基于IV-MLP耦合模型的龙陵县滑坡易发性评价

滑坡易发性评价模型会直接影响到研究结果准确性,为探究不同耦合模型对滑坡易发性分析的影响,以云南省龙陵县为研究区,共选取高程、坡度、工程岩组等8个因子构建滑坡易发性评价体系,引入多层感知器方法(MLP)与信息量模型(IV)耦合以开展滑坡易发性评价,与传统信息量-逻辑回归模型(IV-LR)进行分析比较,并通过AUC值进行精度验证。结果表明:IV-MLP模型、IV-LR模型及IV模型的AUC值分别为0.862、0.813与0.799。IV-MLP耦合模型AUC值高于IV-LR耦合模型,MLP模型在与IV模型进行滑坡易发性耦合分析中表现更优秀;IV-MLP、IV-LR耦合模型的AUC值分别高于单一IV模型0.063、0.014,对滑坡进行易发性分区时耦合模型较单一模型效果更佳。研究结果能够为龙陵县滑坡易发性评价提供科学的理论依据,并为该地区的防灾工作提供参考。

Inverse reliability analysis and design for tunnel face stability considering soil spatial variability

The traditional deterministic analysis for tunnel face stability neglects the uncertainties of geotechnical parameters,while the simplified reliability analysis which models the potential uncertainties by means of random variables usually fails to account for soil spatial variability.To overcome these limitations,this study proposes an efficient framework for conducting reliability analysis and reliability-based design(RBD)of tunnel face stability in spatially variable soil strata.The three-dimensional(3D)rotational failure mechanism of the tunnel face is extended to account for the soil spatial variability,and a probabilistic framework is established by coupling the extended mechanism with the improved Hasofer-Lind-Rackwits-Fiessler recursive algorithm(iHLRF)as well as its inverse analysis formulation.The proposed framework allows for rapid and precise reliability analysis and RBD of tunnel face stability.To demonstrate the feasibility and efficacy of the proposed framework,an illustrative case of tunnelling in frictional soils is presented,where the soil's cohesion and friction angle are modelled as two anisotropic cross-correlated lognormal random fields.The results show that the proposed method can accurately estimate the failure probability(or reliability index)regarding the tunnel face stability and can efficiently determine the required supporting pressure for a target reliability index with soil spatial variability being taken into account.Furthermore,this study reveals the impact of various factors on the support pressure,including coefficient of variation,cross-correlation between cohesion and friction angle,as well as autocorrelation distance of spatially variable soil strata.The results also demonstrate the feasibility of using the forward and/or inverse first-order reliability method(FORM)in high-dimensional stochastic problems.It is hoped that this study may provide a practical and reliable framework for determining the stability of tunnels in complex soil strata.

密度调控对杉木人工林林分特征的影响

以洪雅林场杉木人工林为研究对象,研究密度调控对杉木林分生长、植物多样性、林分结构的影响。结果表明:杉木人工林分经密度调控后,低密度经营有利于林分的胸径、树高、材积加快生长,也能使树干更饱满,但不利于林分自然整枝;适宜的林分经营密度(750株·hm-2)能够增加灌草层的物种丰富度,而林分密度过高(1200株·hm-2)或过低(550株·hm-2)均降低了灌草层的物种丰富度,不利于林下植被演替发育;低经营密度林分的灌木和草本植物的物种多样性指数和均匀度指数都高于高经营密度林分,低经营密度林分使林下植物的群落复杂程度和物种个体分配均匀度更优异;随着林分经营密度的增大,林分中的大径级植株的比例逐步降低;合理密度(750株·hm-2)有利于林分树高生长;低经营密度有利于培育大径材植株,而高经营密度有利于培育中小径材植株。

山地灾害防治GIS思政教学案例库构建

深化高等教育改革,全面提高人才培养素质是建设人才强国的迫切需要,将思想政治教育内容融入高校理工科大类专业课程体系是其一项重要的改革目标.高校教师工作不应局限于传道授业解惑,更应迎合时代的趋势,将思政教育融入课堂,以专业知识为内容,结合道之以德、齐之以礼的教学形式,在培养过硬的专业素养的同时,真正让学生做到有耻且格.本文以GIS专业为例,结合地质灾害主题,致力于建设GIS思政案例库.案例库通过梳理知识讲授与思政教育的结合点,大力推动以"课程思政"为目标的课堂教学改革,基于课程本身内容的不同特点,在每个合理切入点中穿插思政教育,引领学生对课程本身所蕴含的思政教育元素进行思考;基于本校地学人才培养特色、针对学生思想特点,从案例库的教学设计、实施方案和平台支持等几方面探讨对GIS专业课开展思政教育的路径和具体举措.

基于主客观赋权法的城市生态环境评价

针对目前的城市生态环境评价体系复杂多变、评价指标选取混乱、移植性较差等问题,基于层次分析法和变异系数法相结合的主客观赋权法构建起具有较强通用性的城市生态环境评价体系和评价模型,并利用该模型对天府新区成都直管区进行了城市生态环境评价。结果表明:该区域城市生态环境等级整体较好,生态环境等级为较好、好、一般的面积占总面积的71.07%,主要分布在直管区中部和南部区域;而等级为较差和差的面积占总面积的28.93%,集中分布于直管区西北部和东部边界区域。该评价法对于城市环境评价精度较高,评价体系及模型简洁实用,为城市生态环境评价提供了新的思路。

一种改进的三维地质体模型存储与重构方法

目前,在不同的三维地质建模软件下建立的模型无法在统一的场景中集成显示和分析应用,数据交换共享难,数据存储量普遍较大。在现有的建模方法下,三维地质体的布尔运算比较困难。因此探索一种存储量小、易于数据共享交换与空间分析的三维存储方法是当前趋势。基于空间位置枚举法提出了一种存储量小、易于数据共享交换与空间分析的三维存储和重构方法。首先用任意已建好的地质模型建立栅格金字塔加快显示速度;在此基础上对地质模型进行剖分生成剖分长方体,再将剖分长方体存储成六位编码;最后对六位编码进行三维重构,利用Open GL技术基于VC++平台进行三维重绘。计算了重构模型的均方根误差(RMSE),其平均值为0. 39。实验结果表明:此存储与重构的方法是可行的,对减少三维地质体模型存储量、数据的迁移共享交换有一定的价值。

面向输变电工程三维设计模型整合研究

针对输变电工程三维设计模型的多源、异构和模型整合应用所导致仿真系统设计难度大且数据管理和共享困难,而目前相关研究较少的问题,提出了一种面向输变电工程三维设计模型流程化整合方案。该方案基于SuperMap10平台和行业通用格式,采用模型层级分类、三维缓存技术、几何细节层次(levels of detail, LOD)优化体系和纹理优化等方法,设计出面向不同特性的三维设计模型与GIS数据融合方案。实验结果表明,该方案能在保证模型坐标系、属性和语义完整的同时,将不同三维模型格式的电力模型进行了统一,将有利于电力仿真系统的设计实现和进行电力数据协同分析;结合数据实际情况分析,对模型顶点和面进行针对性优化方法,使表面模型的数据量下降95%左右,并采用LOD模型构建和对场景进行三维缓存切片来控制场景性能,渲染时间较优化前减少约1倍;利用GIS软件二次开发接口,实现方案的流程化处理,大大减少了传统模式所需的人力资源。

基于移动GIS的农村资源信息管理系统设计与实现

在政府大力推进"三农"问题解决的背景下,针对传统农村资源信息管理系统无法提供实时、便捷、可移动的地理空间信息服务现状,本文运用"移动互联网+三农"的新农村建设模式,综合移动GIS技术、地图切片技术、数据库技术初步设计了基于移动终端的农村资源信息管理系统。该系统采用了在线/离线的地图服务模式,实现了村组人口、经济、区域现状概况统计,民房住建、水利、学校等农村基础设施可视化地图查询,地理空间数据及属性数据采集、删除、修改及GPS定位功能,为地级政府在新农村政务规划中提供了一种可行的方法。

Effect of 2D spatial variability on slope reliability: A simplified FORM analysis

To meet the high demand for reliability based design of slopes, we present in this paper a simplified HLRF(Hasofere Linde Rackwitze Fiessler) iterative algorithm for first-order reliability method(FORM). It is simply formulated in x-space and requires neither transformation of correlated random variables nor optimization tools. The solution can be easily improved by iteratively adjusting the step length. The algorithm is particularly useful to practicing engineers for geotechnical reliability analysis where standalone(deterministic) numerical packages are used. Based on the proposed algorithm and through direct perturbation analysis of random variables, we conducted a case study of earth slope reliability with complete consideration of soil uncertainty and spatial variability.

基于随机森林的成都市2015—2020年土地利用变化检测

土地利用变化检测对于合理地组织土地利用、国土空间规划和城市可持续发展等具有重要意义。鉴于成都市新一轮城市总体规划“一山连两翼”(以龙泉山为界,西部为中心城市,东部塑造产业新城)建设目标逐步实施,对土地利用类型的变化影响较大。基于此,本研究以成都市为研究区,以2015年和2020年Landsat-8遥感影像作为数据源,在GEE平台上对数据预处理,采用随机森林算法和众数滤波处理实现土地利用分类和精度评价。结果表明,2015年和2020年数据Kappa系数和总体精度均分别在0.75和80.00%以上,同时浅析成都市2015—2020年土地利用类型变化主要原因,为成都市城区发展提供合理的参考规划。

Discrete element modeling on the crack evolution behavior of brittle sandstone containing three fissures under uniaxial compression

Based on experimental restilts of brittle, intact sandstone under uniaxial compression, the micro-parameters were firstly confirmed by adopting particle flow code （PFC2D）. Then, the validation of the simulated models were cross checked with the experimental results of brittle sandstone containing three parallel fissures under uniaxial compression. The simulated results agreed very well with the experimental results, including the peak strength, peak axial strain, and ultimate failure mode. Using the same micro- parameters, the numerical models containing a new geometry of three fissures are constructed to investigate the fissure angle on the fracture mechanical behavior of brittle sandstone under uniaxial compression. The strength and deformation parameters of brittle sandstone containing new three fissures are dependent to the fissure angle. With the increase of the fis- sure angle, the elastic modulus, the crack damage threshold, and the peak strength of brittle sandstone containing three fissures firstly increase and secondly decrease. But the peak axial strain is nonlinearly related to the fissure angle. In the entire process of deformation, the crack initiation and propagation behavior of brittle sandstone containing three fissures under uniaxial compression are investigated with respect to the fissure angle. Six different crack coalescence modes are identified for brittle sandstone containing three fissures under uniaxial compression. The influence of the fissure angle on the length of crack propagation and crack coalescence stress is evaluated. These investigated conclusions are very important for ensuring the stability and safety of rock engineering with intermittent structures.

Spatial variability effect of internal friction angle on the post-failure behavior of landslides using a random and non-Newtonian fluid based SPH method

This study proposed a random Smoothed Particle Hydrodynamics method for analyzing the post-failure behavior of landslides,which is based on the Karhunen-Loeve(K-L) expansion,the non-Newtonian fluid model,and the OpenMP parallel framework.Then,the applicability of this method was validated by comparing the generated random field with theoretical result and by simulating the post-failure process of an actual landslide.Thereafter,an illustrative landslide example was created and simulated to obtain the spatial variability effect of internal friction angle on the post-failure behavior of landslides under different coefficients of variation(COVs) and correlation lengths(CLs).As a conclusion,the reinforcement with materials of a larger friction angle can reduce the runout distance and impact the force of a landslide.As the increase of COV,the distribution range of influence zones also increases,which indicates that the deviation of influence zones becomes large.In addition,the correlation length in Monte Carlo simulations should not be too small,otherwise the variation range of influence zones will be underestimated.

An efficient probabilistic design approach for tunnel face stability by inverse reliability analysis

In order to maintain the safety of underground constructions that significantly involve geo-material uncertainties,this paper delivers a new computation framework for conducting reliability-based design(RBD)of shallow tunnel face stability,utilizing a simplified inverse first-order reliability method(FORM).The limit state functions defining tunnel face stability are established for both collapse and blow-out modes of the tunnel face failure,respectively,and the deterministic results of the tunnel face support pressure are obtained through three-dimensional finite element limit analysis(FELA).Because the inverse reliability method can directly capture the design support pressure according to prescribed target reliability index,the computational cost for probabilistic design of tunnel face stability is greatly reduced.By comparison with Monte Carlo simulation results,the accuracy and feasibility of the proposed method are verified.Further,this study presents a series of reliability-based design charts for vividly understanding the limit support pressure on tunnel face in both cohesionless(sandy)soil and cohesive soil stratums,and their optimal support pressure ranges are highlighted.The results show that in the case of sandy soil stratum,the blowout failure of tunnel face is extremely unlikely,whereas the collapse is the only possible failure mode.The parametric study of various geotechnical uncertainties also reveals that ignoring the potential correlation between soil shear strength parameters will lead to over-designed support pressure,and the coefficient of variation of internal friction angle has a greater influence on the tunnel face failure probability than that of the cohesion.

Polyoxometalates-engineered hydrogen generation rate and durability of Pt/CNT catalysts from ammonia borane

Heterogeneously catalyzed hydrolytic dehydrogenation of ammonia borane is a remarkable structure sensitive reaction. In this work, a strategy by using polyoxometalates(POMs) as the ligands is proposed to engineer the surface and electronic properties of Pt/CNT catalysts toward the enhanced hydrogen generation rate and durability. Three kinds of POMs, i.e., silicotungstic acid(STA), phosphotungstic acid(PTA)and molybdophosphoric acid(PMA), are comparatively studied, among which the STA shows positive effects on the catalytic activity and durability. A catalyst structure-performance relationship is established by a combination of kinetic and isotopic analyses with multiple characterization techniques, such as HAADF-STEM, EDS, Raman spectroscopy and XPS. It is shown that the STA compared to the other two POMs can increase the Pt binding energy and thus promote the reaction. The insights demonstrated here could open a new avenue for boosting the reaction by employing the POMs as the ligands to engineer the catalyst electronic properties.

Emerging pro-drug and nano-drug strategies for gemcitabine-based cancer therapy

Gemcitabine has been extensively applied in treating various solid tumors. Nonetheless,the clinical performance of gemcitabine is severely restricted by its unsatisfactory pharmacokinetic parameters and easy deactivation mainly because of its rapid deamination, deficiencies in deoxycytidine kinase (DCK), and alterations in nucleoside transporter. On this account, repeated injections with a high concentration of gemcitabine are adopted, leading to severe systemic toxicity to healthy cells. Accordingly, it is highly crucial to fabricate efficient gemcitabine delivery systems to obtain improved therapeutic efficacy of gemcitabine. A large number of gemcitabine pro-drugs were synthesized by chemical modification of gemcitabine to improve its biostability and bioavailability. Besides,gemcitabine-loaded nano-drugs were prepared to improve the delivery efficiency. In this review article, we introduced different strategies for improving the therapeutic performance of gemcitabine by the fabrication of pro-drugs and nano-drugs. We hope this review will provide new insight into the rational design of gemcitabine-based delivery strategies for enhanced cancer therapy.

17-4PH不锈钢在不同浓度HCl环境中的电化学腐蚀行为

为了探明17-4PH不锈钢在HCl溶液中的腐蚀行为,采用动电位极化和电化学阻抗测量了其在不同浓度HCl溶液中腐蚀性能,通过扫描电镜(SEM)、能谱(EDX)和X射线光电子能谱(XPS)等技术研究了锈层对腐蚀行为的作用机制。结果表明:17-4PH不锈钢在HCl溶液中随着HCl浓度的增大,腐蚀电流密度(J corr)增大,锈层电阻和电荷转移电阻减小;当HCl浓度超过10%,腐蚀电流密度快速增加,15%HCl溶液中的J corr比10%的增加1倍多。基于此,提出了2种不同的等效电路对17-4PH不锈钢的电化学阻抗谱进行了拟合。HCl溶液浓度小于等于10%时,17-4PH试样表面具有双锈层结构,其中,Cu元素富集在外层结构中;而浓度大于10%时为单一锈层结构。锈层的不同结构是腐蚀机制和性能产生差异的原因。

不同覆盖模式对毛竹林出笋的影响

通过对毛竹林开展传统促笋覆盖(糠壳+鸡粪+稻草,记作F1),两种新型覆盖(糠壳+鸡粪+高粱秆、竹酒糟+鸡粪+高粱秆,分别记作F2和F3),以及不覆盖(对照,F0)的对比试验,分析了相应的发笋历程、笋体大小及单位面积产量和产值,结果表明:1)3种覆盖模式不同程度地促进了毛竹笋早出,F2和F3模式效果好于F1,3者在3月20日前出笋的比例分别较对照多出约20%、18%和4.5%;2)就同期笋高而言,仅F2、F3显著大于对照,F1的影响不明显,但3种模式均显著地增加了毛竹笋基径;3)尽管F1对笋早出和个体大小的促进作用不突出,单位面积出笋数量却远较其他模式大。毛竹林采用F1、F2和F3模式后,笋产量分别可达对照的2.5倍、1.9倍和1.6倍,收益则分别为对照的2.5倍、2.2倍和1.8倍。建议在山区毛竹林笋用经营中,就地取用农林废料实施覆盖是可行的,既节约成本和增加收益,又利于资源的循环利用。

Electrospun fiber membrane with asymmetric NO release for the differential regulation of cell growth

The high incidence of cardiovascular disease has led to significant demand for synthetic vascular grafts in clinical applications.Anti-proliferation drugs are usually loaded into devices to achieve desirable anti-thrombosis effects after implantation.However,the non-selectiveness of these conventional drugs can lead to the failure of blood vessel reconstruction,leading to potential complications in the long term.To address this issue,an asymmetric membrane was constructed through electro-spinning techniques.The bilayer membrane loaded and effectively released nitric oxide(NO),as hoped,from only one side.Due to the short diffusion distance of NO,it exerted negligible effects on the other side of the membrane,thus allowing selective regulation of different cells on both sides.The released NO boosted the growth of endothelial cells(ECs)over smooth muscle cells(SMCs)-while on the side where NO was absent,SMCs grew into multilayers.The overall structure resembled a native blood vessel,with confluent ECs as the inner layer and layers of SMCs to support it.In addition,the membrane preserved the normal function of ECs,and at the same time did not exacerbate inflammatory responses.By preparing this material type that regulates cell behavior differentially,we describe a new method for its application in the cardiovascular field such as for artificial blood vessels.

42CrMo连铸辊堆焊层的组织结构与性能演变规律

采用埋弧堆焊工艺对42CrMo连铸辊的表面进行1层430合金和2层414N合金焊材堆焊。通过堆焊层的成分分析、组织观察和维氏硬度测量,计算合金元素的稀释率和烧损率,研究连铸辊堆焊层的组织演变、合金成分分布与硬度之间的关系。结果表明:430合金焊丝堆焊、第1层414N合金焊丝堆焊和第2层414N合金焊丝堆焊的稀释率分别为27.3%,22.3%和12.5%,Cr元素的烧损率分别为1.17%,1.55%和0.82%;堆焊42CrMo连铸辊沿径向由心部到硬面层可分为42CrMo基体、热影响区、过渡层、430堆焊层、414N堆焊内层和414N堆焊外层的结构;42CrMo连铸辊经埋弧堆焊后可获得厚度约3 mm、成分适中、硬度均匀的硬面层,硬面层组织为细小的板条马氏体。

Evaluation of the bone metabolism balance and traumatic reaction of minimally invasive mippo intramedullary nail internal fixation treatment of femoral shaft fractures

Objective:To evaluate the bone metabolism balance and traumatic reaction of minimally invasive mippo intramedullary nail internal fixation treatment of femoral shaft fractures. Methods:80 patients with femoral shaft fractures who were treated in our hospital between May 2011 and December 2016 were collected and divided into control group (n=40) and observation group (n=40) according to random number table, control group received conventional steel plate internal fixation treatment, and observation group received minimally invasive mippo intramedullary nail internal fixation treatment. Differences in serum levels of bone formation indexes, bone resorption indexes, inflammatory factors, and pain mediators and so on were compared between two groups of patients before operation and 1 week after treatment.Results: Before operation, differences in serum levels of bone formation indexes, bone resorption indexes, inflammatory factors and pain mediators were not statistically significant between two groups of patients. After operation, serum bone formation indexes P ICP, BGP, BALP and ALP levels in observation group were higher than those in control group;serum bone resorption indexesβ-CTX and OPG levels were lower than those in control group;serum inflammatory factors IL-1β, IL-6, IL-8 and CRP levels were lower than those in control group;serum pain mediators SP, PGE2 and 5-HT levels were lower than those in control group.Conclusion:Minimally invasive mippo intramedullary nail internal fixation treatment of femoral shaft fractures can promote the bone formation, relatively inhibit bone resorption and cause less traumatic reaction.