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1. chinaXiv:202104.00062 [pdf]

Training Image Optimization Method Based on Convolutional Neural Network

Siyu, YU; Shaohua, LI
Subjects: Geosciences >> Other Disciplines of Geosciences

As a prior geological model, which can effectively describe the internal structure of the reservoir, geometry and distribution of sedimentary facies, training image(TI) is the key input data of multipoint statistics(MPS). Before implementing MPS modeling, appropriate TIs must be provided to match the spatial correlation of the work area condition data. The essence of choosing the training image that best matches the conditional data is to quantitatively evaluate the similarity of spatial features between the discrete points and the regular grid. This paper presents a new training image optimization method based on Convolutional Neural Network(CNN). Firstly, candidate TIs were randomly sampled several times to obtain the sample point set. Then, CNN was used to conduct transfer learning for all samples. Finally, the optimal TI of the conditional data is selected through the trained CNN model. Based on the strong learning ability of CNN in image feature recognition, the proposed method can automatically identify the spatial feature differences between the conditional data and the sample points of the training image, and effectively solves the difficulty of spatial matching between discrete points and grid structures. Through four different TI optimization cases, it is proved that the new method can effectively select suitable TI. In the discussion, we put forward a trick to improve the accuracy of continuous TI recognition by discretizing continuous variables. Finally, sensitivity analysis was carried out, and it was found that sufficient conditional data was the key factor to select suitable TI.

submitted time 2021-04-14 Hits60Downloads26 Comment 0

2. chinaXiv:202102.00079 [pdf]

均等分区问题模型、算法及应用

孔云峰
Subjects: Geosciences >> Geography

分区问题广泛应用于地理、经济、政治、商业、公共服务等领域。均等分区问题是其中一类问题,通常要求分区人口数量或任务量均等、几何形状紧凑和空间连续,应用于选区、销售区和巡逻区的划分。本文针对均等分区问题提出了一个混合整型线性规划模型,并设计了一个基于迭代局部搜索(ILS)的混合算法。该算法从三个方面扩展ILS:群解搜索、VND搜索及SPP模型改进。选择5个区域对模型和算法进行测试,结果表明:数学模型能够求解空间单元数量为324的案例;混合算法优化性能优异,鲁棒性强,计算效率较高。所提出的均等分区问题适用于政治分区等经典问题,在新冠疫情应急服务等领域也具有应用潜力。

submitted time 2021-02-24 Hits889Downloads242 Comment 0

3. chinaXiv:201904.00072 [pdf]

Impact of Urban Rail Transit on Business Districts Based on Time Distance: Urumqi Light Rail.pdf

常烃
Subjects: Geosciences >> Geography

基于超制图学的思想,建立模型将乘坐轻轨的时间距离换算成以米(m)为单位的空间距离。在此基础上,通过地理信息系统(GIS)的地图投影空间变换方法,用换算出的距离重新定义两地间距离,变形原地图形成时间距离地图。将时间距离空间化,利用技术手段,对时间距离进行可视化表达。结果发现,轻轨对于城市形态的影响受到站点离所选取的中心点距离的影响,呈现离中心点越远变形越大;离中心点越近变形越小。轻轨对商业中心布局的影响基本呈现圈层分布。时间距离压缩了传统城市形态。随着乌鲁木齐地铁建设进程的推进和基础设施的完善,城市内部进一步压缩时间距离仍有很大余地,已有商业中心应进行升级。本研究为乌鲁木齐城市建设提供一种新的参考与思路。

submitted time 2019-03-31 Hits9641Downloads1613 Comment 0

4. chinaXiv:201710.00017 [pdf]

Low-T Thermo: a new program for arbitrarily combining low-T thermochronological data to model thermal history

丁汝鑫
Subjects: Geosciences >> Geology
Subjects: Geosciences >> Geochemistry

A robust code, called Low-T Thermo, has been developed to combine low-T thermochronological data arbitrarily to model thermal history. After apatite fission-track age and confined length are decoupled into two completely independent data to inverse thermal history and thermal history inversion using mica Ar-Ar age or bedrock quartz optically stimulated luminescence age are developed, there are eight kinds of low-T thermochronological data used to inverse thermal history including apatite fission-track age, apatite fission-track confined length, zircon fission-track age, apatite (U–Th)/He age, zircon (U–Th)/He age, mica Ar-Ar, bedrock quartz optically stimulated luminescence age and vitrinite reflectance. A total of 247 kinds of combination modes?can be used to jointly inverse thermal history in theory (except the eight single methods modelling). These arbitrary combinations are helpful to model thermal history with the “incomplete” low-T thermochronological data set regarded to be unuseful for thermal history modelling and reduce experimental cost. For arbitrary combination of different low-T thermochronological data, each low-T thermochronological method is independent incompletely and the equivalent p-value is used to be the identical evaluation?indicator in the inverse process. The usefulness of the code is demonstrated by modelling thermal history of existing low-T thermochronological data in the areas of Dabie Mountain, Ahimanawa Range and Southern Alps.

submitted time 2017-10-26 Hits10034Downloads1521 Comment 0

5. chinaXiv:201703.01172 [pdf]

304不锈钢在淡化海水中的点蚀行为

高丽飞; 杜敏
Subjects: Materials Science >> Materials Science (General)

运用开路电位、交流阻抗、阳极极化曲线和电化学频率调制技术研究了304不锈钢在不同温度(60~90℃)及不同海水(一级反渗透淡化海水、天然海水、1.6倍浓缩海水)中的点蚀行为。结果表明,304不锈钢在一级反渗透淡化海水中随着温度的升高点蚀敏感性增加;在发生点蚀前的钝化状态下,304不锈钢在一级反渗透淡化海水中比在海水中腐蚀严重;304不锈钢的点蚀敏感性随Cl-浓度的升高而增加;304不锈钢在80℃下的一级反渗透淡化海水中随浸泡时间的延长,腐蚀速率逐渐增大,且在浸泡1d时即有发生点蚀的倾向,在第10d时已经发生了点蚀。

submitted time 2017-03-31 From cooperative journals:《腐蚀科学与防护技术》 Hits38353Downloads1465 Comment 0

6. chinaXiv:201703.01169 [pdf]

模拟海洋大气条件下直流电场作用对碳钢初期腐蚀行为的影响

林德源; 戴念维; 陈云翔; 倪清钊; 张鑫; 张俊喜
Subjects: Geosciences >> Marine Sciences

采用失重分析、极化曲线测试和SEM分析手段,研究了模拟海洋大气环境下直流电场对碳钢初期腐蚀行为的影响。结果表明,直流电场的存在加速了碳钢的初期腐蚀速率,但并没有改变其腐蚀动力学;直流电场存在有利于具有亚稳片状结构的γ-FeOOH的形成,同时抑制了γ-FeOOH向具有保护性能的α-FeOOH的转化,从而导致锈层的保护性能下降,加速了碳钢的腐蚀。

submitted time 2017-03-31 From cooperative journals:《腐蚀科学与防护技术》 Hits34605Downloads2269 Comment 0

7. chinaXiv:201703.01148 [pdf]

海水飞溅区含镍钢的锈层及耐蚀性研究

黄桂桥huangguiqiao; 杨海洋; 张万灵
Subjects: Geosciences >> Marine Sciences

通过海水飞溅区暴露试验,获得了2种含镍钢和碳钢3a的腐蚀结果。采用X-射线衍射(XRD)和电子探针显微分析(EPMA)技术,研究了含镍钢飞溅区锈层的特性,讨论了Ni对钢飞溅区锈层及耐蚀性的影响。结果表明,添加2%~3%Ni,使钢锈层中的裂纹和孔洞减小, 锈层的致密度提高;外锈层中的?-FeOOH的含量增加。2%~3%Ni的加入有利于盐分中的Na+和Mg++向锈层和钢基体界面渗透,对Cl?的渗透有抑制作用。添加3%Ni,使钢的蚀孔中的Cl?富集程度显著降低。加入2%~3%Ni能大幅度提高钢在飞溅区的耐蚀性。

submitted time 2017-03-31 From cooperative journals:《腐蚀科学与防护技术》 Hits14414Downloads1760 Comment 0

8. chinaXiv:201703.01143 [pdf]

热带滨海红壤中碳钢Q235的宏观非均匀腐蚀研究

胡杰珍; 邓培昌; 张际标; 刘泉兵; 胡欢欢; 王贵; 高虓
Subjects: Geosciences >> Marine Sciences

由于土壤成分的非均匀性,决定土壤中金属易发生非均匀腐蚀。本文利用阵列电极技术与腐蚀埋片相结合的方法,以碳钢Q235为研究材料,经自然热带临海红壤埋片,研究了碳钢Q235的宏观非均匀腐蚀行为。碳钢Q235材料在时间维度上和垂直地面的空间维度上皆发生非均匀腐蚀。时间维度上发生非均匀腐蚀的原因是降雨频率与降雨量对土壤湿度的影响,从而影响碳钢Q235材料腐蚀的环境;垂直地面的空间维度上发生非均匀腐蚀的原因是随土壤深度增加,土壤湿度变化、含氧量变化及土壤组成成分差异的影响。在0-90cm深度土壤范围内,随土壤深度的增加,碳钢Q235材料的腐蚀速率增加。垂向埋于热带滨海红壤中的长尺寸碳钢Q235材料在30cm-50cm、80cm和 140cm-150cm三个范围内,因电偶腐蚀影响,腐蚀速率较大。

submitted time 2017-03-31 From cooperative journals:《腐蚀科学与防护技术》 Hits13301Downloads1504 Comment 0

9. chinaXiv:201703.00485 [pdf]

快速沉积与侵蚀对地温场及天然气水合物成藏演化的影响:以南海北部陆坡为例 Impacts of fast sedimentation and erosion on the evolution of geothermal field and gas hydrate system: cases of Northern South China Sea

张毅, 何丽娟, 汪集旸
Subjects: Geosciences >> Space Physics

海洋沉积物中天然气水合物的存在与分布与地温条件紧密相关。南海北部陆坡大部分区域更、全新世沉积速率较高,同时局部地区(如神狐天然气水合物钻探区)发育有大量的海底冲蚀谷。这些快速沉积或侵蚀作用可以对地温场及天然气水合物的形成与赋存产生重要影响,然而目前注意到这些问题的研究相对较少。本文中我们结合南海北部陆坡的实际情况,建立了针对地温场发生动态变化时的水合物成藏数值模型。我们给出两个成藏模拟案例,其一是快速沉积的情形,其二是地形遭受侵蚀、产生冲蚀谷时的情形。结果表明,在这两种情形下地温场将发生不同的瞬态调整,并对天然气水合物在地层中聚集及分布产状产生重要影响。在快速沉积发生时,地温梯度将变小,天然气水合物稳定带(HSZ)将增厚;然而当其底界将随着热传递而上升,天然气水合物将不断在原稳定带底界分解,而后在新的稳定带底界处重新生成水合物。这样长时间的快速沉积作用可以造成水合物主要富集在稳定带底界处。而当快速侵蚀作用发生时,地温梯度将变大,天然气水合物稳定带的厚度将变薄,原来位于冲蚀谷处的水合物藏将被侵蚀作用破坏。而后,随着热平衡的发展,逐渐形成新的、类似于似海底反射层的稳定带底界。单纯考虑甲烷扩散作用下,高丰度水合物的形成需要较长的时间,相对而言脊下的水合物成藏较好,形成矿点的概率较大。 The occurrence and distribution of gas hydrate in marine sediments is closely related to the state of geothermal field. The sedimentation rate is relatively high during the Pleistocene and Holocene in the northern margin of the South China Sea. Moreover, there are many erosional canyons at the sea bottom in some local areas. Such fast sedimentation and erosion can greatly affect the geothermal regime and the formation and occurrence of gas hydrate deposits. However, there are few studies that consider such scenarios. In this study, considering the geological reality, we build a numerical reservoir model aimed to simulate the evaluation of the gas hydrate system upon two cases: the fast sedimentation and the development of erosional canyons. The results indicate the geothermal filed and the accumulation and distribution of gas hydrate can be adjusted dynamically when the fast sedimentation or erosion occurs. Under fast sedimentation, the geothermal gradient becomes smaller and the thickness of gas hydrate stability zone (HSZ) becomes larger. However, due to the role of heat transfer, the bottom of HSZ rises upward. This process leads to the hydrate near the previous bottom of HSZ being dissociated and depositing near the bottom of new HSZ. After a long duration, the fast sedimentation will result the formation of hydrate being mainly enriched near the bottom of HSZ. By contrast, when fast erosion occurs, the geothermal gradient increases and the HSZ turn thinner. The gas hydrate deposit system can be partially destroyed by the formation of canyons. A long time is necessary for the recovery of a gas hydrate deposit with significant abundance. Relatively, the deposits under the residual ridges are more possible to be potential “sweet spots”.

submitted time 2017-03-23 Hits39231Downloads3321 Comment 0

10. chinaXiv:201703.00429 [pdf]

江苏海门蛎岈山牡蛎礁恢复工程的生态评估

全为民; 冯美; 周振兴; 吴祖立; 唐峰华; 王云龙; 包小松; 沈辉; 成伟
Subjects: Biology >> Ecology

江苏海门蛎岈山牡蛎礁是我国目前现存的面积最大的潮间带活体牡蛎礁,但由于人类活动干扰及泥沙淤积等原因,该自然牡蛎礁面积不断缩小,影响着该牡蛎礁的生态功能与保护管理。于2013-2014年开展了首期江苏海门蛎岈山牡蛎礁恢复工程,基于生态监测结果评估该牡蛎礁恢复工程的生态效果。多层礁体上活体牡蛎丰度显著高于单层礁体(P < 0.05);随着礁体的发育,恢复礁体上牡蛎丰度显著下降(P< 0.05)。非参数Kruskal-Wallis检验结果显示,在两个生活周期内(2013-09-2013-11,2014-03-2014-05)牡蛎均呈现快递的生长(Q=10.519,Q=6.527,P< 0.05),而在越冬期内(2013-11-2014-03)牡蛎几乎停止了生长(Q=0.35,P > 0.05)。随着礁体的发育,恢复牡蛎礁上大型底栖动物群落的物种丰度并没有增加,但其平均总密度和总生物量均呈现显著性的增长(P < 0.05);礁体构建后1a时恢复牡蛎礁中大型底栖动物的平均总密度和生物量均接近于自然牡蛎礁(P > 0.05),但显著高于未恢复区(P < 0.05);恢复牡蛎礁与自然牡蛎礁具有显著不同的大型底栖动物群落(ANOSIM,P=0.001)。研究结果表明该牡蛎礁恢复工程取得初步成功。

submitted time 2017-03-22 From cooperative journals:《生态学报》 Hits2483Downloads1170 Comment 0

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