11 resultados para Banks and banking, Cooperative.
em Chinese Academy of Sciences Institutional Repositories Grid Portal
Resumo:
In this paper, two models of coalition and income's distribution in FSCS (fuzzy supply chain systems) are proposed based on the fuzzy set theory and fuzzy cooperative game theory. The fuzzy dynamic coalition choice's recursive equations are constructed in terms of sup-t composition of fuzzy relations, where t is a triangular norm. The existence of the fuzzy relations in FSCS is also proved. On the other hand, the approaches to ascertain the fuzzy coalition through the choice's recursive equations and distribute the fuzzy income in FSCS by the fuzzy Shapley values are also given. These models are discussed in two parts: the fuzzy dynamic coalition choice of different units in FSCS; the fuzzy income's distribution model among different participators in the same coalition. Furthermore, numerical examples are given aiming at illustrating these models., and the results show that these models are feasible and validity in FSCS.
Resumo:
In this paper, a low-power, highly linear, integrated, active-RC filter exhibiting a multi-standard (IEEE 802.11a/b/g and DVB-H) application and bandwidth (3MHz, 4MHz, 9.5MHz) is present. The filter exploits digitally-controlled polysilicon resister banks and an accurate automatic tuning scheme to account for process and temperature variations. The automatic frequency calibration scheme provides better than 3% corner frequency accuracy. The Butterworth filter is design for receiver (WLAN and DVB-H mode) and transmitter (WLAN mode). The filter dissipation is 3.4 mA in RX mode and 2.3 mA (only for one path) in TX mode from 2.85-V supply. The dissipation of calibration consumes 2mA. The circuit has been fabricated in a 0.35um 47-GHz SiGe BiCMOS technology, the receiver and transmitter occupy 0.28-mm(2) and 0.16-mm(2) (calibration circuit excluded), respectively.
Mechanisms of Yb3+ sensitization to Tm3+ for blue upconversion luminescence in fluorophosphate glass
Resumo:
The sensitization mechanisms of Yb3+ to Tm3+ for the blue upconversion luminescence in fluorophosphate glass were studied. Two different mechanisms exist in the sensitization. One is the sequential sensitization that Tm3+ is excited from H-3(6) to (1)G(4) through absorbing three photons transferred from Yb3+ one by one. Another is the cooperative sensitization that two Yb3+ ions form a couple cluster firstly, and then the couple cluster Yb3+ ions transfer their energy to Tm3+ and excite it to (1)G(4). With the increment of the concentration of Yb3+ ions, the sequential sensitization becomes weak and the cooperative sensitization becomes intense, and the transformation trend of sensitization mechanism with the increment of Yb3+ concentration can be clarified by the introduction of Th3+ ions in the glass. (c) 2006 Elsevier B.V. All rights reserved.
Resumo:
Luminescence characteristics of Yb3+, La3+ codoped yttrium oxide nanopowders were investigated. The grain size and the crystallinity of (Yb0.05Y0.90La0.05)(2)O-3 nanopowders increase with the increase of calcination temperature. The average grain size of the nanopowders calcined at 1100 degrees C is 66 nm and its cooperative up-conversion luminescence centered at 498 nm was detected due to nanometer size effect and perfect crystallinity. However, the cooperative up-conversion luminescence of (Yb0.05Y0.90La0.05)(2)O-3 transparent ceramics was not detected. (c) 2008 Elsevier B.V. All rights reserved.
Resumo:
选取内蒙古草原三种主要草原类型(草甸草原、典型草原和荒漠草原)代表性群落羊草杂类草群落、羊草群落和大针茅群落、小针茅群落,应用样线法沿水分梯度研究放牧对内蒙古草原不同植物群落功能群组成、多样性、生产力以及多样性与生产力关系的影响和放牧对土壤种子库组成、大小以及多样性的影响,在此基础上,研究土壤种子库与地上植被间的关系。主要结论如下: 1 放牧对植物群落的影响 荒漠草原的放牧演替规律为小针茅群落→猪毛菜 + 小针茅群落→猪毛菜群落;典型草原为羊草或大针茅群落→糙隐子草 + 大针茅群落或克氏针茅群落→星毛委陵菜 + 糙隐子草群落;草甸草原为羊草杂类草群落→羊草 + 贝加尔针茅群落,这是不同物种对牧压的不同适应结果造成的。 放牧使4种草原群落生活型功能群组分间发生强烈的生态替代作用,但不同的群落生态替代模式不同:放牧使小针茅群落多年生丛生禾草作用减弱,一二年生草本作用增强;羊草群落和大针茅群落多年生丛生禾草、多年生根茎禾草作用减弱,多年生杂类草作用增强;羊草杂类草群落多年生根茎禾草作用减弱,多年生丛生禾草作用增强。放牧使非旱生和C3植物作用减弱,而旱生、C4植物作用增强。 放牧对4种群落物种和功能群多样性的影响随不同的群落而表现不同:物种丰富度、物种多样性、生活型多样性 和水分生态类型多样性除羊草杂类草群落外随放牧强度的加大而降低,但适度放牧增加了羊草杂类草群落的上述多样性指标。 群落地上现存量一般随放牧强度的增大而下降,但小针茅群落反之,主要与一年生植物猪毛菜的生物量迅速增加有关。除羊草群落外,0~10 cm 地下生物量随放牧强度的变化不显著;除大针茅群落外,放牧显著降低0~30 cm 地下生物量。 放牧影响下内蒙古草原植物群落生物量随水分生态类型多样性的升高而升高,其回归方程为:Y = 809 + 774x (R2=0.84, P<0.001),其中Y代表群落地上现存量和地下生物量之和,x代表群落水分生态类型多样性。 2 放牧对土壤种子库的影响 小针茅群落、大针茅群落、羊草群落和羊草杂类草群落土壤种子库组成中均以多年生杂类草为主,分别占各自群落种子库总物种数的40%、52%、54%和67%。 生活型功能群种子库密度除羊草杂类草群落外,均以一二年生草本占优势。中度放牧升高了除小针茅群落外多年生禾草种子库密度;放牧增大了小针茅群落和羊草杂类草群落一二年生草本种子库密度;除羊草杂类草群落外,放牧对多年生杂类草种子库密度影响不大;总种子库组成中,灌木半灌木和小半灌木种子库密度不大,不随取样时间和牧压而变化。 中度放牧种子库总密度最大,小针茅群落在重度放牧最大,主要是由于猪毛菜种子库密度在重度放牧突增所致。总体上,内蒙古草原4种群落在不同取样时间不同牧压下种子库总密度波动在20.8~3819.2粒/m2。 土壤种子库物种丰富度最大值一般出现在10月份,除羊草杂类草群落外,不放牧群落较放牧群落为高,中度放牧使羊草杂类草群落土壤种子库物种丰富度增加。中度放牧增加了小针茅群落、大针茅群落7月份和羊草杂类草群落各取样时间土壤种子库物种多样性。 3 地上植被与土壤种子库的关系 土壤种子库的优势种在特定时间特定放牧强度下与地上现有植被优势种一致,但一致率仅为三次取样时间不同放牧强度下总体的23.3%。 地上植被与土壤种子库物种组成相似性指数受不同取样时间的影响,一般的10月取样最大。不同放牧强度对二者间的相似性亦有影响,中度放牧提高了小针茅群落、羊草杂类草群落各取样时间和大针茅群落、羊草群落4月份的相似性指数。隔年二次萌发法提高了二者间的相似性水平。总体上相似性指数变动在0.1~0.75之间。 地上植被现存量、总密度与各取样时间土壤种子库总密度之间不存在显著的相关性。 4 对于估计土壤种子库密度、物种组成和确定种子库与地上植被间的关系,隔年二次萌发法对于弥补直接萌发法本身所具有的不足不失为一种有益的尝试。
Resumo:
Explaining "Tragedy of the Commons" of evolution of cooperation remains one of the greatest problems for both biology and social science. Asymmetrical interaction, which is one of the most important characteristics of cooperative system, has not been sufficiently considered in the existing models of the evolution of cooperation. Considering the inequality in the number and payoff between the cooperative actors and recipients in cooperation systems, discriminative density-dependent interference competition will occur in limited dispersal systems. Our model and simulation show that the local but not the global stability of a cooperative interaction can be maintained if the utilization of common resource remains unsaturated, which can be achieved by density-dependent restraint or competition among the cooperative actors. More intense density dependent interference competition among the cooperative actors and the ready availability of the common resource, with a higher intrinsic contribution ratio of a cooperative actor to the recipient, will increase the probability of cooperation. The cooperation between the recipient and the cooperative actors can be transformed into conflict and, it oscillates chaotically with variations of the affecting factors under different environmental or ecological conditions. The higher initial relatedness (i.e. similar to kin or reciprocity relatedness), which is equivalent to intrinsic contribution ratio of a cooperative actor to the recipient, can be selected for by penalizing less cooperative or cheating actors but rewarding cooperative individuals in asymmetric systems. The initial relatedness is a pivot but not the aim of evolution of cooperation. This explains well the direct conflict observed in almost all cooperative systems.
Resumo:
以六盘山森林植被为研究对象,通过20多年的森林土壤种子库变化与植被演替过程的试验研究,分析了8种森林群落类型的不同生长年限、生长坡位、枯枝落叶层和土壤深度对土壤种子库形成过程的影响。结果表明:六盘山森林群落不同生长坡位,土壤种子库的储量坡中部>坡下部>坡上部;不同层次土壤种子库,枯枝落叶层远高于0-15 cm深土层,8种森林群落类型排序为华北落叶松林>油松林>华山松林>辽东栎林>山杨林>白桦林>灌丛>草地;土壤种子库储量高峰期,不同群落有显著差异,华山松林和油松林在林龄的30~40年,华北落叶松林在20年,辽东栎林、山杨林、白桦林在15~20年,灌丛和草地在10~20年,其森林群落生长年限与土壤种子库储量变化趋势呈拟合曲线,符合指数方程,相关性极为显著;土壤种子库物种组成丰富,草本和灌木植物远高于乔木树种,乔木树种仅有3~5种,但多数为外来入侵种,而在每一类型中出现频率最高的草地植物多为蒿类,灌木植物为柔毛绣线菊和沙棘,乔木为辽东栎树种。因此,在六盘山林区植被自然更新与合理演替的驱动种和先锋种草地植物为蒿类,灌木植物为柔毛绣线菊和沙棘,乔木为辽东栎,其次是华北落叶松、油松和华山松。
Resumo:
A low-power, highly linear, multi-standard, active-RC filter with an accurate and novel tuning architec-ture is presented. It exhibits 1EEE 802. 11a/b/g (9.5 MHz) and DVB-H (3 MHz, 4 MHz) application. The filter exploits digitally-controlled polysilicon resistor banks and a phase lock loop type automatic tuning system. The novel and complex automatic frequency calibration scheme provides better than 4 comer frequency accuracy, and it can be powered down after calibration to save power and avoid digital signal interference. The filter achieves OIP3 of 26 dBm and the measured group delay variation of the receiver filter is 50 ns (WLAN mode). Its dissipation is 3.4 mA in RX mode and 2.3 mA (only for one path) in TX mode from a 2.85 V supply. The dissipation of calibration consumes 2 mA. The circuit has been fabricated in a 0.35μm 47 GHz SiGe BiCMOS technology; the receiver and transmitter filter occupy 0.21 mm~2 and 0.11 mm~2 (calibration circuit excluded), respectively.
Resumo:
岷江上游地区高山/亚高山植被分布的坡向性分异显著,阴阳坡高山林线不仅物种组成差异明显,并且分布海拔呈现出阴坡高阳坡低的格局.阳坡林线树种主要是圆柏属乔木,林线类型多为渐变型,海拔高度大约在3 400m~3 800m;阴坡林线树种主要是冷杉,林线类型多为骤变型,海拔高度约在3 800m~4 400m.本研究采用土壤种子库物理筛选、室内萌发实验及野外群落调查等方法,对岷江上游地区阴坡岷江冷杉和阳坡祁连圆柏两类林线树种不同海拔梯度上土壤种子库以及幼苗库特征进行了调查,从土壤种子库和幼苗更新特征的角度对林线乔木树种种群更新特征进行了分析,进而对该地区高山林线在阴阳坡分布差异的原因进行了探讨,结果显示: 1.土壤种子库 阴坡:阴坡高山林线附近岷江冷杉土壤种子的平均密度大约为50.96粒/m2,其中树线以上10m处土壤种子密度为1.00粒/m2,树线处大约19.33粒/m2,林线交错带内土壤种子密度最高为136.83粒/m2,郁闭林内种子密度小于林线交错带,只有30.50粒/m2,种子平均空壳率为52%,霉变率达34%,完好种子只有6%.土壤种子库垂直分布特征为地被物层含种子比重最大,大约在67.50%左右;其次为0~2cm层,约18.84%左右;2~5cm层所占种子比例最小,约13.66%左右.霉变种子数量与土壤深度呈负相关. 阳坡:阳坡祁连圆柏土壤种子的平均密度为60.16粒/m2.树线以上10m处密度为1.92粒/m2,树线位置大约108.16粒/m2,林线交错带内平均为75.80粒/m2,郁闭林内种子密度小于林线交错带,只有20.00粒/m2.种子平均空壳率为36%,完好种子占49%,霉变率较低,大约为10%.阴阳坡林线树种土壤种子库垂直分布特征为:地被物层含种子最多,其次为0~4cm层,4~10cm层所占种子比例最小,霉变种子数量与土壤深度也呈负相关. 2. 幼苗库调查 阳坡:在树线以上区域没有发现幼苗,林线交错带内幼苗密度平均达3 250株/hm2,郁闭林内仅2 750株/ hm2.整个样地内1~2a幼苗很少甚至没有出现,3~10a的幼苗相对较多.空间分布上,祁连圆柏幼苗在林线交错带内接近随机分布,郁闭林内则介于随机分布和均匀分布之间. 阴坡:在树线以上幼苗密度为1 250株/ hm2,全部为1~2a幼苗,林线交错带内幼苗密度平均达7 000株/ hm2,郁闭林内达6 250株/ hm2.林线附近岷江冷杉幼苗丰富度以及幼苗的出现频率明显高于祁连圆柏,年龄结构也较祁连圆柏完整.岷江冷杉幼苗空间分布除了树线处幼苗的分布为随机分布,其他海拔则为集群分布. 3.从不同土壤深度的种子总量和幼苗数量的相关性检验发现,当年生幼苗数量跟表层种子总量相关性极显著, 但是两年生幼苗的数量与底层种子数量相关性显著.土壤种子在土壤中的垂直分布格局从一定程度上可以反映种子库的年际特征.岷江冷杉土壤种子库较丰富,种子散布后的存活力随着时间的变化逐渐下降,属于季节性瞬时种子库;祁连圆柏土壤种子散布格局为集群型分布,成熟种子大部分散布在母株冠幅内,属于永久性土壤种子库. 4.在阴坡林线交错带及以上区域还存在较为丰富的乔木土壤种子,并且在树线以上区域还发现了少量的岷江冷杉幼苗.从样地乔木的年龄结构发现,在林线交错带内上部到树线位置主要以幼龄林为主,且年龄结构完整,基本符合入侵性林线特征;阳坡林线交错带内幼苗出现频率很低,树线以上区域虽然存在种子库,但是没有幼苗出现,在林线交错带内乔木径级差距很大,年龄结构异常不完整,这种特征的林线将会面临两个可能结果:一种是维持现有状态,保持平衡;另外一种就是退化,但阳坡林线的实际动态趋势还有待长期定点研究. Treelines on the upper region of Minjiang River differ between the north aspect and the south aspect in their appearances, altitudes and tree species. On the north aspect, trees of Abies form a sharp and abrupt treeline ranging from 3800m to 4400m, while on the south the treeline is generally lower(3 400~3 800m), more open and gradual and mostly composed of Sabina. In this study, we examined the altitudinal gradients of soil seed banks and seedling recruitments at the treeline ecotones of a N-aspect and a S-aspect by using soil sieving, germination experiment and field investigations, analyzed the characteristics of population regeneration of tree species at the transitional zone and presented a analysis of the causes to the aspect-related difference in treeline patterns in the study area. Major results of our study include: 1. Soil seed bank N-aspect: Of the 50 plots investigated, the average density of soil seeds is 50.96/m2, in which well-formed seeds account for 6%, empty seeds 52%, parasitized seeds34%, and seeds damaged by animals 8%. The size of soil seed bank varies along altitude, being 1.00 seeds /m2 at the 10m above the treeline and ca.19.33 seeds/m2 at the upper limit of treeline. The highest density (136.83 seeds/m2) occurs at the treeline ecotone. By contrast, the density of soil seed for the closed forest is only 30.50 seeds/m2. In terms of vertical strata, 67.50% of the total seeds are at the surface layer, 18.84% at the middle layer (0~2cm) and 13.66% at deeper layer (2~5cm). The number of parasitized seeds is negatively correlated to soil depth. S-aspect: Of the 50 plots investigated, the average density of soil seeds is 60.16 seeds/m2, and the well-formed seeds account for 49%, empty seeds 36%, parasitized seeds10%, and seeds damaged by animals 1%. The size of soil seed bank varies along altitude, with 1.92 seeds/m2 recorded at the10m above the treeline,108.16 seeds/m2 at the upper limit of treeline, and 75.80 seeds/m2 at the treeline ecotone, while that for the closed forest is 20.00 seeds/m2. The number of seeds decreases with the depth of soil. As is on the N-aspect, the size of soil bank, from large to small, follows the order of the surface layer, the middle layer (0~4cm) and the bottom layer (4~10cm). The number of parasitized seeds is also negatively correlated to the depth of the soil. 2. Seedling bank N-aspect: A mean maximum seedling abundance of 31 000 seedlings/hm2 was recorded near alpine treeline at growing season. The density of seedlings is 1 250 seedlings/ha (all being 1 or 2 years old) at the alpine meadow 10m away above treeline, 7 000 seedlings/ha at treeline ecotone and 6 250 seedlings/ha for closed forest.The spatial distribution of Abies faxoniana seedlings is random at the upper limit of the treeline but clumped at other altitudes. S-aspect: No seedlings were found at the alpine meadow 10m away from the treeline. The density of seedlings was 3 250 seedlings/ha at treeline ecotone and 2 750 seedlings/ha for the closed forest.Hardly any 1 year current and 2 year-old seedlings appeared at the plots. The spatial distribution of Sabina przewalskii seedlings is random at treeline ecotone and between “random” and “even” forest closed forest. 3.Correlation tests of seedling population and seed bank at different soil layers indicated that the emergents were strongly correlated to seed bank at surface layer while the number of two-year seedlings was significantly correlated to the seed bank at the bottom of soil layer, indicating that germination mainly occurs at the soil surface while the middle or bottom layer was the reserve for non-germination or dead seeds. It can thus be postulated that Abies faxoniana soil seed bank is of seasonal transient type. By contrast, the soil seed bank of Sabina przewalskii is of persistent type and the soil seeds and seedlings of this species occurred more frequently near the islands of adult trees. 4.A good many soil seeds of both tree species were found near the treeline ecotone and above at N- and S-aspects. A few young seedlings were found above the Abies treeline. Investigation of five altitudinal transects respectively on N- and S-aspects indicated that Abies faxoniana has a more complete age structure than the stands of Sabina przewalskii. The age of firs decreased from closed forest to the upper limit of treeline, which suggests that the Abies treeline is advancing to higher altitude. While on the south aspect, only few Sabina przewalskii soil seeds and nearly no seedlings were found above the treeline ecotone. The stands exhibit extremely great difference in diameter classes with significantly incomplete age structure. This would lead to two possible results for the treelines: maintaining an equilibrium state at the current position or degenerating. But more studies should be carried out at longer time scales or larger spatial scales to understand whether the Sabina treeline is degenerating.
Resumo:
Located in the Central and West African, Chad, which is not well geological explored, is characterized by Mesozoic- Cenozoic intra-continental rift basins. The boreholes exposed that, during Mesozoic-Cenozoic times, volcanic activities were intense in these basins, but study on volcanic rocks is very weak, especially on those embedded in rift basins, and so far systematic and detailed work has still no carried out. Based on the project of China National Oil and Gas Exploration and Development Corporation, “The analysis of reservoir condition and the evaluation of exploration targets of seven basins in block H in Chad”, and the cooperative project between Institute of Geology and Geophysics, CAS and CNPC International (Chad) Co. Ltd., “Chronology and geochemistry studies on Mesozoic-Cenozoic volcanic rocks from southwestern Chad Basins”, systematic geochronology, geochemistry and Sr-Nd-Pb isotopic geochemistry studies on volcanic rocks from southwestern Chad basins have been done in the thesis for the first time. Detailed geochronological study using whole-rock K-Ar and Ar-Ar methods shows the mainly eruption ages of these volcanic rocks are Late Cretaceous- Paleogene. Volcanic rocks in the well Nere-1 and Figuier-1 from Doba basin are products of the Late Cretaceous which majority of the K-Ar (Ar-Ar) ages fall in the interval 95-75 Ma, whereas volcanic rocks in the well Ronier-1 from Bongor Basin and the Well Acacia-1 from Lake Chad Basin formed in the Paleogene which the ages concentrated in 66-52Ma. Two main periods of volcanic activity can be recognized in the study area, namely, the Late Cretaceous period and the Paleogene period. Volcanic activities have a general trend of south to north migration, but this may be only a local expression, and farther future studies should be carried on. Petrology study exhibits these volcanic rocks from southwestern Chad basins are mainly tholeiitic basalt. Major- and trace elements as well as Sr-Nd-Pb isotopic geochemistry studies show that the late Cretaceous and the Paleogene basalts have a definitely genetic relationship, and magmas which the basalts in southwestern Chad basins derived from were produced by fractional crystallization of olivine and clinopyroxene and had not do suffered from crustal contamination. These basalts are prominently enriched light rare earth elements (LREE), large-ion lithophile elements (LILE) and high field strength elements (HFSE) and depleted compatible elements. They have positive Ba, Pb, Sr, Nb, Ta, Zr, Hf anomalies and negative Th, U, P,Y anomalies. It is possible that the basalts from southwestern Chad basins mainly formed by mixing of depleted mantle (DM) and enriched mantle (EMⅡ) sources. The late Cretaceous basalts have higher (87Sr/86Sr)i ratios than the Paleogene basalts’, whereas have lower (143Nd/144Nd)i ratios than the latter, showing a significant temporal evolution. The mantle sources of the Late Cretaceous basalts may have more enriched mantle(EMⅡ) compositions, whereas those of the Paleogene basalts are relatively more asthenospheric mantle (DM) components. The mantle components with temporal change observed in basalts from Chad basins were probably correlated with the asthenospheric mantle upwelling and lithospheric thinning in Central and Western Africa since Mesozoic. Mesozoic- Cenozoic Volcanism in Chad basins probably is a product of intra- plate extensional stress regime, corresponded to the tectonic setting of the whole West and Central African during Cretaceous. Volcanism is closely correlated with rifting. As time passed from early period to late, the basaltic magma of Chad basins, characterized with shallower genetic depth, higher density and smaller viscosity, probably indicates the gradual strengthening evolution of the rifting. In the initial rife stage, volcanic activities are absent in the study area. Volcanic activities are basiccally corresponded with the strong extensional period of Chad basins, and the eruption of basalts was slightly lagged behind the extensional period. In the post-rift stage (30-0Ma), these basins shifted to the thermal sag phase, volcanic activities in the study area significantly decreased and then terminated.