安徽铜陵硫铁矿集中开采区矿山地质环境评价研究

安徽铜陵地区是我国典型的硫铁矿集中开采区。研究区内新桥硫铁矿等数座硫铁矿山的长期开采造成了生态环境的破坏,对铜陵地区硫铁矿集中开采区矿山进行地质环境评价可为矿山生态恢复提供依据。本文在资料分析和实际调查的基础上,选取了地质环境背景、矿业开发、矿山地质环境问题和地质灾害4种要素下20种评价指标,采用层次分析(analytic hierarchy process,AHP)法确定了各要素和指标的权重值。在此基础上运用模糊数学综合评判对研究区进行矿山地质环境评价,并采用ArcGIS的网格化插值评价法对比验证。结果表明:地质环境背景、矿业开发、矿山地质环境问题和地质灾害对矿山地质环境影响的权重值分别为0.10、0.14、0.37、0.39。模糊综合评价二级初判结果为:矿山地质环境问题对研究区矿山地质环境总体上影响较大,其中水土污染问题最为突出;一级初判结果为研究区内矿山地质环境总体较好。网格化插值评价将研究区矿山地质环境划分为严重区、较严重区和轻微区,面积占比分别为4.62%、32.04%、63.34%。模糊数学综合评价与网格化插值评价结果基本一致,AHP与模糊数学综合评判法对硫铁矿集中开采区的地质环境评价适用性较好。评价结果可为当地开展矿山地质环境保护和治理工作提供依据。     

基于SDSM的珠江中上游气候模拟及未来情景预估

预估喀斯特生态脆弱区的未来气候变化对于区域资源的合理开发利用及生态环境保护具有重要参考价值,而目前应用降尺度方法模拟喀斯特地区的未来气候情景仍存在较大的探讨空间。本文依据珠江流域红柳江区13个气象站1961-2001年的实测日气温、日降水量资料和全球大气NCEP再分析资料,采用SDSM模型预测流域在HadCM3模式SRES A2和B2两种排放情景下未来年份气温和降水的变化趋势。结果表明:（1）SDSM模型可以较为准确地模拟研究区的气温和降水变化,确定性系数分别可达99%和65%左右;（2）A2、B2两种情景下,21世纪气温和降水均表现出明显的上升趋势,且随时间推移增幅逐渐增大。截至21世纪末,A2、B2两种情景下的年平均气温变化分别为+3.39 ℃和+2.49 ℃,日均降水将分别增加117.30 %和80.90 %;（3）未来的气温上升以秋季和春季变化最为明显,降水则表现为夏季降水增幅最大。分析成果可为喀斯特区的气候变化影响评价与应对决策提供数据基础和理论依据。      

Overview of goaf water hazards control in China coalmines

Since 1990s, goaf water has become a frequent cause of water disaster in China coalmines, inflicting severe human casualties and huge economic losses. Based on the analysis of the goaf water disaster cases in China coalmines, this article put forward the theoretical and technological system of goaf water control, which include (1) the area and volume of goaf water are reasonably determined due to existence form of goaf water and geophysical prospecting results, (2)retaining sufficient water-resistant coal (rock) pillar to prevent goaf water inrush from adjacent and above, (3)grouting insecure or failure water-resistant coal (rock) pillar, and (4) draining goaf water using “fanned-out” normal drill and long-distance directional drill, and of all, draining goaf water through long-distance drill has been proved to be technically superior in engineering practices. The research results can be of reference to other coal-producing countries in similar geological conditions.     

地铁竖井联系测量三角形布设及解算取位的探讨

在城市地铁竖井平面联系测量中运用误差理论,联系三角形的最优形状进行了探讨。并指出在联系三角形解算时,使用函数型计算器计算时由于两钢丝绳之间的距离S1算的取位不足会导致正弦定理和余弦定理解算的β角存在较大差异。通过对工程实例进行研究,发现只有把两钢丝间距的计算结果保留到0.000 1 mm时,才能使正、余弦定理计算的β角相等,从而保证了井下起始边方位角的正确性和可靠性,避免因联系测量结果有误给工程带来不利影响。     

“21世纪海上丝绸之路”集装箱海运网络的脆弱性变化

为探究“21世纪海上丝绸之路”集装箱海运网络在蓄意攻击下的脆弱性变化情况,基于蓄意攻击下集装箱海运网络的地理空间联系变化和网络分裂过程,提出了集装箱海运网络崩溃临界点的识别方法,进而建立了集装箱海运网络脆弱性变化趋势和程度的量化方法,并利用2015年和2019年海上丝绸之路中港口和航线的统计数据构建网络进行分析。结果表明：2015年和2019年“海上丝路”网络的蓄意攻击承受能力分别为4.21%和5.51%,说明2019年的“海上丝路”海运网络比2015年更加强壮,其相对变化率为30.88%;“海上丝路”网络脆弱性变化的驱动机制主要包括港口层级结构的差异性减弱、关键港口备份机制日趋完备、东亚和东南亚与其他区域间的集装箱海运联系更加紧密等。最后,从持续保障中国与“海上丝路”沿线各国集装箱海运互联互通的角度,提出了相应的对策和建议。研究成果对于揭示“海上丝路”海运网络的脆弱性变化及其驱动机制和影响因素,进而有针对性的持续保障该网络的互联互通,具有重要的理论意义和实用价值,且本文的分析方法对其他运输网络脆弱性变化的相关研究也可提供借鉴。     

新疆S214省道防沙体系对近地表风沙流的影响

对新疆S214省道台特玛湖干涸湖盆段防沙体系内外的风沙流输沙和风速进行了同步观测,数据分析表明：观测时防沙体系中阻固沙带已拦截了大量风沙,虽近地表风速被削弱程度不大,但风沙流输沙的43.26%仍可被防沙体系所拦截和固定,而剩余部分则可借助路侧输沙带的较大风力输移到公路下风侧,且不产生路面沙害,表明阻-固-输结合型防沙体系非常适宜单风向强风沙环境。S214省道防沙实践可为其他强风沙环境公路防沙提供重要借鉴经验。     

中国梯田撂荒程度及空间格局分异研究

在城镇化和工业化的驱动下,中国丘陵山区耕地逐渐被边际化,耕地撂荒范围也迅速从劣质的坡耕地延展至优质的梯田,大规模梯田撂荒将会引发一系列社会和生态效应,科学评估中国山区梯田的撂荒程度及空间分布将有助于有效地应对耕地撂荒问题。本文通过全国抽样调查的方式对中国梯田的撂荒程度进行了调查,利用获取的中国329个县的560份村问卷测算了中国梯田撂荒规模,并进一步分析了梯田撂荒空间分异特征及驱动因素。结果显示：(1)全国梯田撂荒现象分布广泛,发生梯田撂荒的村庄占总调查村庄的比例为54%,撂荒面积占梯田总面积的比例达到9.79%;(2)梯田撂荒程度呈现“南高北低”的特征,南方丘陵山区较为严重,尤以长江中下游地区为最;(3)梯田撂荒的主要因素可归结为农业劳动力外出务工、梯田耕作机械化程度、灌溉条件、耕作交通条件等。减缓梯田撂荒,应因区精准施策,提高梯田区机械化水平等措施具有普适性,针对质量较差的梯田,可有序“退耕”,对于质量较好的梯田,可采用调整种植结构、加强农业基础设施建设、鼓励流转与规模经营等方式。     

长江三峡坝区断层泥的裂变径迹法年龄

仙女山断裂带和九湾溪断裂带是位距三峡工程坝址最近的两条主断裂。本文对断裂带中断层泥、断裂壁岩和断裂带围岩内选出的磷灰石进行了裂变径迹断代学的研究,并对径迹长度的频率分布进行统计测量。研究证实,仙女山断裂带与九湾溪断裂带发生的时期分别为0.60±0.05MaB.P.和0.29±0.04MaB.P.,与它周边的围岩经受的主要构造-热事件年龄(22.30±1.8Ma)截然不同。与其它方法年龄测定结果对比分析,均未见到全新世以来有明显的活动迹象,以此确认三斗坪坝址属稳定地壳区。     

Stability of the classical type of relative equilibria of a rigid body in the J 2 problem

The motion of a point mass in the J ₂ problem is generalized to that of a rigid body in a J ₂ gravity field. The linear and nonlinear stability of the classical type of relative equilibria of the rigid body, which have been obtained in our previous paper, are studied in the framework of geometric mechanics with the second-order gravitational potential. Non-canonical Hamiltonian structure of the problem, i.e., Poisson tensor, Casimir functions and equations of motion, are obtained through a Poisson reduction process by means of the symmetry of the problem. The linear system matrix at the relative equilibria is given through the multiplication of the Poisson tensor and Hessian matrix of the variational Lagrangian. Based on the characteristic equation of the linear system matrix, the conditions of linear stability of the relative equilibria are obtained. The conditions of nonlinear stability of the relative equilibria are derived with the energy-Casimir method through the projected Hessian matrix of the variational Lagrangian. With the stability conditions obtained, both the linear and nonlinear stability of the relative equilibria are investigated in details in a wide range of the parameters of the gravity field and the rigid body. We find that both the zonal harmonic J ₂ and the characteristic dimension of the rigid body have significant effects on the linear and nonlinear stability. Similar to the classical attitude stability in a central gravity field, the linear stability region is also consisted of two regions that are analogues of the Lagrange region and the DeBra-Delp region respectively. The nonlinear stability region is the subset of the linear stability region in the first quadrant that is the analogue of the Lagrange region. Our results are very useful for the studies on the motion of natural satellites in our solar system.     

Application of Hamiltonian structure-preserving control to formation flying on a J 2-perturbed mean circular orbit

The bounded quasi-periodic relative trajectories are investigated in this paper for on-orbit surveillance, inspection or repair, which requires rapid changes in formation configuration for full three-dimensional imaging and unpredictable evolutions of relative trajectories for non-allied spacecraft. A linearized differential equation for modeling J ₂ perturbed relative dynamics is derived without any simplified treatment of full short-period effects. The equation serves as a nominal reference model for stationkeeping controller to generate the quasi-periodic trajectories near the equilibrium, i.e., the location of the chief. The developed model exhibits good numerical accuracy and is applicable to an elliptic orbit with small eccentricity inheriting from the osculating conversion of orbital elements. A Hamiltonian structure-preserving controller is derived for the three-dimensional time-periodic system that models the J ₂-perturbed relative dynamics on a mean circular orbit. The equilibrium of the system has time-varying topological types and no fixed-dimensional unstable/stable/center manifolds, which are quite different from the two-dimensional time-independent system with a permanent pair of hyperbolic eigenvalues and fixed-dimensions of unstable/stable/ center manifolds. The unstable and stable manifolds are employed to change the hyperbolic equilibrium to elliptic one with the poles assigned on the imaginary axis. The detailed investigations are conducted on the critical controller gain for Floquet stability and the optimal gain for the fuel cost, respectively. Any initial relative position and velocity leads to a bounded trajectory around the controlled elliptic equilibrium. The numerical simulation indicates that the controller effectively stabilizes motions relative to the perturbed elliptic orbit with small eccentricity and unperturbed elliptic orbit with arbitrary eccentricity. The developed controller stabilizes the quasi-periodic relative trajectories involved in six foundational motions with different frequencies generated by the eigenvectors of the Floquet multipliers, rather than to track a reference relative configuration. Only the relative positions are employed for the feedback without the information from the direct measurement or the filter estimation of relative velocity. So the current controller has potential applications in formation flying for its less computation overload for on-board computer, less constraint on the measurements, and easily-achievable quasi-periodic relative trajectories.