A fast-settling frequency-presetting PLL frequency synthesizer with process variation compensation and spur reduction

This paper proposes a fast-settling frequency-presetting PLL frequency synthesizer. A mixed-signal VCO and a digital processor are developed to accurately preset the frequency of VCO and greatly reduce the settling time. An auxiliary tuning loop is introduced in order to reduce reference spur caused by leakage current. The digital processor can automatically compensate presetting frequency variation with process and temperature, and control the operation of the auxiliary tuning loop. A 1.2 GHz integer-N synthesizer with 1 MHz reference input Was implemented in a 0.18μm process. The measured results demonstrate that the typical settling time of the synthesizer is less than 3μs,and the phase noise is -108 dBc/Hz@1MHz.The reference spur is -52 dBc.

Block and parallel modelling of broad domain nonlinear continuous mapping based on NN

The necessity of the use of the block and parallel modeling of the nonlinear continuous mappings with NN is firstly expounded quantitatively. Then, a practical approach for the block and parallel modeling of the nonlinear continuous mappings with NN is proposed. Finally, an example indicating that the method raised in this paper can be realized by suitable existed software is given. The results of the experiment of the model discussed on the 3-D Mexican straw hat indicate that the block and parallel modeling based on NN is more precise and faster in computation than the direct ones and it is obviously a concrete example and the development of the large-scale general model established by Tu Xuyan.

沈阳城市森林生态系统健康与管理研究

本文系统研究了沈阳城市森林的布局与结构、城市森林功能、城市森林病虫害发生与树木健康状况和城市自然资源与社会经济状况等指标对沈阳城市森林生态系统健康与管理的影响。同时一，采用2种生态系统健康评价方法对沈阳城市森林生态系统健康状况进行了评价，并提出了沈阳城市森林生态系统健康管理的对策。研究结果如下：1、截至2004年末，沈阳城市森林植被覆盖率已经达到35％，城市森林林地分布基本合理，但需要进一步加强道路林地、居住区林地和城郊大面积生态林建设。2、沈阳城市森林以乔木为主，乔灌株数比为1.7：1，乔灌的覆盖度比约为7:1。3、沈阳城市森林不同类型林地中植物组成不同。公园林地中有74个属，137个种（变种）；庭院林地中有53个属，104个种（变种）；居住区林地中有45个属，81个种（变种）；道路林地中有43个属，94个种（变种）；运河风景林地中有75个属，142个种（变种）；棋盘山风景林地中有48个属，118个种（变种）。4、公园林地、庭院林地、居住区林地、道路林地和运河风景林地的Shannon一Wiener多样性指数分别为2.78、3.05、3.15、3.18和3.18，均匀度指数分别为0.56、0.66、0.72、0.70和0.64。除了棋盘山风景林地外，沈阳城市森林中栽植总量超过乔木总量5％的乔木树种有7个属，分别为李、柳树、杨树、桧柏、榆树、槐树和银杏，7种树木总量达到了全部乔木总量的82.09％；栽植总量超过灌木总量5％的灌木树种也有7个属，分别为水腊、丁香、李属，小聚、玫瑰、忍冬和连翘，7个属灌木总量达到了全部灌木总量的87.92％。5、公园林地、庭院林地、道路林地和防护林地中OBH＜20cm、20cm＜DBH＜60cm和DBH＞60cm树木的比例分别为：57.9％、40.0％、2.1％，49.2％、47.8％、3.0％，65.3％、33.1％、1.6％和64.6％、34.9％、0.5％，表明沈阳城市森林树木的规格总体上偏小。6、经样方调查和CITYgreen模型计算，沈阳城市森林的生态效益约2.0亿USD／yr.。公园林地、庭院林地和风景林地的景观指标相对较高；道路林地和居住区林地的景观效果一般；防护林地的景观效果较差。7、目前已经发现的沈阳城市森林病害约600余种，虫害约700余种，其中杨树主要病虫害39种，柳树的主要病虫害有33种，榆树和槐树的主要病虫害均为，1种。杨柳树腐烂病、光肩星天牛、天幕毛虫、桃红颈天牛和美国白蛾等是近10年来沈阳城市森林中普遍发生和造成严重危害的主要病虫害。沈阳城市森林主要树木的平均健康指数为2.68，处于一般健康状态。8、沈阳城市森林的土壤和水资源状况均不利于树木的健康生长，沈阳的社会经济发展也有待于进一步提高。9、经过生物指示物法（光肩星天牛为生物指示物）、专家权重法、公众问卷调查和对比研究，沈阳城市森林生态系统总体上处于亚健康状态。10、通过对沈阳城市森林资源、管理状况的调查研究和健康状况的评价，本文提出了沈阳城市森林生态系统健康管理的对策，包括合理规划沈阳城市森林林地布局，增加道路林地、居住区林地和城郊林地的面积和植被覆盖率；调整树木种类组成，避免单一或少数树种的大量栽植，提高生物多样性水平；保护大树和古树；增加城市森林管理资金的投入；应用先进技术，采取科学的病虫害防治和植物养护方法，促进树木的健康生长等。This project systematically studied the urban forest ecosystem health and management in Shenyang. The study explored factors, such as urban forest structure, distribution, pests, aesthetic value, ecological benefit, natural resources and socieo-economic status, that affecting the urban forest ecosystem health and management. Two methods were used to evaluate the ecosystem health. This project also proposed Shenyang's urban forest ecosystem health management strategies. The research results can be summarized as follows: 1. As of the end of 2004, urban forest coverage in Shenyang is about 35%, and is in relatively even patch distribution pattern. However, the street trees and roadside forest patches, residential block forest patches should be enhanced. 2. Trees are the major component of the Shenyang s urban forest, followed by shrubs. The quantity ratio of tree to shrub is about 1.7:1, and the coverage ratio of trees to shrub is about 7:1. 3. Species composition varies by location. There are 74 genera, 137 species (including varieties) in the public parks; 53 genera, 104 species (and var.) in the green spaces of the institution (including school), factory, and company; 45 genera, 81 species (var.) in residential blocks; 43 genera, 94 species (var.) in streets and roadside forest patches; 75 genera, 142 species (var.) in the Canal landscape forest patches; 48 genera, 118 species (var.) in the Qipan Mountain recreation forest. 4. The Shannon-Woener indices varies in parks, in institution, factory, and company yards, in streets and roadside forest patches, in residential blocks.there are 2.78, 3.05, 3.18, 3.15, 3.18, respectively; and the evenness indices are 0.56, 0.66, 0.70, 0.72, 0.64, respectively. Besides the Qipan Mountain forest patches, trees of 7 genera, Prunus spp., Salix spp., Populus spp., Sabina spp., Ulmus spp., Robinia spp. and Ginkgo biloba are of more than 5% the total urban trees, respectively. In fact, trees from these 7 genera are about 82% of all trees in Shenyang's urban forests. In terms of shrubs, species of 7 genera, Ligustrum spp., Syringa spp., Prunus spp., Berberis spp., Rosa spp., Lonicera spp., and Forsythia spp. are more than 5% the total urban shrubs, respectively. 88% of all the shrubs in Shenyang s urban forest are from these 7 genera. 5. The diameter class of DBH<20cm, 20cm60cm of trees in parks, in institution, factory, and company yards, in in streets and roadside forests, and in protective forests are 57.9%, 40.0%, 2.1%; 49.2%, 47.8%, 3.0%; 65.3%, 33.1%, 1.6%; and 64.6%, 34.9%, 0.5%, respectively. The result indicated that the DBH is relatively small in Shenyang s urban forests. 6. Using random plots sampling and CITYgreen model calculation, the ecological benefit of Shenyang's urban is about 0.2 billion US dollars per year. The aesthetic value of parks, institution and company yards, and scenary forest patches is relative high; however, the aesthetic value of protective forest patches is low. 7. There are more than 600 types of diseases and more than 700 kinds of insects in Shenyang's urban forest. Among them, Populus spp., Salix spp., Ulmus spp. and Robinia spp., are attached mainly by 39, 33, 11, and 11, difference types of pests respectively. The rot disease of the Populus spp. and Salix spp., and the insects such as, Anoplophora glabripennis, Malacosoma neustria, Aromia bungii, and Hyphantria cunea are major pests in Shenyang s urban forest for the past 10 years. The trees health condition is relatively poor by having the average health index of 2.68 for major species. 8. The urban soil and water resource are not favorable to tree's growth in Shenyang, and so is the socieo-economic status. 9. Through using bio-indicator, professional and public evaluation, and comparision with other urban forests, it can be concluded that the status of Shenyang s urban forest is not very healthy in general. 10. To improve the urban forest ecosystem health in Shenyang, a better urban forest design need to be implemented to enhance the area and vegetation coverage of the street and roadside forests, the residential block forests, and the surburb forest Species biodiversity need to be enhanced by adjust the species composition of urban forest trees to reduce the single or several tree species populations and to plant more varieties. A better fundings for urban forest health management need to be budgeted. Advanced technologies in tree care and scientific measures to control pests need to be adopted to prove better care for plants and to keep trees grow healthfully.

Comparison of aggregation behaviors between branched and linear block polyethers: MesoDyn simulation study

The comparison of aggregation behaviors between the branched block polyether T1107 (polyether A) and linear polyether (EO)(60)(PO)(40)(EO)(60) (polyether B) in aqueous solution are investigated by the MesoDyn simulation. Polyether A forms micelles at lower concentration and has a smaller aggregation number than B. Both the polyethers show the time-dependent micellar growth behaviors. The spherical micelles appear and then change to rod-like micelles with time evolution in the 10 vol% solution of polyether A. The micellar cluster appears and changes to pseudo-spherical micelles with time evolution in the 20 vol% solution of polyether A. However, the spherical micelles appear and change to micellar cluster with time evolution in the 20 vol% polyether B solution. The shear can induce the micellar transition of both block polyethers. When the shear rate is 1x10(5) s(-1), the shear can induce the sphere-to-rod transition of both polyethers at the concentration of 10 and 20 vol%. When the shear rate is lower than 1x10(5) s(-1), the huge micelles and micellar clusters can be formed in the 10 and 20 vol% polyether A systems under the shear, while the huge micelles are formed and then disaggregated with the time evolution in the 20 vol% polyether B system.

大气CO2浓度升高对红桦碳水化合物含量和分配的影响

碳水化合物按其存在的形式可分为结构性碳水化合物和非结构性碳水化合物两种。前者主要用于植物体的形态建成；后者是参与植物生命代谢的重要物质。迄今为止，有关CO2浓度升高对植物叶片中的碳水化合物含量的研究较多，而对其它器官中碳水化合物含量以及碳水化合物在植物体内的分配响应研究较少。碳水化合物含量在植物各器官中的变化能够反映光合同化产物在叶和茎、枝和根中的转运情况；碳水化合物的分配与植物的生长模式相关，它的变化会对植物的生长情况产生影响。因此，为全面认识植物生理生化与生长过程对大气CO2浓度升高响应情况，需要对CO2浓度升高条件下植物体内碳水化合物的含量及分配变化进行深入的研究与探讨。本文应用自控、独立、封闭的生长室系统，研究了红桦幼苗根、茎、叶和枝的碳水化合物含量以及分配格局对大气CO2浓度升高(环境CO2浓度+350 µmol·mol-1) 的响应。研究结果表明：1) CO2浓度升高使红桦幼苗叶片中的非结构性碳水化合物含量显著增加。这可能会对光合作用造成反馈抑制，降低光合速率。2) CO2浓度升高使红桦幼苗根、茎和枝中的还原糖、蔗糖、总可溶性糖、淀粉和总的非结构性碳水化合物(TNC) 含量显著增加。说明CO2浓度升高促进了碳水化合物由叶片向枝、茎和根中的运输转移，支持了Finn和Brun的假设。3) 在总的非结构性碳水化合物(TNC) 中，淀粉所占比例最大。同样地，CO2浓度升高使TNC含量增加的部分中，淀粉所占的比例也最大。在叶片、枝、茎和根中淀粉含量增加部分占TNC含量增加部分的91.45%、88.23%、83.23%和82.01%。4) CO2浓度升高使红桦幼苗根、茎、叶和枝内的纤维素含量有增加的趋势，但未达到显著水平。需要进一步研究长期CO2浓度升高下，纤维素含量的响应程度。5) CO2浓度升高使碳水化合物在红桦幼苗体内的分配发生了改变。红桦幼苗体内碳水化合物分配变化的一致趋势是由地上部分向地下部分分配转移。其中，测定的所有碳水化合物均向根中分配增多。同时，CO2浓度升高使红桦幼苗的根冠比显著增大；根系干重显著增加。这些结果支持了Gorissen 和Cotrufo的假设，即碳水化合物向根中分配增多是根冠比增大的主要原因。6) CO2浓度升高使红桦幼苗体内的氮含量显著下降。氮含量的下降可能主要是由生长的加快和TNC (主要是淀粉) 含量的增加对氮的稀释造成的。Carbohydrates found in plants are frequently grouped into two different classes:structural carbohydrates and non-structural carbohydrates. The former mainlyconstruct the plant basic framework, while the latter are essential for plant growth andmetabolism. As yet there is lack of information on the effects of elevated CO2concentration on carbohydrate contents in stem, branch and root of plant, and oncarbohydrate allocation in organs of plant although there have been many reports onthe responses of carbohydrate contents to elevated CO2 concentration in plant foliages.A shift of carbohydrate contents in plant reflects a change in transporting ofphotosynthetic production from leaf to stem, branch and root of plant. The allocationof carbohydrates that is correlated to plant growth patterns affects plant growth. Thus,in order to understand the influences of elevated CO2 on biochemical process,physiological change and plant growth well, the response of carbohydrate contentsand allocation in plant to elevated CO2 should be further investigated. In our study, theeffects of elevated CO2 on carbohydrate contents and their allocation between leaf,stem, branch and root tissue of Betula albosinensis seedlings were determined. Theseedlings were grown in independent and enclosed-top chambers. Chambers werecontrolled to reproduce ambient (CK) and ambient + 350 µmol·mol-1 CO2 (EC)concentration for 1 year. The results here showed that,1) Elevated CO2 significantly increased non-structural carbohydrate contents in leafof red birch seedlings. This will reduce photosynthetic rate.2) Elevated CO2 also significantly increased non-structural carbohydrate contentsin root, stem and branch of red birch seedlings. These findings supported thehypothesis that elevated CO2 accelerated carbohydrates from leaf to branch, stem androot.3) Starch makes up the largest parts of total non-structural carbohydrate. In thesame way, the increase of starch plays a main role in the increase of totalnon-structural carbohydrate under elevated CO2. In leaf, branch, stem and root, theincrements of starch contents comprised 91.45%, 88.23%, 83.23% and 82.01% of theincrements of total non-structural carbohydrate contents.4) Under elevated CO2 the cellulose contents have an increasing tendency in redbirch seedlings. It is needed to investigate the effects of long-term elevated CO2 oncellulose contents in plant.5) There are significant CO2 effects on the allocation of carbohydrate in organs ofred birch seedlings. Under elevated CO2 more carbohydrates were allocated to root.Moreover, CO2 enrichment significantly increased the root to shoot ratio of red birchseedlings and the dry weight of roots. These results supported Gorissen and Cotrufo ‘shypothesis that increase of carbohydrate allocation to root mostly contributed to theincrease of root to shoot ratio.6) Elevated CO2 brought about a reduction in the nitrogen contents of leaf, stem,branch and root. The decline of nitrogen contents under elevated CO2 is mainlycaused by the dilution effects of increasing starch level and growth of red birchseedlings.

The effect of the scalar-isovector meson field on hyperon-rich neutron star matter

We investigate the effect of the calar-isovector delta-meson field on the equation of state (EOS) and composition of hyperonic neutron star matter, and the properties of hyperonic neutron stars within the frame work of the relativistic mean field theory. The influence of the delta-field turns out to be quite different and generally weaker for hyperonic neutron star matter as compared to that for npe mu neutron star matter. We find that inclusion of the delta-field enhances the strangeness content slightly and consequently moderately softens the EOS of neutron star matter in its hyperonic phase. As for the composition of hyperonic star matter, the effect of the delta-field is shown to shift the onset of the negatively-charged (positively-charged) hyperons to slightly lower (higher) densities and to enhance (reduce) their abundances. The influence of the delta-field on the maximum mass of hyperonic neutron stars is found to be fairly weak, where as inclusion of the delta-field turns out to enhance sizably both the radii and the moments of inertia of neutron stars with given masses. It is also shown that the effects of the delta-field on the properties of hyperonic neutron stars remain similar in the case of switching off the Sigma hyperons.

Separation of acidic and basic compounds in capillary electrochromatography with polymethacrylate-based monolithic columns

Methacrylate-based monolithic columns with electroosmotic flow (EOF) or very weak EOF are prepared by in situ copolymerization in the presence of a porogen in fused-silica capillaries pretreated with a bifunctional reagent. Satisfactory separations of acidic and basic compounds on the column with EOF at either low or high pH are achieved, respectively. With sulfonic groups as dissociation functionalities, sufficient EOF mobility still remains as high as 1.74 x 10(-4) cm(2) s(-1) V-1 at low pH. Under this condition, seven acidic compounds are readily separated within 5.7 min. Moreover, at high pH, the peak shape of basic compounds is satisfactory without addition of any masking amines into running mobile phase since the secondary interaction between the basic compounds and the monolithic stationary phase are minimized at high pH. Reversed-phase mechanism for both acidic and basic compounds is observed under investigated separation conditions. In addition, possibilities of acidic and basic compound separations on a monolithic column with extremely low EOF are discussed. (C) 2004 Elsevier B.V. All rights reserved.