全尾膏体动态压密特性及其数学模型

深锥浓密机是膏体技术中尾矿浓缩工艺的关键设备,深锥浓密机底流质量分数与泥层压力密切相关,孔隙比是表征底流质量分数的重要物理参数,但是孔隙比随泥层压力的变化规律并不清晰。针对这一问题,首先,提出了尾矿可浓缩性能表征的物理概念--有效孔隙比,即孔隙比减去饱和孔隙比;其次,采用某矿全尾砂进行了动态压密试验,结果表明,当泥层高度为31～200 mm,对应泥层压强为2 477～4 410 Pa,获得的底流质量分数范围为73.26%～78.30%,该质量分数范围对应的有效孔隙比为0.433～0.191。回归有效孔隙比与泥层压强数学关系得知,二者遵循幂函数Allometric模型;最后,提出了膏体动态压密数学模型,并根据模型曲线,将膏体动态压密分为3个区域：（1）线性压缩区,孔隙比随泥层压强增大而基本呈线性关系,孔隙比变化幅度较大;（2）衰减压缩区,随着压强继续增大,孔隙比下降幅度变缓,膏体趋于饱和;（3）恒定压缩区,该区域膏体达到饱和状态,孔隙比随着压强增大而基本恒定。该研究揭示了尾矿浓缩过程中孔隙比随泥层压强的变化规律,为浓密机设计及运行提供理论依据。     

音频大地电磁法强干扰压制试验研究

压制非相关噪声已经有多种比较成熟的技术方法,如多次叠加、远参考、Robust阻抗估计等,但这些方法对压制矿集区存在的强电磁噪声(通常属于相关噪声)基本没有效果.本文在前期提出的针对矿集区大地电磁强噪声压制的数学形态滤波基础上,开展了音频大地电磁法强干扰压制的试验研究.在四川西昌某AMT测点附近,布置了大功率电磁发送站,通过接地导线向地下供20A的方波电流,同时在供电期和间歇期用凤凰公司MTU-5A仪器观测4个水平分量的电磁场.在室内采用数学形态滤波和阈值法相结合的手段在时间域对含有人工源强干扰的电磁场数据进行处理,以视电阻率对比、频谱和极化方向等参数对处理效果进行评价.结果表明:结构元素恰当的数学形态滤波可以对人工源强干扰进行识别、去除,阈值法则可以消除形态滤波后的脉冲干扰,二者结合可以有效地压制AMT中的强干扰噪声,提高数据可靠性.本文结果对AMT实际资料处理具有重要的实用和参考价值.     

Influence of junction angle on three‐dimensional flow structure and bed morphology at confluent meander bends during different hydrological conditions

Recent field and modeling investigations have examined the fluvial dynamics of confluent meander bends where a straight tributary channel enters a meandering river at the apex of a bend with a 90° junction angle. Past work on confluences with asymmetrical and symmetrical planforms has shown that the angle of tributary entry has a strong influence on mutual deflection of confluent flows and the spatial extent of confluence hydrodynamic and morphodynamic features. This paper examines three‐dimensional flow structure and bed morphology for incoming flows with high and low momentum‐flux ratios at two large, natural confluent meander bends that have different tributary entry angles. At the high‐angle (90°) confluent meander bend, mutual deflection of converging flows abruptly turns fluid from the lateral tributary into the downstream channel and flow in the main river is deflected away from the outer bank of the bend by a bar that extends downstream of the junction corner along the inner bank of the tributary. Two counter‐rotating helical cells inherited from upstream flow curvature flank the mixing interface, which overlies a central pool. A large influx of sediment to the confluence from a meander cutoff immediately upstream has produced substantial morphologic change during large, tributary‐dominant discharge events, resulting in displacement of the pool inward and substantial erosion of the point bar in the main channel. In contrast, flow deflection is less pronounced at the low‐angle (36°) confluent meander bend, where the converging flows are nearly parallel to one another upon entering the confluence. A large helical cell imparted from upstream flow curvature in the main river occupies most of the downstream channel for prevailing low momentum‐flux ratio conditions and a weak counter‐rotating cell forms during infrequent tributary‐dominant flow events. Bed morphology remains relatively stable and does not exhibit extensive scour that often occurs at confluences with concordant beds. Copyright © 2014 John Wiley & Sons, Ltd.     

Coma morphology of Jupiter-family comets

We present a general review of cometary coma morphology, with specific reference to how it used in studies of Jupiter-family comets. We introduce the most common features that are seen in gas and dust observations, and summarize of how they are used to infer the properties of the nucleus and coma. We also expand the discussion to cover other topics relating to morphology, including the general shape of the coma (characterized by radial gradient profiles) and spatial maps of the color, albedo and polarization of the dust. We address the pros and cons of the different approaches used in the interpretation and analysis of the features. Finally, we review the results obtained for specific comets and compare the Jupiter-family comets to those from other classes.     

Edge Flow and Canopy Structure: A Large-Eddy Simulation Study

Sharp heterogeneities in forest structure, such as edges, are often responsible for wind damage. In order to better understand the behaviour of turbulent flow through canopy edges, large-eddy simulations (LES) have been performed at very fine scale (2 m) within and above heterogeneous vegetation canopies. A modified version of the Advanced Regional Prediction System (ARPS), previously validated in homogeneous conditions against field and wind-tunnel measurements, has been used for this purpose. Here it is validated in a simple forest-clearing-forest configuration. The model is shown to be able to reproduce accurately the main features observed in turbulent edge flow, especially the “enhanced gust zone” (EGZ) present around the canopy top at a few canopy heights downwind from the edge, and the turbulent region that develops further downstream. The EGZ is characterized by a peak in streamwise velocity skewness, which reflects the presence of intense intermittent wind gusts. A sensitivity study of the edge flow to the forest morphology shows that with increasing canopy density the flow adjusts faster and turbulent features such as the EGZ become more marked. When the canopy is characterized by a sparse trunk space the length of the adjustment region increases significantly due to the formation of a sub-canopy wind jet from the leading edge. It is shown that the position and magnitude of the EGZ are related to the mean upward motion formed around canopy top behind the leading edge, caused by the deceleration in the sub-canopy. Indeed, this mean upward motion advects low turbulence levels from the bottom of the canopy; this emphasises the passage of sudden strong wind gusts from the clearing, thereby increasing the skewness in streamwise velocity as compared with locations further downstream where ambient turbulence is stronger.     

流域沟壑密度理论极值数学模式商讨

对张丽萍等建立的流域沟壑密度理论极值圆形数学模式进行了更正。鉴于更正的模式又与实际相矛盾,又推导出更符合实际的正六边形数学模式。     

形态学在X-射线检测中的应用

本文以射线检测发动机图像为研究对象,通过与传统分割算法相比较,同时结合最新发展的数学理论及数字图像处理技术,采用了一种有效分割方法,使其在提取效果和处理速度上都能获得预期的满意结果.     

广东庙湾岛风化坑的地貌特征及成因

风化坑是常见的岩石坑穴地形,但容易被误解或与其他成因坑穴地形混淆。通过对庙湾岛风化坑地貌特征及形态参数进行详细测量和分析,采集风化坑内残积碎屑物、坑外岩石和当地风化壳样品进行粉晶X射线荧光光谱化学主量分析（XRF）和X射线衍射矿物分析（XRD）,对风化坑发育的成因机制进行了探讨,并得出以下结论：1）风化坑的发育与地形坡度有关,通常出现在平坦裸露的岩石面上。2）风化坑的形态特征表现为宽且浅,口缘有出水口,底部平坦,侧壁最凹处与出水口高度一致,其口径发育的速度远大于深度,长轴发育速度远大于短轴。3）同一岩石面上的风化坑具有不同的大小和深度,显示了其发育程度不一,其最大、最小深度对比反映了风化坑的发育过程。4）风化坑碎屑物与表岩之间的元素迁移和化学蚀变指数（CIA值）的差异,反映了风化坑的化学风化成因。5）风化坑碎屑物的英长比大于表岩,证明了化学风化导致的矿物差异风化作用。研究表明：庙湾岛风化坑形成和发育的主要作用为坑内积水的化学风化。     

荔枝海绵（Tethya sp.）形态及愈伤过程的观察研究

海绵动物具备很强的愈伤再生能力。荔枝海绵是海绵动物中比较特殊的类群,它有皮质层细胞（cortex）和领细胞层细胞（choanoderm）的初步分化。本文对荔枝海绵的形态结构进行观察,并通过切割的方法,有针对性地移除荔枝海绵的特定结构,观察其愈伤过程,以期了解海绵愈伤过程的主要变化及各部分在愈伤过程中的作用。结果发现,愈伤过程发生的主要变化为未受创部分的细胞向受创部分迁移导致的细胞重新排布;其身体结构中的领细胞层和皮质层对其生存愈伤是必要的,而骨针核心对其愈伤影响较小。     

我国东南海域2个新记录拟菱形藻物种及其产毒特征

为丰富我国拟菱形藻属的物种多样性,并澄清其产毒特征,本文从我国东南海域分离和建立了拟菱形藻的单克隆培养株系,结合光学显微镜下的群体特征和透射电镜下的超微形态特征,还有基于核糖体转录间隔区的分子系统学数据,以及基于ITS2转录RNA的二级结构分析,鉴定到我国拟菱形藻属的2个新记录种:镰刀拟菱形藻(P.sabit Teng,Lim,LimLeaw)和中鼓拟菱形藻(P.inflatula(Hasle)Hasle)。镰刀拟菱形藻的典型形态特征是壳面呈现镰刀状,点条纹由两排孔纹组成,与并基拟菱形藻(P.decipiens)的系统学关系最为接近,ITS2-RNA有2个补偿碱基差异。中鼓拟菱形藻主要形态特征是壳面呈直线形,点条纹由单排孔纹组成,孔纹内部以上下两分区为主,与格氏拟菱形藻(P.granii)和亚弧线拟菱形藻(P.subcurvata)的亲缘关系接近,ITS2-RNA二级结构分别有4个补偿碱基差异。另外,利用高效液相色谱-质谱联用法对培养藻株的产毒特征进行了分析,未检测到多莫酸。本文为我国拟菱形藻属的物种多样性做了必要的补充,还可为拟菱形藻的毒理研究提供基础数据。