Assessment of water level threshold for groundwater restoration and over-exploitation remediation the Beijing-Tianjin-Hebei Plain

The Beijing-Tianjin-Hebei Plain(BTHP)is the political,economic and cultural center of China,where groundwater is the main source of water supply to support social and economic development.Continuous overdraft of the resources has caused a persistent decline of groundwater level and formed a huge cone of depression at a regional scale.This paper addresses current groundwater situation over the BTHP area.The paper also delineates the groundwater flow field,using groundwater level data,in order to provide an effective method for the restoration of groundwater level and associated water resources management.Based on the analysis of multiple factors,such as groundwater level,soil salinization,ground subsidence,groundwater recharge and storage,urban underground space security,formation of fractures,and seawater intrusion,the threshold for groundwater level restoration is defined,and some measures for groundwater over-exploitation management are accordingly proposed.The study shows that:(i)Since the 1980s to 2020,shallow groundwater level in the western part of the BTHP area has dropped by 25 m to 60m,while the cumulative decline of deep groundwater in the central and eastern regions is in the range of 40–80 m;(ii)The water table of the shallow groundwater within the depression zone over the Western Piedmont Plain should be controlled in the range of 15–30 m below ground level(mbgl),while the depth of groundwater level in large and medium-sized urban areas should be controlled within 20–30 mbgl.The groundwater level in the resource preservation area should be controlled within 10–15 mbgl,and the groundwater level in the area with identified soil salinization in the central and eastern plain should be controlled within 3–10 mbgl.However,for the deep groundwater in the central and eastern plainwater,the main focus of the resources management is to control the land subsidence.The water level in the severe land subsidence area should be controlled within 45–60 mbgl,and in the general subsidence area should be controlled within 30–45 mbgl;(iii)Based on the water level recovery threshold and proposed groundwater overdraft management program,if the balance of abstraction and recharge is reached in 2025,the shallow groundwater abstraction needs to be gradually reduced by about 2×10^(8) m^(3).Meanwhile,the ecological water replenishment of rivers through the South-to-North Water Transfer Project should be increased to 28.58×10^(8) m^(3)/a,and the deep groundwater abstraction needs to be gradually reduced by 2.24×10^(8) m^(3).To reach the target of shallow groundwater level in 2040,surface water replacement is recommended with a rate of 25.77×10^(8) m^(3)/a and the ecological water replenishment of rivers in the South-to-North Water Diversion Project should reach 33.51×10^(8) m^(3)/a.For deep groundwater recovery,it is recommended to replace the deep freshwater extraction with the utilization of shallow salt water by 2.82×10^(8) m^(3),in addition to the amount of 7.86×10^(8) m^(3) by water diversion.The results are of great significance to the remediation of groundwater over-exploitation,the regulation of water resources development and utilization,and ecological protection in Beijing-Tianjin-Hebei plain.

Fuzzy C Mean Thresholding based Level Set for Automated Segmentation of Skin Lesions

Accurate segmentation is an important and challenging task in any computer vision system. It also plays a vital role in computerized analysis of skin lesion images. This paper presents a new segmentation method that combines the advan-tages of fuzzy C mean algorithm, thresholding and level set method. 3-class Fuzzy C mean thresholding is applied to initialize level set automatically and also for estimating controlling parameters for level set evolution. Parameters for performance evaluation are presented and segmentation results are compared with some other state-of-the-art segmentation methods. Increased true detection rate and reduced false positive and false negative errors confirm the effectiveness of proposed method for skin cancer detection.

The Method of Flotation Froth Image Segmentation Based on Threshold Level Set

A novel flotation froth image segmentation based on threshold level set method is put forward in view of the problem of over-segmentation and under-segmentation which occurs when the existing method segmented the flotation froth images. Firstly, the proposed method adopts histogram equalization to improve the contrast of the image, and then chooses the upper threshold and lower threshold from grey value of histogram of the image equalization, and complete image segmentation using the level set method. In this paper, the model which integrates edge with region level set model is utilized, and the speed energy term is introduced to segment the target. Experimental results show that the proposed method has better segmentation results and higher segmentation efficiency on the images with under-segmentation and incorrect segmentation, and it is meaningful for ore dressing industrial.

社会保障水平提升如何影响共同富裕?——基于省级面板数据的实证分析

基于2011—2020年中国31个省级行政区的面板数据,利用熵权TOPSIS法分别对社会保障水平和共同富裕水平进行测度,然后通过静态和动态面板回归计量模型实证检验了社会保障和共同富裕之间的关系。研究发现:中国社会保障水平和共同富裕水平在2011—2020年整体呈现增长趋势,其中社会保障水平在空间上呈现东部地区高于西部地区、西部地区高于中部地区的特征,共同富裕水平在空间上则呈现“东-中-西”逐级递减趋势。经检验,社会保障水平的提高能够显著促进共同富裕的实现,且这种促进作用具有边际效应递减的非线性特点。机制分析表明,社会保障可以通过提高居民消费水平和促进人力资本积累两条路径促进共同富裕的实现。进一步研究发现,社会保障水平对共同富裕水平的影响还存在区域异质性,中部地区社会保障水平的提升对共同富裕水平的影响程度大于东部和西部地区。

市场化水平提升对农业高质量发展的促进效应研究

农业高质量发展是我国从农业大国向农业强国迈进的必然要求,是我国经济高质量发展的应有之义。基于2011—2021年我国30个省份(未统计西藏及港澳台地区的数据)的面板数据样本,运用广义矩估计的系统GMM模型、中介效应模型和动态门槛效应模型研究市场化水平提升对农业高质量发展的影响。研究表明:市场化水平提升对农业高质量发展具有显著促进作用,但过度市场化会降低这种促进效应;无论从农业高质量发展和市场化水平的不同构成维度,还是从不同区域视角分析,市场化水平提升对农业高质量发展的影响均存在异质性;市场化水平提升可通过技术创新和产业结构调整两条中介路径对农业高质量发展产生影响;在促进农业高质量发展过程中,政府财政支农与市场化水平提升存在互补作用。为此,我国应从四个方面来提升市场化水平,促进农业高质量发展:一是要深化改革,充分发挥市场的积极作用;二是要因应施策,提升市场化推进的针对性;三是要激励创新,畅通市场化功能发挥路径;四是要优势互补,促进市场与政府协同契合。

Using the concept of ecological groundwater level to evaluate shallow groundwater resources in hyperarid desert regions

This paper, based on the analysis and calculation of the groundwater resources in an arid region from 1980 to 2001, put forward the concept of ecological groundwater level threshold for either salinity control or the determination of ecological warning. The surveys suggest that soil moisture and soil salinity are the most important environmental factors in determining the distribution and changes in vegetation. The groundwater level threshold of ecological warning can be determined by using a network of groundwater depth observation sites that monitor the environmental moisture gradient as reflected by plant physiological characteristics. According to long-term field observations within the Ejin oases, the groundwater level threshold for salinity control varied between 0.5 m and 1.5 m, and the ecological warning threshold varied between 3.5 m and 4.0 m. The quantity of groundwater re- sources （renewable water resources, ecological water resources, and exploitable water resources） in arid areas can be calculated from regional groundwater level information, without localized hydrogeological data. The concept of groundwater level threshold of ecological warning was established according to water development and water re- sources supply, and available groundwater resources were calculated. The concept not only enriches and broadens the content of groundwater studies, but also helps in predicting the prospects for water resources development.

苏北平原区河流生态水位阈值计算方法适用性研究

针对平原区多数河流缺乏有效的流量资料的情况,研究适用于平原区河流生态水量阈值的计算方法具有重要现实意义。本文对比分析7Q10法、保证率法、湿周法、基于Tennant改进的生态水位法等4种代表性生态水量计算方法与结果,以水文节律、生态水位满足度为判别原则,评价了上述方法的适用性。分析结果显示:(1)在水文节律相应性方面,7Q10法、Q90法、湿周法计算的生态水位值为单一的特定值,无法反映水文节律的天然变化过程;(2)在生态满足度方面,7Q10法的多年平均生态水位的满足度最小;(3)基于Tennant法改进的生态水位法的水文节律模拟效果最好、生态水位满足度最高。研究表明:在选择的4种计算方法中,相较于7Q10法、Q90法及湿周法,基于Tennant法改进的生态水位法能较好地满足水文节律相应性和生态水位满足度原则,对平原区河流生态水位(阈值)计算具有一定的适用性。该研究成果可为苏北平原河网区流量资料缺乏型河流生态需水的确定和管理提供有益的参考。

基于Level Set算法的医学图像分割的研究与实现

提出了一种改进的结合基于阈值分割特点的Level Set方法。首先用滤波器对原始图像进行平滑,然后根据当前曲线找到区域的统计特性,最后根据区域之间的统计特性的相似度重新定义了Level Set方法的演化停止准则,从而提高了算法的准确性和自动性。实验结果表明,该方法具有较好的分割效果和较高的分割效率。

不同分级方法对区域滑坡易发性区划的影响

易发性分区是开展区域地质灾害风险评价的基础步骤,选取合理的分级方法对有效绘制区域滑坡易发性图意义显著,但鲜有研究对比了各易发性分级方法的优缺点,尤其是未能将历史滑坡与预测出的易发性指数相联接。针对该问题,以陕西省延长县为例采用3种机器学习模型计算滑坡易发性指数,即分类和回归树、随机森林和径向基函数;设计了5种易发性分级方法,划分不同的滑坡易发性等级,包括4种常规的基于地理信息系统的分级方法(自然断点、等间隔、分位数和几何间隔),同时考虑了滑坡与易发性指数间的非线性关联性的频率比阈值法。结果表明:3种模型的受试者工作特征(ROC)曲线下面积均大于0.75,但划分的易发性分级图分布模式却存在较大差异,使用几何间隔和分位数法的易发性图能在极高易发区中识别出更多滑坡,但这两种方法划分的极高和高易发区的总面积过大;使用等间隔法和频率比阈值法在极高和高易发区中的滑坡比率更大,说明识别出的滑坡更为集中。本文提出的频率比阈值法用于滑坡易发性分级,能为易发性的准确分区提供思路,为边坡稳定性较差区域的工程选址以及土地利用规划提供科学参考,提高地质安全评估及应急管理能力。

高管团队异质性对企业风险承担的影响——基于企业数字化转型视角

以我国2009—2020年沪深A股上市公司为样本,以企业数字化转型程度为中介变量,实证研究高管团队异质性对企业风险承担水平的影响。研究结果表明,高管团队异质性能够显著提升企业的风险承担水平,但当高管团队异质性大于0.333时会产生门槛效应,抑制企业风险承担水平,这一结论在控制联合固定效应、进行工具变量及内生性检验之后依旧稳健。中介效应分析表明,高管团队异质性能够通过拓宽企业数字化转型的渠道进而提升企业的风险承担水平。异质性分析发现,高管团队异质性在非国有企业中对企业风险承担水平的提升非常显著,但对国有企业影响不显著;对处于生命周期中成长期和衰退期的企业风险承担水平的提升作用显著,对处于成熟期的企业没有显著影响。

数字普惠金融对农业规模经营的影响效应——基于空间面板模型与门槛模型的实证分析

从农村地区信贷约束与农业规模经营互为矛盾的现实困境出发,文章进一步着眼于数字普惠金融视角,基于2011—2019年省际面板数据,并运用普通面板模型、空间面板模型和面板门槛模型考察了数字普惠金融对农业规模经营的影响及其空间溢出效应与门槛特征。研究发现:数字普惠金融通过缓解农村地区信贷约束而对农业规模经营的总量和效率两个层面具有显著的推动作用;数字普惠金融对本地区和邻近地区的农业规模经营的总量和效率层面均具有促进作用,说明这种促进作用存在空间关联效应;数字普惠金融之覆盖广度、使用深度对农业规模经营总量和效率的促进作用表现出显著的空间溢出效应,而数字化程度对农业规模经营的影响较为有限;随着农村教育水平提高,数字普惠金融对农业规模经营总量和效率的推动作用表现出边际递增特征。文章的政策建议是强化农村地区数字普惠金融服务、构建区域之间交流协作机制,以及加大农村地区的教育投入,以推动农业适度规模经营进程。

共同富裕的文化空间策略:逻辑、挑战与路径

随着五大发展理念的贯彻落实,文化空间在经济社会资源配置中的作用不断增强,对共同富裕的辐射带动效能日益凸显,因此以文化空间策略推动共同富裕正当其时。而以文化空间策略推动共同富裕,其关键是文化空间布局的均等化;其挑战则是文化空间资源分布的不均衡与共同富裕的均等化之间的矛盾。因而,实施共同富裕的文化空间策略,须抓住文化空间布局均等化这一关键,参照“横店模式”和经验,以政府、企业、社会三维合力破解文化资源非均衡分布与均等化的矛盾难题。

长江上游王爷庙—兰家沱河段航道计划尺度边界研究

针对长江上游王爷庙—兰家沱河段航道计划尺度边界问题,采用对多年航道预报尺度及实测水位数据进行统计分析的方法,同时参考实际航道维护经验,得出该河段重点水道为温中坝、东溪口和叉鱼碛水道,各重点水道的航道计划尺度边界分别为泸州羊角滩水位0.95 m、斗笠子水位0.30 m、小桃竹水位0.60 m,降低维护尺度的方案为舍深保宽。

基于多级阈值的车辆换道预测方法

车辆换道行为是机动车在道路行驶时的一种常见行为,对其进行预测能有效减少交通事故。为准确预测目标车辆换道行为,根据车辆在时间内的横向位移,提出基于多阈值的车辆换道预测方法。该方法根据法规,结合车速设置换道时的横向位移阈值、方向盘转角与转速阈值,探索多阈值间的相互作用关系,通过多阈值协同预测驾驶员换道意图。结果表明,系统的预判准确率可达95%以上,说明该方法能准确预测车辆换道意图,且实时性较好,能为辅助驾驶技术的发展提供一定参考。

堆积层滑坡在库水位变动与降雨共同作用下的阈值研究——以墓坪滑坡为例

堆积层滑坡是三峡水库运行过程中的重要地质灾害,其变形演化往往受库水位变动与降雨强度的影响,如何确定库水位与降雨共同作用下的合理有效阈值判据,准确为滑坡防范与应急处置提供及时可靠的信息成为当务之急。以堆积层滑坡——墓坪滑坡为例,基于实时监测数据,并结合数值模拟方法,对库水位变动与降雨强度下的阈值进行研究。结果表明,当库水位下降速率为0.11~<0.42 m/d、4~10 d累积降雨量≥57.3 mm时,墓坪滑坡易发生变形;当库水位下降速率为0.42~<0.83 m/d、4~10 d累积降雨量≥45.8 mm时,墓坪滑坡易发生变形;当库水位下降速率≥0.83 m/d、4~10 d累积降雨量≥22.3 mm时,墓坪滑坡易发生变形。通过数值模拟分析,当库水位下降速率≥0.4 m/d、且连续3 d累积降雨量≥100 mm时,墓坪滑坡易发生变形。研究成果可以为墓坪滑坡的监测预警预报工作提供依据,对涉水堆积层滑坡监测预警也有一定的借鉴。

营养包与6~24月龄婴幼儿Hb水平和贫血率的阈值效应关系研究

目的:探讨营养包(Ying Yang Bao,YYB)服用时长和频率与6~24月龄婴幼儿血红蛋白(Hemoglobin,Hb)水平和贫血率之间的阈值效应关系。方法:研究数据来自于早期儿童营养包干预长期营养健康作用评估项目。采用t检验和卡方检验比较连续变量和分类变量的组间差异。采用限制性立方样条回归检验YYB服用时长和频率与儿童血红蛋白(Hb)水平和贫血率之间的非线性趋势,探索可能存在的阈值效应关系。结果:YYB服用时长与Hb水平和贫血率的非线性趋势检验P值分别为0.665和0.211,服用频率与Hb水平和贫血率的非线性趋势检验P值分别为0.110和0.157。YYB服用时长达到8.68个月时,Hb水平变化的斜率β=0,贫血发生风险的OR=1;YYB服用频率达5.6袋/周时,Hb水平变化的斜率β=0,服用频率达4.6袋/周时,贫血发生风险的OR=1。结论:YYB服用时长和频率与6~24月龄婴幼儿Hb水平和贫血率之间存在线性关联;改善Hb水平和贫血率的最低有效时长约为8.6个月,最低有效频率约为5~6袋/周。

人力资本水平对烟叶产量的影响研究

人力资本一直是影响农业生产的重要因素,优质的人力资本对于烟叶生产也具有十分重要的促进作用。基于对攀枝花市烟技员和烟农的调查数据,通过将烟农与负责其烟点的烟技员进行信息匹配,借助熵值法测度烟农的人力资本水平,使用混合OLS回归和截面门槛回归探究人力资本水平对烟叶产量产生的影响。结果表明,烟农的人力资本水呈现出较为明显的“橄榄球型”特征且对烟叶产量具有显著的正向影响,与此同时,肥料和农药投入与烟叶产量之间存在显著的边际递减规律。因此,在追求烟草行业高质量发展的目标下,应多元化提升烟农种植烟叶的技术水平;以烟技员队伍为有力的抓手,促进烟技员与烟农的有效沟通,保证政策与技术的落实推广,从而提高种烟收益、稳定烟农队伍。

数字普惠金融对农村收入差距的影响

文章利用2011—2020年中国31个省份的面板数据,以及衡量中国农村收入差距的基尼系数,探讨了数字普惠金融对农村内部收入差距的影响。研究结果表明:从整体上看,数字普惠金融具有缩小农村内部收入差距的显著潜力;从单一维度来看,数字普惠金融的覆盖广度指数和使用深度指数都具有显著缩小农村内部收入差距的能力;此外,政府支农支出和城镇化水平对缩小农村内部收入差距也有趋同作用。要有效缩小农村内部收入差距,不仅要重视数字普惠金融的发展,还要考虑其他因素的影响。

Subjective annoyance caused by indoor low-level and low frequency noise and control method

The influence of low_level noise has not been widely noticed. This paper discovered that low_level and low frequency noise(A_weighted equivalent level L eq <45 dB) causes higher probability of subjective annoyance. The fuzzy mathematic principle was applied to deal with the threshold level of subjective annoyance from noise in this study; there is preferable relationship between the indoor noise and noise annoyance at low frequency noise level. Study indicated at the same centered noise level, the change of annoyance probability is mainly caused by the change of the frequency spectrum characteristic of the indoor noise. Under low noise level environment, without change of the medium_low frequency noise, the slight increase of medium_high frequency noise level with the help of noise sheltering effect can significantly reduce the noise annoyance. This discovery brings a new resolution on how to improve the environmental quality of working or living places. A noise control model is given in this study according to the acoustic analysis.

面向跨级可信协作服务的大规模节点组网共识算法

为有效提升业务数据跨级可信协作服务的可扩展性、高鲁棒性、高并发能力与处理效能,提出一种面向多层级大规模节点组网场景的高效共识算法——高效拜占庭容错(Efficient Byzantine Fault Tolerance, EBFT)。在现有共识算法的基础上,把轮换主节点作为常规共识流程的一部分,实现所有节点轮流担任主节点进行提案,以减轻单一主节点带来的压力并保证节点间的公平性。通过合并视图切换流程和正常流程实现了快速共识,进一步提升算法灵活性、可靠性和数字签名性能。仿真实验表明,所提算法满足了跨级大规模业务数据流转对业务系统处理能力和响应速度的实际需求。