Efficient building facade structure extraction method using image-based laser point cloud

Facade structures from three-dimensional (3D) point cloud data (PCD) and two-dimensional (2D) optical images can provide significant information for 3D building modeling. However, a unified data model for integrating 2D imagery pixels and 3D PCD is absent in current methods, leading to a complex implementation process, large calculations, and inefficiency. An efficient facade structure extraction method for building facades is proposed in this study. Based on the conversion matrix, 2D image and 3D PCD information are merged to build an image-based laser point cloud (ILPC) data model first. Second, both the line segment detection and random sample consensus algorithms are improved according to the structure and characteristics of the ILPC data model. Finally, building facade structures are extracted and optimized. Facade structures can be extracted accurately and efficiently by the proposed method, which contains rich information support from the ILPC data model. The proposed method extracts fine building facade structures with accuracy over 0.68 in all experiments and recall up to 0.81, which are better than the Wang method. Extracted structures constitute valuable support for numerous fields, such as 3D building modeling and building information modeling construction.     

微塑料添加对小麦苗期生长及干物质分配的影响

土壤环境中微塑料污染已成为全球关注的环境问题。关于微塑料对于植物生长的直接影响和由于土壤理化性状改变的间接影响研究已逐步开展,但针对小麦的研究鲜见报道。试验选择两个旱地小麦品种(甘春27和禾尚头)作为研究对象,选取高密度聚乙烯作为微塑料添加,设置3种质量浓度(0、1、4 g·kg^-1)开展盆栽试验,对不同微塑料组合处理下小麦的出苗率、株高、全株生物量和地上/地下干物质分配进行了分析。结果表明：(1)微塑料添加对两个品种出苗率没有影响。(2)禾尚头在添加1 g·kg^-1微塑料时比添加0、4 g·kg^-1时全株生物量分别高46.7%、8.5%,甘春27在添加1 g·kg^-1微塑料时比添加0、4 g·kg^-1时全株生物量分别高28.7%、17.2%;甘春27整体比禾尚头在3种浓度处理下全株生物量分别高24.9%、9.6%、1.5%。(3)不同试验处理条件下,甘春27将更多的干物质分配在地上植株的构建,其在地下(根系)和地上(茎叶)部分的分配比例整体小于禾尚头。整体上,适度微塑料添加可...     

九江市蓼花剖面末次冰期中晚期沉积的粒度端元特征与气候变化

鄱阳湖湖滨地区广泛分布着晚第四纪风沙沉积序列。在星子县沙岭沙山进行野外调查后选择蓼花剖面开展工作,测试了地质时代和粒度,对粒度结果使用端元分析模型进行研究,探讨该区域末次冰期中晚期的气候变化规律。结果显示：该剖面由湖相-古土壤-沙丘砂等沉积相叠覆堆积组成,形成于末次冰期中晚期（48.8—17.1 ka）。端元分析模型将粒度数据分解出3个不同的粒度端元,不同端元组分在垂向上呈峰谷交替的旋回变化,EM1代表粉砂端元组分,峰值对应湖相和古土壤发育时期;EM2和EM3代表中砂—粗砂端元组分,峰值对应沙丘砂发育期,这些峰谷交替变化的规律指示了末次冰期的季风演变以及气候波动变化,万年尺度上表现为LH10 (48.8—39.9 ka)和LH3～LH5 (28.1—17.1 ka)的冬季风强盛期,分别对应深海氧同位素的MIS3b和MIS2阶段。LH6～LH9 (39.9—28.1 ka)为温暖的夏季风时期,对应深海氧同位素的MIS3a阶段。这些变化与YZ洞石笋氧同位素以及格陵兰冰心有良好的对应,与全球气候变化基本一致。     

Effects of oxytetracycline dihydrate and sulfamethoxazole on Microcystis aeruginosa and Chlamydomonas microsphaera

The increasing use of pharmaceuticals has become a major environmental issue in China.The presence of antibiotics in water may have deleterious effects on non-target aquatic organisms such as microalgae.In this study,a cyanobacterium and an alga species in surface waters,Microcystis aeruginosa and Chlamydomonas microsphaera,were exposed to 0,0.1,0.5,1.0,2.0,5.0,10.0,and 20.0 mg/L of oxytetracycline dihydrate(OXY) and sulfamethoxazole(SMZ) for 96 h to determine the effects of these antibiotics on the growth and surface morphology.Moreover,the photosynthetic activity and the contents of superoxide dismutase(SOD),malondialdehyde(MDA),and protein were measured to examine the biochemical characteristics of M.aeruginosa and C.microsphaera under OXY and SMZ stress.The effects of both antibiotics on the growth of both species were concentration-dependent and characterized by low-dose stimulation and high-dose inhibition.C.microsphaera was more sensitive to both antibiotics than M.aeruginosa was.The algal cell membranes of both species disintegrated after exposure to a high concentration of OXY.All of the physiological parameters measured in this study were relatively stable at low concentrations of OXY and SMZ.After exposure to high concentrations of OXY and SMZ,photosynthetic activity decreased significantly,whereas lipid peroxidation and the abundance of SOD,MDA,and protein increased significantly.Thus,low-dose antibiotics may increase algal blooms in eutrophic waters.     

Three-dimensional mesoscale eddy identification and tracking algorithm based on pressure anomalies

Journal of Oceanology and Limnology - The Kuroshio Extension (KE) is one of the most eddy-energetic regions in the global ocean. However, most mesoscale eddy studies in the region are focused on...     

Changes in Land Use and Agricultural Production Structure Before and After the Implementation of Grain for Green Program in Western China–Taking Two Typical Counties as Examples

Soil erosion becomes a serious environmental problem in the world, especially in western China. An effective management practice called the Grain for Green Program （GGP）, which was launched in 1999, aims to reduce soil and water loss and alleviate the ecological environment problem in western China. Two typical counties in western China, the Zhongxian （in Chongqing Municipality） and Ansai （in Shaanxi Province） were chosen to evaluate the dynamic changes of land use and agricultural production structure before and after the implementation of the Program in this paper. The results showed that the cultivated land area was reduced by 7.08% from 1989 to 2003. The cultivated land per person was decreased by 8.42% during 1999-2003. Moreover, the stability index of the secondary sector of the economy was increased from 0.91 in the period 1990-1999 to 0.94 in the following ten years. In addition, the stability index of tertiary economic sector increased from 0.88 to 0.92 in Zhongxian county. Meanwhile, the cultivated land area was reduced by 15.48% from 1990 to 1999. The soil erosion modulus was decreased by 33.33% from 1999 to 2006. Also, the stability index of secondary and tertiary economic sectors was 0.86 in the period 1998-2002. However, it decreased by 77% during 2002 to 2007 in Ansai County. These results imply that the Grain for Green Program had different impact on the two regions. Several effective strategies of soil and water conservation have been carried out to ameliorate the sustainable development of ecological environment and economy in these two counties of western China.     

汉江上游3200-2800aBP特大古洪水重建研究(英文)

Palaeoflood hydrology study is a leading subject in global change study. Through field investigation in the upper reaches of Hanjiang River, palaeoflood slackwater deposits(SWD) were found in the bedrock gorges of the Yunxi reach. The results of field observation, laboratory analysis including particle-size distribution and magnetic susceptibility, and comparison with modern flood deposits, the SWD were identified as the most typical Holocene palaeoflood deposits of the Hanjiang River. By using stratigraphic correlation and OSL dating method, the palaeoflood event was dated to be 3200–2800 a BP at the turn from the middle to late Holocene. According to the palaeoflood peak stage and hydraulic parameters, the peak discharges of the palaeoflood were reconstructed as 48,830–51,710 m3/s by using the slope-area method. At same time, the flood peak discharges of 1983, 2005 and 2010 severe floods were reconstructed with the same method and hydraulic parameters in the same cross section. The error between the reconstructed and gauged discharges was 1.99%–4.21%. This showed that the reconstructed palaeoflood peak discharges were reliable. The flood peak discharge-frequency relationship at 10,000-year time scale was established by a combination of the gauged flood, historical flood and palaeoflood hydrological data. These results are very important for hydraulic engineering and flood mitigation on the Hanjiang River.     

不同生境下红砂(Reaumuria soongorica)的生理生化特征及适应性

测定了荒漠地区超旱生小灌木红砂在3种生境(山前荒漠、山前戈壁和中游戈壁)下的叶片水分状态、抗氧化酶活性及渗透调节物质含量,以探讨荒漠植物在不同生境下的生理生化特征及对荒漠极端环境的适应机制。结果表明:在3种生境下,红砂叶片相对含水量和叶片水势随着土壤含水量的下降而下降,叶绿素含量随着土壤含水量的下降而升高。随着生境土壤干旱的加剧,超氧化物歧化酶(SOD)及过氧化物酶(POD)活性逐渐升高,而过氧化氢酶活性下降。在土壤含水量较少的戈壁生境,渗透调节物质含量上升。SOD和POD活性的升高是红砂抵御干旱环境的主要抗氧化保护机制;渗透调节在红砂叶片适应干旱胁迫的过程中发挥着重要作用,高的渗透调节能力使红砂在水分不足的条件下维持较低的渗透势,有利于植物吸水,从而增强其耐旱性。     

南极普里兹湾可培养浮游细菌群落结构研究

针对南极普里兹湾内达恩利角附近海域的3个测站共12份海水样品,采用寡营养培养基分离培养极地浮游细菌,通过PCR方法获取其中95株细菌的16S rRNA基因序列。序列分析结果表明,分离获得的95株细菌分属α-变形杆菌纲(Alphaproteobactia)、γ-变形杆菌纲(Gammaproteobacteria)和拟杆菌门(Bacteroidetes)3个类群下的35个不同分类单元,其中α-变形杆菌纲为优势细菌,在不同水层中所占的比例为52.6%—62.5%。通过Shannon多样性指数分析发现,南极普里兹湾陆架区测站P2-14多样性指数较陆坡区两测站P2-11和P2-8的高,细菌多样性与浮游植物量和生产力水平呈现正相关。表层细菌Shannon多样性指数最低,50 m水层最高,100和200 m水层多样性指数变化不明显,真光层水体中细菌垂直分布与营养盐和溶解氧浓度存在关联。此外,采用寡营养陈海水培养基,还获得了一些与已报道的16S rRNA基因序列相似性较低的菌株,它们代表了微生物新物种,可能也是南极真光层特有的细菌。研究工作表明,南极普里兹湾真光层水体中蕴藏着丰富的浮游细菌资源,它们有待保护、开发和利用。     

A new insight into land use classification based on aggregated mobile phone data

Land-use classification is essential for urban planning. Urban land-use types can be differentiated either by their physical characteristics (such as reflectivity and texture) or social functions. Remote sensing techniques have been recognized as a vital method for urban land-use classification because of their ability to capture the physical characteristics of land use. Although significant progress has been achieved in remote sensing methods designed for urban land-use classification, most techniques focus on physical characteristics, whereas knowledge of social functions is not adequately used. Owing to the wide usage of mobile phones, the activities of residents, which can be retrieved from the mobile phone data, can be determined in order to indicate the social function of land use. This could bring about the opportunity to derive land-use information from mobile phone data. To verify the application of this new data source to urban land-use classification, we first construct a vector of aggregated mobile phone data to characterize land-use types. This vector is composed of two aspects: the normalized hourly call volume and the total call volume. A semi-supervised fuzzy c-means clustering approach is then applied to infer the land-use types. The method is validated using mobile phone data collected in Singapore. Land use is determined with a detection rate of 58.03%. An analysis of the land-use classification results shows that the detection rate decreases as the heterogeneity of land use increases, and increases as the density of cell phone towers increases.