Delineation of Prospecting Prospect Area Based on Maximum Entropy Model

Taking the Dapingzhang copper-polymetallic deposit in Yunnan Province, China as the research object, the maximum entropy model was used to extract the mining information, and the mineral resource prediction model was established by using the exploration data of the deposit and related regions in this area, so as to determine the prospecting prospect area in the study area. In this paper, the Jacknife analysis module of maximum entropy model is used to quantitatively rank the importance of 39 geochemical element variables, and finally obtain the prospecting prospect map of the study area. The research results show that the Dapingzhang mining area has the potential to find hidden ore in the deep and surrounding areas, and the northern and southern ends and western sides of the rock ore control structural belt in the eastern region of the mining area have good prospecting prospects. The research results provide an important basis for the deployment of follow-up exploration work in the study area, and the maximum entropy model has a good application effect in mineral resources exploration.

Age, Maximum Cup Depth, Central Corneal Thickness, Disc Area and Mean Defect in Patients with Open Angle Glaucoma and Ocular Hypertension

Purpose: The main objective was to analyze the relationship between maximum cup depth (MCD), mean defect (MD), central corneal thickness (CCT), age and disc area, in patients with ocular hypertension (OHT) and primary open angle glaucoma (POAG). Methods: Cross-sectional study of patients diagnosed with OHT and POAG. Visual fields were obtained using an Octopus 300 analyzer, TOP strategy. MCD and disc area were obtained using a Heidelberg Retina Tomograph. Results: The study sample comprised 234 eyes of 143 patients, 91 women and 52 men, mean age 63.55 years (SD 10.49). Mean values were: MCD 0.52 mm (SD 0.27), MD 2.78 dB (SD 5.02), CCT 543.5 μm (SD 36.63), IOP 16.73 mmHg (SD 2.93), and disc area 2.01 mm2 (SD 0.39). A significant correlation was observed between MCD and age in patients under 60 years, between MCD and disc area, and between MD and disc area. Conclusions: Our study showed a correlation between MCD and age which was significant in patients under 60 years of age, between MCD and disc area and between MD and disc area, suggesting that the larger the disc area, the greater the MCD and the MD in patients with OHT and POAG.

Discussion on Principles and Methods in Estimating the Maximum Potential Earthquakes in Low Seismicity Areas

Five principles and methods are proposed for estimating the maximum potential earthquakesin low seismicity areas,and their applicabilities are discussed,taking Sichuan basin as asample area.The proposed principles and methods are not only on the grounds of thegeological tectonics but also considered fully the mutual complementation between geologicaland seismological methods.They will be helpful to the study of engineering seismology andthe assessment of designing ground motion parameters in low seismicity areas.

汶川震区山洪灾害场次洪水最大携沙量预测模型

汶川地震后,震区产生了大量松散堆积体,受强降水影响产生了破坏性更强的山洪灾害,加剧了灾害的危险性,增加了灾害防治的困难度,研究震区山洪灾害可为评估灾害的风险性及后续的管理提供依据。本研究以66处历史山洪灾害作为样本数据,进行可量算影响因子的相关性分析,揭示山洪灾害的携沙量影响机制,确定流域面积、主沟长度、相对高差、物源量四个影响因子作为主控因子,基于SPSS进行非线性回归分析,建立了基于场次洪水最大携沙量及最大携沙距离的估算模型,并选取了汶川县和都江堰市的共23处山洪水沙灾害数据进行了模型的验证且与其他模型对比。结果表明,本研究建立的模型可靠性好,精度更高。研究成果有助于预测汶川震区潜在的山洪水沙灾害区域,为山洪水沙灾害的风险评估提供依据。

气候变化情景下茶角胸叶甲在中国的潜在适生区预测

【目的】研究当前及未来气候情景下茶树上重要的鞘翅目害虫茶角胸叶甲潜在适生区的变化,可为其监控和预警提供科学指导,有效防止其大范围扩散造成更大危害。【方法】通过搜集整理茶角胸叶甲在中国的分布点数据,利用MaxEnt模型预测其在中国当前及未来气候变化情景下的潜在适生区分布范围及适生程度。【结果】模型重复运行10次的平均AUC值为0.907,标准差为0.007,测试样本遗漏率与预测遗漏率基本吻合,预测效果表现为非常好。当前气候条件下,茶角胸叶甲的潜在适生区均主要集中在中国华南、华东、华中、西南大部分地区,总适生区面积为267.73万km^(2)。未来气候情景下沿当前适生区继续向北方扩张,最北扩散至黑龙江省,在2061—2080年SSP5_85情景下总适生区面积达到最大,为376.58万km^(2),占中国总面积的39.23%。影响茶角胸叶甲潜在适生区分布的主要环境变量是最干月份降水量、最湿月份降水量、最热月份最高温、温度变化方差。【结论】茶角胸叶甲当前在中国的潜在适生区模拟结果与其实际分布区域相符;未来气候变化情景下茶角胸叶甲在中国的潜在适生区呈明显扩张趋势,中国更多地区均有可能成为其适生区。

机场终端区晴好天气容量评估方法的初步研究

在我国航空运输需求迅速增长,运营压力激增的背景下,采用适当的容量评估模型对于繁忙机场的理论容量研究和机场运行规划具有重要意义。以最大流最小割定理为基础,建立了进离场航段容量模型和交叉点容量模型,并选择西安咸阳机场进行仿真验证。研究结果表明,该模型能够高度准确地预测机场容量,其预测结果接近实际运行最大小时流量的105%~110%。表明该模型在终端区容量评估方面具有出色的精确性,特别适用于晴朗天气条件下的情况。这一研究为机场管理者提供了强大的决策工具,有助于更有效地满足不断增长的航空交通需求,确保机场运行的高效性和安全性。

太原盆地隐伏断裂潜在最大震级及地震危险性

采用双差方法对太原盆地中小地震进行精定位,建立太原盆地隐伏断层统计小区,采用按一定时间尺度归算的震级-频度关系模型,拟合太原盆地隐伏断层的最大地震震级M_(max)与震级频度关系a_(t)/b参数值之间的经验评估模型,综合分析后给出各隐伏活动断层小区的潜在震级上限预测值。采用泊松概率模型,给出各隐伏活动断层发生潜在最大地震震级和中强地震的概率预测结果。结果表明,太原盆地中西部的田庄-文水-汾阳断层统计片区和太原盆地东南部的三佳-洪山-平遥断层统计片区未来发生M_(S)≥6.5地震的概率水平较高;以NW向隐伏活动断层为主的棋子山、北田-王湖断层小区未来发生M_(S)≥6.0地震的概率水平较低。

东北及邻区过去两万年来有机碳同位素记录特征

末次冰盛期(LGM)距今大约21ka,两万年来气候演化是过去气候变化研究的重要内容,也是预测未来气候变化的关键。基于湖泊、泥炭长链正构烷烃单体碳同位素(δ^(13)C)和土壤有机质碳同位素(δ^(13)CSOM)记录,重建了LGM以来东北及邻区区碳同位素时间演化序列。结果表明,从LGM至早全新世δ^(13)C值增加至最大值(-23‰),中全新世下降后趋于稳定。对比古气候记录,揭示LGM以来有效湿度可能是东北及邻区δ^(13)C值变化的主导因素。

气候变化背景下的天山云杉潜在分布区预测

天山云杉(Picea schrenkiana)是天山地区最主要的树种之一,为天山山地的水土保持和水源涵养发挥着重要的作用。本文基于气候相似性原理以最大熵(MaxEnt)模型为基础结合ArcGIS预测当前(2000—2020年)与2020—2040年、2040—2060年两个时段3种气候情景低温室气体排放条件(SSP1-2.6)、中温室气体排放条件(SSP3-7.0)和高温室气体排放条件(SSP5-8.5)下天山云杉的潜在分布范围,并分析影响天山云杉分布的主要环境因子。结果表明:(1)MaxEnt模型对天山云杉的分布区预测可信度高,所有模型AUC值均大于0.99。温度(等温性、季节性温度变异、年平均温度)与降水(最冷季度的降水量、最湿月的降水量、最干季度的降水量)是影响天山云杉潜在分布的主导因子;其中温度为当前主要的影响因子,最冷季度的降水量为未来的主要影响因子。(2)当前时期天山云杉的适生区主要分布在新疆、青海、内蒙古、西藏、甘肃、宁夏、陕西、四川等地区的山区,总适生区面积为299.17×104km2,高适区面积为49.45×104km2。未来各情景下天山云杉的潜在适生区面积变化不大且分布仍以这些地区为主,但高适生区较当前均表现增加。除2020—2040年SSP5-8.5情景下天山云杉的适宜分布向东南方向迁移外,其他情景天山云杉的适宜分布有向西扩展的趋势。

基于FLAC^(3D)对某铅锌矿巷道稳定性及采空区治理方案研究

根据Hoek-Brown准则,采用Roclab1.0软件对岩石力学实验参数数据计算,获取矿体和围岩的岩石力学参数,在此基础上运用FLAC^(3D)数值模拟铅锌矿山矿体回采后,采空区围岩及巷道最大主应力、竖向位移、塑性区的变化情况,判定铅锌矿体回采对现有巷道的影响,最终为现场采空区治理提供相应的理论依据。

基于MaxEnt模型的湖北烟区潜在适宜性分布及其环境特征分析

为全面评价生态气候因子对湖北省烟叶生长发育的影响,利用2008—2020年中国气象局陆面数据同化系统(CMA land data assimilation system,CLDAS)数据集和其他环境因子,基于最大熵模型(MaxEnt),利用湖北省西部烟区实际种植点位模拟湖北省烟区的潜在适宜性分布,并评估影响适宜性分布的主导环境因子。结果显示:MaxEnt模型对烟草适宜性分布的模拟预测精度较高(AUC=0.854)。海拔(650~1750 m)、土壤类型(黄壤)、团棵期平均最低气温(8.9~15.0℃)、旺长期平均气温(16.0~22.9℃)、成熟期平均气温(18.8~25.6℃)是影响湖北烟草分布的主导环境因子。烟草的高适生区主要分布在恩施、十堰和襄阳南部及宜昌东南部,占湖北省总面积的18.2%,80%区域的海拔为700~1350 m、团棵期平均最低气温11.2~14.5℃、旺长期平均气温19.2~22.8℃、成熟期平均气温22.0~25.4℃。在所有环境因子中,海拔高度起决定性作用,温度则是影响烟草生长发育的重要气象因子。研究表明,本研究结果与湖北烟区实际空间分布基本相符。

不同冰盖条件下导流体对桥墩局部冲刷防护作用研究

基于桥墩基础的减冲防护原理,设计了一种稳定性高的防冲装置—导流体。为探究导流体对桥墩局部冲刷的防冲效果,在不同流速及覆盖条件下,采用不同形状的导流体进行模型试验。通过分析冲刷特性、最大冲坑深度、下潜流水力特性、冲坑体积和冲坑面积,选出最优形状和最佳安装位置。试验结果表明:当导流体底边高8 cm、安装位置在墩前2d时,防冲效果最好;当流速为0.32 m/s时,安装导流体可使桥墩最大冲深减小59.3%,冲坑体积减小76.1%,冲坑面积减小79.0%,下潜流流速及紊动强度明显减小。通过敏感性分析得出安装距离是影响导流体防冲效果的主要影响因素。

Similarities between Yangshan Harbor area and the Yangtze estuary

By analysis of published papers on the Yangtze estuary and hydrological and sediments data in Yangshan Harbor area, many similarities are found between Yangshan Harbor area and the Yangtze estuary. These similarities include the phenomenon of stagnating flow areas, the distributive characteristics of the highest suspended sediment concentration areas, superficial sediments and shoal bars. The stagnating flow area is the major similarity which causes other similarities. These similarities indicate that: 1) Turbidity Maximum and mouth bars in estuaries are mainly caused by the hydraulic balance of stagnating flow areas of estuaries; 2) The stagnating sand area of sands caused by stagnating flow area often locates on the narrower side of the stagnating flow area; 3) The location (or shape) of fine sediments area caused by stagnating flow area reflects the location (or shape) of the stagnating flow area. Both Yangshan Harbor area and the Yangtze estuary are the important developmental areas in the future (man-made similarity). In-depth studies on these similarities between Yangshan Harbor area and the Yangtze estuary will have momentous theoretical and practical significance.

山西莫底沟矿区含硫矿物产酸潜力评估

含硫矿物产酸潜力的综合评估对于酸性矿山废水防治和生态环境保护具有重要意义。以山西省河津市莫底沟矿区为例,基于岩石样品地球化学静态测试结果,结合含硫矿物储量和矿井涌水量估算,综合评估了莫底沟矿区含硫矿物的产酸潜力。结果表明:莫底沟矿区内太原组10号煤、本溪组铝土矿和本溪组硫铁矿均具有产酸潜力,太原组煤层间的灰岩不具备产酸潜力;估算出莫底沟矿区的最大产酸量为1.9万t H_(2)SO_(4),年产酸性废水量为30.9万m^(3),产酸年限为265.5 a;对评估过程中的不确定因素进行分析发现,最大产酸量偏大,年产酸性废水量偏小,产酸年限偏大。

Glacier variations and rising temperature in the Mt.Kenya since the Last Glacial Maximum

High-resolution imagery can be used to reconstruct former glacier boundaries through the identification of glacial erosional and sedimentary geomorphology. We employed moraine mapping and the accumulation–area ratio method(AAR), in conjunction with Landsat, Google Earth, and SRTM imagery, to reconstruct glacier boundaries and equilibrium-line altitudes(ELAs) for Mt. Kenya in the Last Glacial Maximum(LGM), the Little Ice Age(LIA), and at present. Our results show that the areas of Lewis Glacier and the Tyndall-I glacier system were 0.678 km^2 and 0.390 km^2, respectively, during the maximum of LIA. Those mean that the both glaciers have shrunken by 87.0% and 88.7%, respectively since the LIA. Area change ratios for each glacier were significantly larger in the period of 2000 through 2015 than the former periods, indicating that glacier recession has accelerated. Continuous ice loss in this region has been driven by rising temperature and fluctuating precipitation. Linear regression data for Lewis glacier show that mass balance sensitivity to dry season temperature was –315 mm w.e./℃, whereas the sensitivity to dry season precipitation was 5.2 mm w.e./mm. Our data also show that the ELA on the western slope of Mt. Kenya rose by 716-816 m from the LGM to the modern era, corresponding to that temperature rose by 5.2℃-6.5℃.

Distribution Prediction of Suitable Growth Area for Eucommia ulmoides in China under Climatic Change Background

[ Objective] The research aimed to study distribution prediction of suitable growth area for Eucommia ulmoides in China under climatic change background. [ Method] By using the maximum entropy model and many kinds of climate change scenarios, we predicted current and future distribution pattems of suitable growth area for Eucommia ulmoides in China and its change process. [ Result ] At present, highly suitable growth area of E. ulmoides mainly distributed in Sichuan, Shaanxi and Chongqing, Under climate change background, total suitable growth areas in future three decades all drastically reduced when compared with that at present. It was noteworthy that moderately and highly suitable growth areas of wild E. ulmoides all disappeared, and junction between Shaanxi and Gansu and Taibai Mountain would be stable suitable growth area of wild E. ulmoides. [ Condusioa] The research could provide useful reference data for investigation, protection and sustainable development of the wild E. ulmoides resources.

Propagation Mechanisms of Incident Tsunami Wave in Jiangsu Coastal Area,Caused by Eastern Japan Earthquake on March 11,2011

At 13：46 on March 11, 2011（Beijing time）, an earthquake of Mw=9.0 occurred in Japan. By comparing the tsunami data from Guanhekou marine station with other tsunami wave observation gathered from southeast coastal area of China, it was evident that, only in Guanhekou, the position of the maximum wave height appeared in the middle part rather than in the front of the tsunami wave train. A numerical model of tsunami propagation based on 2-D nonlinear shallow water equations was built to study the impact range and main causes of the special tsunami waveform discovered in Jiangsu coastal area. The results showed that nearly three-quarters of the Jiangsu coastal area, mainly comprised the part north of the radial sand ridges, reached its maximum tsunami wave height in the middle part of the wave train. The main cause of the special waveform was the special underwater topography condition of the Yellow Sea and the East China Sea area, which influenced the tsunami propagation and waveform significantly. Although land boundary reflection brought an effect on the position of the maximum wave height to a certain extent, as the limits of the incident waveform and distances between the observation points and shore, it was not the dominant influence factor of the special waveform. Coriolis force＇s impact on the tsunami waves was so weak that it was not the main cause for the special phenomenon in Jiangsu coastal area. The study reminds us that the most destructive wave might not appear in the first one in tsunami wave train.

SOME REMARKS ABOUT THE AREA-PRESERVING CONVEX CURVE FLOW IN THE PLANE

Using Picard's theorem and the Leray-Schauder fixed point theorem to reinvestigate the area-preserving convex curve flow in the plane which is considered as a coupled system and thus different from the setting handled by Gage.

基于量测数据时序谱分布特性的电力系统暂态功角稳定在线判别

基于响应信息的电力系统暂态稳定判别是实现“实时决策,实时控制”的基础。然而此类方法的准确性受限于场景匹配以及发电机分群等中间环节。为更有效地辨识系统的暂态稳定性,该文以随机矩阵理论为基础,提出一种基于量测数据时序谱分布特性的电力系统暂态功角稳定判别方法。首先根据电力系统的暂态响应特性构建数据模型,并在实时分离窗矩阵的基础上构建插入矩阵模型以降低冗余历史数据对谱分布特性的影响。然后结合谱分布理论和增广矩阵法获取表示数据相关性的最大特征值偏移度(maximum eigenvalue deviation,MED)差值轨迹,并以物理机理严格分析不同稳定模式下MED差值轨迹与暂态功角稳定间的映射关系,从数据相关性的角度制定暂态功角稳定判据,基于量测数据实现暂态响应特性分析和暂态功角稳定在线判别。