Analysis on Three-dimensional Structure and Echo Characteristic Quantity of a Supercell Storm

[Objective] The research aimed to study three-dimensional structure and echo characteristic quantity of a supercell storm in central Gansu on May 30,2005.[Method] By monitoring data of Lanzhou CINRAD/CC Doppler radar,the three-dimensional structure characteristics of a rare supercell storm which happened in central Gansu on May 30,2005 were analyzed.We tried to reveal three-dimensional structure and echo characteristic index of supercell storm in the northeast of Qinghai-Tibet Plateau,and find reason of rare heavy hail appearance.[Result] The large-scale strong storm was formed by the common effect of Mongolia cold vortex,low-level jet and ground cold front.When the development of main echo was mature,on reflectivity factor map,it presented obvious inverted 'V' shaped structure in left front of low-level storm,typical hooked and 'person'-type echo characteristics in the right rear.The bounded weak echo zone(vault) in low level corresponded with strong echo overhanging body in high level.It surpassed 60 dBz in the strong reflectivity factor zone.It presented one weak meso-cyclone on corresponding radial velocity map.The jumped increase characteristic of VIL could be as one of indices for judging that hail started to grow.Almost all storms(VILD ≥4.0 g/m3) had more obvious indication significance than VIL for judging heavy hail(diameter ≥20 mm).[Conclusion] The research provided reference for nowcasting of strong convection weather and artificial hail suppression.

Discontinuity development patterns and the challenges for 3D discrete fracture network modeling on complicated exposed rock surfaces

Natural slopes usually display complicated exposed rock surfaces that are characterized by complex and substantial terrain undulation and ubiquitous undesirable phenomena such as vegetation cover and rockfalls.This study presents a systematic outcrop research of fracture pattern variations in a complicated rock slope,and the qualitative and quantitative study of the complex phenomena impact on threedimensional(3D)discrete fracture network(DFN)modeling.As the studies of the outcrop fracture pattern have been so far focused on local variations,thus,we put forward a statistical analysis of global variations.The entire outcrop is partitioned into several subzones,and the subzone-scale variability of fracture geometric properties is analyzed(including the orientation,the density,and the trace length).The results reveal significant variations in fracture characteristics(such as the concentrative degree,the average orientation,the density,and the trace length)among different subzones.Moreover,the density of fracture sets,which is approximately parallel to the slope surface,exhibits a notably higher value compared to other fracture sets across all subzones.To improve the accuracy of the DFN modeling,the effects of three common phenomena resulting from vegetation and rockfalls are qualitatively analyzed and the corresponding quantitative data processing solutions are proposed.Subsequently,the 3D fracture geometric parameters are determined for different areas of the high-steep rock slope in terms of the subzone dimensions.The results show significant variations in the same set of 3D fracture parameters across different regions with density differing by up to tenfold and mean trace length exhibiting differences of 3e4 times.The study results present precise geological structural information,improve modeling accuracy,and provide practical solutions for addressing complex outcrop issues.

蔬菜废弃物堆肥对设施蔬菜连作土壤生态质量的改良效果

为了探究利用蔬菜废弃物堆肥制备的生物有机肥对设施蔬菜连作土壤的改良效果,将芹菜、白菜、胡萝卜、花椰菜等蔬菜废弃物与玉米秸秆进行堆肥,并施用于不同连作年限的设施小白菜土壤。研究表明,受试的4种土壤中细菌、放线菌及真菌数量,土壤酶活性及小白菜品质均随着堆肥添加量的增加而提高;而土壤尖孢镰刀菌数量则随着堆肥添加量的增加而降低。在连作5年的土壤中,高剂量施肥处理与未施肥对照相比,土壤细菌、放线菌及真菌数量,土壤蔗糖酶、过氧化氢酶、脲酶及磷酸酶活性分别提高0.77、1.63、1.53、3.50、1.66、0.99及1.65倍;小白菜维生素C与可溶性糖含量分别提高了88.56%和50.42%;土壤尖孢镰刀菌数量减少了94.55%。结果表明,利用蔬菜废弃物堆肥制备的生物有机肥能够显著改善连作土壤的生态质量,并且对连作年限长的土壤有着更显著的效果。

Evaluating soil acidification risk and its effects on biodiversity–ecosystem multifunctionality relationships in the drylands of China

Background:Soil acidifcationn caused by anthropogenic activities may aft soil biochemical cydling,bidiversity,productivity,and multiple eosystem-related functions in drylands.However,to date,such information is lacking to support this hypothesis.Methods Based on a transect survey of 78 naturally assembled shrub communities,we caloulated acid deposition flux in Northwest China and evaluated its likely ecological ffets by testing three altemnative hypotheses,namely:.nidche complementarity,mass ratio,and vegetation quantity hypotheses Rao's quadratic entopy and community-weighted mean traits were employed to represent the complementary aspect of niche complementarity and mass ratio effects,respectively.Resulbs:We observed that in the past four decades,the concentrations of exchangeable base cations in soil in Northwest China have decreased significantly to the extent of having faced the risk of depletion,whereas changes in the calium carbonate content and pH of soil were not significant.Adid deposition primani ly increased the aboweground biomass and shrub density in shrublands but had no sigmificant effect on shrub richness and ecasystem multifunctionality(EMF),indicating that acid deposition had positive but weak ecological effects on dryland ecosystems.Community wd ghted mean of functional traits(representing the mass ratio hypothesis)correlated negatively with EMF,whereas both Rao's quadratic entropy(representing the niche complementarity hypothesis)and aboveground biomass(representing the vegetation quantity hypothesis)correlated positively but insignifcantly with EMF.These biodiversity-EMF relationships highlight the fragility and instability of drylands relative to forest ecasystems.Concuions:The findings from this study serve as important reference points to understand the ris of soil acidification in arid regions and its impacts on biodiversity-EMF relationships.

Time, Length, and Mass Are Derived Quantities

Fundamental units of measurements are kilograms, meters, and seconds—in regards to mass length, and time. All other measurements in mechanical quantities including kinetic quantities and dynamic quantities are called derived units. These derived units can be expressed in terms of fundamental units, such as acceleration, area, energy, force, power, velocity and volume. Derived quantities will be referred to as time, length, and mass. In order to explain that fundamental units are not equivalent with fundamental quantities, we need to understand the contraction of time and length in Special Relativity. If we choose the velocity of light as fundamental quantity and length and time as derived quantities, then we are able to construct three-dimensional space-time frames. Three-dimensional space-time frames representing time with polar coordination, time contraction and length contraction can be shown graphically.

基于L-system算法的植物信息模型构建和三维绿量分析

【目的】当前广泛使用的三角面网格模型并不能全面表达植物模型特征,探索行业内植物信息模型构建与三维绿量计算新方法具有重要意义。【方法】在梳理L-system植物生成算法发展背景和研究进展的基础上,基于华中农业大学襄阳现代农业研究院本科宿舍区的规划情景,使用L-system算法,基于24种植物的分枝结构和形态特征,生成参数化的L-system植被模型。【结果】构建出研究区域建成初期绿地规划模型与植物成熟期绿地规划模型,并提出了4项三维绿量的评估指标定义和计算方法,对场地建成初期和植物成熟期的绿量特征进行了对比分析。结果表明,场地建成初期三维绿量为13497.08 m^(3),单位面积三维绿量为12.25 m^(3)/m^(2);植物成熟期三维绿量可达215097.42 m^(3),单位面积三维绿量达到195.00 m^(3)/m^(2)。【结论】在规划设计领域,基于L-system算法的植物模型建模,可实现模型构建的参数化和便捷化,并适用于不同的细节层级,在规划设计算法模型标准制定、植物数字孪生模型构建和生态效能评估方面具备着广泛的应用前景。

地形和森林植被因子对落叶松毛虫越冬代发生及数量的影响

[目的]探讨地形和森林植被对落叶松毛虫越冬代发生的影响,并明确这两类因素与落叶松毛虫发生数量的关系,为该类虫害的防治提供科学参考。[方法 ]在大兴安岭落叶松毛虫主要分布区域的不同林型中设立142块20 m×20 m的样地,调查地形、森林植被等因子,以及落叶松毛虫幼虫数量。运用二元Logistic回归和数量化理论Ⅰ分别建立落叶松毛虫发生概率模型和发生数量化模型,并进行模型评估。[结果 ]发生概率模型的判别精度较高(AUC=0.826),坡向和草本盖度为影响落叶松毛虫发生的关键因子,阴坡发生概率最低,而阳坡最高。随着草本盖度的增加,落叶松毛虫发生概率增加。坡向、坡度等级、坡位、海拔、草本盖度和林分密度不同的林分的落叶松毛虫发生数量存在显著差异(P<0.05)。用坡向、坡度等级、坡位、郁闭度和林分密度5个因子建立的数量化模型与全因子模型拟合度差异小,决定系数(R2)分别为0.635和0.685,均方根误差(RMSE)分别为0.964和0.936。数量化模型显示,落叶松毛虫发生数量阴坡最少、阳坡最多。而随坡度等级增加,发生数量随之减少,山脊的落叶松毛虫发生数量最多。同样,森林郁闭度增加或林分密度降低,落叶松毛虫发生数量随之增多。[结论 ]研究揭示落叶松毛虫在阳坡、平坡和山脊的林分易发生,应作为防治重点,而配合补植、疏伐和定期除草等森林经营措施,有助于压低种群。

榆林市植被固沙作用年内变化情况研究

为评估植被防风固沙效应的年内动态变化情况并为相关研究提供参考,以黄河中游水土流失重点治理区之一的榆林市为研究对象,基于2012年遥感影像资料等,按分辨率为1 km的栅格对单位面积植被的固沙量进行了逐月评估,结果表明:榆林市以县(区、市)为单元计算的单位面积植被年固沙量为6 375~15 371 t/km^(2),其时空分布差异显著,在时间上单位面积植被年固沙量约90%分布在3—6月,在空间上东南部黄土丘陵沟壑区单位面积植被年固沙量明显大于西北部风沙区的;季节变化对风蚀、植被生长及其防风固沙作用有明显影响,黄土丘陵沟壑区植被防风固沙作用对季节变化较为敏感。

不同植被类型下黑河湿地土壤养分、酶活性、微生物数量的变化特征

研究了栽种不同植被对湿地生态系统的恢复成效,以期为完善黑河湿地恢复策略提供科学依据。于2016年开展植被恢复工程,在黑河北岸红军纪念林以西分别栽种2年生的沙枣(Elaeagnus angustifolia)、红柳(Tamarix chinensis)和胡杨(Populus euphratica),2020年12月采集各植被的根际土壤,同时以不栽种植被自然恢复方式为对照,研究栽种不同植被后土壤养分、酶活性和微生物数量间的差异及相关性。结果表明,植被恢复改善了黑河湿地生态环境,缓解了湿地盐碱化;栽种沙枣对降低土壤盐分含量、提高土壤有机质和碱解氮含量效果最明显;栽种胡杨对提高土壤速效磷、速效钾含量及土壤脲酶和碱性磷酸酶活性效果最明显;栽种红柳对提高土壤微生物总量效果最明显;土壤养分含量、酶活性和微生物数量间具有密切相关性。总体来看,植被恢复工程降低了黑河湿地土壤盐分,提高了土壤养分含量、酶活性和微生物数量,对黑河湿地的生态系统恢复行之有效。

Soliton solutions,travelling wave solutions and conserved quantities for a three-dimensional soliton equation in plasma physics

Many physical systems can be successfully modelled using equations that admit the soliton solutions.In addition,equations with soliton solutions have a significant mathematical structure.In this paper,we study and analyze a three-dimensional soliton equation,which has applications in plasma physics and other nonlinear sciences such as fluid mechanics,atomic physics,biophysics,nonlinear optics,classical and quantum fields theories.Indeed,solitons and solitary waves have been observed in numerous situations and often dominate long-time behaviour.We perform symmetry reductions of the equation via the use of Lie group theory and then obtain analytic solutions through this technique for the very first time.Direct integration of the resulting ordinary differential equation is done which gives new analytic travelling wave solutions that consist of rational function,elliptic functions,elementary trigonometric and hyperbolic functions solutions of the equation.Besides,various solitonic solutions are secured with the use of a polynomial complete discriminant system and elementary integral technique.These solutions comprise dark soliton,doubly-periodic soliton,trigonometric soliton,explosive/blowup and singular solitons.We further exhibit the dynamics of the solutions with pictorial representations and discuss them.In conclusion,we contemplate conserved quantities for the equation under study via the standard multiplier approach in conjunction with the homotopy integral formula.We state here categorically and emphatically that all results found in this study as far as we know have not been earlier obtained and so are new.

城市森林结构的量化研究——以沈阳树木园森林群落为例

采用遥感图像判读和野外调查相结合的方法 ,定量分析了沈阳树木园植物群落的物种结构及空间格局 .结果表明 ,沈阳树木园植被的生长状况良好 ;物种丰富 ,其中黄蘖 (Phellodendronamurense)、刺槐(Robiniapseudoacacia)、榆树 (Ulmuspumila)在树木株数和相对优势度上均占优势 ,为群落的主林木 ;植被在高度和胸径上的分布均表现为具有向上发展的潜力 ,整个植被群落正处于一个快速的生长期 ,属于发挥生态效益的最佳时期 .沈阳树木园的树种多度与基于叶面积的相对优势度之间无明显关联 ,数量上占优势的树种 ,其相对优势度不一定很高 .沈阳树木园植被树木株数与不同树高等级间的分布关系表现为上凸的曲线 ,随着树木高度级的增加 ,树木株数开始分布比较平稳 ,当高度超过 12m后 ,树木株数明显减少 ,曲线急骤下降 .树木株数分布与不同胸径等级间的关系也呈现类似的情况 .

武汉钢铁公司厂区绿地绿量的定量研究

针对城市绿地结构复杂、破碎化程度高的特点,在武汉钢铁公司厂区园林绿地层片结构及其盖度调查的基础上,借助GIS对其绿量进行了定量研究.结果表明,不同生活型植物的单叶面积和叶面积指数差异较大,植物种的叶面积指数大小不仅取决于单叶面积,而且取决于树冠的冠形和枝叶的密集程度.该厂区园林绿地的平均叶面积指数为7.75,总绿量为1 694.2 hm2.其中,乔-灌-草型和乔-灌型绿地的面积和绿量分别占厂区总绿地面积和总绿量的79.7%和92.3%,反映了该厂区绿化以乔木为主,乔-灌-草型和乔-灌型绿地类型占绝对优势.结构单一的纯草坪型绿地在厂区应用较少,但草本层片的绿量占总绿量的22.9%.园林绿地的绿量取决于绿地面积、绿地的层片结构、不同层片植物的叶面积指数及其盖度.城市园林绿地应在扩大绿地面积的基础上,尽量选择叶面积指数较高的树种,完善层次结构,以增加总体绿量.以层片作为基础定量单元,在各层片代表种叶面积指数测定的基础上,通过绿地群落类型的层片结构及其盖度调查,并借助遥感影像和GIS提取各类群落的面积,可较为准确地定量城市园林绿地的绿量.

西安市植被净化大气物质量的测定及其价值评价

从生态系统服务功能着手 ,运用 GIS技术 ,依据相应植被净化大气物质量计量模型 ,计算了西安市 2 1种植被类型净化大气的物质量 ,结果显示 :西安市植被每年吸收 SO2 1 7.1 0万 t、HF0 .49万 t,植被每年固定 CO2 2 0 5 96.1 7万 t,释放 O2 1 5 0 1 8.5 7万 t,植被每年滞尘3883.1 5万 t,并运用替代法进行了价值估算 ,结果为 30 83.71百万元 .a- 1,其占 1 999年西安市国内生产总值的 5 % ,。在植被净化大气单位价值量数据库基础上 ,绘制了专题图 ,由此分析得到植被净化大气的区域差异和不同植被类型净化大气的差异 ,最后 ,初步形成西安市植被净化大气评价系统。

稀疏天然植被对输沙量的影响

在内陆沙漠和海滨沙丘地区,均生长着不同类型低密度的天然植被,它对风沙流活动和风成地貌形态的形成与演变都具有一定的影响,但在大多数情况下是不足以防止风沙危害的。因此,为了达到防沙的要求,其中就存在着一个稀疏天然植被的有效临界密度问题。为此,通过对3个不同类型植物种、10组植株密度的风洞模拟研究表明,当平均输沙率减少到流沙表面的50%左右时,其相应的植物株密度为:呈紧密结构半球状植株密度为6株·m-2;呈漏斗形上密下疏者为7株·m-2和呈线状具有弯曲弹性的植株介于6～10株·m-2之间。在各种植株密度的影响下,输沙率与有效起沙风呈正比关系,即q=a×(VL-Vt)b。

城市工业区园林绿地滞尘效应的研究——以武汉钢铁公司厂区绿地为例

在测定武钢工业区园林植物滞尘能力的基础上,结合绿地实地调查和武钢工业区园林绿地GIS,比较分析了园林绿地不同植物种类和层片类型的滞尘能力,并定量研究了武钢厂区园林绿地的滞尘效应。结果表明,不同园林植物的滞尘能力有较大差异,这主要与不同植物的叶表面特性、树冠结构、枝叶密集程度等差异有关。不同层片类型滞尘能力依次为落叶阔叶灌木>常绿阔叶灌木>绿篱>常绿阔叶乔木>落叶阔叶乔木>针叶乔木>草本。武钢厂区园林绿地的日滞尘量是9.51 t,年总滞尘量为3 089.98 t。其中常绿阔叶乔木层片年滞尘量最大,达991.68 t,落叶阔叶灌木层片最小,只有0.0181 t。由于园林绿地的滞尘量取决于所构成植物的滞尘能力及其叶面积绿量,因此,选择滞尘能力强的植物,并以乔灌草不同生活型植物进行合理配置,是提高园林绿地滞尘效应的有效途径。

城市绿化对街道空气污染物扩散的影响

以CO为环境示踪物,通过对西安市典型街道的实测和数据分析,讨论了绿化形式对街道污染物扩散效果的影响,指出绿化带对气态污染物扩散存在阻碍作用的因素是郁闭度,而不是绿量,车流量的大小对行道树树冠的生态净化功能有直接影响,并据此对街道绿化的生态设计给出了建议.

哈尔滨市紫丁香绿量

选取了哈尔滨市园林绿化上数量最多、应用最广的木犀科丁香属植物中的紫丁香为研究对象 ,立足于哈尔滨市的环境特点 ,具体分析紫丁香姿态、冠形、枝形、叶形的特点及其之间的关系。采用生态学、生理学、统计数学和模型构建等方法对紫丁香样本数据进行分析 ,深入研究紫丁香绿量的内涵 ,探索出了哈尔滨市紫丁香绿量的量化方法。它克服了绿化覆盖率等指标在绿色植物生态功能表达上的不足 ,使绿色植物与其生态功能、生态效益联系起来 ,可供其他灌木植物绿量的研究借鉴 ,具有实际应用和推广价值 ,可为不同地区绿色植物的配置及其生态功能的发挥提供科学数据和参考。

玛曲沙化高寒草甸植被、土壤理化性质及土壤微生物数量研究

对不同沙化程度高寒草甸植被特征、土壤理化性质及土壤微生物数量进行调查分析,结果表明:1)随着沙化程度的加剧,植物多样性指数、地上/地下生物量、土壤含水量及浅层土壤有机质、全氮、速效磷含量呈逐渐下降趋势,植物优势度、pH值呈增加趋势;深层土壤有机质、全氮、速效磷在轻度沙化样地上达到最高值。2)在不同沙化程度的土壤中,细菌数量最多,之后依次为放线菌、固氮菌、真菌;微生物在轻度沙化样地中的数量比其他3个样地都大。3)以土壤深层速效磷作为控制因子,偏相关关系分析显示,土壤微生物总量及土壤细菌数量变化与地上植物丰富度指数、植物生物量、地下生物量呈极显著负相关关系,而与植物地上/地下生物量之比呈极显著正相关关系;固氮菌数量与地上生物量呈显著相关关系,而真菌数量与地下生物量呈显著相关关系;除地上/地下生物量之比与土壤微生物数量之间呈正相关关系外,其余植被特征值与土壤微生物数量之间均呈现负相关关系。

不同种植年限蔬菜大棚土壤微生物初步研究

以江西省吉安市蔬菜大棚地为样地,通过对蔬菜大棚土壤微生物的分离、培养、计数和鉴定来初步研究土壤微生物的种类与数量。结果显示:大棚使用年限长,微生物总含量一般较高,棚龄18年的微生物总数为4.432×109cfu/g,棚龄5年的微生物总数为2.303×109cfu/g;土壤微生物的数量及种类与土壤的养分尤其是土壤的有机质有明显的正相关关系,微生物数量愈大,土壤微生物活性越高,肥力亦大。土壤中的三大类主要微生物以细菌最多,放线菌次之,真菌最少。

我国北方农牧交错带气候对植被的影响——以宁夏盐池为例

为了解我国北方农牧交错带气候对植被的影响规律,以宁夏盐池县为对象,采用样方调查法进行植被调查,并收集研究区降水、气温等气象资料。通过统计学方法对调查资料进行处理,并结合多年的气象数据分析了宁夏盐池气候变化对各种植被参数的影响。结果表明：在大时间尺度上,气温与植被生长呈负相关;在短期内,植被生长与气温关系不很明显;降水与盐池地区植被生长呈现明显的正相关,是植被生长的主要限制因子;降水的变化对植被的影响存在滞后效应,主要体现在植被盖度、植被高度和生物量上。