JOURNAL OF LANZHOU UNIVERSITY(NATURAL SCIENCES)
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2017 Vol.53 Issue.5,
Published 2017-10-28

1
2017 Vol. 53 (5): 1-1 [Abstract] ( 16 ) [HTML 1KB] [ PDF333KB] ( 52 )
2
2017 Vol. 53 (5): 2-2 [Abstract] ( 3 ) [HTML 1KB] [ PDF202KB] ( 30 )
569 Characteristics of antimony mineralization in the Baogutu intrusive body Ⅲ-2, Xinjiang Province
Wei Shao-ni1, Zhu Yong-feng2, Zheng Bo2
Antimony mineralization developed in the east boundary of the intrusion III-2 in Baogutu area
in the south of the West Junggar. The mineralization process can be divided into three stages: the early native
antimony stage when native antimony coexisted with pyrrhotite; the middle gudmundite stage when
gudmundite coexisted with pyrrhotite, pyrite and arsenopyrite; the late stibnite stage when plenty of stibnite
replaced native antimony and pyrrhotite. Mineral compositions and phase relations indicated that precipitations
of native antimony were mainly controlled by the decrease of oxygen fugacity during the early
stage. The decreases in temperature resulted in the precipitation of stibnite during the late stage. The
sulfur fugacity of the ore-forming process was log f (S)2 = -8 - -13, increasing from the early to the late
stages. The study of antimony mineralization supplements the mineral types in the West Junggar and is of
great theoretical and practical value.
2017 Vol. 53 (5): 569-575 [Abstract] ( 9 ) [HTML 1KB] [ PDF6822KB] ( 47 )
576 Spatial information retrieval method for petroleum exploration and production
Wang Zhi-bao1, Wang Cheng-bo2, Wen Bi-long1, Xia Hao2, Qiao Yan-you2
A technical framework of spatial information retrieval was put forward for petroleum exploration
and production, a method of spatial theme mining proposed and a high-performance hybrid index structure supporting
query composed by text and 3 dimensions space were also designed. The prototype named PetroScope
based on original research was implemented. It was proved that the PetroScope could meet requirements of
spatial information retrieval in petroleum exploration and production with its accuracy and performance verification.
2017 Vol. 53 (5): 576-581 [Abstract] ( 4 ) [HTML 1KB] [ PDF659KB] ( 29 )
582 Mechanism and processes of intensity deterioration of earthen ruin's soil undergoing salinized and dry-wet coupling effect
Cui Kai1, 2, Chen Meng-meng1, ChenWen-wu2, Guan Xi-peng1, HanWen-feng2
It was found that there are differences in frequencies and degrees of coupling effects for soil
located in the inner earthen sites of different places, according to real time monitoring of the temperature
and moisture content for three typical sites during concentrated rainfall processes. The remolded soil
with different contents of NaCl and Na2SO4 that had experienced different periods of wet-dry cycles
was used to measure strength indexes and analyze particle sizes. Regular and regulatory experiment results
were obtained, showing that the compression strength, tensile strength, cohesion values, coarse
grain and silt contents and granularity fractal dimension value of samples all increased with the higher salinity
and more times of wet-dry cycles. Mathematical statistical analysis showed that a quantitative relation exists between macroscopic intensity and grain size analysis indexes under different frequencies and
degrees of coupling effects. The essential reasons for soil strength degradation under the wet-dry and saline
coupling effect were analyzed and discussed, and a relationship was found to exist between those
sites' forms of dying processes and the speed and soil strength degradation.
2017 Vol. 53 (5): 582-588 [Abstract] ( 7 ) [HTML 1KB] [ PDF2387KB] ( 34 )
588 Petrogenesis and tectonic implications of the Eocene Shilicun syenite from western Yunnan
Zhang Jiang-su1, 2, Liao Shi-yong3, Liu Zheng4
The Shilicun pluton from western Yunnan is exposed adjacent to the Ailaoshan fault zone. It
comprises quartz alkali- feldspar syenite and quartz syenite. The pluton was emplaced at ~36.8 Ma. All
the samples, being metaluminous, have a high alkali content, high Sr and low Yb and low Y content.
The initial Sr-Nd isotopic data were plotted in the field of xenolithes from the mafic lower crust. The
occurrence of the Shilicun pluton indicated that the Cenozoic potassic magmatic belt was formed in a
post- collisional setting, in response to asthenospheric upwelling triggered by removal of the thickened
lithospheric mantle root.
2017 Vol. 53 (5): 588-592 [Abstract] ( 6 ) [HTML 1KB] [ PDF1154KB] ( 40 )
593 Influence of topographical factors on debris flow in valley cities in northwest China
Zhang Peng-li, Li Yu
With a view to the local geographical environment and terrain factors, the relationship between
debris flow distribution and topographic factors in Lanzhou were quantitatively analyzed, using documents,
meteorological data, physical geographic data, digital elevation models, GIS technology as well as
the Logistic model. The results showed that, during the last one hundred years, debris flow disasters
occurred frequently but on smaller scales. A predictive formula of debris flow disasters was established
using the Logistic regression model, and it was found that the occurrence probability of debris flow disasters
had a negative correlation with the elevation and distance from a river, and the slope and aspect had
little effect on occurrence probability. We tested the model and found that the prediction accuracy rate of
this model is as high as 73.7%, with a much better predicting effect than others.
2017 Vol. 53 (5): 593-597 [Abstract] ( 4 ) [HTML 1KB] [ PDF696KB] ( 42 )
598 Drought variations and their influential climate factors in the Shiyang River Basin
Zhang Xue-lei, WangWan-rui, Wang Liu-ming, Wang Shuai-bing, Li Chang-bin
Based on the determination of the Thornthwaite aridity index (AI), methods of Sen's slope and
spatical analysis were used to analyze the spatial and temporal characteristics and variation tendency and
climate sensitivity of drought across the Shiyang River Basin from 1981 to 2014. The results revealed
that the AI increased spatially from the area of the upper reaches to the lower reaches in the Shiyang River
Basin. From 1981 to 2014, there presented a decrease of AI in the area of northeastern Wushaoling,
western Yongchang and the northern Minqin, with an increase in other areas of the Shiyang River Basin.
Sensitivity analysis showed that variations of drought in the basin were influenced more by the three
key climate factors including precipitation, relative humidity and net radiation. The decrease of precipitation
led to aridity in the upper mountainous area to be strengthened, while the weakened aridity in area of
the middle and lower reaches was due to an increase of precipitation. The increase of relative humidity in
the upper mountainous area led to less evapotranspiration, which, to some extent, remitted the aridification
in the area.
2017 Vol. 53 (5): 598-604 [Abstract] ( 7 ) [HTML 1KB] [ PDF2514KB] ( 39 )
604 Impact of topography on land use pattern in the central area of Lanzhou City
Zhang Ling-ling, Xie Yao-wen, Mu Ya-chao
The central areas of Lanzhou City were chosen for study and classification, a regression
decision tree was constructed to extract land use information automatically and then terrain
factors were calculated based on DEM. The character of land use was analyzed with the
changes of elevation and slope. The results showed that more than 80% of residential and industrial
land and more than 90% of water occupation were distributed in the lower and more moderate
areas, 60% of the forest and grassland in higher and steeper areas, about 50% of the unused
land was located in the elevation range of less than 2 000 m and slope of less than 15°,
which could be considered for a certain degree of exploitation. The region in an elevation range
of less than 1 600 m and slope ranging between 5° to 8° appeared the most tattered in landscape,
with the most irregular shapes and most fragile ecological environment. The most rich
type of landscape was in the elevation range from 1 600 m to 2 000 m and slope ranging between
of 8° and 15° . The same types of land use appeared gathering and merging within the
range greater than 2 800 m with the best effect of integration.
2017 Vol. 53 (5): 604-608 [Abstract] ( 5 ) [HTML 1KB] [ PDF1929KB] ( 28 )
609 Schedule of coupling coordinative degree of industrialization, urbanization and agricultural modernization in Gansu Province
Pang Jia-xing, Chen Xing-peng, HanWen-yan, He Xuan-lei
Using the coupling coordinative degree model, the indicator structure of industrialization, urbanization
and agricultural modernization was put forward, the coupling coordination degrees were analyzed
of the industrialization, urbanization and agricultural modernization of Gansu Province from 1990
to 2011. The results showed that the coupling coordinative degrees of industrialization, urbanization and
agricultural modernization was rising from 1990 to 2011, but still belonging to the barely coordinative
level. That was why the coupling coordination degree for the three aspects was restricted by the industrialization
level during nearly a decade in Gansu Province. A forecast analysis predicts that the coordination
degree will continue to be barely coordinative.
2017 Vol. 53 (5): 609-613 [Abstract] ( 10 ) [HTML 1KB] [ PDF893KB] ( 35 )
614 Circulation classification of heavy rain in the Kumtagh Desert in the typical weather process of different circulation patterns
Hu Yu-ling1, Zhao Zhong-jun2, Kang Cai-yan3, Wang Shi-gong1, 3, Shang Ke-zheng1
Based on four meteorological stations' daily precipitation data of 1960-2014 and NCEP/NCAR
reanalysis data, 500 hPa circulation patterns of heavy rain in the Kumtagh Desert were analyzed. The
HYSPLIT model was used to track water vapor transport paths in this area. The results showed that 500
hPa main circulation patterns of heavy rain were the low vortex shear and low though in Xinjiang and the
transverse trough from Lake Baikal to Xinjiang. For heavy rain, there were three water vapor branches
in the Kumtagh Desert: the western moist flow from the Atlantic Ocean, the Arctic Ocean and
the Aral and Caspian seas; the southwest warm moist flow from the Indian Ocean-the Bay of Bengal; the southeast warm moist flow from the bay of Bengal- the South China sea and western Pacific. Regional
mean water vapor flux increased with height in the Kumtagh Desert. For different levels, the water vapor
flux at 700 hPa was the largest. The vertical ascending motion was strong during the heavy precipitation,
which provided dynamic conditions for the development and maintenance of heavy rain.
2017 Vol. 53 (5): 614-621 [Abstract] ( 3 ) [HTML 1KB] [ PDF8582KB] ( 46 )
622 Characteristics of net ecosystem CO2 exchange over typical vegetation types above different regions
Yao Jing-yu, Wang Guo-yin, Li Chen-rui, Yu Hai-peng
The characteristics of net ecosystem CO2 exchange (NEE) over three regions (North America,
Europe and Asia) in different typical vegetation types has been analyzed using the global network flux
data sets and the results showed that the average NEE over the study region was -1.093×10- 2 kg/a. The
spatial distribution of NEE was highly related to the variation of vegetation types. The croplands and
evergreen needle leaf forest vegetation type had the strongest CO2 absorption capacity, with the grassland
having the weakest. It also showed a peak carbon absorption rate at approximately 10:00-12:00 am over
all of the vegetation types. The diurnal cycle of NEE was an evident "U" shaped curve with negative
values during the daytime and reversed values during nighttime. The seasonal variation of NEE was
obvious in different latitudes, and the absorptive capacity of carbon was decreased in relation with the
increase of the latitudes. The annual cumulative NEE in mid-latitudes was sensitive to the variations
of precipitation and soil moisture.
2017 Vol. 53 (5): 622-627 [Abstract] ( 5 ) [HTML 1KB] [ PDF1713KB] ( 32 )
628 Effects of two types of ENSO events on the blockings in the Eurasian Region in winter
Li Yan, Lu Yao, Wang Jia-he, Wang Qi
By using the reanalysis data from the NCEP/NCAR and El Niño/La Niña Modoki anomaly
index (EMI) provided by the Japan Marine Science and Technology Center, the influences of two types of
El Niño-southern oscillation (ENSO) on the blockings and their atmospheric circulation mechanisms over key regions of Eurasia were analyzed for winter during the last 36 years, with main results that, when
the El Niño (EN) event happened, the blocking frequency over the 3 key areas of Eurasia all decreased to
different degrees, especially in the Urals area. The instantaneous blocking frequency was reduced by
32%, and the average duration of blocking events was reduced by 14.7%; La Niña (LN) event might have
caused the instantaneous blocking frequency of the Ural region to increase by more than 53% and the
average duration of blocking events to increase by 27.9%, but it led to the average duration of blocking
events in the Okhotsk region to reduce by 24%; the influences of ENSO Modoki differed from that of the
traditional ENSO. Compared with the normal years, EN Modoki event made the instantaneous blocking
frequency in Eurasian to increase by different degrees and, the instantaneous blocking frequency in the
Okhotsk region increased by more than 55%, and the average duration of blocking events increased by
18.2%; in LN Modoki years, the frequency of instantaneous blocking and mean duration of blocking
events increased by 15% and 25% in the Urals region, respectively. The frequency of instantaneous
blocking and mean duration of blocking events decreased by 29% and 10.6% in the Okhotsk region,
respectively. The influence of two types of ENSO was comparably weak in the Baikal region. The reasons
for the different influences of two types of ENSO were directly related to the atmospheric circulation,
which could be seen from the 500 hPa geopotential heights and the wind fields. When an EN event
occurred, there was a cyclonic circulation accompanying by a negative anomaly of geopotential
heights in the Ural and Okhotsk areas, which was in favor of less blocking over these regions, and
vice versa in LN years. When an EN Modoki event happened, 500 hPa potential heights increased in
Eurasian by different degrees, indicating that the EN Modoki event was beneficial to the generation of
blocking events. In an LN Modoki event, geopotential heights in the Ural and Baikal were higher,
thus being beneficial to the occurrence and development of blocking high over there.
2017 Vol. 53 (5): 628-635 [Abstract] ( 7 ) [HTML 1KB] [ PDF3834KB] ( 33 )
636 Impacts of two types of El Niño events on the Hadley circulation and climate of China
Li Yan, Ma Bai-sheng, Wang Qi, Lu Yao, Wang Jia-he
With 1979-2014 NCEP/NCAR reanalysis findings, the impacts of two types of El Niño events
on the Hadley circulation and the climate in China were analyzed, the results showing that either in the
cold or warm season during El Niño events, Hadley circulation was strengthened with the unconverted
position of its rising and sinking branches. In the warm season of El Niño Modoki year, rising and
sinking branches of Hadley circulation both move northward. This character was not depicted in the cold
season of El Niño Modoki year. The influence of El Niño on Hadley circulation was bigger than that of
El Niño Modoki, which was caused by a different sea surface temperature (SST) distribution during the
two types of El Niño events. In an El Niño year, low temperature and floods appeared more easily in
southern China and high temperature and drought more easily in northern China. The northeast areas of China underwent a cool summer. The temperature in winter in China would be higher. In an El Niño Modoki
year, the temperature distribution in the cold season showed a law of being lower in the north and
east area and higher in the southwest area. The region to the south of Yangtze River experienced less precipitation.
The typical examples indicating that the two types of El Niño events had the biggest influence
on the Hadley circulation were picked out to analyze the reasons behind the different influences of the
two types of El Niño on China climate and the results showed that the anomaly of temperature and precipitation
during these typical events was basically consistent with the influence climatology of the two types
of El Niño events in Chinese climate, indicating that the Hadley circulation was an important element
among a number of factors through which the anomaly of SST in the equatorial Pacific influenced the climate
in China. There were other contributing factors too, making it not easy to figure out the mechanism
of the SST influence in Chinese climate.
2017 Vol. 53 (5): 636-645 [Abstract] ( 4 ) [HTML 1KB] [ PDF8273KB] ( 32 )
646 Effects of a shelter forest on soil physical and chemical properties in the Kubuqi Dersert
Gu Meng-he1, Zhou Li-hua1, 2, Wang Rui1, 3, Zhao Min-min1, 3, Guo Xiu-li1, 3
Combining the field sampling and laboratory analysis, soil water between 0-100 cm and soil
nutrient between 0-60 cm of 8 kinds of shelter forest in the Kubuqi Desert were analyzed. Soil water gradually
increased with the increase of soil depth. Soil layer and shelter forest type both had significant
effect on soil water of a shelter forest. From being big to small, the soil water of 8 kinds of shelter forest
were respectively: Salix matsudana+Populus popular's, Salix matsudana, Elaeagnus angustifolia+Salix
psammophila, Elaeagnus angustifolia, Populus Spp., Populus Spp.+Hedysarum fruticosum, Caragana
korshinskii, Hedysarum fruticosum. The soil nutrient of the 0-60 cm soil layer showed that this layer had no significant effect on the soil nutrient and the topsoil (0-10 cm) nutrient was higher than deep soil (10-
60 cm). Shelter forest type had a significant effect on the seven soil nutrient indexes. Soil nutrient of
Caragana korshinskii and Salix matsudana were relatively higher and Hedysarum fruticosum was relatively
lower in the 8 kinds of shelter forest. The results showed that Salix matsudana, Salix matsudana+
Populus popular's and Caragana korshinskii could better improve the quicksand, not only having better
water and nutrient conditions and also higher species diversity and vegetation coverage. Hedysarum
fruticosum and Populus Spp. could decrease the quicksand, not only having worse water and nutrient conditions
and also lower species diversity and vegetation coverage.
2017 Vol. 53 (5): 646-651 [Abstract] ( 4 ) [HTML 1KB] [ PDF662KB] ( 29 )
652 Effects of zokor disturbance on species diversity and community productivity of Subalpine meadows in Qinghai-Tibet Plateau
Yang Ying-bo1, 2, Cao Quan2, Yang Qian2, Lai Xing-fa2, Qian Ya-li2, Zhang Xue-mei2,Wang Xian-zhi2, Zhang Mei-yan3, Shen Yu-ying2
Based on the two levels of community and functional groups, differences of species diversity
and community production of vegetation on zokor mounds were compared along the successional stages,
aiming at understanding the effects of a small scale disturbance on species composition and functional
traits of plant communities, and the relationship between species diversity and community production during
the restoration process was discussed. The results showed that, during the succession of plant community
on zokor mounds in the enclosure site of subalpine meadows and at the community level, both the
species richness and diversity index showed a logarithmic and increasing pattern, species evenness were
also gradually increased and community production presented a significant linear increasing trend. At the
functional group level, the trend on species richness of ephemeral forbs was not significant: it declined in
the relative coverage, and its aboveground biomass first increased and then declined. All of the three
indexes (species richness, the relative coverage and aboveground biomass) of perennial forbs exhibited a
remarked significant increasing trend. Species richness and aboveground biomass of leguminous plants
were of a significant increasing pattern, the relative coverage underwent an increasing trend but very
insignificant; all of the three indexes (species richness, the relative coverage and aboveground biomass)
of gramineous plants were of a significant increasing pattern. At the community level, species richness
was remarkable and positively related with community productivity while at the functional group level,
all of the four functional groups (ephemeral forbs, perennial forbs, leguminous and gramineous plants)
exhibited a positive and remarkable correlation with community production. The Shannon-Wiener index
of perennial forbs and leguminous plants was also significantly correlated with the referenced production,
but the results of Shannon-Wiener index of ephemeral forbs and gramineous plants had no significant
correlation with the referenced production. The above results indicated that, under the enclosure background,
the increasing species richness could help improve community production, which may result
from niche differences in functional groups, and from the complementary utilization ability of resources
for different species and dispersal limitation.
2017 Vol. 53 (5): 652-658 [Abstract] ( 9 ) [HTML 1KB] [ PDF1376KB] ( 40 )
659 Response of herbaceous plant diversity to terrain factors in the southeast stretch of the northern slope of Motianling
Song Ling-ling, Li Zong-jie, Tian Qing
Correlation analysis and stepwise regression analysis were used to illustrate the herbaceous
plant diversity pattern and discuss the diversity of forest community's herbal responses to terrain factors
of the typical forest community in the northern slope of Motianling, through an investigation into vegetation
and environmental factors. The results showed that the Simpson diversity index, Shannon-Wiener diversity
index and Pielou evenness index underwent the same trend of first increasing and then lowering,
along with the changes in elevation gradient; with the increase of the elevation gradient those indexes
lowered first, then appeared the changing trend of rise and fall. The Simpson dominance index experienced
a likewise trend. Slope was the most important terrain factor that affected the plant diversity in the
study area, but slope direction and slope-shape also influenced the plant diversity index significantly, and
a highly significant correlation existed between the slope and diversity index.
2017 Vol. 53 (5): 659-663 [Abstract] ( 6 ) [HTML 1KB] [ PDF1487KB] ( 41 )
664 Heavy metal pollution in soil and its effect on plants on the main roads of Lanzhou City
Yang Ying-li, Li Qiong, Ma Ting, Li Cui-xiang, Teng Yu-jin, Yin Jin-mei, Gao Xiao-xia, Jia Ling-yun
In order to investigate the contamination of heavy metals in roadside soil and green plants associated
with traffic operation in Lanzhou City, samples were collected from north riverside road and
Anning east and west roads, and distribution characteristics and potential ecological risks of Cr, Cu, Zn,
Pb, Mn, Ni, Fe and Ca were evaluated. The results showed that the amount of w(Cr), w(Pb), w(Zn),
w(Cu) and w(Mn) in roadside soil was higher than that in public parks and campuses, and the order of
contamination degree caused by traffic operation was Cu>Pb>Cr>Zn, but Mn and Ni missed pollution
level. Road sections with frequent braking, a large traffic flow, crossroad exhibited a higher amount of w
(Cr), w(Pb), w(Zn) and w(Cu) in comparison with other sample points, suggesting that the contamination
of these four heavy metals was due to automobile exhaust emission, dust production from the friction
between the car parts as well as the friction between the tire and road surface. The accumulation of Pb,
Zn and Mn was higher in the leaves of Euonymus japonicus grown in soil with a low content of heavy metal, indicating a strong ability of heavy metal uptake by its roots and partial transport to the ground
in Euonymus japonicus. w(Pb), w(Zn) and w(Mn) were the highest in plants cultured in soil with a high
content of heavy metals. w(Ca) was higher in the leaves of most plants on An ning east and west roads
than in most plants on the north riverside road.
2017 Vol. 53 (5): 664-670 [Abstract] ( 5 ) [HTML 1KB] [ PDF748KB] ( 39 )
671 A non-autonomous SIRS epidemic model with general incidence rate and immune delay
Han Yi-ru, Wu Shi-liang
A more general incidence rate and immune delay were investigated in a non-autonomous SIRS
epidemic model. It was showed that the disease-free solution was globally asymptotically stable with the
construction of a Liapunov functional and application of the comparison principle. Sufficient conditions
of extinction and strong persistence of infective were obtained. The results implied that the immune delay
should have no effect on the strong persistence and extinction of the infectives and global asymptotic
stability of disease-free solutions. Some simulations of the periodic system were presented to support our
results.
2017 Vol. 53 (5): 671-678 [Abstract] ( 7 ) [HTML 1KB] [ PDF1520KB] ( 29 )
679 Stability and Hopf bifurcation in a delayed differential-algebraic biological economic system with Holling type III functional response
Wang Lie
A differential-algebraic biological economic system with time delay and Holling type III functional
response is considered, into which are incorporated a constant prey refuge and prey harvesting. A
sufficient condition for the existence of a positive equilibrium is discussed and then an ordinary differential
equation is transformed from the system by homeomorphic transformation. The time delay is considered
as a bifurcation parameter, and the stability and Hopf bifurcation of the system were analyzed based
on the characteristic root method and the bifurcation theorem. It is found that the Hopf bifurcation will occur
when the bifurcation parameter is via an exceptive value. Numerical simulations illustrate the effectiveness
of our results.
2017 Vol. 53 (5): 679-684 [Abstract] ( 4 ) [HTML 1KB] [ PDF972KB] ( 38 )
685 Sparse spectral clustering method and its application
Xu Xue-li1, 2, Su Jin-xia1
A new sparse spectral clustering algorithm- sparse spectral clustering based on K- Medoids
(SSKM) was explored, which takes advantage of the sparse similarity matrix in computation, and also the
superiority of the partitioning around medoids algorithm over k-means. To ensure the utilization of highdimensional
data, the principal component analysis method was also investigated in the algorithm, i.e. a
modified version-HSSKM, which could reduce the dimension of the data. Under the adjusted rand index
and classification error rate evaluation criteria, the new proposed method had its superiority in the simulation
studies as well as real data.
2017 Vol. 53 (5): 685-690 [Abstract] ( 3 ) [HTML 1KB] [ PDF1056KB] ( 30 )
691 Global stability of a delayed epidemic model with saturation infection
Li Xiao-ling1, Liang Xin1, Liu Ya-dong1, Li Dong-liang2, Hu Guang-ping1
This paper was concerned with a mathematical model dealing with a delayed SEIR epidemic
model with a saturation infection rate and a calculation method for the basic reproduction number R0 was
given. Through constructing suitable Lyapunov functionals and using LaSalle invariant principle, we
showed that the disease- free equilibrium was globally asymptotically stable if R0 ≤1 while the infected
equilibrium was globally asymptotically stable if R0>1.
2017 Vol. 53 (5): 691-695 [Abstract] ( 8 ) [HTML 1KB] [ PDF659KB] ( 31 )
696 Limit property of the delayed risk model under dependent claims and investment
Xiao Hong-min, Liu Ai-ling, He Yan
The limit property of ruin probability on the delayed risk model with investment was investigated.
The case of an insurance company allowed to invest a constant fraction of its wealth in a stock
market which was described by a geometric Brownian motion, while the remaining wealth in a bond with
a nonnegative interest force. Under the assumptions that the sequences of the main and delayed claims
were negatively dependent random variables and belonged to the heavy-tailed distribution class respectively,
asymptotic formulas of finite-time ruin probability were obtained. The effectiveness of the results
was remarkably verified by a numerical simulation. The conclusion of this paper can provide a kind of
investment idea for insurance company.
2017 Vol. 53 (5): 696-700 [Abstract] ( 4 ) [HTML 1KB] [ PDF750KB] ( 30 )
701 Particle swarm algorithm based on pattern search for absolute value equations
Feng Jing-mei1, 2, Liu San-yang1
Improved particle swarm algorithm was used to solve a class of NP-hard and non-differentiable
problem of absolute value equations: Ax - | x |= b. This algorithm effectively combined a strong local
exploration ability of pattern search method with a strong global exploitation of the particle swarm algorithm.
This hybrid method integrated the good advantages of the two methods and balanced the local and
global optimization ability. Numerical experiments showed that this improved method had such advantages
as a high precision and less number of iterations for solving absolute value equations with different
types of solutions.
2017 Vol. 53 (5): 701-705 [Abstract] ( 5 ) [HTML 1KB] [ PDF1186KB] ( 31 )
706 Preparation and simulation of the field emission character of Spindt cathode with the nanosphere method
Zhang Mei-xiao1, Ma Yu-long1, 2, Zhou Hu1, ZhouWang1, Zhou Li-hua1, XiangWei2, Zhao Xing-hai2, Zeng Bao-qing3, Cui Ying1
A new method for preparing the Spindt field emission cathode array was proposed by combining
the polystyrene nanosphere self- assembly with micro- mechanical manufacturing technologies. The
fabricated hole array based on the present method possessed a high density and highly uniform periodic
sub-micrometer size, where the diameter of the gate hole was in the range of 300-500 nm, the depth of
the hole was 500 nm, and the periodic of the structural unit was 750 nm. The high micro- hole density
could reach 108/cm2, being more than ten times the density of ordinary lithography. The field emission
characteristics of the Spindt cathode were simulated with the particle-in-cell solver of CST particle studio.
Simulation results showed that the radius of the emission tip, diameter of the gate hole as well as the
relative height difference between the emitter tip and the gate are key factors affecting the field emission
current.
2017 Vol. 53 (5): 706-710 [Abstract] ( 5 ) [HTML 1KB] [ PDF2323KB] ( 28 )
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