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Riemann Boundary Value Problem of Non-Normal Type on the Infinite Straight Line 被引量:2
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作者 Lixia Cao 《Applied Mathematics》 2013年第8期1226-1230,共5页
Various kinds of Riemann boundary value problems (BVPs) for analytic functions on closed curves or on open arc, doubly periodic Riemann BVPs, doubly quasi-periodic Riemann BVPs, and BVPs for polyanalytic functions hav... Various kinds of Riemann boundary value problems (BVPs) for analytic functions on closed curves or on open arc, doubly periodic Riemann BVPs, doubly quasi-periodic Riemann BVPs, and BVPs for polyanalytic functions have been widely investigated in [1-8]. The main ap- proach is to use the decomposition of polyanalytic functions and their generalization to transform the boundary value problems to their corresponding boundary value problems for analytic functions. Recently, inverse Riemann BVPs for generalized analytic functions or bianalytic functions have been investigated in [9-12]. In this paper, we consider a kind of Riemann BVP of non-normal type on the infinite straight line and discuss the solvable conditions and the general solution for it. 展开更多
关键词 Non-normal type RIEMANN BOUNDARY VALUE Problem The INFINITE STRAIGHT Line
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Doubly Periodic Riemann Boundary Value Problem of Non-Normal Type for Analytic Functions on Two Parallel Curves
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作者 Lixia Cao Huijun Zheng 《Advances in Pure Mathematics》 2015年第1期51-58,共8页
In this paper, we present and study a kind of Riemann boundary value problem of non-normal type for analytic functions on two parallel curves. Making use of the method of complex functions, we give the method for solv... In this paper, we present and study a kind of Riemann boundary value problem of non-normal type for analytic functions on two parallel curves. Making use of the method of complex functions, we give the method for solving this kind of doubly periodic Riemann boundary value problem of non-normal type and obtain the explicit expressions of solutions and the solvable conditions for it. 展开更多
关键词 DOUBLY PERIODIC HOLDER Continuous Functions RIEMANN Boundary Problem Non-normal type
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Comparison of up ladder type and terraced type normalizing heat treatments of heavy cylinder 被引量:1
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作者 孙建亮 彭艳 +1 位作者 邱丑武 张永振 《Journal of Central South University》 SCIE EI CAS CSCD 2016年第11期2777-2783,共7页
Because of the mixed grain and coarse grain structure, the long heat treatment cycle and large energy conservation in the heavy cylinder heat treatment process, the up ladder type and terraced type normalizing heat tr... Because of the mixed grain and coarse grain structure, the long heat treatment cycle and large energy conservation in the heavy cylinder heat treatment process, the up ladder type and terraced type normalizing heat treatment of heavy cylinder after rolling were put forward. The microstructure and mechanical properties of 2.25Cr1Mo0.25 V steel after the up ladder type normalizing, terraced type normalizing and isothermal type normalizing were studied. Experimental results show that: 1) For the grain refinement, the twice terraced type normalizing is better than the up ladder type and isothermal type normalizing, and the average grain size is 18 μm; 2) The yield strength, tensile strength and-30℃ charpy impact energy after twice terraced type normalizing are 681 MPa, 768 MPa and 181 J, respectively, and the mechanical properties are better than those of the up ladder type and isothermal type normalizing; 3) Compared with the isothermal type normalizing, the holding time of terraced type normalizing can be shortened by 30%, which greatly reduces the energy consumption. 展开更多
关键词 heavy cylinder terraced type normalizing up ladder type normalizing mechanical properties
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Continental Dynamics in High Tibetan Plateau: Normal Faulting Type Earthquake Activities and Mechanisms
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作者 徐纪人 赵志新 《Journal of China University of Geosciences》 SCIE CSCD 2009年第2期484-492,共9页
Various earthquake fault types were analyzed for this study on the crust movement in the high region of the Tibetan plateau by analyzing mechanism solutions and stress fields. The results show that a lot of normal fau... Various earthquake fault types were analyzed for this study on the crust movement in the high region of the Tibetan plateau by analyzing mechanism solutions and stress fields. The results show that a lot of normal faulting type earthquakes are concentrated in the central High Tibetan plateau. Many of them are nearly perfect normal fault events. The strikes of the fault planes of normal faulting earthquakes are almost in an N-S direction based on the analyses of the Wulff stereonet diagrams of fault plane solutions. It implies that the dislocation slip vectors of the normal faulting type events have quite great components in the E-W direction. The extensions probably are an eastward extensional mo- tion, being mainly a tectonic active regime in the plateau altitudes. The tensional stress in the E-W or NWW-SEE direction predominates earthquake occurrences in the normal event region of the central plateau. The eastward extensional motion in the high Tibetan plateau is attributable to the gravitational collapse of the high plateau and the eastward extrusion of hotter mantle materials beneath the east boundary of the plateau. Extensional motions from the relaxation of the topography and/or gravitational collapse in the high plateau hardly occurred along the N-S direction. The obstruction for the plateau to move eastward is rather weak. 展开更多
关键词 normal faulting type earthquake focal mechanism solution eastward extensional motion stress field gravitational collapse.
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SAMPLING INSPECTION OF RELIABILITY IN (LOG)NORMAL CASE WITH TYPE I CENSORING 被引量:4
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作者 吴启光 吕建华 《Acta Mathematica Scientia》 SCIE CSCD 2006年第2期331-343,共13页
This article proposes a statistical method for working out reliability sampling plans under Type I censored sample for items whose failure times have either normal or lognormal distributions. The quality statistic is ... This article proposes a statistical method for working out reliability sampling plans under Type I censored sample for items whose failure times have either normal or lognormal distributions. The quality statistic is a method of moments estimator of a monotonous function of the unreliability. An approach of choosing a truncation time is recommended. The sample size and acceptability constant are approximately determined by using the Cornish-Fisher expansion for quantiles of distribution. Simulation results show that the method given in this article is feasible. 展开更多
关键词 type I censoring lognormal distribution normal distribution reliability sampling plans
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A New Location Invariant Moment-Type Estimator and Its Asymptotic Normality
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作者 Weiqi LIU Shanshan LIANG 《Journal of Mathematical Research with Applications》 CSCD 2018年第3期293-302,共10页
The moment estimator has been widely used in extreme value theory in order to estimate the extreme value index, however it is not location invariant. In this paper, based on the moment-type estimator, we propose a new... The moment estimator has been widely used in extreme value theory in order to estimate the extreme value index, however it is not location invariant. In this paper, based on the moment-type estimator, we propose a new location invariant moment-type estimator,and discuss its asymptotic normality under the second order regular variation. Finally, a simulation is presented to compare this new estimator with another location invariant momenttype estimator γn^M(k0, k) proposed by Ling, which indicates that the new estimator has good performances. 展开更多
关键词 extreme value index moment-type estimator regular variation location invariant asymptotic normality
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新质生产力视域下师范院校大学生就业能力提升路径研究
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作者 黄谭腾 《教育思想理论研究》 2026年第3期111-113,共3页
新质生产力作为推动高质量发展的核心动力,正在深刻重塑教育生态与人才需求结构。师范院校作为基础教育师资培养的主阵地,其大学生就业能力培养面临数字化转型、智能化升级与创新型发展的多重挑战。本研究基于新质生产力的理论内涵,系... 新质生产力作为推动高质量发展的核心动力,正在深刻重塑教育生态与人才需求结构。师范院校作为基础教育师资培养的主阵地,其大学生就业能力培养面临数字化转型、智能化升级与创新型发展的多重挑战。本研究基于新质生产力的理论内涵,系统分析当前师范院校大学生就业能力的现实困境,从数字素养培育、创新思维锻造、跨界融合能力、实践教学重构四个维度构建就业能力提升的理论框架,并提出“课程—实践—平台—评价”四维协同的培养路径,为师范院校深化人才培养改革、精准对接新时代教育发展需求提供理论参考与实践指引。 展开更多
关键词 新质生产力 师范院校 就业能力 数字化转型 教师教育
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基于“治风先治血”理论探讨针灸治疗阴虚阳亢型正常高值血压的思路
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作者 林琳 《内蒙古中医药》 2026年第1期64-67,共4页
正常高值血压是高血压的前期阶段,也是高血压防治的中心环节。中医认为正常高值血压与内风有关,因此基于“治风先治血”理论,从“血”论治。而阴虚阳亢型正常高值血压为本虚标实,阴虚阳亢,故从活血和养血两方面入手,进一步探讨针灸治疗... 正常高值血压是高血压的前期阶段,也是高血压防治的中心环节。中医认为正常高值血压与内风有关,因此基于“治风先治血”理论,从“血”论治。而阴虚阳亢型正常高值血压为本虚标实,阴虚阳亢,故从活血和养血两方面入手,进一步探讨针灸治疗该病的新思路。 展开更多
关键词 治风先治血 阴虚阳亢型 正常高值血压 针灸
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2000—2022年重庆市植被覆盖变化的驱动敏感度研究
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作者 李佳潼 吴华 +3 位作者 张鑫 徐悦 谢雪 朱嘉琦 《西北林学院学报》 北大核心 2026年第1期215-223,234,共10页
定量分析重庆市植被覆盖变化的驱动敏感度,揭示气候与人为活动的差异影响,为生态阈值判定、资源管理及政策优化提供依据。基于Theil-Sen斜率估计、地理探测器及复相关分析等方法,定量解析2000—2022年重庆市归一化植被指数(NDVI)的时空... 定量分析重庆市植被覆盖变化的驱动敏感度,揭示气候与人为活动的差异影响,为生态阈值判定、资源管理及政策优化提供依据。基于Theil-Sen斜率估计、地理探测器及复相关分析等方法,定量解析2000—2022年重庆市归一化植被指数(NDVI)的时空演变特征及其驱动敏感度。结果表明:重庆市NDVI呈增速减缓的上升趋势,平均增速为9.977%,空间异质性显著。植被退化敏感区集中于城市化热点区,生态改善敏感区分布在东北部林草交错带。土地利用类型和人口密度驱动敏感性较高,其中土地利用类型驱动敏感区域达549.08 km^(2)。不同土地利用类型对应NDVI排序为林地>草地>耕地>其他>城乡用地,其与土地利用类型的面积占比表现不具一致性。未来重庆市大部分地区植被呈退化趋势,尤其是城市化进程较快的主城区,后续城市发展要注意对植被的影响,同时土地利用类型和人口密度也会显著影响植被覆盖变化。 展开更多
关键词 归一化植被指数(NDVI) 复相关分析 土地利用类型 地理探测器
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川东北龙会场地区凉高山组烃源岩有机地球化学特征
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作者 张航 张洁伟 +3 位作者 曾令平 李丹 罗宇卓 许承武 《西部探矿工程》 2026年第1期16-19,22,共5页
近年来,四川盆地侏罗系凉高山组页岩油勘探捷报频传,表明凉高山组油气勘探潜力巨大。龙会场地区位于川东北凉高山组沉积中心,具备页岩油勘探的地质条件,烃源岩品质决定页岩油的资源品位。为了对凉高山组烃源岩品质进行精细评价,对凉高... 近年来,四川盆地侏罗系凉高山组页岩油勘探捷报频传,表明凉高山组油气勘探潜力巨大。龙会场地区位于川东北凉高山组沉积中心,具备页岩油勘探的地质条件,烃源岩品质决定页岩油的资源品位。为了对凉高山组烃源岩品质进行精细评价,对凉高山组泥页岩进行了有机地球化学评价。通过总有机碳(TOC)、热解S_(1)+S_(2)、氯仿沥青“A”、族组成、干酪根镜检以及色谱质谱分析等多种技术手段对烃源岩的丰度、类型以及成熟度进行了评价,同时对沉积环境进行了分析。结果表明,凉高山组TOC一般为0.52%~2.69%,S_(1)+S_(2)一般为0.38~7.43mg/g,氯仿沥青“A”为0.0561%~0.02476%,族组成中饱/芳比为2.46,显示了凉高山组具有较好的生烃潜力;凉高山组有机质类型为Ⅱ1;Ro为1.09%~1.2%,进入大规模生油气阶段。凉高山组烃源岩正构烷烃以低碳数为主,主峰碳为nC_(18)、nC_(19),呈现前峰型,揭示母质类型主要来源于水生生物和微生物,但凉高山组烃源岩C_(27)、C_(28)、C_(29)规则甾烷呈反“L”形分布,C_(29)规则甾烷占优势,陆源高等植物输入较大,存在少量藻类输入,揭示了凉高山组母质来源表现为混源的特点。 展开更多
关键词 凉高山组 有机质丰度 有机质成熟度 有机质类型 干酪根镜检 正构烷烃 甾烷
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契合临床路径2型糖尿病大鼠模型建立、维持与评估
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作者 汝姝逸 王天宇 +3 位作者 王旭 房城 赵良友 吴修红 《中国实验动物学报》 北大核心 2026年第1期10-22,共13页
目的对比2型糖尿病(type 2 diabetes mellitus,T2DM)模型建成后不同饮食干预方案及二甲双胍联合干预效果,建立及维持更契合临床实际的T2DM大鼠模型。方法50只雄性SD大鼠随机分为2组:空白对照(Control,n=10)组、模型制备(n=40)组,模型制... 目的对比2型糖尿病(type 2 diabetes mellitus,T2DM)模型建成后不同饮食干预方案及二甲双胍联合干预效果,建立及维持更契合临床实际的T2DM大鼠模型。方法50只雄性SD大鼠随机分为2组:空白对照(Control,n=10)组、模型制备(n=40)组,模型制备组大鼠采用高糖高脂饲料喂养,从第3周起联合每日灌胃脂肪乳,4周后两次腹腔注射25 mg/kg链脲佐菌素(streptozotocin,STZ)诱导T2DM大鼠模型。模型建成后,将模型制备组随机分为高糖高脂-模型(HSHF-M)组、常规饮食-模型(ND-M)组、高糖高脂-二甲双胍(HSHF-Met)组、常规饮食-二甲双胍(ND-Met)组,每组10只。HSHF-Met组与ND-Met组大鼠采用饮食联合二甲双胍干预,HSHF-M组与ND-M组大鼠仅进行饮食干预,Control组大鼠采用常规饮食,持续12周。饮食干预期间监测大鼠一般状态及生存指标检测;12周干预结束后,进行口服葡萄糖耐量实验(OGTT),检测大鼠血清空腹胰岛素(FINS)水平并计算胰岛素抵抗指数(HOMA-IR)、胰岛β细胞功能指数(HOMA-β),检测大鼠血清中血脂水平、肝功能、肾功能、氧化应激指标及炎症因子水平;并对大鼠胰腺、肝、肾组织病理变化观察且进行病理学分析。结果实验表明,T2DM模型大鼠制备成功后,采用常规饮食,12周内模型稳定,与HSHF-M组相比,ND-M组体质量显著增加(P<0.05),尿量及血糖显著下降(P<0.05);OGTT实验0、30、60、120 min血糖明显低于HSHF-M组(P<0.05),曲线下面积显著减小(P<0.05);血糖相关指标中GSP、FINS、HOMA-IR出现显著性差异(P<0.05);血脂相关指标中TC、TG、FFA、LDL-C水平显著降低(P<0.05),HDL-C水平显著升高(P<0.05);肝功能相关指标ALT、ALP、AST及肾功能相关指标CRE、BUN指标显著降低(P<0.05)、NO显著升高(P<0.05);氧化应激指标中MDA水平显著下降(P<0.05)、SOD水平显著上升(P<0.05);炎症因子TNF-α、IL-1β水平显著下降(P<0.05);组织病理学显示,ND-M组因未长期摄入高糖高脂饮食,其肝索紊乱、胰岛细胞减少及肾小球空泡等病理变化较HSHF-M组显著减轻。与HSHF-M组相比,HSHF-Met组和ND-Met组的生存指标及生化指标均显著改善(P<0.05),其中ND-Met组改善效果更显著,胰腺、肝和肾病理损伤较HSHF-Met组较弱。结论模型建成后喂养常规饮食可有效避免高糖高脂所致糖脂代谢紊乱、氧化应激、炎症反应及多器官病理损伤,成功建立并维持更契合临床路径的T2DM大鼠模型。 展开更多
关键词 2型糖尿病 大鼠模型 链脲佐菌素 常规饮食 高糖高脂饮食
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Countermeasures against Prominent Problems of Forestry in Yutian County under the New Normal
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作者 Yongzhen LEI 《Asian Agricultural Research》 2019年第7期38-41,共4页
The prominent problems faced by forestry development in Yutian County under the new normal of deep integration of social poverty alleviation and local forestry construction are analyzed in depth in this article. Combi... The prominent problems faced by forestry development in Yutian County under the new normal of deep integration of social poverty alleviation and local forestry construction are analyzed in depth in this article. Combined with the current situation, specific measures are proposed, in order to provide a theoretical basis for the construction and development of forestry in arid oasis-type agro-ecological areas. 展开更多
关键词 NEW normal Arid oasis-type agro-ecological zone FORESTRY development PROBLEMS and COUNTERMEASURES
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Unique Common Fixed Point Theorems for Lipschitz Type Mappings under c-Distance on Cone Metric Spaces
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作者 Yongjie PIAO 《Journal of Mathematical Research with Applications》 CSCD 2014年第6期713-722,共10页
In this paper, new unique common fixed point theorems for four mappings satisfying Lipzchitz type conditions in the term of c-distance on normal cone metric spaces were given.The obtained results generalize and improv... In this paper, new unique common fixed point theorems for four mappings satisfying Lipzchitz type conditions in the term of c-distance on normal cone metric spaces were given.The obtained results generalize and improve many known common fixed point theorems. 展开更多
关键词 normal cone metric space c-distance common fixed point Lipschitz type condition
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Proposal and Pilot Study: A Generalization of the W or W'Statistic for Multivariate Normality
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作者 José Moral-De La Rubia 《Open Journal of Statistics》 2023年第1期119-169,共51页
The aim of this paper is to present a generalization of the Shapiro-Wilk W-test or Shapiro-Francia W'-test for application to two or more variables. It consists of calculating all the unweighted linear combination... The aim of this paper is to present a generalization of the Shapiro-Wilk W-test or Shapiro-Francia W'-test for application to two or more variables. It consists of calculating all the unweighted linear combinations of the variables and their W- or W'-statistics with the Royston’s log-transformation and standardization, z<sub>ln(1-W)</sub> or z<sub>ln(1-W</sub><sub>'</sub><sub>)</sub>. Because the calculation of the probability of z<sub>ln(1-W)</sub> or z<sub>ln(1-W</sub><sub>'</sub><sub>)</sub> is to the right tail, negative values are truncated to 0 before doing their sum of squares. Independence in the sequence of these half-normally distributed values is required for the test statistic to follow a chi-square distribution. This assumption is checked using the robust Ljung-Box test. One degree of freedom is lost for each cancelled value. Defined the new test with its two variants (Q-test or Q'-test), 50 random samples with 4 variables and 20 participants were generated, 20% following a multivariate normal distribution and 80% deviating from this distribution. The new test was compared with Mardia’s, runs, and Royston’s tests. Central tendency differences in type II error and statistical power were tested using the Friedman’s test and pairwise comparisons using the Wilcoxon’s test. Differences in the frequency of successes in statistical decision making were compared using the Cochran’s Q test and pairwise comparisons using the McNemar’s test. Sensitivity, specificity and efficiency proportions were compared using the McNemar’s Z test. The generated 50 samples were classified into five ordered categories of deviation from multivariate normality, the correlation between this variable and p-value of each test was calculated using the Spearman’s coefficient and these correlations were compared. Family-wise error rate corrections were applied. The new test and the Royston’s test were the best choices, with a very slight advantage Q-test over Q'-test. Based on these promising results, further study and use of this new sensitive, specific and effective test are suggested. 展开更多
关键词 Multivariate normality Statistical Power type II Error SPECIFICITY EFFICIENCY
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Structural Vector Description and Estimation of Normal Boiling Points for 66 Aromatic Hydrocarbons
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作者 Shu Shen LIU Chun Sheng YIN +1 位作者 Shao Xi CAI Zhi Liang LI 《Chinese Chemical Letters》 SCIE CAS CSCD 2000年第12期1089-1092,共4页
A molecular vector-type descriptor containing 6 variables is used to describe the structure of aromatic hydrocarbons (AHs) and relate to normal boiling points (bp) of AHs. The col relation coefficient (R) between the ... A molecular vector-type descriptor containing 6 variables is used to describe the structure of aromatic hydrocarbons (AHs) and relate to normal boiling points (bp) of AHs. The col relation coefficient (R) between the estimated bp and experimental bp is 0.9988 and the root mean square error (RMS) is 7.907 degreesC for 66 AHs. The RMS obtained by cross-validation is 9.131 degreesC, which implies the relationship model having good prediction ability. 展开更多
关键词 molecular vector-type descriptor aromatic hydrocarbon normal boiling point
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一类带根号的Riemann边值逆问题在正则情况下的解法
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作者 柏淞玮 孙梦 +1 位作者 李平润 王文静 《曲阜师范大学学报(自然科学版)》 2025年第2期25-30,共6页
该文研究了在正则型情况下无穷直线上的一类带有根号的Riemann边值逆问题.通过分析未知函数的结构,进行一系列的积分变换,将Riemann边值逆问题转化为经典的全纯函数边值问题.利用解析开拓原理和推广的Liouville定理等,给出了边值问题的... 该文研究了在正则型情况下无穷直线上的一类带有根号的Riemann边值逆问题.通过分析未知函数的结构,进行一系列的积分变换,将Riemann边值逆问题转化为经典的全纯函数边值问题.利用解析开拓原理和推广的Liouville定理等,给出了边值问题的一般解. 展开更多
关键词 RIEMANN边值逆问题 解析开拓原理 指标 典则函数 正则型
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1990—2020年平顶山市的生境质量时空演变及驱动力分析
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作者 支梦辉 杨帆 +1 位作者 安岩 李梦博 《环境污染与防治》 北大核心 2025年第8期138-145,共8页
为了探究平顶山市生境质量的时空演变和退化情况,基于1990—2020年4期土地利用/覆盖(LULC)数据,结合InVEST模型和Google Earth Engine(GEE)云计算平台,对平顶山市土地利用类型、植被覆盖度和生境质量的时空变化特征进行了定量分析,并探... 为了探究平顶山市生境质量的时空演变和退化情况,基于1990—2020年4期土地利用/覆盖(LULC)数据,结合InVEST模型和Google Earth Engine(GEE)云计算平台,对平顶山市土地利用类型、植被覆盖度和生境质量的时空变化特征进行了定量分析,并探讨了生境质量的驱动因素。结果表明,平顶山市的城镇及建设用地面积在这30年间从131.56 km^(2)增至387.43 km^(2),而草地面积减少约276.71 km^(2),部分转化为林地。2000年至2004年间,植被覆盖度(归一化植被指数(NDVI))降低,2015年后又明显上升,显示出生态改善趋势。生境质量总体呈下降趋势,生境质量等级较低的区域有所增加;但优等生境质量的区域面积也有所增加,集中分布在鲁山县、舞钢市南部和宝丰县西部。生境退化区域集中在白龟湖水库周边,主要受城镇扩张的影响。建议未来加强引导,合理规划土地利用,以促进平顶山市的绿色和可持续发展。 展开更多
关键词 生境质量 土地利用类型 归一化植被指数 InVEST模型
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基于超高性能混凝土与普通混凝土优化Z形试件的界面抗剪性能 被引量:5
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作者 方钰 张大山 +3 位作者 王慧青 董毓利 戴玉成 曾婷婷 《科学技术与工程》 北大核心 2025年第8期3349-3358,共10页
针对常见界面抗剪性能测试的试件形式存在不能有效反映界面上切应力的实际情况,提出对传统Z形试件的优化改进方案。采用优化改进的Z形试件,开展超高性能混凝土(ultra-high performance concrete,UHPC)与普通混凝土(normal concrete,NC)... 针对常见界面抗剪性能测试的试件形式存在不能有效反映界面上切应力的实际情况,提出对传统Z形试件的优化改进方案。采用优化改进的Z形试件,开展超高性能混凝土(ultra-high performance concrete,UHPC)与普通混凝土(normal concrete,NC)界面处抗剪强度的试验研究,考察抗剪钢筋配筋率和界面粗糙度对界面抗剪强度的影响程度。结果表明:界面受剪时的破坏面发生在NC侧或者部分界面与部分NC侧,为典型的脆性破坏特征;界面的抗剪强度随着粗糙度的增大而增大,但当粗糙度大于1.8时,增大界面粗糙度来提高界面抗剪强度的效果不太明显;带肋钢筋作为抗剪钢筋能充分发挥钢筋的销栓作用,比光圆钢筋提高界面抗剪强度的效果有显著提高。建立能考虑抗剪钢筋和界面粗糙度贡献的UHPC和NC界面抗剪承载力计算公式,其理论计算值和试验结果吻合良好,能够为具有UHPC和NC界面的叠合构件在进行工程设计时提供参考。 展开更多
关键词 超高性能混凝土(UHPC)-普通混凝土(NC)界面 优化Z形试件 界面抗剪性能 粗糙度 抗剪钢筋
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金沙江流域植被时空演变特征及对气候因子的响应
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作者 张文杰 赵乾佐 +3 位作者 崔磊 李冲 张璇 程红光 《应用生态学报》 北大核心 2025年第11期3419-3430,共12页
植被是生态系统的重要组成部分,是能量流动及物质循环的纽带。研究植被动态变化及其对气候因子的响应,对于陆地生态系统保护具有重要意义。本研究选取金沙江流域为研究区,基于2001—2022年归一化植被指数(NDVI)、降水、气温数据,利用Man... 植被是生态系统的重要组成部分,是能量流动及物质循环的纽带。研究植被动态变化及其对气候因子的响应,对于陆地生态系统保护具有重要意义。本研究选取金沙江流域为研究区,基于2001—2022年归一化植被指数(NDVI)、降水、气温数据,利用Mann-Kendall趋势检验和Sen's斜率分析探究了流域内植被覆盖的变化趋势和空间分布特征,利用偏相关分析讨论了植被对气温和降水的滞后响应,以及不同土地类型响应的滞后差异。结果表明:2001—2022年,金沙江流域植被覆盖呈现整体向好趋势,NDVI的增长速度为0.002·(10 a)^(-1);植被变化的空间分异性特征明显,植被显著改善区域占流域面积的25.4%;研究区域NDVI均值与海拔之间呈显著负相关,相关系数为-0.76。金沙江流域气候呈干热发展趋势,流域平均NDVI对降水的响应约滞后1个月,对温度呈现出即时响应的特点。耕地和灌木区植被覆盖增加,草地和林地区则保持稳定。草地NDVI与降水和温度的相关性均最高,林地对于二者的相关性均最低。不同土地类型NDVI对降水和温度响应的滞后性有差异,耕地、草地和灌木对降水响应滞后时间为1个月,林地则表现为即时响应;耕地和林地对温度表现为即时响应,而草地和灌木的滞后时间差异较大。本研究结果可为该流域的生态保护和资源管理提供科学依据,研究方法对其他地区的植被演变研究具有参考价值。 展开更多
关键词 金沙江流域 归一化植被指数 土地类型 气候因子
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串并联型软开关短路故障保护方案
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作者 储琳琳 宗明 +4 位作者 易越 陈妍君 周剑桥 张建文 施刚 《哈尔滨理工大学学报》 北大核心 2025年第6期111-118,共8页
串并联型软开关(series-shunt SNOP,SS-SNOP)拓扑具备体积小、成本低、功率密度高的特点,但由于其结构固有特性,在电网出现短路故障时无法实现有效隔离,存在装置本体损坏和非故障馈线误动作等问题。依据SS-SNOP的拓扑结构与工作原理,提... 串并联型软开关(series-shunt SNOP,SS-SNOP)拓扑具备体积小、成本低、功率密度高的特点,但由于其结构固有特性,在电网出现短路故障时无法实现有效隔离,存在装置本体损坏和非故障馈线误动作等问题。依据SS-SNOP的拓扑结构与工作原理,提出了一套面向串并联型软开关SS-SNOP的配电网短路故障保护方案,实现装置本体保护、故障快速定位与隔离以及非故障馈线的快速运行恢复。详细阐述了基于SS-SNOP互联的配电线路故障短路特性以及所提故障保护方案的设计方法,并通过仿真验证了所提方案的可行性与有效性。 展开更多
关键词 串并联型软开关 柔性互联 短路电流 故障检测 故障保护
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