New normalized nonlocal hybrid level set method for image segmentation

This article introduces a new normalized nonlocal hybrid level set method for image segmentation.Due to intensity overlapping,blurred edges with complex backgrounds,simple intensity and texture information,such kind of image segmentation is still a challenging task.The proposed method uses both the region and boundary information to achieve accurate segmentation results.The region information can help to identify rough region of interest and prevent the boundary leakage problem.It makes use of normalized nonlocal comparisons between pairs of patches in each region,and a heuristic intensity model is proposed to suppress irrelevant strong edges and constrain the segmentation.The boundary information can help to detect the precise location of the target object,it makes use of the geodesic active contour model to obtain the target boundary.The corresponding variational segmentation problem is implemented by a level set formulation.We use an internal energy term for geometric active contours to penalize the deviation of the level set function from a signed distance function.At last,experimental results on synthetic images and real images are shown in the paper with promising results.

Evaluation of regional water resources carrying capacity based on binary index method and reduction index method

Based on the regional water resources carrying capacity(WRCC)evaluation principles and evaluation index system in the National Technical Outline of Water Resources Carrying Capacity Monitoring and Early Warning(hereafter referred to as the Technical Outline),this paper elaborates on the collection and sorting of the basic data of water resources conditions,water resources development and utilization status,social and economic development in basins,analysis and examination of integrity,consistency,normativeness,and rationality of the basic data,and the necessity of WRCC evaluation.This paper also describes the technique of evaluating the WRCC in prefecture-level cities and city-level administrative divisions in the District of the Taihu Lake Basin,which is composed of the Taihu Lake Basin and the Southeastern River Basin.The evaluation process combines the binary index evaluation method and reduction index evaluation method.The former,recommended by the Technical Outline,uses the total water use and the amount of exploited groundwater as evaluation indices,showing stronger operability,while the latter is developed by simplifying and optimizing the comprehensive index system with greater systematicness and completeness.The mutual validation and adjustment of the results of the above-mentioned two evaluation methods indicate that the WRCC of the District of the Taihu Lake Basin is overloaded in general because some prefecture-level cities and city-level administrative divisions in the Taihu Lake Basin and the Southeastern River Basin are in a severely overloaded state.In order to explain this conclusion,this paper analyzes the causes of WRCC overloading from the aspects of basin water environment,water resources development and utilization,water resources regulation and control ability,water resources utilization efficiency,and water resources management.

考虑宏观结构性能的多材料微结构拓扑优化设计

多孔微结构材料以其质量轻、比刚度/比强度高、抗冲击等优异力学性能,被广泛应用于航空航天等工程领域。相比单一材料设计,多材料设计可获得力学性能更优的微结构拓扑构型。拓扑优化是实现多材料布局设计的有效方法之一。通过构建基于差集的多材料水平集描述模型和交替活动相算法,提出了基于参数化水平集的多材料微结构拓扑优化设计方法。首先,构建了基于差集的多材料水平集描述模型,利用N个水平集函数实现N+1相材料拓扑的精确描述。然后,引入交替活动相算法,将原始N+1相多材料优化问题分解为N(N+1)/2个双相材料优化子问题,以减少设计变量与约束条件,提高计算效率。最后,采用均匀化方法计算多材料微结构的等效弹性张量,以宏观结构柔度最小化为优化目标,各相材料用量为约束条件,构建多材料微结构拓扑优化模型,并利用优化准则法实现上述优化模型的高效求解。数值算例结果表明,所提方法可有效实现多材料微结构的拓扑优化设计,所设计微结构均具有光滑的结构边界和清晰的材料界面。

中国生态经济发展水平的统计测度

加强生态环境保护、推进生态文明建设可促进经济社会全面绿色转型,赋能生态经济高质量发展。文章选取2005—2021年我国30个省份的面板数据作为研究样本,构建了生态经济发展水平测度指标体系,并使用纵向拉开档次法、等距离划分法及TOPSIS模型对生态经济发展水平进行综合测度,为生态经济高质量发展提供数据支撑。研究结果显示:2005—2021年我国生态经济发展水平增速显著,生态经济取得较大发展成效;分维度来看,生态发展效益指数最高,生态投资次之,生态产出再次,生态环境水平增速相对缓慢。据此提出加大生态经济投资力度、提高生态经济产出效率、优化生态环境保护方式、强化生态效益发展根基的建议。

甲磺酸倍他司汀片结合活血化瘀法治疗感应神经性耳聋的临床探讨

目的研究甲磺酸倍他司汀片和活血化瘀法联合应用于感应神经性耳聋治疗中的临床疗效。方法选取2020年8月—2022年8月张家港市中医医院收治的48例感应神经性耳聋患者作为研究对象,按随机数表法分为两组,对照组(n=24)使用甲磺酸倍他司汀片治疗,观察组(n=24)使用甲磺酸倍他司汀片联合活血化瘀法治疗。比较两组患者的疗效和不良反应发生情况。结果治疗后,观察组的耳鸣评分(0.39±0.08)分、耳胀闷感评分(0.26±0.07)分、恶心呕吐评分(0.49±0.08)分以及眩晕评分(0.38±0.07)分均低于对照组,差异有统计学意义(t=25.648、25.390、14.176、26.301,P均<0.05);治疗后,观察组的听力测试值低于对照组,差异有统计学意义(P<0.05);两组患者的不良反应发生率对比,差异无统计学意义(P>0.05)。结论感应神经性耳聋患者应用甲磺酸倍他司汀片和活血化瘀法治疗可有效改善疾病症状,提升听力水平,且具有较高的安全性。

Impacts of climate change and human activities on water resources in the Ebinur Lake Basin, Northwest China

Changing climatic conditions and extensive human activities have influenced the global water cycle.In recent years,significant changes in climate and land use have degraded the watershed ecosystem of the Ebinur Lake Basin in Xinjiang,Northwest China.In this paper,variations of runoff,temperature,precipitation,reference evapotranspiration,lake area,socio-economic water usage,groundwater level and water quality in the Ebinur Lake Basin from 1961 to 2015 were systematically analyzed by the Mann-Kendall test methods(M-K)mutation test,the cumulative levelling method,the climate-sensitive method and land-use change index.In addition,we evaluated the effects of human activities on land use change and water quality.The results reveal that there was a significant increase in temperature and precipitation from 1961 to 2015,despite a decrease in reference evapotranspiration.The Wenquan station was not significantly affected by human activities as it is situated at a higher altitude.Runoff at this station increased significantly with climate warming.In contrast,runoff at the Jinghe station was severely affected by numerous human activities.Runoff decreased without obvious fluctuations.The contributions of climate change to runoff variation at the Jinghe and Wenquan stations were 46.87%and 58.94%,respectively;and the contributions of human activities were 53.13%and 41.06%,respectively.Land-use patterns in the basin have changed significantly between 1990 and 2015:urban and rural constructed lands,saline-alkali land,bare land,cultivated land,and forest land have expanded,while areas under grassland,lake,ice/snow and river/channel have declined.Human activities have dramatically intensified land degradation and desertification.From 1961 to 2015,both the inflow into the Ebinur Lake and the area of the lake have declined year by year;groundwater levels have dropped significantly,and the water quality has deteriorated during the study period.In the oasis irrigation area below the runoff pass,human activities mainly influenced the utilization mode and quantity of water resources.Changes in the hydrology and quantity of water resources were driven primarily by the continuous expansion of cultivated land and oasis,as well as the growth of population and the construction of hydraulic engineering projects.After 2015,the effects of some ecological protection projects were observed.However,there was no obvious sign of ecological improvement in the basin,and some environmental problems continue to persist.On this basis,this study recommends that the expansion of oasis should be limited according to the carrying capacity of the local water bodies.Moreover,in order to ensure the ecological security of the basin,it is necessary to determine the optimal oasis area for sustainable development and improve the efficiency of water resources exploitation and utilization.

考虑居民热负荷主动需求响应的园区综合能源系统分布式优化运行方法

主动需求侧响应(active demand response,ADR)不仅可降低综合能源系统运行和投资费用,还可应用其灵活性更多地消纳清洁间歇性可再生能源和降低碳排放。为深度挖掘居民热负荷动态特性所蕴含的灵活性ADR资源以及考虑用户隐私需要,该文通过对其进行精细化建模,提出了一种可适用于多用户的园区综合能源系统分布式优化运行方法。首先,对居民热负荷ADR资源进行精细化状态空间建模;其次,以此为基础,建立考虑居民热用户ADR的园区综合能源系统优化运行模型;然后,考虑用户隐私保护需要,提出基于交替方向乘子法将系统整体大规模优化问题解耦为供给侧和需求侧子问题后实现分布式精确求解;最后,通过对含128户居民用户的典型园区综合能源系统算例进行分析,验证了该文方法的有效性。

Active Contours and Mumford-Shah Segmentation Based on Level Sets

This paper is to detect regions (objects) boundaries, also to isolate and extract individual components from a medical image. This can be done using an active contours to detect regions in a given image, based on techniques of curve evolution, Mumford Shah functional for segmentation and level sets. The paper classified the images into different intensity regions based on Markov random field, then detected regions whose boundaries are not necessarily defined by gradient by minimizing an energy of Mumford Shah functional for segmentation which can be seen as a particular case of the minimal partition problem. In the level set formulation, the problem becomes a mean curvature flow like evolving the active contour, which will stop on the desired boundary. The stopping term does not depend on the gradient of the image, as in the classical active contour and the initial curve of level set can be anywhere in the image, and interior contours are automatically detected. The final image segmentation is one closed boundary per actual region in the image.

开关电容有源箝位型多电平逆变器的多电压区间调制方法及电容电压控制策略

针对一种开关电容有源箝位型(switched-capacitor active-neutral-point-clamped,SC-ANPC)多电平逆变器的冗余开关状态数量不足,造成电容电压平衡困难的问题,提出一种适用于该拓扑结构的多电压区间调制方法及电容电压控制方法,解决了现有调制方法计算复杂及开关频率受限的问题。首先分析了逆变器的工作原理,根据逆变器开关状态,提出了三电平区间开关状态组合模型,并设计了满足开关电容电压静态平衡约束条件的多电压区间载波移相调制方法。由于满足静态平衡条件,开关电容电压体积和纹波得到了减少,并且开关管的载波之间只有简单的移相关系,工程实现简单。在此基础上,扩展到三相系统,建立了电容电压的纹波模型,提出了相应的电容电压控制方法,通过调节占空比实现开关电容电压控制,注入零序电压实现母线电容电压控制。通过仿真和实验验证所提调制方法、控制方法的可行性。

基于有源中点钳位五电平电路的双有源桥DC/DC变换器

采用多电平电路构建的双有源桥(dual active bridge,DAB)DC/DC变换器可适用于更高的电压等级并能显著地提高功率密度及性能。基于九开关管五电平有源中点钳位(five-level active neutral point clamed,5L ANPC)电路构建DAB变换器,消除传统的八开关管5L ANPC电路所存在的电平跳变问题。通过分析开关状态之间的切换过程,选取的零开关状态实现所有高压开关管的软开关运行;通过分析不同开关序列对飞跨电容电压和直流侧中点电压的影响,提出一种飞跨电容电压的平衡控制方法。基于1kW样机的实验结果表明,该文构建的5L ANPC DAB变换器获得了优良的性能。

五电平有源钳位型变换器SVPWM死区效应分析与补偿方法研究

针对五电平有源钳位型变换器SVPWM调制的死区时间会导致跨电平跳变电压尖峰,产生过高的dv/dt影响系统稳定性的问题,提出一种不影响SVPWM调制效果的死区跨电平跳变补偿方法。首先对死区寄生模态导致电压误差的产生原理进行分析,列举了所有跳变过程中寄生电流的导通路径,采用在特定参考电压限定开关模态、筛选开关序列和脉冲调整等方法,重新规划电流导通过程,分类消除了跨电平跳变现象。最后搭建了实验样机,通过仿真和实验的手段对补偿方法进行了验证,对相同条件下的实验结果进行快速傅里叶对比分析,证明提出的死区补偿方法对输出电压谐波含量只产生了0.51%的微弱影响,且能有效消除跨电平跳变电压尖峰,表明该方法能维持五电平SVPWM良好的调制效果的同时,消除跨电平跳变隐患。

2022年我国城市建筑市场环境分析

基于各地级区划人民政府及其相关机构公开披露的信息和建设通的数据,对2022年我国地级行政区划的建筑市场环境进行了分析。分析内容包括:建筑市场风险指数、建筑市场开放指数、建筑市场竞争指数、建筑市场集中指数、民营建筑业企业活跃指数和建筑市场综合环境指数。同时,分别按6个指数,给出了表现较优的100个地级行政区划的位次,并进行了较优、较差的100个地级行政区划省域分布分析。

中国大陆成组强震活动水平的三分法及其应用

对中国大陆 1 9世纪末以来 ,M≥ 6.7成组强震活动的过程分析表明 ,可以将其活动水平分为三档 :高水平 ,中等水平和低水平强震活动期 ,它们分别对应每年平均发生大于 1 .2次、0 .6～ 1 .2次和小于 0 .6次的M≥ 6.7地震活动水平。活动过程的外推表明 ,2 1世纪的前 1 0年 ,中国大陆可能处于低水平的强震活动期 ,期中可能发生 5次 M≥ 6.7的强震 。

用于图像分割的自适应距离保持水平集演化

Li等人提出的距离保持水平集方法有传统变分水平集方法不具备的许多优点,然而,它有初始曲线必须包围目标物体或完全置于目标物体内部或外部的缺点.提出一种自适应距离保持水平集方法,它无须初始曲线包围目标物体或完全置于目标物体内部或外部,即初始曲线可以置于图像的任何地方.它能够解决原方法所不能解决的一些图像分割问题,例如,能够从任意选取的一条初始曲线出发自动检测目标物体的内外轮廓,检测多目标物体以及深度凹陷区域的边缘,并能较好地提取目标物体的弱边界.对几幅具有不同目标边界形态的合成图像和自然图像进行了实验,结果都取得了预期的分割效果.

边坡稳定验算中全面搜索的一种新方法

提出圆弧滑动法中一种新的搜索方法———三向搜索法。圆弧滑动法可以利用其共性而不局限于一些经验假设 ,在坡顶线及其下部各道坡线间都存在一个安全系数最小的圆弧 ,针对这些圆弧的寻找 ,给出了具体办法 ,并给出几个计算实例。

村级土地利用规划中的土地利用分区

为在村级土地利用规划中科学划分土地利用区,有效落实规划任务、实现规划目标,在分析村级土地利用规划特点的基础上,明确土地利用分区的任务与原则,探索建立了由产业功能区与土地用途区构成的两级分区类型体系,提出了公众参与为主、GIS技术为辅的分区方法。两级分区类型体系有利于实现土地组织利用、生产经营管理和土地利用管理的一体化。同时,在土地利用分区中贯穿公众参与式方法,有利于构建村内民主管理和业主参与土地利用管理的体制。

基于水平集方法的数字胸片图像分割

水平集方法能有效地解决曲线演化过程中的拓扑变化问题 ,基于全局特性的活动轮廓模型采用水平集方法给出的迭代解 ,能有效进行分割。用这种方法对 CR胸片图像进行分割研究 ,并根据 CR图像的特点 ,给出了只需一次演化的方法 :直接针对原图像可以得到肺部大致区域 ;而针对 CR的局部标准偏差图像可以得到肋骨的边缘图像。实验结果表明 ,该方法能很好地对

河北省新型城镇化水平综合评价与区划

国家经济不断发展,社会文明程度或水平、素养等日益提升,而且国家发展和社会文明与城镇化、工业化之间没有必然的因果关系。随着国家城镇格局变化,产业结构调整转型,会出现一些民生问题,因此,政府应当合理解决城镇化发展过程中出现的各种问题,保证城镇化的健康有序发展,为当地经济社会协调统一提供有力保障。文章以河北省市域为基本单元,在阐明河北省新型城镇化发展现状特征的基础上,运用AHP-熵值法从人口、经济、社会创新、居民生活、基础设施等方面,对其各个地级市的新型城镇化水平进行综合评价及现状诊断,并依据城镇化发展水平的格局差异,划分为高、中、中低及低水平四大城镇化水平类型区,并因地制宜指出具有地域差异化新型城镇化发展路径,旨在为河北省城镇化建设提供合理、科学的理论支持与决策依据,同时可为同类地区的新型城镇化发展提供借鉴。

数学基本活动经验主成分和层次水平划分研究

在文献分析和调查研究基础上,给出了数学基本活动经验构成要素的研究假设,通过自编测试卷进行题目测试,借助因素分析找出了数学基本活动经验的4个主成分,分别是归纳概括、类比推广、数学表达、证明;借助聚类分析得到数学基本活动经验的层次水平划分.

一种用于SAR图像分割的几何活动轮廓模型

基于SAR图像边缘检测算子和变分水平集方法,依据能量最小化准则,提出了一种新颖的几何活动轮廓模型。其基本思想是,直接定义关于水平集函数的能量泛函,并将经典模型中基于梯度算子的边缘指示函数,替换为基于ROEWA算子的边缘指示函数,提高了模型对于SAR图像的边缘检测能力;同时在新模型中加入水平集函数惩罚项,确保水平集函数逼近符号距离函数。由于该项的作用,模型的数值求解可采用简单的显式差分格式迭代,并保持较快的收敛速度。针对仿真图像、Radarsat和华东电子研究所实测数据的实验结果表明,该模型具有实现简单、分割边界定位准确和收敛速度较快等优点。