Ecological Optimization Design Methods for the Green Space System in Densely Built-up Areas

This paper is aimed at studying the environmental degradation of densely built-up areas in the process of urbanization in Qiina. In consideration of the severe environmental conditions of die densely built-up afeas, such as the lack of green space and. open space, ecological disturbance in some areas, poor landscape quality, this paper focused on the ecological space optimization in the process of urban renewal Firstly, theories related to this field were analyzed, and a comprehensive ecological efficiency evaluation sjrstem was established based on disciplines such as urban ecology, landscape ecology, urban sociology, behavioral psychology, biology, urban planning and design. Secondly, this system was used to judge the ecological efficiency of typical blocks on GIS platform and to find out the key spatial nodes that need to be updated. Thirdly, in different cases, space optimization projects witii different theories were designed, and the spatial model of influence was used to comprehensively evaluate their ecological efficiency. Finally, the parameters under different conditions were corrected to get a systematic system for evaluating the green space system in densely built-up areas＊ Due to the lack of undetstanding of the ecological fonction of green space in the past, die environmental condition of densely built-up areas is not good. Therefore, the most important task of urban oigauic renewal is ecological restoiation. In this paper, die exploiation is based on the reservation for built-up afeas to avoid repeated reconstruction and interference. Authors of this paper tried to find out a way to rebuild green space system that performed more complex functions with limited spatial resources. The application of “micfo-ttansfotmation” of green space system in densely built-up areas turns out to improve the quality of landscape while reducing the construction costrds

Assessment of Human Impacts on Vegetation in Built-up Areas in China Based on AVHRR,MODIS and DMSP_OLS Nighttime Light Data,1992–2010

Since the reform and opening-up program started in 1978,the level of urbanization has increased rapidly in China.Rapid urban expansion and restructuring have had significant impacts on the ecological environment especially within built-up areas.In this study,ArcGIS 10,ENVI 4.5,and Visual FoxPro 6.0 were used to analyze the human impacts on vegetation in the built-up areas of 656Chinese cities from 1992 to 2010.Firstly,an existing algorithm was refined to extract the boundaries of the built-up areas based on the Defense Meteorological Satellite Program Operational Linescan System(DMSP_OLS)nighttime light data.This improved algorithm has the advantages of high accuracy and speed.Secondly,a mathematical model(Human impacts(HI))was constructed to measure the impacts of human factors on vegetation during rapid urbanization based on Advanced Very High Resolution Radiometer(AVHRR)Normalized Difference Vegetation Index(NDVI)and Moderate Resolution Imaging Spectroradiometer(MODIS)NDVI.HI values greater than zero indicate relatively beneficial effects while values less than zero indicate proportionally adverse effects.The results were analyzed from four aspects:the size of cities(metropolises,large cities,medium-sized cities,and small cities),large regions(the eastern,central,western,and northeastern China),administrative divisions of China(provinces,autonomous regions,and municipalities)and vegetation zones(humid and semi-humid forest zone,semi-arid steppe zone,and arid desert zone).Finally,we discussed how human factors impacted on vegetation changes in the built-up areas.We found that urban planning policies and developmental stages impacted on vegetation changes in the built-up areas.The negative human impacts followed an inverted′U′shape,first rising and then falling with increase of urban scales.China′s national policies,social and economic development affected vegetation changes in the built-up areas.The findings can provide a scientific basis for municipal planning departments,a decision-making reference for government,and scientific guidance for sustainable development in China.

The Incorporation of Precautionary Principle in the Planning of Global System for Mobile Communications Mast Locations in Built-up Areas： Proposals for Jimeta, Nigeria

This paper aimed at incorporating the precautionary principles into the planning and development of GSM （global system for mobile communications） masts within the built-up areas of Jimeta. Using GIS （geographic information system） analysis technique, the zone of precautionary principle was defined to 500 meters radius as the zone within which precautionary measures are exercised. The criteria for siting GSM base station are also equally identified. For instance, the presence of certain elements within the precautionary zone like schools, hospitals, residential density and overlap of RF （radio frequency） occurrences, may disqualify any mast location. Analysis of the land use within precautionary zone has shown various proportions of exposure to RF, whereas, only 3.39% of the masts are suitably located and 94.92% are not and therefore should be relocated. The study recommend measures for addressing physical development within precautionary areas, including land conversion and mast sharing to reduce potential harmful effects of RF emanating from GSM base stations.

WCDMA Outdoor Antenna Selection for Dense Urban Areas

Interference control can be realized by selecting the antenna' s electrical and engineering parameters such as gain and radiation pattern, height, azimuth and downtilt to directly influence the field intensity distribution of radio signals and effectively and reasonably distribute the electro-magnetic energy. This paper discusses how to select an antenna for a densely populated urban area. The discussion is based on the simulation platform of ZTE ' s WCDMA planning system.

Examining Rate of Built-Up Areas on the Vegetation Cover along River Riara Riparian within Kiambu Town, Kenya

Urban river riparian spaces and their natural systems are valuable to urban dwellers;but are increasingly affected and ruined by human activities and in particular, urbanization processes. In this research, land sat and sentinel satellite imagery apt for change detection in vegetation cover, both landsat and sentinel imagery, covering the period between 1970 and 2021 in epochs of 1973, 1984, 1993, 2003, 2015 and 2021 years were used to establish the correlation between vegetation cover and built-up area along River Riara river reserve. The images were analysed to extract the built-up areas along the river reserve, including the buildings, and the rate of human settlements, which influenced vegetation cover. Normalized Difference Built-Up Index (NDBI) and Normalized Difference Vegetation Index (NDVI) were computed using the Short-Wave Infrared (SWIR) and the Near Infra-Red (NIR) bands to show the rate of change over the years. Results indicate NDVI values were high, compared to NDBI values along river Riara in the years 1973 and 1993 implying that there was more vegetation cover then. However, in the year 2021, the NDVI indicated the highest value at 0.88, with the complementary NDBI indicating the highest NDBI value at 0.47. This represents a significant increase in built-up areas since 2015 more than in previous epochs. Either, there was a significant increase in NDBI values, from 0.24 in 1993 to 0.47 in 2021. More so, the R-squared value at 0.80 informed 80% relationship between NDBI and NDVI values indicating a negative correlation.

Space-time Relationship Between Urban Municipal District Adjustment and Built-up Area Expansion in China

Municipal district adjustment and built-up area expansion are two main forms of urban spatial expansion. Using geometric methods, this study constructed a space-time path method to characterize the space-time relationship between municipal district adjustment and built-up area expansion, and drew the space-time path sets of major prefecture level cities from 2000 to 2010 by constructing a coordinate system of the standardized built-up areas and municipal district areas. This divided them into four quadrants, namely, H-H, L-H, L-L, and H-L, based on the relative mean value to evaluate overall and individual stability by three indexes of the trajectory vectors, namely, direction, length, and slope. Results provide the following conclusions. 1) Municipal district adjustment is an effective spatial expansion way for city-scale promotion in China. Since 2000, municipal district adjustments have been mainly distributed in the eastern coastal regions and mid-western capital cities along with their surrounding cities. 2) Municipal district adjustment affects the scale and status of a city in China. Many cities that have expanded municipal districts behave stably and cross quadrants. 3) Great majority second-tier cities have effectively promoted their scale and status through municipal district adjustment. The municipal district adjustment of medium and small cities in the mid-west area is relatively advanced compared with city development. 4) Municipal district adjustment with minimal magnitude is severely restricted from upgrading the scale and status of a city. The transformation from entirely incorporated counties or cities to municipal districts should be the mainstream in future municipal district adjustment.

Quantitative Analysis of Spatial Vitality of Urban Built-up Area: A Case Study of Shenzhen

As an important goal of urban design research,the evaluation of urban spatial vitality has been widely concerned.Taking Shenzhen as an example,the urban built-up area of Shenzhen was identifi ed using improved DENsi-Graph analysis,from the perspective of quantifi cation of urban spatial morphological features.The accessibility of urban streets,degree of construction and architectural form,and degree of functional mixing were quantitatively analyzed through space syntax,space matrix and mixeduse index(MXI),and the spatial vitality of urban built-up area was evaluated.Research results demonstrated that the improved Densi-Graph analysis could better identify the built-up area of Shenzhen,and the overall classifi cation accuracy was 0.810.The analysis results of spatial vitality showed that the urban spatial vitality in Shenzhen urban built-up area was well created.The street accessibility of Shenzhen generally hindered the creation of urban vitality;the spatial matrix value in the north of Shenzhen urban built-up area was lower;and the MXI of most areas within the study area was above the medium.

宽行密植模式对旱区黄冠梨根系构型的影响

【目的】筛选宽行密植栽培模式的适宜定植密度,为合理高效利用土壤资源和水肥精准化管理提供参考。【方法】以甘肃省干旱区不同宽行密植模式(株行距1.0 m×4.0 m、1.5 m×4.0 m、2.0 m×4.0 m)下的黄冠梨为研究对象,利用Win-RHIZO根系分析系统,对根系的构型参数进行测定,对比分析不同径级((φ>2 mm和φ≤2 mm))根系的分布与吸收范围,【结果】不同栽培模式下单位面积的群体数量的差异导致根系功能和结构的显著变化,0~20 cm土层是株行距1.0 m×4.0 m处理根系的集中分布区域,比根长、比根面积和总根体积均显著高于株行距2.0 m×4.0 m处理。在20~40 cm土层,株行距1.5 m×4.0 m处理的比根长较其他处理提升了3.7%~26.8%,第2年比根面积较株行距1.0 m×4.0 m处理提升了82.1%,株行距2.0 m×4.0 m处理根体积和根尖数量较株行距1.0 m×4.0 m处理分别提升了62.3%和34.2%。在40~60 cm土层,株行距2.0 m×4.0 m处理的比根长、比根面积、根长密度较株行距1.0 m×4.0 m处理最高分别增加了38.5%、95.5%和175.0%。栽植密度由大变小时,根系(φ>2 mm)集中分布现象逐渐减轻,水平分布扩展距离由近到远逐渐减小,且根系垂直与水平分布的差异减小。【结论】株行距1.0 m×4.0 m处理下细根(φ≤2 mm)分布离散度大,偏向性分布特点突出,垂直分布集中于表层土壤,根长、根表面积和根尖数量占比均超过50%,根系构型“浅表化”明显,株行距1.5 m×4.0 m处理细根的水平和垂直分布较均衡,但根长和根表面积均显著减小,吸收能力减弱,株行距2.0 m×4.0 m处理细根的分布明显向深层和离树干较远的区域扩展,根系的吸收能力显著增强,根系构型较好。

密井网区叠前高分辨率反演及其在薄储层预测的应用

针对大庆长垣油田密井网区SⅡ油层组陆相河流-三角洲相沉积微相类型变化快、井间厚度2 m以下的窄小河道砂体预测误差大、河道走向预测多解性强、砂体间连通关系判别差异性大等问题,以长垣油田A区块为例,开展叠前井控道集处理技术、基于改进的Xu-White岩石物理模拟技术、基于“波形指示马尔科夫链-蒙特卡洛”随机模拟算法的叠前波形指示反演技术研究。结果表明:研究区砂岩储层具有低纵波阻抗、低纵横波速度比值的特征,纵波阻抗为3.8~8.2 Gg/(m^(2)·s),纵横波速度比为1.7~2.1;随时砂岩厚度的增加,其纵波阻抗及纵横波速度比有减小的趋势。通过70口后验井的定量分析及评价,在密井网区叠前波形指示反演对厚度为[1,2)m的薄互层砂体识别精度为80.7%,对厚度大于等于2 m的砂体识别精度为85.1%。研究成果对河流―三角洲相薄储层开发方案的合理制定及措施调整具有指导意义。

川中中台山地区致密砂岩储层层序特征及有利区优选

川中中台山地区须三下亚段(须三下)层序构成差异性明显、河流相砂体横向变化较快,层序地层划分较为困难,进而影响优质储层的识别与刻画。为此,基于测井、录井和地震资料,分析中台山地区须三下层序特征,圈定不同朵页体的分布范围,对储层有利区进行优选。结果表明:川中中台山地区须三下地层沉积继承了须二上亚段的地层特征,为东南高西北低、洼中隆的缓坡古构造背景,共识别出3期层序界面和2期湖泛面;致密砂岩储层矿物组分主要为岩屑和长石,孔隙类型以溶蚀孔隙、微裂缝为主;岩性组合主要有厚层砂岩组合、厚层砂夹薄层泥岩组合和厚层泥夹薄层砂岩组合三大类;结合高产井具有断裂、裂缝、储层发育,位于构造相对高部位的特征,将研究区储层划分为3类有利区。研究成果可为后续的勘探开发提供重要参考和理论支撑。

密集城区深基坑工程施工安全管理研究--以某中医院工程为例

随着城市化进程的加速,高层建筑和地下空间的利用越来越普遍,深基坑工程也日益增多。而深基坑工程施工事故频发,且一旦发生事故,极易造成群死群伤,后果严重,究其原因,主要是相关管理经验不足,施工过程管理控制措施不到位。近10年来,深基坑开挖和支护成为国内岩土工程最为关注的问题之一。该文以某中医院工程为例,就深基坑的类型、适用范围及施工安全风险进行了剖析,并结合案例,总结了一些对于密集城区深基坑施工的安全管理经验,为类似工程提供参考。

城镇密集区公路桥群绿色建造创新探索

为提升城镇密集区公路绿色建造水平,结合南(沙)—中(山)高速的项目特点及工程需求,将绿色发展理念贯彻到公路设计、施工、运营、养护和管理的全寿命周期,重点研发了公路桥群工业化智能建造、公路资源综合利用、滨海湿地区公路环境保护与粤港澳大湾区交旅融合设计等四类十项创新技术。其中,预制梁环形生产线、非标准八车道等为项目特色首创技术,初步构建了典型城市群绿色桥群公路技术体系,并对未来重点发展方向进行了展望,以期丰富和完善粤港澳大湾区绿色公路技术体系,为其他高度城镇化区域可持续发展提供参考。

基于拐点密集区凹凸波动特性的直流配网故障检测方法

基于模块化多电平换流器(modular multilevel converter,MMC)的柔性直流配电网具有不存在换相失败等优点。但换流器存在低惯性、弱阻尼等特性,导致故障电流上升速度快且峰值高,对系统危害极大。针对直流配电网发生单极接地故障难以准确选择故障馈线的问题,提出了一种基于拐点密集区凹凸波动特性的直流配网故障检测方法。首先,利用变分模态分解算法对各馈线零模电流进行分解,选取特征分量。然后,计算特征分量的二阶导数,选择拐点密集区并进行归一化处理,得到各馈线的凹凸波动性。最后,判定凹凸波动性与其他馈线相异的线路为故障线路。仿真结果表明,所提方法能够快速识别故障馈线,且受过渡电阻、采样频率、数据窗和噪声等因素影响小。

绿洲灌区密植对氮肥减量玉米产量的补偿潜力

【目的】针对绿洲灌区玉米生产氮肥用量过高的问题,探究通过密植补偿氮肥减量对玉米产量负效应的可行性。【方法】2019—2021年,以施氮水平为主区,设地方习惯施氮(N_(2),360 kg·hm^(-2))、减量25%施氮(N_(1),270 kg·hm^(-2))两个水平;以种植密度为副区,设传统(M_(1),7.8万株/hm^(2))、中(M_(2),10.4万株/hm^(2),增密33%)、高(M3,12.9万株/hm^(2),增密66%)3个密度水平,进行裂区试验,重点研究氮肥减量条件下增密对玉米产量及其构成因素的影响。【结果】(1)氮肥减量导致玉米籽粒产量、生物产量分别降低4.0%、4.9%。减氮条件下,中密度可以产生籽粒产量补偿效应,N_(1)M_(2)较对照N_(2)M_(1)提高4.1%;高密度处理N_(1)M3生物产量补偿效应最大,较对照提高14.2%。(2)通过回归分析模拟得到:减氮条件下,当种植密度提高至8.4万株/hm^(2)可以与对照N_(2)M_(1)籽粒产量持平,并在10.6万株/hm^(2)时获得最大产量13537kg·hm^(-2),较对照提高4.9%。(3)氮肥减量引起穗数、穗粒数和千粒重分别降低5.0%、3.3%和3.4%;中、高密度分别较传统密度提高穗数27.9%、49.7%,降低穗粒数3.8%、8.4%,降低千粒重5.2%、8.9%。中密度较传统密度对收获指数无显著影响,而高密度使收获指数降低14.2%。N_(1)M_(2)较对照N_(2)M_(1)通过穗数增加补偿了减氮引起穗数、穗粒数及千粒重的下降,从而实现丰产。(4)氮肥减量降低拔节期至抽雄吐丝期的玉米生长率7.2%—8.4%;中、高密度较传统密度提高苗期至大喇叭口期玉米生长率27.3%、60.3%。(5)氮肥减量条件下,N_(1)M_(2)较对照提高叶、茎和鞘干物质转运量达9.6%、13.6%和3.7%,提高叶和茎对籽粒产量的贡献率5.3%和9.0%。【结论】通过合理密植可以补偿减氮引起的玉米产量下降,在施氮量270 kg·hm^(-2)的基础上增密至10.4万株/hm^(2),能够最大化产量补偿效应,是绿洲灌区玉米节氮稳产丰产的可行措施。

多视觉传感器协同弱小目标检测

多视觉传感器协同对空实现全区域覆盖的弱小目标检测,在近距离防空领域中具有重要意义。现有的全区域覆盖方法存在覆盖率低、随机性差等问题,弱小目标检测算法存在模型大、定位及分类准确性低等问题。提出了一种高效的对空全区域覆盖算法和轻量级弱小目标检测算法,通过结合最大面积优先法和最小曼哈顿离法改善存在覆盖死角和随机性差等问题。提出密集通道扩展网络(dense and channel expand network,DCENet)模型,基于轻量级稠密拼接和自适应尺寸通道扩展方法,在弱小目标数据集上获得了比原算法更有竞争力的平均精度结果。

通州—三河地区沉积层高分辨率三维S波速度结构和径向各向异性

北京大都市区位于冀中凹陷与太行山隆起和燕山褶皱带的交汇区,区内被第四系松软沉积层覆盖,历史和现今的地震活动性表明,其面临潜在的巨震风险.地震风险评估和强地面运动模拟依赖准确的沉积层三维S波速度模型.本文基于布设在通州—三河地区前所未有的密集台阵数据,构建了该区域高分辨率三维S波速度结构和径向各向异性模型.首先将919个台站组成的密集台阵划分为若干子台阵,利用修正的背景噪声聚束分析方法,提取各个子台阵的Love波频散曲线,通过深度反演构建了通州—三河地区三维SH波速度模型.结合由基阶和一阶Rayleigh波模式反演构建的三维SV波速度模型,获得了台阵下方的径向各向异性模型.模型显示,大兴断裂在穿过牛堡屯之后,继续向北东向延伸约20 km.大兴凸起以大兴断裂为界,表现出明显不同的构造特征和沉积过程.断裂的北西侧第四系沉积层较浅,推测约为100~400 m;断裂的南东侧第四系沉积层厚度横向变化较大,发育夏垫凹陷和甘棠凹陷.沉积盆地径向各向异性的幅度可达±20%,地表约0~60 m范围有一较强的负径向各向异性(VSH<VSV)覆盖层,推测与该地区垂直地裂缝发育有关.正的径向各向异性(VSH>VSV)是沉积作用造成的水平层序排列的沉积分层的反映.

晋城市不同区域洪涝驱动要素分析

兼顾城市不同空间特征的内涝问题,是提升城市防洪排涝能力的关键.本文以晋城市主城区为例,针对不同开发程度的管网密集区与管网稀疏区2类下垫面,构建SWMM-ICM-WCA2D模型,模拟不同降雨情景下管网排水与地表淹没状态,分析城市内涝驱动要素.结果表明:管网密集区的内涝积水主要受降雨强度、管网排水能力和地形特征的影响,主城区现状管网设计标准较低,5 a一遇降雨条件下排水容量已趋于饱和;管网稀疏区高程≤751 m的淹没区水深较大,其余高程大的区域积水深度较小而流速较大;不同降雨情景下,管网指标与淹没要素间均表现出较强的相关性,特别在高水深(>1 m)时的联系更为密切,相关系数>0.78.

分段多簇密切割压裂技术在淮南矿区煤层气抽采中的应用

针对淮南矿区碎软低渗煤层瓦斯抽采技术难题,以13-1煤层为例,在分析煤层及其顶底板概况的基础上,采用煤层顶板分段压裂水平井技术,充分利用水平井水平段,单段分3簇射孔,簇间距25 m,实现分段多簇密切割体积压裂改造。微地震监测结果表明,单段裂缝长度102.5~211.4 m,缝高17.3~27 m,裂缝主体向下延伸,实现了井筒与煤层的沟通。排水采气效果表明,最高产气量1519 m^(3)/d,取得了良好的产气效果。研究成果为淮南矿区煤层气地面预抽和瓦斯区域治理提供了工程借鉴。

基于叠覆朵体模式的厚层三角洲前缘砂体精细刻画——以大庆油田杏六中区PⅠ油层组为例

为了厘清大庆油田杏六中区PⅠ油层组厚层三角洲前缘砂体的内部结构特征,为剩余油开发提供地质支撑,文中针对按照水下分流河道模式无法精细刻画目标砂体的问题,引入叠覆朵体模式,提出六步剖析法,依据密井网资料,对目标砂体的内部结构进行了精细刻画。结果表明:1)按照叠覆朵体模式,能够较清楚地刻画目标砂体的内部结构特征。2)运用六步剖析法(即确定标志层,划分等时地层单元;进行底拉平处理,认识等时地层单元内砂体的内部结构特征;识别较大的沉积界面,区分并追踪复合朵体;在复合朵体内识别单朵体,刻画其分布;分析朵体间接触关系,确定朵体间连通性;结合生产动态资料,验证剖析结果的正确性),对目标砂体的刻画结果打破了三角洲前缘砂体呈层状结构的传统认识。3)目标砂体内部可以以进积、退积特征划分为一系列的沉积复合朵体和单朵体。按照叠覆朵体模式,运用六步剖析法对砂体内部结构的刻画结果,避免了传统的基于相带的砂体结构剖析法中跨沉积时间单元所造成的对砂体内部结构认识的偏差,为剩余油分析提供了可靠的依据。