Rock mechanical characteristics and landscape evolutionary mechanism of the slit-type Danxia landform on the Chinese Loess Plateau

Since 2015,the newly discovered slit-type Danxia landform on the Chinese Loess Plateau has become a hot topic in the field of geomorphology worldwide.However,the relationships among its formation,evolutionary mechanism,and mechanical characteristics of its strata and rocks are not clear.In this paper,the Ganquan canyon group is used as the research object.Basic physical and mechanical indices of sandstone in the Ganquan canyon group were measured through field investigation and indoor experiments,and the deterioration trends for the mechanical parameters of sandstone in this area under the action of infiltration,acid dry-wet cycles,and freeze-thaw cycles were revealed.Lastly,the formation and evolutionary mechanism of the slit-type Danxia landform were discussed.The results showed that:(1)The sandstone in the canyon group had a low cementation degree and weak cohesive force,which was easily weakened under the action of water,resulting in a decrease in compressive strength and elastic modulus.(2)Acidic dry-wet cycles caused the mineral composition of the sandstone to be dissolved,and the micropores continued to grow and develop until new cracks were produced.Macroscopically,the compressive strength and elastic modulus of sandstone were greatly reduced,and this damage was cumulative and staged.The greater the acidity,the greater the damage.(3)As the number of freeze-thaw cycles increased,the uniaxial compressive strength and elastic modulus of the sandstone decreased continuously.During the freeze-thaw cycle process,the growth and development of cracks were primarily in fracture mode and usually developed along parallel bedding positions.(4)The interaction of tectonic activity and lithology with different weathering processes was a key factor in the formation and evolution of the slit-type Danxia landform.In conclusion,the intricate process of weathering influenced by historical climatic fluctuations has been pivotal in shaping the topography of Danxia landform.

基于α-shape与SSA-XGBoost算法的无人机点云孔洞修补

针对极限梯度提升树算法在进行无人机点云孔洞修补时核心超参数难以选取、点云孔洞修补范围识别困难以及孔洞修补精度较低等问题,提出基于麻雀搜索算法优化极限梯度提升树的点云孔洞修补方法。首先利用α-shape算法进行点云的孔洞识别,在此基础上,获取点云孔洞和周围点云的位置信息并将其作为模型的输入样本。再利用麻雀搜索算法优化极限梯度提升树算法中的核心超参数,构建SSA-XGBoost点云孔洞修补模型,并将该模型应用于无人机点云孔洞的修补中。最后将SSA-XGBoost与XGBoost、BP神经网络两组算法进行预测精度的对比。实验结果表明:SSA-XGBoost模型的预测结果相较于其它两组对比算法预测精度更高,在点云孔洞修补方面具有一定的意义。

Evaluation of “J”-shaped Uterine Incision during Caesarean Section in Patients with Placenta Previa:A Retrospective Study

This study evaluated the efficacy and safety of ＂J＂-shaped uterine incision for caesarean section for patients diagnosed with placenta previa. A total of 55 consecutive cases of placenta previa treated in Union Hospital were retrospectively analyzed over a period of two years and 10 months. The subjects were divided into two groups with respect to the uterine incision. Twenty-four pregnant women with placenta previa who were indicated for caesarean section underwent the procedure using a new ＂J＂-shaped uterine incision and 31 pregnant women with placenta previa received caesarean section that used the traditional transverse incision. The two groups were compared in terms of operation time, estimated blood loss, infant expulsion time, exhaust time and postoperative recovery. Meanwhile, comparison was also made in neonatal clinical data between the two groups. Compared with the ＂J＂-shaped incision group, the traditional incision group had a lower Apgar scores （P〈0.05）. However, there existed no statistically significant differences in the overall time of operation and postoperative period of breaking wind （P〉0.05）. It is concluded that, with caesarean section for placenta previa patients, the ＂J＂-shaped uterine incision significantly decreases intraoperative blood loss and facilitates the fetal delivery.

Shortening turn-on delay of SiC light triggered thyristor by7-shaped thin n-base doping profile

A new 4 H–SiC light triggered thyristor（LTT） with 7-shaped thin n-base doping profile is proposed and simulated using a two-dimensional numerical method. In this new structure, the bottom region of the thin n-base has a graded doping profile to induce an accelerating electric field and compensate for the shortcoming of the double-layer thin n-base structure in transmitting injected holes. In addition, the accelerating electric field can also speed up the transmission of photongenerated carriers during light triggering. As a result, the current gain of the top pnp transistor of the SiC LTT is further increased. According to the TCAD simulations, the turn-on delay time of the SiC LTT decreases by about 91.5% compared with that of previous double-layer thin n-base SiC LTT. The minimum turn-on delay time of the SiC LTT is only 828 ns,when triggered by 100 mW/cm^2 ultraviolet light. Meanwhile, there is only a slight degradation in the forward blocking characteristic.

Ground fissure development regularity and formation mechanism of shallow buried coal seam mining with Karst landform in Jiaozi coal mine: a case study

A comprehensive study was undertaken at Jiaozi coal mine to investigate the development regularity of ground fissures in shallow buried coal seam mining with Karst landform,shedding light on the development type,geographical distribution,dynamic development process,and failure mechanism of these ground fissures by employing field monitoring,numerical simulation,and theoretical analysis.The findings demonstrate that ground fissure development has an obvious feature of subregion,and its geographical distribution is significantly affected by topography.Tensile type,open type,and stepped type are three different categories of ground fissure.Ground fissures emerge dynamically as the panel advances,and they typically develop with a distance of less than periodic weighting step distance in advance of panel advancing position.Ground fissures present the dynamic development feature,temporary fissure has the ability of self-healing.The dynamic development process of ground fissure with closed-distance coal seam repeated mining is expounded,and the development scale is a dynamic development stage of“closure→expansion→stabilized”on the basis of the original development scale.From the perspective of topsoil deformation,the computation model considering two points movement vectors towards two directions of the gob and the ground surface is established,the development criterion considering the critical deformation value of topsoil is obtained.The mechanical model of hinged structure of inclined body is proposed to clarify the ground fissure development,and the interaction between slope activity and ground fissure development is expounded.These research results fulfill the gap of ground fissures about development regularity and formation mechanism,and can contribute to ground fissure prevention and treatment with Karst landform.

Learning curve for a surgeon in robotic pancreaticoduodenectomy through a“G”-shaped approach:A cumulative sum analysis

BACKGROUND Robotic pancreaticoduodenectomy(RPD)can achieve similar surgical results to open and PD;however,RPD has a long learning curve and operation time(OT).To address this issue,we have summarized a surgical path to shorten the surgical learning curve and OT.AIM To investigate the effective learning curve of a“G”-shaped surgical approach in RPD for patients.METHODS A total of 60 patients,who received“G”-shaped RPD(GRPD)by a single surgeon in the First Hospital of Shanxi Medical University from May 2017 to April 2020,were included in this study.The OT,demographic data,intraoperative blood loss,complications,hospitalization time,and pathological results were recorded,and the cumulative sum(CUSUM)analysis was performed to evaluate the learning curve for GRPD.RESULTS According to the CUSUM analysis,the learning curve for GRPD was grouped into two phases:The early and late phases.The OT was 480±81.65 min vs 331±76.54 min,hospitalization time was 22±4.53 d vs 17±6.08 d,and blood loss was 308±54.78 mL vs 169.2±35.33 mL in the respective groups.Complications,including pancreatic fistula,bile leakage,reoperation rate,postoperative death,and delayed gastric emptying,were significantly decreased after this surgical technique.CONCLUSION GRPD can improve the learning curve and operative time,providing a new method for shortening the RPD learning curve.

A Novel Open C-shaped Molar Band for Orthodontic Applications： Mechanical Characterizations and Clinical Trials

To evaluate the retention properties of the novel ‘C＇-shaped molar bands at a laboratory level. Resin-modified glass ionomer cement（RMGIC） was used as a luting agent for the novel C-shaped molar band. The mechanical properties of the band were examined and the retention performance was characterized in the mesial, distal and vertical directions. A clinical trial was conducted using a spilt-mouth design on 50 patients. The novel C-shaped molar bands fit most molars without a repeated try-in process.The use of both nanoHA coating and RMGIC enhanced the tensile（8.00 ± 1.8 MPa） and shear strengths（27.17 ± 8.6 MPa） of the molar bands, leading to high retention in vertical, mesial and distal directions（ p 〈 0.001）. In clinical trials, the C-shaped molar bands had a failure rate（15%） comparable to that of traditional bands, and 93% of the failed bands demonstrated an adhesive remnant index score of 0, corroborating the observation that no luting agent residue remained on the tooth surface in most cases. The novel C-shaped molar bands appear to be a promising appliance that requires further clinical investigations, and may be used effectively in orthodontics.

Natural Walls of Anatolia: formation and development of Diş Kayalıkları as a structural landform (Sivas, Türkiye)

The Diş Kayalıkları is one of the largest and most striking examples of crests in the world and is located between Eskidere and Boğazören villages of the İmranlı district of the Sivas province in Turkey. The crests, which resemble castle walls when viewed from afar, have a real wall pattern due to the right-angled crack system of the bedrock when viewed closely. This study aims at investigating the geomorphological features of the Diş Kayalıkları and determining how the geological and geomorphological evolution of the Diş Kayalıkları took place and how the current formation mechanism continues. In the region, the mid-latitude continental climate prevails with cold humid winters and warm dry summers. The bedrock consists of Miocene bedded deposits of different resistance, folded by young tectonic movements. Diş Kayalıkları was formed by selective erosion of less resistant terrain around a pack of resistant rock on the steeper southern slope of an asymmetrical anticline. It has a length of 4750 m in the approximately northwest-southeast direction, a maximum height of 30 m, and a width varying between 5 and 8 m. In the present morphological appearance of the Diş Kayalıkları, it can be stated that the structure formed after the tectonic formation process was eroded under the control of the local climate and crest formation was realized. In the following process, the crest experienced a polycyclic process where different landforms were formed. There are smaller landforms such as karren, cave and rock window on Diş Kayalıkları, and macrofossil beds in some places. This highly attractive geomorphosite, unknown to wider public, should be investigated from various scientific aspects and should be brought to regional tourism by making the necessary infrastructure and promotion studies.

Hierarchical pattern recognition of landform elements considering scale adaptation

Landform elements with varying morphologies and spatial arrangements are recognized as feature indicator of landform classification and play a critical role in geomorphological studies.Differential geometry method has been extensively applied in prior landform element research,while its efficacy in differentiating similar morphological characteristics remains inadequate to date.To reduce reliance on geomorphometric variables and increase awareness of landform patterns,geomorphons method was generated in previous study corresponding to specific landform reclassification map based on lookup table.Besides,to address the problem of feature similarity,hierarchical classification was proposed and effectively utilized for terrain recognition through the analytical strategy of fuzzy gradient features.Thus,combining the advantages of these two aspects,a hierarchical framework was proposed in this study for landform element pattern recognition considering the morphology and hierarchy factors.First,the local triplet patterns derived from geomorphons were enhanced by setting the flatness threshold,and subsequently adopted for the primary landform element recognition.Then,as geomorphic units with the same morphology possess different spatial analytical scales,the unidentified landform elements under the principle of scale adaptation were determined by calculating the spatial correlation and entropy information.To ensure the effectiveness of this proposed method,the sampling points were randomly selected from NASADEM data and then validated against a real 3D terrain model.Quantitative results of landform element pattern recognition demonstrate that our approach can reach above 77%average accuracy.Additionally,it delineates local details more effectively than geomorphons in visual assessment,resulting in a 7%accuracy improvement in overall scale.

江西丹霞地貌演化阶段与分布及其构造控制探讨

晚白垩世至古近纪期间,江西省内沿区域性断裂构造发育30余个断陷盆地,沉积了巨厚的红色陆相碎屑岩,为丹霞地貌的形成提供了物质基础。已发现的228处丹霞地貌点主要分布于江西东部武夷山北麓和西麓的红层盆地内。利用面积—高程积分法,对江西省9个盆地的丹霞地貌演化阶段进行了定量分析,结果表明省内丹霞地貌景区的面积—高程HI为0.17~0.52,平均为0.38,即其演化阶段处于壮年晚期至老年早期,在空间分布上具有由南向北,由壮年期转为老年期的趋势。该趋势可能与武夷山的构造隆升有关。构造分析显示,节理与武夷山的隆升对江西丹霞地貌演化起控制作用,具体表现为:(1)龙虎山、九仙湖、仙岩、蛤蟆坞、赭亭山、龟峰等地发育的崖壁、一线天、巷谷、石墙、石寨、峰丛、峰林等丹霞典型景观均与节理有关。(2)流水侵蚀等外营力的作用对丹霞地貌的剥露、削平起重要作用,统计表明距离武夷山越近,丹霞地貌山峰越密集、崖壁越陡峻,指示武夷山的隆升与丹霞地貌的发育有直接关系。总体来看,江西省内的红层为丹霞地貌的发育提供了物质基础,武夷山的隆升控制了丹霞地貌的分布。值得注意的是,丹霞地貌区的节理构造是否与武夷山的隆升存在直接因果关系还需进一步研究。

基于井震融合的碳酸盐岩古岩溶残丘储层刻画方法

北大港构造带千米桥奥陶系潜山顶部发育的碳酸盐岩古岩溶残丘作为一种重要的古地貌和油气储集单元,具备良好的成藏条件,有效地刻画古岩溶残丘储层对于残丘储层的油气运移聚集分析及勘探开发有着非常重要的意义。本文首先应用地震印模法对千米桥奥陶系潜山风化壳岩溶古地貌进行精细刻画,揭示该区发育5个岩溶残丘,4个岩溶沟谷,表现为山上有山的特征;同时井震融合分析认为潜山风化壳储层大多分布在风化壳面以下0~200 m范围内,主潜山各区块风化壳残余厚度差别较大,岩溶残丘之上构造高点残余厚度大。通过成像测井和常规测井曲线上异常显示识别残丘风化壳内幕发育的岩溶洞穴,主要有大溶洞和中小溶蚀孔洞两种。应用提频地震体开展正演模拟,明确优势缝洞体储层的地震反射特征,结合张量方向场裂缝定量预测技术,能精细地预测碳酸盐岩缝洞复合体储层,以指导残丘风化壳储层油气潜力目标区的评价开发。

广东韶关丹霞山生态系统多样性及其空间定位

丹霞山复杂地形地貌塑造了很高的生态系统多样性和复杂的景观多样性,全面的系统分类、空间定位和生态系统类型描述对该区域的生态特征研究具有重要意义。本研究基于IUCN全球生态系统分类框架,结合植被类型和特殊地形地貌特征,对韶关丹霞山国家级自然保护区全境的生态系统类型进行研究,并利用遥感数据与实地调查数据,对各级生态系统进行空间定位和可视化制图。结果显示:(1)该保护区生态系统类型可划分为81类,包括3个I级类型、6个Ⅱ级类型、12个Ⅲ级类型、28个Ⅳ级类型和81个Ⅴ级类型;(2)除空间定位与格局分析外,特别对丹霞山的4个大类的特色生态系统进行了单独的空间展示,包括用面来展示的山顶生态系统23类和沟谷生态系统13类,用点来代表的洞穴生态系统4类,用线来代表崖壁生态系统4类。本研究关于生态系统类型的划分及空间定位,揭示了丹霞山地区的独特地形地貌特征和生态系统多样性特征,深化了丹霞山生态系统多样性和形成机制的理解,结果可为开展生态系统保护和管理提供重要的参考。

塔河油田走滑断裂与古岩溶耦合关系研究及其对奥陶系储层发育的影响

走滑断裂与古岩溶作用耦合关系方面的研究报道较少。本文通过对TH12518走滑断裂在奥陶系一间房组地层内构造样式时空叠加改造特征和不同期岩溶作用的研究,明确不同期次走滑断裂内幕结构与古地貌、古水系间的耦合关系。在TH12518走滑断裂在多期构造活动改造下,一间房组地层构造样式多次差异叠加,形成5种分段类型:Ⅰ型,拉分+平移+拉分段;Ⅱ型,拉分+平移+平移段;Ⅲ型,平移+挤压+拉分段;Ⅳ型,平移+挤压+平移段;Ⅴ型,逆冲推覆改造段。即加里东中期Ⅰ~Ⅲ幕形成平移段和拉分段;加里东晚期形成平移+挤压段、拉分+平移段、逆冲推覆段3种样式;海西早期发生“弯曲效应”,形成平移+挤压+平移段、拉分+平移+平移段、平移+挤压+拉分段、拉分+平移+拉分叠加构造样式。不同期岩溶地貌差异大。加里东中期Ⅰ幕岩溶台地水系欠发育;加里东中期Ⅱ-Ⅲ幕,北部抬升形成岩溶准平原,南部岩溶斜坡区发育近南北向地表水系及暗河;加里东晚期,岩溶斜坡区发育多组水系,沿北东东向断裂新形成北东东向暗河和地表水系。海西早期,岩溶斜坡发育大型曲流河。一间房组地层在不同岩溶期,不同区域不同类型段的岩溶作用不同。加里东中期Ⅰ幕整体发育开发式裸露型岩溶,沿断裂带下渗溶蚀,北北东向断裂拉分段溶蚀较强。加里东中期Ⅱ-Ⅲ幕北部发育开发式裸露型岩溶,南部为半开放式承压型岩溶,拉分段溶蚀进一步增强,Ⅱ幕还发育“下降型”埋藏断控岩溶。加里东晚期发育开发裸露型岩溶、半开放承压岩溶和“下降型”埋藏断控岩溶,北部受岩溶基准面控制,向下在寒武系顶面白云岩岩性界面岩溶作用受阻。南部不受基准面控制,向下至少溶蚀至寒武系阿瓦塔格组顶面,纵向上岩溶缝洞体分层明显。海西早期,发育半开放式承压型岩溶,除弯曲效应拉分段外,岩溶作用较弱。在空间上存在某一区域储层由某一期或多期关键岩溶期和关键岩溶方式控制决定,如覆盖区加里东中期Ⅱ幕“下降型”埋藏断控岩溶作用是奥陶系一间房组顶面缝洞型储层形成的关键因素。研究成果有助于为滚动开发实践提供地质依据。

使用虚拟现实技术提高冰川地貌表达维度的研究

冰川侵蚀与堆积地貌含有重要的古气候、古环境信息,是鉴别冰川作用范围和性质的标志,也是冰川动力学研究的基础。冰川地貌的表达研究经过150多年的发展,已经形成了较完备的冰川地貌制图方案,为冰川形成过程、冰川类型及冰川作用的动力学特征判断提供了重要依据。然而,冰川地貌专题图的专业性为古冰川重建和古环境研究提供支撑的同时,也提高了非专业人士的解读难度。以虚拟现实/增强现实地图、混合现实地图、微地图、语义地图和隐喻地图等的泛地图表达机制提供了更多维度的表达方案,在传统的空间几何维度的基础上增加了状态和读图者视角等维度,为冰川地貌表达提供了新的视角。本文使用虚拟现实(virtual reality,VR)技术构建了卡若拉冰川西沟的交互式三维冰川地貌场景,增加了三维、动态和读图者视角等表达维度。通过前期研究工作基础(沉积物特征、测年等工作)对场景内典型的冰川地貌进行标注,将前期冰川地貌的研究认识与VR场景进行较好的对应。该场景可以720°自由变换,包含末次冰盛期-晚冰期、早全新世、新冰期、小冰期和现代冰川共40个分场景,可以激发读图者的沉浸感、交互感和构想感。VR等技术对冰川地貌进行泛地图式的更多维度表达,可以为冰川地貌教学、科普及学术交流提供良好的交互式三维冰川地貌素材,也可以辅助读者更加准确地判别冰川遗迹和认知冰川发育条件。

峨眉山玄武岩与台状山地地貌

广泛分布于云、贵、川三省的二叠纪至三叠纪的峨眉山玄武岩是我国唯一被国际学术界认可的大火成岩省。其中,晚二叠世地幔柱活动喷发形成的峨眉山玄武岩面积达26万km2,形成了风光旖旎多彩地貌,是国内潜在的宝贵旅游资源之一。其中扬子板块西沿陆相喷发的“厚层”以钙碱性玄武岩、致密性和杏仁状构造玄武岩为主,形成了北起瓦屋山,南到大山包独特的桌山式玄武岩和斜台式玄武岩台状山地,是国内可贵的旅游地貌资源。在此,初步揭示峨眉山玄武岩台状地貌的特征,提出峨眉山玄武岩台状地貌在旅游资源的重要性,以期引起学者们对这一宝贵旅游资源的进一步研究与重视。

塔河油田良里塔格组迷宫型岩溶洞穴系统发育特征

为了明确塔河油田上奥陶统良里塔格组迷宫型岩溶洞穴系统的样式和结构,利用古地貌恢复、古水系刻画、测井地层对比、构造断裂解析、地震属性刻画等方法,进行了塔河油田11区的古水文地貌恢复、岩溶层组格架构建、岩溶洞穴识别和成因模式分析。结果表明:塔河油田南部加里东运动中期Ⅱ幕古地貌西北高、东南低,发育北北西—南南东向树枝状地表深切沟谷,良里塔格组发育近水平状分布、闭合管道结构及溶蚀强度较高的迷宫型岩溶洞穴系统;良里塔格组岩溶洞穴系统与澳大利亚Judbarra地区Bullita洞穴系统成因相似,属于典型的表生岩溶扩散下渗型迷宫型岩溶洞穴系统;上奥陶统恰尔巴克组泥岩段为隔水层,控制了良里塔格组迷宫型岩溶洞穴系统的侧向溶蚀作用;沟通地表水系的断裂为岩溶水主要下渗溶蚀通道,随着区域基准面下降,岩溶水沿断裂下渗进入中奥陶统,中奥陶统一间房组形成断溶体。塔河油田加里东运动中期Ⅱ幕表生岩溶“双层”迷宫型岩溶洞穴系统的认识对上奥陶统油藏开发具有重要意义。

基于正负地形的喀斯特地貌分类研究——以贵州喀斯特区为例

地形因子具有直观性、可视性,常被作为喀斯特地貌分类的主要依据。已有关于喀斯特地貌分类研究所用的地形因子较多且复杂,分类特征不易被公众学习和理解,导致成果的应用和推广难度较大。因此以贵州喀斯特区为研究对象,运用地形开度法和随机森林模型,筛选重要性正负地形指标,探讨喀斯特地貌分类方法。结果表明:1)贵州喀斯特区的蚕食度均值为1.35,深切度均值为215.36 m,平均粗糙度比均值为1.01,负地形面积大于正地形面积,正负地形不规则且破碎度较大,正地形被沟谷深切明显,地貌的异质性强烈。2)蚕食度和深切度2个指标的重要性指数分别为0.93和1.16,能较好地反映喀斯特地貌的差异性。3)根据蚕食度和深切度贵州喀斯特地貌分为23类,分类精度优良达93.33%。在不同的喀斯特地貌区,因为蚕食度和深切度不同,导致水、土、光、热资源丰度不同,因而它们的土地利用方式各异。研究简化了分类判别喀斯特地貌的地形指标,降低了公众对喀斯特地貌的认识和理解难度,并为数字地形技术在喀斯特地貌分类中的推广应用提供参考。

声学探测技术在海上风电桩基检测中的应用

海上风机维护是保障海上风电场正常运行的重要工作,水声学海底探测方法在海上风电场运维中的应用越来越广泛。提出在风电桩基检测中综合使用多波束测深仪、侧扫声纳、浅地层剖面仪的联合探测作业技术,利用多波束获取全覆盖水深地形,利用侧扫声纳获取海底地貌,利用浅地层剖面仪获取海缆埋藏状态,通过对3类声纳数据综合分析,确定风电桩基及附近地形、地貌、电缆等的位置、深度、状态等信息。将该方法应用于阳江风电场故障风机抢修项目中,验证了方法的有效性。实践表明:该方法可以广泛应用于海上风电桩基检测等海洋工程领域,对其他海上风电场桩基检测有一定借鉴意义。

基于多尺度半耦合卷积稀疏编码的遥感地貌影像纹理识别方法

遥感地貌影像通常包含大量的数据,具有高度的复杂性和多样性,难以捕捉到不同层次的纹理信息,从而影响识别效果;因此,为提高纹理特征提取的效果,确保识别精度,采用多尺度半耦合卷积稀疏编码对遥感地貌影像纹理识别进行了研究;去除遥感地貌影像噪声,增强遥感地貌影像整体质量,通过分水岭算法分割遥感地貌影像,探究不同尺度下遥感地貌影像纹理特征区别,以有效捕捉到不同层次的纹理信息,提高遥感地貌影像纹理的识别性能;然后应用灰度共生矩阵(GLCM)获取遥感地貌影像的多尺度纹理特征,构建半耦合卷积稀疏编码模型,完成多尺度纹理特征提取过程的学习与多尺度纹理特征的有效融合,以能够在保持特征丰富性的同时,减少冗余信息,提高纹理识别的准确性;选取适当的分类器——朴素贝叶斯分类器,并对其进行训练;并以此为基础,制定遥感地貌影像纹理识别程序,执行制定程序即可获取地貌纹理识别结果;测试结果显示:应用提出方法获得的遥感地貌影像处理结果清晰度与对比度较高,地貌纹理特征提取结果更加完整与清晰,地貌纹理识别结果与实际结果一致,充分证实了提出方法应用效果更好。

贵州喀斯特地貌地区GNSS站坐标时间序列特性研究

使用GAMIT/GLOBK10.71软件解算贵州省北斗卫星导航定位基准站网(GZCORS)25个基准站数据,获得各站单天解坐标时间序列。利用主成分分析法提取站坐标共模误差,利用谱分析法分析共模误差基本特性,采用极大似然估计法确定站点最优噪声模型及其运动速度。结果表明,GZCORS坐标序列共模误差中包含有周期项,N方向最大振幅周期分别出现在0.2周/a、1.2周/a、3.2周/a和4.2周/a;GZCORS站点最优噪声模型以WN+FN和WN+GM为主,剔除共模误差后,36%的测站分量噪声特性发生变化;剔除共模误差后,坐标时间序列噪声水平明显降低,各坐标分量速度参数的估计精度均有明显提升,其中N、E、U分量分别提高52%、56%和50%。