市场化配置方式出让用海的海域使用论证内容优化的探索

海域使用论证是取得海域使用权的一项基础工作,现行的《海域使用论证技术导则》主要适用于以行政配置方式申请用海的海域使用论证,对于市场化配置方式出让海域使用权,因为委托业主的不同和对海域利用方案的不确定性,对海域使用论证的关注点也有所不同,文章讨论对市场化配置方式出让用海的海域使用论证内容进行适当优化,主要从项目用海基本情况、用海资源环境影响分析和用海合理性分析等方面优化进行初步探讨,并提出完善海域市场化配置制度和相关的技术规范的建议。     

桂东南容县花岗岩残积土粒度分形与物理参数的关系

桂东南容县花岗岩残积土滑坡灾害频发。为明确残积土粒度组成以便揭示滑坡形成机制,文中基于花岗岩残积土的土工试验数据和详查资料,利用分形理论揭示四个深度(0~30cm、30~50cm、50~70cm、滑动面(1~3m))土体粒度分形特征与颗粒含量、物理性质参数的关系。结果表明:(1)花岗岩残积土主要由细砾(粒径2~5mm)和砂粒(粒径 0.075~2mm)组成,粒度分布在无标度区间[0.075,5]内具有一重分形特征;(2)残积土平均分形维数由大即小依次是:D50-70(2.7244)>D滑动面(2.6910)>D0-30(2.6893)>D30-50(2.6480);(3)分形维数与粉砂含量呈极显著正相关,正相关性随深度增加而增大,与细砾和粗砂含量呈负相关性,即分形维数越大,粉砂含量越高,而细砾和粗砂含量越低;(4)D30-50、D滑动面与渗透系数、干密度呈显著负相关。     

老挝固体钾盐矿选矿设计的优化与创新—以开元500 kt/a氯化钾项目为例

选矿厂设计是矿山建设中极其重要的关键环节。做好选矿厂设计工作,对于节省项目建设投资,确保工厂如期达产达标,并取得良好的经济效益,具有决定性的作用。本文结合老挝开元500 kt/a氯化钾项目选矿厂生产过程中的技术改造与创新,对该类型选矿厂设计进行经验总结,并指明设计中仍需优化与创新的环节。选矿厂设计中工艺流程的选择应具有较强的生产兼容性,且工艺流程主要环节之间有灵活的可切换性,以适应井下开采过程中性质多变的原矿。工艺配置,设备选型和厂房设计既要兼顾原矿和产品性质,也要充分考虑当地的气候条件和自然环境。厂房和工艺设备的防腐,自动化技术的开发应用和工艺流程样品的自动采集与分析是未来仍需优化和创新的重要环节。本研究可为今后同类选矿厂的设计提供有益的参考。     

Sediment grain size measurements are affected by site-specific sediment characteristics and analysis methods: implications for environmental monitoring

Sediment grain size, and specifically changes in the percent mud content (i.e. the fraction <63?µm) over time is often used as an indicator of estuarine environmental health. Using sediment samples from three distinct estuarine systems, we determined that different analytical methods (laser diffraction and wet sieving) gave significantly different results in terms of percent mud content. These differences are also ecologically meaningful when considering the influence of mud on estuarine macrofauna. We propose an approach to measuring sediment grain size termed Environmentally Available Sediment (EAS), which advocates for the measurement of the sediment that biota are directly exposed to. For the purposes of environmental monitoring, it is also essential to monitor sediment grain size in a repeatable way which is likely to be achieved using consistent (or no) pre-treatment and the use of a measurement technique that is unlikely to change over time, e.g. wet sieving.     

Smart Sediment Particle: A novel approach to investigating fluvial bed entrainment using instrumented sensors

The Smart Sediment Particle(SSP) instrumented with multiple sensors to obtain tri-axial linear accelerations is used for studying the mechanism of coarse grain entrainment. Three bed arrangements are tested to examine their influences on entrainment processes and the threshold force and impulse conditions. The SSP shows satisfactory precision to capture the imperceptible movement tendencies immediately(e.g., 0.15 s) after the dislodgement. The experimental results show that bed packing can signi...     

Experimental study of the settling of twin spherical particles released side by side: The impact of particle size,fluid viscosity,initial spacing,and particle density

The settling of solid particles in a fluid is an important process that needs to be considered in many fields of research. For example, the interactions among particles and between particles and the surrounding fluid are important topics in studying suspended sediment transport and water clarification. In this paper, the settling processes and interactions of twin spherical particles released side by side were experimentally studied. The Reynolds number varied in the range of 1-300, which is wit...     

用中子星限制暗物质粒子散射截面

中子星可以通过重子物质和暗物质的相互作用吸积暗物质,且在一定条件下, 中子星吸积的暗物质粒子可以引发自引力塌缩形成小型黑洞, 生成的黑洞可能会进一步吞噬中子星.依据文献已有模型, 基于以上物理过程给出了在暗物质粒子不同质量下对暗物质粒子--中子的散射截面的限制.使用弱相互作用大质量粒子(Weakly Interacting Massive Particle, WIMP)模型, 并考虑暗物质粒子是玻色子的情形, 讨论了暗物质粒子有无自相互作用以及有无湮灭等条件下对限制暗物质参数的影响.既考虑了已发现的两个中子星系统来给出对暗物质参数空间的限制,也考虑了两个可能存在的年老中子星来预测未来观测可能对暗物质参数空间的限制.对于考虑玻色--爱因斯坦凝聚(Bose-Einstein Condensate, BEC)的玻色子暗物质, 在无自相互作用或有弱自相互作用, 无湮灭或有很小湮灭截面的条件下,中子星给出的间接观测对暗物质粒子-中子散射截面的限制的强度比XENON1T直接探测实验来得更强.未来, 如果在银心附近能观测到年老中子星, 其观测结果可以提升模型给出的对暗物质粒子--中子散射截面的限制, 从而帮助人们进一步理解暗物质.     

EXPERIMENTAL STUDY ON THE RELATION OF BED MORPHOLOGY WITH SURFACE FLOW IN MEANDER CHANNELS

1 INTRODUCTION The plane shape of a river channel is very important for river improvement planning, because it must allow floodwater to flow off safely. Natural rivers wind from side to side, which creates meandering forms. From the history of river impro…     

Accuracy of asymptotic series for the kinematics of high solitary waves

The accuracy of several asymptotic series expansions for wave speed and particle velocity under the crest of a solitary wave (on a fluid at rest) up to maximum height is investigated. The very accurate numerical results of Williams (1985) are the measure for our comparisons. The results are based on a scaling of calculated properties of long periodic waves to the case of solitary waves.For wave speeds the classical Boussinesq–Rayleigh expression gives good agreement up to a relative wave height of, say, 0.3. An asymptotic fourth-order expression based on Fenton (1990) can be used up to a relative wave height of 0.7, whereas the corresponding fifth-order expression is slightly less accurate.The Eulerian particle velocity profile under the wave crest is examined using a cnoidal wave expression from Fenton (1990) in the limit of the solitary wave. For low waves a `consistent' (i.e. properly truncated) fifth-order expression and an `inconsistent' ditto both coincide with Williams' results. Beginning at medium high waves, the consistent expression surprisingly exhibits oscillations in the velocity profile, and the oscillations become stronger as the wave gets higher. The inconsistent expression, however, yields the same shape as Williams' profile, but is displaced parallel to this, resulting in slightly larger velocities. For high waves also the inconsistent expression begins to differ in shape from Williams' profile, and asymptotic theory fails. Only for low waves `lowest order theory' gives acceptable results. We show analytically that for the highest wave the particle velocity profile has a horizontal tangent at the water surface; this is corroborated by Williams' numerical results.We also study the particle velocity at the wave crest as a function of wave height. It is shown that the variation has a vertical tangent for the highest wave. Two fifth-order asymptotic series for this velocity, based on the wave speed through the Bernoulli equation, show very good agreement with Williams up to a relative wave height of about 0.6.It is finally shown that it is possible to produce very accurate rational-function approximations to Williams' results for the wave speed as well as for the particle velocity at the wave crest.     

Increased Particle Fluxes at the INDEX Site Attributable to Simulated Benthic Disturbance

Particle fluxes were measured 7 m above the sea bottom during the predisturbance, disturbance, and postdisturbance periods by using time series sediment traps attached to seven deep-sea moorings deployed in the INDEX experiment site in the Central Indian Basin. The predisturbance particle fluxes varied between 22.3 to 55.1 mg m -2 day -1 . Increased and variable particle fluxes were recorded by the sediment traps during the disturbance period. The increase observed was 0.5 to 4 times more than the background predisturbance fluxes. The increases in particle fluxes (~4 times) recorded by the sediment trap located in the southwestern direction (DMS-1) were the greatest, which could be the result of preferential movement of resuspended particles generated during the deep-sea benthic disturbance along the general current direction prevailing in this area during the experimental period. Also, the traps located closer to the disturbance area recorded greater fluxes than did the traps far away, across the Deep Sea Sediment Resuspension System path. This variability in recorded particle fluxes by the traps around the disturbance area clearly indicates that physical characteristics such as grain size and density of the resuspended particles produced during the disturbance had an important effect on particle movement. The postdisturbance measurements during ~5 days showed a reduction in particle fluxes of ~50%, indicating rapid particle settlement.