particle analyzer to collect different size fractions for analysis. The function of the column cyclonic zone of was evaluated by comparing the quality of tailing and circulation middling. The flotation results showed that the concentrate with Ni grade of 1.78% and recovery of 65.56% was obtained under given test conditions. The content of main sulfide minerals and coarse particles in the circulation middling was higher than that in the tailing. The results indicated that, unlike conventional cyclone classification, separation achieved in the cyclonic zone of the column was not dependent on the particle size and density. Sulfide minerals with good floatability were easily captured by bubbles and moved toward the center of the column, even if these particles were coarser and heavier.

5

Adaptive control of a pressure tank system with saturation nonlinearities

80%

Ma Z. , Jutan A. , Bajic V. B.

Journal of Applied Computer Science

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2001

|

tom Vol. 9, nr 1

61-83

EN

The paper presents the design of a new nonlinear real-time adaptive control algorithm which is suitable the systems with saturation nonlinearity at the input. The linear part of the system can be non-minimum phase and/or unstable. The control algorithm is of the self-tuning type. The algorithm utilizes an auxiliary control parameter that can be chosen online to keep the controller output in the linear zone of the saturation nonlinearity. Stability of the algorithm is discussed. Several simulation experiments are performed to demonstrate effectiveness of the algorithm. Finally, the algorithm is applied to the real time pressure tank process control system successfully.

6

Neural network based adaptive internal model control for nonlinear plants

80%

Ma Z. , Bajić V. B. , Ho D. W. C.

Journal of Applied Computer Science

|

1999

|

tom Vol. 7, nr 1

63-78

EN

A novel non-parametric adaptive control method for nonlinear plants is proposed. It combines neural network (NN) based identification and internal model control (IMC) strategy. The NN is used to determine on-line an approximation of the unknown nonlinear process model. The NN parameters are updated according to the error between the plant output and the NN output. The NN can track the system output very well, so that an adaptive IMC can be implemented successfully. The design does not require computation of the inverse of the internal model of the process. Instead, it uses only system input-output data and NN output. The effectiveness of the proposed method is illustrated by a simulation experiment.

7

Silencing of the type 1 insulin-like growth factor receptor increases the sensitivity to apoptosis and inhibits invasion in human lung adenocarcinoma A549 cells

80%

Ma Z. , Dong A. , Kong M. , Qian J.

Cellular and Molecular Biology Letters

|

2007

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tom 12

|

nr 4

556-572

EN

The type 1 insulin-like growth factor receptor (IGF-1R), which is over-expressed or activated in many human cancers, including lung cancer, mediates cancer cell proliferation and metastasis. Several studies indicate that blocking IGF-1R expression can inhibit tumor cell proliferation and metastasis. In this study, inhibition of the endogenous IGF-1R by recombinant adenoviruses encoding short hairpin RNAs against IGF-1R was found to significantly suppress IGF-1R expression, arrest the cell cycle, enhance the apoptotic response, and inhibit proliferation, adhesion, invasion and migration in A549 cells. Moreover, silencing IGF-1R decreases the expression of invasive-related genes including matrix metalloproteinase-2 (MMP-2), MMP-9, and urokinase-plasminogen activator (u-PA), and the phosphorylation of Akt and ERK1/2. These results suggest that the silencing of IGF-1R has the potential to be an effective cancer gene therapy strategy for human lung cancer.

8

Ultrasound-assisted transdermal delivery of alendronate for the treatment of osteoporosis

80%

Li B. , Huang G. , Ma Z. , Qin S.

Acta Biochimica Polonica

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2020

|

tom 67

|

nr 2

9

A homolog of Class IV HD-Zip transcription factors, EsHdzip1, confers drought resistance in tobacco via enhanced the capacity of water conserving and absorbing

80%

Zhou C. , Zhu L. , Ma Z. , Wang J.

Acta Physiologiae Plantarum

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2015

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tom 37

|

nr 07

EN

Previous studies have indicated that homeodomain-leucine zipper (HD-Zip) transcription factors play important roles during abiotic stress, but there is no information on the functions of HD-Zip genes in a new model plant Eutrema salsugineum for studying plant abiotic stress tolerance. Here, EsHdzip1 (GenBank No. XM_006390503) belonging to the Class IV subgroup of HD-Zip transcription factor family was isolated from E. salsugineum and characterized for its physiological rolesunder drought stress conditions. Transgenic tobacco plants overexpressing EsHdzip1 exhibited increased drought resistance with promoted root growth and reduction of water loss. Furthermore, these transgenic plants had lower ion leakage (IL), malondialdehyde (MDA), and reactive oxygen species (ROS) accumulation, but higher content of osmotic solutes (proline and total soluble sugars) and activities of antioxidant enzymes including superoxide dismutase (SOD) and ascorbate peroxidase (APX) relative to wild-type (WT) plants when subjected to drought stress treatments. The content of abscisic acid (ABA) was also observed to be remarkably higher in the transgenic lines than WT plants under drought stress conditions. In addition, the expression levels of three important stress-related genes (NtP5CS, NtERD10C, and NtLEA5) involved in the osmotic adjustment and water maintenance were significantly higher than WT plants under drought stress conditions. Therefore, we have revealed important roles of the EsHdzip1 gene in response to drought stress, suggesting that this gene has a great potential for improving plant drought tolerance by engineering manipulation.

10

Conceptual design and performance analysis of an exhaust gas weste heat recovery system for a 10000TEU container ship

80%

Ma Z. , Yang D. , Guo Q.

Polish Maritime Research

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2012

|

tom 19

|

nr 2

EN

According to operation characteristics of the main engine 9K98ME-C7, a combined turbines-exhaust gas waste heat recovery system is proposed to recover waste heat and increase system energy efficiency. Thermodynamic models based on the first thermodynamic law and the second thermodynamic law are formulated. The superheated steam yield, the total electric power yield, the first thermodynamic law efficiency, the exergy efficiency at different exhaust gas boiler working pressure, and the variation of the exergy efficiency under different feed water temperature and different steam turbine back pressure are analyzed. Thermodynamic results indicate that the most appropriate exhaust gas boiler pressure is 0.8MPa for studied main engine and the total thermal efficiency with combined turbines arrangement has climbed up to 53.8% from 48.5%

11

Performance optimization of organic Rankine cycles for waste heat recovery for a large diesel engine

80%

Ma Z. , Wu J. , Zhang Y.

Archives of Thermodynamics

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2018

|

tom Vol. 39, no 1

3--23

EN

In order to recover the low grade waste heat and increase system fuel economy for main engine 10S90ME-C9.2-TII(part load, exhaust gas bypass) installed on a 10000 TEU container ship, a non-cogeneration and single-pressure type of waste heat recovery system based on organic Rankine cycle is proposed. Organic compound candidates appropriate to the system are analyzed and selected. Thermodynamic model of the whole system and thermoeconomic optimization are performed. The saturated organic compound vapor mass flow rate, net electric power output, pinch point, thermal efficiency and exergy efficiency varied with different evaporating temperature are thermodynamically analyzed. The results of thermodynamic and thermoeconomic optimization indicate that the most appropriate organic compound candidate is R141b due to its highest exergy efficiency, biggest unit cost benefit and shortest payback time.

12

Accurate gradient computations at interfaces using finite element methods

80%

Qin F. , Wang Z. , Ma Z. , Li Z.

|

2017

|

tom Vol. 27, no. 3

527--537

EN

New finite element methods are proposed for elliptic interface problems in one and two dimensions. The main motivation is to get not only an accurate solution, but also an accurate first order derivative at the interface (from each side). The key in 1D is to use the idea of Wheeler (1974). For 2D interface problems, the point is to introduce a small tube near the interface and propose the gradient as part of unknowns, which is similar to a mixed finite element method, but only at the interface. Thus the computational cost is just slightly higher than in the standard finite element method. We present a rigorous one dimensional analysis, which shows a second order convergence order for both the solution and the gradient in 1D. For two dimensional problems, we present numerical results and observe second order convergence for the solution, and super-convergence for the gradient at the interface.

13

Risk evaluation method based on set pair analysis applied to overseas mining investment

80%

Ma Z. , Li G. , Hu N. , Liu D.

Gospodarka Surowcami Mineralnymi

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2018

|

tom T. 34, z. 4

145--164

EN

Overseas mining investment generally faces considerable risk due to a variety of complex risk factors. Therefore, indexes are often based on conditions of uncertainty and cannot be fully quantified. Guided by set pair analysis (SPA) theory, this study constructs a risk evaluation index system based on an analysis of the risk factors of overseas mining investment and determines the weights of factors using entropy weighting methods. In addition, this study constructs an identity-discrepancy-contrary risk assessment model based on the 5-element connection number. Both the certainty and uncertainty of the various risks are treated uniformly in this model and it is possible to mathematically describe and quantitatively express complex system decisions to evaluate projects. Overseas mining investment risk and its changing trends are synthetically evaluated by calculating the adjacent connection number and analyzing the set pair potential. Using an actual overseas mining investment project as an example, the risk of overseas mining investment can be separated into five categories according to the risk field, and then the evaluation model is quantified and specific risk assessment results are obtained. Compared to the field investigation, the practicability and effectiveness of the evaluation method are illustrated. This new model combines static and dynamic factors and qualitative and quantitative information, which improves the reliability and accuracy of risk evaluation. Furthermore, this evaluation method can also be applied to other similar evaluations and has a certain scalability.

PL

Zagraniczne inwestycje wydobywcze są narażone na znaczne ryzyko z powodu różnych czynników mających wpływ na taką działalność. Stosowane wskaźniki często zawierają elementy niepewności i nie można ich w pełni skwantyfikować. Kierując się teorią analizy par (set par analysis), badanie to tworzy system indeksu oceny ryzyka oparty na analizie czynników ryzyka zagranicznych inwestycji górniczych i określa wagi czynników z zastosowaniem entropii. Ponadto w artykule przedstawiono model oceny ryzyka związanego z identyfikacją rozbieżności, oparty na powiązaniu pięciu elementów. Zarówno pewność, jak i niepewność różnych ryzyk są traktowane jednolicie w tym modelu i możliwe jest matematyczne opisanie i ilościowe wyrażenie złożonych decyzji systemowych w celu oceny projektów. Ryzyko inwestycji zagranicznych i ich zmieniające się trendy są oceniane syntetycznie poprzez obliczanie sąsiedniego elementu i analizowanie ustalonego potencjału dla tej pary. Przykładem może być faktyczny zagraniczny projekt inwestycyjny dotyczący górnictwa, gdzie ryzyko inwestycji zagranicznych można podzielić na pięć rodzajów zgodnie z rachunkiem ryzyka, a następnie dokonuje się oceny modelu i uzyskuje się konkretne wyniki oceny ryzyka. Na przykładzie przedstawiono aspekty praktyczne i skuteczność tej metody oceny. Ten nowy model łączy czynniki statyczne i dynamiczne oraz informacje jakościowe i ilościowe, co poprawia wiarygodność i dokładność oceny ryzyka. Co więcej, ta metoda oceny może być również zastosowana do innych podobnych zagadnień i ma pewną skalowalność.

14

Impact of waste heat recovery systems on energy efficiency improvement of a heavy-duty diesel engine

80%

Ma Z. , Chen H. , Zhang Y.

Archives of Thermodynamics

|

2017

|

tom Vol. 38, no. 3

63--75

EN

The increase of ship’s energy utilization efficiency and the reduction of greenhouse gas emissions have been high lightened in recent years and have become an increasingly important subject for ship designers and owners. The International Maritime Organization (IMO) is seeking measures to reduce the CO2 emissions from ships, and their proposed energy efficiency design index (EEDI) and energy efficiency operational indicator (EEOI) aim at ensuring that future vessels will be more efficient. Waste heat recovery can be employed not only to improve energy utilization efficiency but also to reduce greenhouse gas emissions. In this paper, a typical conceptual large container ship employing a low speed marine diesel engine as the main propulsion machinery is introduced and three possible types of waste heat recovery systems are designed. To calculate the EEDI and EEOI of the given large container ship, two software packages are developed. From the viewpoint of operation and maintenance, lowering the ship speed and improving container load rate can greatly reduce EEOI and further reduce total fuel consumption. Although the large container ship itself can reach the IMO requirements of EEDI at the first stage with a reduction factor 10% under the reference line value, the proposed waste heat recovery systems can improve the ship EEDI reduction factor to 20% under the reference line value.

15

On the Dynamics of a Chemostat Model With Delayed Nutrient Recycling

80%

Fergola P. , Jiang L. , Ma Z.

International Journal of Applied Mathematics and Computer Science

|

2000

|

tom Vol. 10, no 1

81-96

EN

This paper studies the dynamics of a chemostat model with n populations competing for one nutrient which can be recycled due to decomposition of dead biomass. Several kinds of results about local and global stability of non-negative equilibria, uniform persistence and control of populations are obtained.

16

Carbon emission and economic growth model of beijing based on symbolic regression

80%

Wen L. , Li Q. , Li Y. , Ma Z.

Polish Journal of Environmental Studies

|

2018

|

tom 27

|

nr 1

EN

With the continuous improvement of the economy, more and more attention has been paid to environmental problems. Beijing is China’s economic, political, and cultural center, and its low-carbon development by external concerns. In this paper, the relationship between economic development and environmental pollution is analyzed by using the symbolic regression method, which is based on the data of per capita CO₂ emissions, total energy consumption, energy intensity, and per capita GDP in Beijing city during 1980-2015. The study found that the presence of the M-curve model between per capita CO₂ emissions and per capita GDP, total energy consumption, and per capita GDP are in line with the traditional model of the EKC curve, and that the L-curve model exists between the energy intensity and per capita GDP, respectively, with promising performance. Based on our analysis, we present policy suggestions for reducing carbon emissions and developing a low-carbon economy in Beijing.

17

De novo sequencing and comparative transcriptome analysis of white petals and red labella in Phalaenopsis for discovery of genes related to flower color and floral differentiation

71%

Yang Y. , Wang J. , Ma Z. , Sun G. , Zhang C.

Acta Societatis Botanicorum Poloniae

|

2014

|

tom 83

|

nr 3

EN

Phalaenopsis is one of the world’s most popular and important epiphytic monopodial orchids. The extraordinary floral diversity of Phalaenopsis is a reflection of its evolutionary success. As a consequence of this diversity, and of the complexity of flower color development in Phalaenopsis, this species is a valuable research material for developmental biology studies. Nevertheless, research on the molecular mechanisms underlying flower color and floral organ formation in Phalaenopsis is still in the early phases. In this study, we generated large amounts of data from Phalaenopsis flowers by combining Illumina sequencing with differentially expressed gene (DEG) analysis. We obtained 37 723 and 34 020 unigenes from petals and labella, respectively. A total of 2736 DEGs were identified, and the functions of many DEGs were annotated by BLAST-searching against several public databases. We mapped 837 up-regulated DEGs (432 from petals and 405 from labella) to 102 Kyoto Encyclopedia of Genes and Genomes pathways. Almost all pathways were represented in both petals (102 pathways) and labella (99 pathways). DEGs involved in energy metabolism were significantly differentially distributed between labella and petals, and various DEGs related to flower color and floral differentiation were found in the two organs. Interestingly, we also identified genes encoding several key enzymes involved in carotenoid synthesis. These genes were differentially expressed between petals and labella, suggesting that carotenoids may influence Phalaenopsis flower color. We thus conclude that a combination of anthocyanins and/or carotenoids determine flower color formation in Phalaenopsis. These results broaden our understanding of the mechanisms controlling flower color and floral organ differentiation in Phalaenopsis and other orchids.

18

Role of seed bank in establishment of single and mixed-sowing artificial grasslands of Tibetan Plateau

71%

Ma Z. , Zhang C. , Zhou H.-K. , Yao B.-Q. , Zhao X.-Q.

Polish Journal of Ecology

|

2017

|

tom 65

|

nr 4

EN

Artificial grassland establishment is one of the fastest and most effective ways to restore the productivity of degraded grasslands. Little is known about the effect of different types of artificial grassland establishment (i.e., single- and mixed-sowing grassland establishment with perennial grasses) on soil seed bank in degraded grassland ecosystems. Single-sowing population of a high yield species usually has a great standing biomass causing shading that may inhibit germination of seeds in soil seed bank. Thus, we hypothesized that there is higher species richness and seed density in the soil seed bank of single-sowing than mixed-sowing grasslands. Here, we investigated the soil seed bank in four-year old single-sowing and mixed-sowing and control (degraded) grasslands on the Qinghai-Tibetan Plateau. We found that the autumn seed bank of mixed-sowing grasslands had lower species richness and seed density than single-sowing grasslands, while the summer soil seed bank (persistent seed bank) showed little differences. There were differences in biomass among the three grasslands (single-sowing > mixed-sowing > control), but there was no differences in species richness of vegetation. In sum, our results of the autumn seed bank support our hypothesis. Greater above-ground biomass in single-sowing grasslands could generally cause low light availability preventing seeds in soil from germinating and support more seed output, which both may indirectly or directly result in the relatively higher species richness and seed density in the soil seed bank. Our results also suggest that artificial grasslands usually returning to native grasslands in terms of production and species composition after several years is likely due to stability of the persistent soil seed bank.

19

The Development of Drilling Engineering Monitoring System Using Wireless Sensor Networks

71%

Yang G. , Ma Z. , Xu W. , Huang X. , Zhou J.

Przegląd Elektrotechniczny

|

2013

|

tom R. 89, nr 1b

37--40

EN

In order to avoid defects of existing drilling engineering monitoring and alarming system, such as the sensors and cable which are difficult to be installed and easy to be damaged, this paper present a new embedded drilling engineering monitoring system which is based on Wireless Sensor Network(WSN) and Wireless Local Area Networks(WLAN). The system is consists of the data acquisition subsystem, duty room controller, tool-pusher room controller and engineer room controller. It acquired the data and exported control commands by WSN. The tool-pusher room controller and engineer room controller are communicated with the duty room controller by WLAN for remote monitoring. For the special field drilling environment, the system achieves the acquiring, transmission, the export of control commands and remote monitoring of drilling data.

PL

Obecnie stosowany system monitorowania I alarmowania w technice wiercenia posiada szereg wad związanych z czujnikami i kablami, które trudno instalować i łatwo uszkodzić. Zaprezentowany w opracowaniu nowy system pozwala na uniknięcie tych wad. Oparty jest o bezprzewodową sieć czujnikową (WSN) oraz bezprzewodową sieć lokalną (WLAN). System obejmuje gromadzenie, transmisję danych i przekazywanie sygnałów sterowania oraz zdalne monitorowania danych wiercenia.

20

Role of Seed Bank in Establishment of Single and Mixed-Sowing Artificial Grasslands of Tibetan Plateau

71%

Ma Z. , Zhang C. , Zhou H.-K. , Yao B.-Q. , Zhao X.-Q.

Polish Journal of Ecology

|

2017

|

tom Vol. 65, nr 4

334--344

EN

Artificial grassland establishment is one of the fastest and most effective ways to restore the productivity of degraded grasslands. Little is known about the effect of different types of artificial grassland establishment (i.e., single- and mixed-sowing grassland establishment with perennial grasses) on soil seed bank in degraded grassland ecosystems. Single-sowing population of a high yield species usually has a great standing biomass causing shading that may inhibit germination of seeds in soil seed bank. Thus, we hypothesized that there is higher species richness and seed density in the soil seed bank of single-sowing than mixed-sowing grasslands. Here, we investigated the soil seed bank in four-year old single-sowing and mixed-sowing and control (degraded) grasslands on the Qinghai-Tibetan Plateau. We found that the autumn seed bank of mixed-sowing grasslands had lower species richness and seed density than single-sowing grasslands, while the summer soil seed bank (persistent seed bank) showed little differences. There were differences in biomass among the three grasslands (single-sowing > mixed-sowing > control), but there was no differences in species richness of vegetation. In sum, our results of the autumn seed bank support our hypothesis. Greater above-ground biomass in single-sowing grasslands could generally cause low light availability preventing seeds in soil from germinating and support more seed output, which both may indirectly or directly result in the relatively higher species richness and seed density in the soil seed bank. Our results also suggest that artificial grasslands usually returning to native grasslands in terms of production and species composition after several years is likely due to stability of the persistent soil seed bank.