期刊文献+
共找到13篇文章
< 1 >
每页显示 20 50 100
洞庭湖流域分布式水文模型 被引量:10
1
作者 孙占东 黄群 Lotz Tom 《长江流域资源与环境》 CAS CSSCI CSCD 北大核心 2015年第8期1299-1304,共6页
流域出口径流观测序列是水文模型参数率定重要依据,不受水文站控制区域的模型应用是水文研究关注点之一。首先根据水文站观测资料建立洞庭湖流域四水控制站之上基于水文响应单元的分布式水文模型,在此基础上结合实验、同质移植和虚拟水... 流域出口径流观测序列是水文模型参数率定重要依据,不受水文站控制区域的模型应用是水文研究关注点之一。首先根据水文站观测资料建立洞庭湖流域四水控制站之上基于水文响应单元的分布式水文模型,在此基础上结合实验、同质移植和虚拟水库等方法,将分布式水文模型拓展到包含无径流站控制区域的丘陵区间和平原圩垸区,最终实现了洞庭湖全流域水文过程模拟。结果表明:在较完备土壤、地形、土地利用等空间数据支持下,通过合理的流域划分和水文响应单元定义,建立的流域分布式水文模型可以较好地在水文响应单元尺度反应降水发生后蒸散、地表径流、土壤和地下水的响应特征。而基于观测实验及基流分割等方法获取的关键水文过程特征对模型参数优化的认识,可以提高模型参数率定效率,在较少优化迭代运算后既可使月径流模拟的效率系数NSE和确定性系数R2值高于0.81(日过程高于0.62)。借助参数同质移植和虚拟水库解决了区间和圩垸区无控制站区域水文过程模拟。在全流域水文过程的模拟中,基流指数和蒸散比例与实际过程具有较好的一致性。说明相关参数较好地反映了其物理机制,具备在相似气候及下垫面条件区域进行同质移植的基础,圩垸区径流交换采用虚拟水库的处理方式也合理可行。 展开更多
关键词 分布式水文模型 水文响应单元(hrus) 径流模拟 洞庭湖 湖泊流域过程
原文传递
基于SWAT模型的气候变化和人类活动对伊洛河径流影响分析 被引量:13
2
作者 刘绿柳 王秀杰 张鹏飞 《人民珠江》 2020年第1期1-6,75,共7页
应用SWAT模型,以黄河流域伊洛河为研究对象,通过设置6种HRUs(Hydrological Response Units)划分方案,分析了HRUs数量对SWAT模型参数和模拟性能的影响,并进一步用于伊洛河年径流变化的归因分析。结果表明:SCS径流曲线值(CN2)、土壤有效... 应用SWAT模型,以黄河流域伊洛河为研究对象,通过设置6种HRUs(Hydrological Response Units)划分方案,分析了HRUs数量对SWAT模型参数和模拟性能的影响,并进一步用于伊洛河年径流变化的归因分析。结果表明:SCS径流曲线值(CN2)、土壤有效含水率(SOL_AWC)、深层土壤水渗透系数(RCHRG_DP)和河岸基流α因子(ALPHA_BNK)是伊洛河SWAT径流模拟敏感性高的几个参数。HRUs数量对SWAT模型参数和径流模拟精度影响较小。相对1971-1985年,1986-2015年气候变化和人类活动共同导致了伊洛河流域径流的减少。其中,1986-1995年、1996-2005年、2006-2015年3个时期气候变化对径流变化相对贡献率分别为68.7%、22.5%、83.1%,LUCC外的其他形式的人类活动对径流变化相对贡献率分别为30.9%、76.7%和16.9%,而LUCC的相对贡献不足1%。人类活动能够有效地缓解气候变化对径流的影响,使河道观测径流保持在相对稳定的变化范围。 展开更多
关键词 SWAT模型 hrus划分 气候变化影响 人类活动影响 径流变化归因 伊洛河
在线阅读 下载PDF
SWAT与MODFLOW模型耦合的接口及框架结构研究及应用 被引量:19
3
作者 初京刚 张弛 周惠成 《地理科学进展》 CSCD 北大核心 2011年第3期335-342,共8页
目前水文科学研究的热点是采用水文模拟途径,在确定水文变化基准期的基础上,利用流域水文模型还原人类活动影响期间的天然径流量,定量评价气候变化和人类活动对流域水资源变化的影响,得出气候变化及人类活动对流域水循环过程影响的响应... 目前水文科学研究的热点是采用水文模拟途径,在确定水文变化基准期的基础上,利用流域水文模型还原人类活动影响期间的天然径流量,定量评价气候变化和人类活动对流域水资源变化的影响,得出气候变化及人类活动对流域水循环过程影响的响应规律和机理,其中应用最为广泛的流域水文模型是SWAT模型和MOD-FLOW模型。首先分析将SWAT模型与MODFLOW模型耦合进行地表水与地下水联合模拟的必要性,然后对实现这两种模型耦合中的单元转换等接口问题及框架结构作了重点研究。由于SWAT模型和MODFLOW模型模拟的最小计算单元分别为水文响应单元(HRU)和网格(CELL),使得要实现SWAT模型与MODFLOW模型的耦合必须首先完成HRU与CELL之间的转换,即实现SWAT与MODFLOW模型耦合的接口,因此提出了一种在Arc-SWAT2005环境下实现HRU与CELL转换的方法,给出了SWAT-MODFLOW耦合模型的框架结构,并将该方法应用到浑河与太子河流域,为其进行地表水与地下水联合模拟奠定基础。 展开更多
关键词 SWAT模型 MODFLOW模型 HRU—CELL转换 接口 框架结构
原文传递
计算机安全中的经典模型 被引量:5
4
作者 周伟 尹青 王清贤 《计算机科学》 CSCD 北大核心 2004年第3期195-200,共6页
安全模型是构造安全计算机系统的基础。到目前为止,已有多种公开发表的安全模型。本文总结了几种重要的早期安全模型,其中包括访问矩阵模型,HRU模型,BLP模型、格模型和无干扰模型,并对它们进行了分类和简要评述。本文将它们称为经典安... 安全模型是构造安全计算机系统的基础。到目前为止,已有多种公开发表的安全模型。本文总结了几种重要的早期安全模型,其中包括访问矩阵模型,HRU模型,BLP模型、格模型和无干扰模型,并对它们进行了分类和简要评述。本文将它们称为经典安全模型。这些经典安全模型都是开创性的,从各个不同的方面对安全问题进行抽象,模型所定义的安全问题具有典型性,并对后续的研究产生了重要影响。目前,共享计算机系统的安全问题仍然是计算机科学的中心问题之一,研究这些经典模型,对于我们全面理解计算机系统的安全问题,展望未来发展方向,具有重要意义。 展开更多
关键词 计算机安全 安全模型 HRU模型 BLP模型 格模型 无干扰模型 访问矩阵模型
在线阅读 下载PDF
Role of Ultrasonography in Evaluation of Peripheral Nerves 被引量:1
5
作者 Mandugula Aruna Devi Ak Meena 《Open Journal of Internal Medicine》 2018年第4期232-247,共16页
Ultrasonography is first line, cost-effective modality in imaging of peripheral nerves. High frequency probes allow high resolution imaging of peripheral nerves located at relatively superficial location. USG can diag... Ultrasonography is first line, cost-effective modality in imaging of peripheral nerves. High frequency probes allow high resolution imaging of peripheral nerves located at relatively superficial location. USG can diagnose and localize various pathologies that involve the peripheral nerves such as traumatic, inflammatory, infective, neoplastic, and traumatic neuropathies. USG exceptionally has an important role to play in evaluation of patients with suspected nerve injury, as MRI may not differentiate neural contusion from nerve disruption. Neurapraxic injury is seen as swollen nerve with hypoechoic appearance. 展开更多
关键词 hrus SUPERFICIAL PERIPHERAL NERVES NERVE LESIONS
暂未订购
不同气候环境下接地电阻对农业电网电能质量的影响
6
作者 熊志伟 林寿英 兰建容 《电工技术》 2023年第17期217-220,共4页
春季雨季土壤湿度高,土壤电阻率降低,系统接地电阻变小;夏秋季高温干旱,土壤电阻率升高;冬季温度太低形成冻土层,土壤电阻率急速增加,系统接地电阻变大。建立了配电网终端农场的电网模型,研究不同气候环境下,接地电阻的变化对具体农业... 春季雨季土壤湿度高,土壤电阻率降低,系统接地电阻变小;夏秋季高温干旱,土壤电阻率升高;冬季温度太低形成冻土层,土壤电阻率急速增加,系统接地电阻变大。建立了配电网终端农场的电网模型,研究不同气候环境下,接地电阻的变化对具体农业用户电能质量的影响。计算表明,当接地电阻变大时,农场电压幅值、有效视在功率变化量超过允许范围,电压总谐波畸变率、HRUh_(vs d,CP99)、THDU_(vs d,CP99)超过限值范围,极端气候时会更严重。当湿度增加、接地电阻变小时,农户电压会发生电压暂降,波形会随湿度变化而波动。 展开更多
关键词 土壤电阻率 接地电阻 电能质量 有效视在功率 HRU THD 电压暂降
在线阅读 下载PDF
Scrotal Filariasis, the Importance of Filarial Dance Sign in Scrotal Ultrasound
7
作者 Mohsen Kamel Arid 《Open Journal of Medical Imaging》 2021年第1期1-5,共5页
<strong>Objective:</strong> To study the value of the filarial dance sign as a diagnostic sign in scrotal ultrasonography in human Bancroftian filariasis. <strong>Methods:</strong> We studied 3... <strong>Objective:</strong> To study the value of the filarial dance sign as a diagnostic sign in scrotal ultrasonography in human Bancroftian filariasis. <strong>Methods:</strong> We studied 3 patients with scrotal pain, with high-resolution ultrasonography (HRUS) of scrotum including power and color Doppler study. All patients underwent peripheral blood smear. <strong>Results:</strong> Multiple cystic spaces containing motile echogenic twisted tubular structures were observed in the 3 patients. Peripheral blood smears in the 3 patients confirmed the presence of microfilaria. Mild hydrocele in two patients. <strong>Conclusions:</strong> HRUS is a useful technique for diagnosing scrotal filariasis in symptomatic patients and is very useful in the follow-up treatment. 展开更多
关键词 Filaria Dance Sign (FDS) hrus of Scrotum Scrotal Filariasis Wuchereria Bancrofti
暂未订购
基于HRU的抚河上游地表径流对土地利用变化响应特征 被引量:1
8
作者 黄嘉伟 黄宏胜 +1 位作者 张浩填 卢鑫 《水文》 CSCD 北大核心 2024年第6期38-43,50,共7页
为定量分析抚河上游地表径流对土地利用变化响应特征,以2005—2019年实测径流数据、气象数据和土地利用数据为基础构建SWAT模型,在HRU(水文响应单元)尺度分析地表径流对土地利用变化的响应规律。研究表明:(1)SWAT模型在抚河上游有较好... 为定量分析抚河上游地表径流对土地利用变化响应特征,以2005—2019年实测径流数据、气象数据和土地利用数据为基础构建SWAT模型,在HRU(水文响应单元)尺度分析地表径流对土地利用变化的响应规律。研究表明:(1)SWAT模型在抚河上游有较好的适用性;(2)2005—2019年抚河上游土地利用主要类型为林地和耕地,而建设用地扩张速度最快;(3)抚河上游土地日益细碎化,主要是林地和建设用地的面状扩张造成耕地破碎导致HRU数量增加;(4)抚河上游流域月地表径流系数与降雨量呈正相关,全年呈现先增加后下降趋势,由于耕地面积的减少和建设用地的扩张,抚河上游地表径流呈增加趋势;(5)2005—2019年4期土地利用现状下,不同土地利用类型的地表径流大小次序为建设用地>耕地>林地。 展开更多
关键词 抚河上游 HRU 地表径流 土地利用变化 SWAT模型
在线阅读 下载PDF
Use of High-Resolution Ultrasound (HRU) in the Assessment of Deep Injections of CHAP-Hyaluronic Acid (CHAP-HA) Fillers for Midface Lift 被引量:1
9
作者 Hsiao-Tung Lee Haw-Yueh Thong 《Journal of Cosmetics, Dermatological Sciences and Applications》 2018年第3期126-132,共7页
High-resolution ultrasound (HRU) imaging is a useful tool to study hyaluronic acid (HA) filler injection in the face. It is noninvasive, quick, well-tolerated, and can provide in vivo and dynamic information. The form... High-resolution ultrasound (HRU) imaging is a useful tool to study hyaluronic acid (HA) filler injection in the face. It is noninvasive, quick, well-tolerated, and can provide in vivo and dynamic information. The formations of pools or pearls in HA fillers could be observed real time during injection. The plane of injection could be determined accurately, and there were no specimen manipulation artifacts. It was observed that HA gel fillers with differing production technologies showed distinct spread and distribution patterns in the periocular tissues on HRU examination. The authors used HRU to assess deep injections of CHAP-Hyaluronic Acid (CHAP-HA) fillers for midface lift. 10 patients who underwent bilateral midface deep injections using CHAP-HA filler were examined with HRU before and immediately after treatment, and in 2 weeks and one month later. The CHAP-HA appeared as hypoechoic densities within the preperiosteal plane in HRU. CHAP-HA adopted variable morphology within the tissue depending on individual tissue densities and the compliance of the tissues in the plane of injection. CHAP-HA was unidentifiable with surrounding tissue after one month in 13 of the 20 injection sites. HRU allows in vivo study of CHAP-HA injection behavior and could be a tool for further studies of HA-tissue reactions. 展开更多
关键词 CHAP-Hyaluronic Acid (CHAP-HA) FILLER High-Resolution Ultrasound (HRU) MIDFACE Lift DEEP INJECTIONS Preperiosteal FILLER INJECTIONS
暂未订购
CHAP-Hyaluronic Acid (CHAP-HA) Filler as an Optimal Candidate for Forehead Filler Augmentation Using a 3-Point Injection Technique
10
作者 Hsiao-Tung Lee Haw-Yueh Thong 《Journal of Cosmetics, Dermatological Sciences and Applications》 2021年第2期76-83,共8页
Minimally invasive forehead augmentation is becoming increasingly popular in Asia. However, treatment of the glabella is associated with injection-related complications. The safety of injections can be increased throu... Minimally invasive forehead augmentation is becoming increasingly popular in Asia. However, treatment of the glabella is associated with injection-related complications. The safety of injections can be increased through a thorough understanding of the anatomy and precise injection planes. The authors propose a 3-point injection technique for forehead augmentation in Asian patients that uses CHAP-hyaluronic acid (CHAP-HA) filler. The longevity of the filler was assessed using high-resolution ultrasound (HRU) imaging. Fifteen patients were examined using HRU before and immediately after treatment and at 1 month, 3 months, 6 months, and 12 months. As evident in HRU imaging, CHAP-HA remained visible within surrounding tissue for 6.4 ± 3.7 months. The mean Global Aesthetic Improvement Scale rating was 2.4 ± 0.5 immediately after treatment, 2.8 ± 0.3 at 1 month, 2.7 ± 0.5 at 3 months, 2.1 ± 0.6 at 6 months, and 1.5 ± 0.6 at 12 months. Minimal side effects were reported. The authors demonstrated that CHAP-HA filler may be an optimal candidate for forehead filler augmentation using a 3-point injection technique. 展开更多
关键词 CHAP-Hyaluronic Acid (CHAP-HA) Filler High-Resolution Ultrasound (HRU) Forehead Augmentation
暂未订购
HRU215SU型草坪修剪机使用中应注意的几个问题
11
作者 桂炳中 罗绍莲 《农业机械》 2002年第8期66-69,共4页
HRU215SU型草坪修剪机是由本田澳大利亚车辆动力设备有限公司生产的,主要用于草坪的修剪,在我国绿化部门有一定保有量。我们根据使用和修理方面的经验,并参考国外有关技术资料,撰写了此文,供同行们参考。启动前的准备工作 1.检查发动机... HRU215SU型草坪修剪机是由本田澳大利亚车辆动力设备有限公司生产的,主要用于草坪的修剪,在我国绿化部门有一定保有量。我们根据使用和修理方面的经验,并参考国外有关技术资料,撰写了此文,供同行们参考。启动前的准备工作 1.检查发动机机油将草坪修剪机停放在一水平地段,打开机油加油口盖。 展开更多
关键词 HRU215SU型 草坪修剪机 运输 保管 高速 使用
在线阅读 下载PDF
Effectiveness Assessment of Soil Erosion Critical Source Areas for Soil and Water Conservation 被引量:3
12
作者 陈腊娇 朱阿兴 +1 位作者 秦承志 刘军志 《Journal of Resources and Ecology》 CSCD 2012年第2期138-143,共6页
Critical source areas (CSAs), characterized by severe soil erosion and high sediment yield, are considered to have a high priority for conservation. How to identify CSAs and assess the effectiveness of conservation ... Critical source areas (CSAs), characterized by severe soil erosion and high sediment yield, are considered to have a high priority for conservation. How to identify CSAs and assess the effectiveness of conservation practices is a key issue in site-specific watershed management. The Soil and Water Assessment Tool (SWAT) model is a useful tool for site-specific conservation practices design and several studies have attempted to identify CSAs based on watershed models. However, limited research has reported about the effectiveness of conservation practices targeting CSAs. The aim of this study was to assess the effectiveness of conservation pracrices targeted on CSAs using the SWAT model. CSA was firstly identified based on the 4-year average yearly erosion of each HRU. Appropriate soil conservation practices were then designed for the CSAs. A scenario with conservation practices for the whole watershed was also established as the contrasting counter parts scheme and then compared to the outcome of CSA-targeted conservation practices. The result shows that SWAT can accurately simulate sediment yield in the study area. CSAs were mainly located in slope farmland areas and steep gullies, coinciding with the distribution of land use and slope. The identified CSA covered 20% of the HRUs and contributed on average 44% of sediment yield. Conservation practices targeting CSAs had higher sediment reduction effectiveness (24 115 t km-2 y-1) than conservation practice covering the whole watershed (20 290 t km-2 y-1). Thus conservation practices targeting CSAs are more effective than broad conservation practices. We conclude that soil conservation practices focusing on CSAs do increase sediment reduction effectiveness. Targeting the placement of soil conservation practices based on the CSAs concept will assist water quality control in watersheds. 展开更多
关键词 effectiveness assessment critical source areas SWAT hrus soil conservation practice
原文传递
Unsupervised learning approach in defining the similarity of catchments:Hydrological response unit based k-means clustering,a demonstration on Western Black Sea Region of Turkey
13
作者 Ersin Aytaç 《International Soil and Water Conservation Research》 SCIE CSCD 2020年第3期321-331,共11页
This study investigated the similarity of the catchments with the k-means clustering method by using the hydrological response unit(HRU)images of 33 catchments located in the Western Black Sea Region of Turkey.HRUs ar... This study investigated the similarity of the catchments with the k-means clustering method by using the hydrological response unit(HRU)images of 33 catchments located in the Western Black Sea Region of Turkey.HRUs are the unit cells in hydrological models and these units are important because the same HRUs have the same hydrological behavior regarding weather inputs and water runoff.Catchments that reside inside a cluster will have high hydrological similarity,the catchments of two separate clusters would be dissimilar to each other.With the help of the clustered catchments,an elimination process can be conducted that can save time and effort in basin selection for future hydrological studies.In the study,the basic process sequence was carried out in 5 steps.These steps were creating HRUs,assigning a color to HRUs,creating HRU images,image embedding,and k-means clustering respectively.Silhouette and multidimensional scaling plots were sketched to visually examine the quality of intra-cluster distribu-tions.Considering the silhouette score values,the optimum number of clusters was determined as 8,and the clustered catchments were illustrated on the study area. 展开更多
关键词 HRU K-means clustering Multidimensional scaling ORANGE Silhouette score QSWAT+
原文传递
上一页 1 下一页 到第
使用帮助 返回顶部