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明代吏员的参充及指参——以《盟水斋存牍》为考察中心 被引量:1
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作者 刘涛 《西南大学学报(社会科学版)》 CSSCI 北大核心 2012年第3期137-144,175-176,共8页
在明代,吏员的参充制度主要有佥充、罚充和求充三种,而且其之间又有一个发展变化的过程。在明代中后期,求充成为主要参充制度,在这种参充制度下,吏员的指参问题日益凸显,如参充中的吏员压参争缺、役满吏员索取顶头钱、役满吏典托故恋参... 在明代,吏员的参充制度主要有佥充、罚充和求充三种,而且其之间又有一个发展变化的过程。在明代中后期,求充成为主要参充制度,在这种参充制度下,吏员的指参问题日益凸显,如参充中的吏员压参争缺、役满吏员索取顶头钱、役满吏典托故恋参占役、吏役借效劳、捏劳指参吏职、吏役移恩指参吏职、贿买吏批参充吏职以及吏与官勾结参充吏职等。这些问题的产生对明代吏治产生了巨大的影响。通过对这些问题的研究,有利于我们总结其利弊得失,并以此警示现行的公务员选拔制度中存在的问题。 展开更多
关键词 明代 吏员 指参 《盟水斋存牍》
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定数截尾两参数指数——威布尔分布形状参数的Bayes估计 被引量:20
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作者 冯艳 师义民 严惠云 《数学的实践与认识》 CSCD 北大核心 2007年第5期65-70,共6页
在不同的损失函数下,本文研究了两参数指数—威布尔分布(EWD)形状参数的Bayes估计问题.基于定数截尾试验,当其中一个形状参数α已知时,给出了另一个形状参数θ在三种不同损失函数下的Bayes估计表达式,并求得了可靠度函数的Bayes点估计.... 在不同的损失函数下,本文研究了两参数指数—威布尔分布(EWD)形状参数的Bayes估计问题.基于定数截尾试验,当其中一个形状参数α已知时,给出了另一个形状参数θ在三种不同损失函数下的Bayes估计表达式,并求得了可靠度函数的Bayes点估计.最后运用随机模拟方法,将Bayes估计和极大似然估计进行了比较.结果表明,LINEX损失下Bayes估计的精度比极大似然估计高. 展开更多
关键词 效-威布尔分布 定效截尾试验 损失函效 BAYES估计 极大似然估计
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A non-parametric indicator Kriging method for generating coastal sediment type map 被引量:2
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作者 刘付程 彭俊 张存勇 《Marine Science Bulletin》 2012年第1期57-67,共11页
Coastal sediment type map has been widely used in marine economic and engineering activities, but the traditional mapping methods had some limitations due to their intrinsic assumption or subjectivity. In this paper, ... Coastal sediment type map has been widely used in marine economic and engineering activities, but the traditional mapping methods had some limitations due to their intrinsic assumption or subjectivity. In this paper, a non-parametric indicator Kriging method has been proposed for generating coastal sediment map. The method can effectively avoid mapping subjectivity, has no special requirements for the sample data to meet second-order stationary or normal distribution, and can also provide useful information on the quantitative evaluation of mapping uncertainty. The application of the method in the southern sea area of Lianyungang showed that much more convincing mapping results could be obtained compared with the traditional methods such as IDW, Kriging and Voronoi diagram under the same condition, so the proposed method was applicable with great utilization value. 展开更多
关键词 sediment type non-parametric indicator Kriging UNCERTAINTY mapping
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论保罗·奥斯特《密室中的旅行》的三重语言观 被引量:1
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作者 李金云 《解放军外国语学院学报》 CSSCI 北大核心 2010年第6期86-90,共5页
美国文论家杰姆逊从语言符号入手来分析现实主义、现代主义与后现代主义三个文化阶段,认为现实主义阶段语言表现为能指、所指与参指三者的统一,现代主义阶段语言则表现为能指与所指的统一,而后现代主义阶段语言只剩下自动的能指。保罗.... 美国文论家杰姆逊从语言符号入手来分析现实主义、现代主义与后现代主义三个文化阶段,认为现实主义阶段语言表现为能指、所指与参指三者的统一,现代主义阶段语言则表现为能指与所指的统一,而后现代主义阶段语言只剩下自动的能指。保罗.奥斯特的小说《密室中的旅行》同时包含了这三种语言观,读者对主人公布兰克这一语言符号意义的追寻也从寻找外在世界的参指,退后到小说文本中它的所指,并最终迷失在小说无穷循环的能指链条中。杰姆逊与奥斯特在揭示语言的实质方面有着殊途同归的旨趣。 展开更多
关键词 保罗·奥斯特 密室中的旅行
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Structure Parameters and Physiological Indices Research of High-quality and High-yield Apple Orchards 被引量:1
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作者 薛晓敏 王翠玲 +2 位作者 王金政 孟海凤 聂佩显 《Agricultural Science & Technology》 CAS 2014年第11期1953-1956,1959,共5页
In order to research environment parameters and physiological indices of high-quality and high-yield apple trees, two orchards with young and mature apples trees were investigated to explore structural parameter of ap... In order to research environment parameters and physiological indices of high-quality and high-yield apple trees, two orchards with young and mature apples trees were investigated to explore structural parameter of apple tree and community, and some physiological indices in fields and by room measurements. The results showed that tree height of high-quality orchard was in the range of 260 to 290 cm, branch angle in 70°-75°, and orchard coverage rate in 75%-94%, and the connec-tion rates between rows and trees were lower. Furthermore, the total branches of mature orchard reached 1.04 ×106 per hm2, while the young orchard was 8.79 ×105 per hm2; the leaves were thick and chlorophyl content was high, with SPAD value at 58.22. Additional y, the photosynthesis of the orchard was strong, and net photo-synthetic rate was 17.48-21.8 μmolCO2/(m2·s). The proportions of lateral shoot of bearing part were 81% and 75% respectively. 展开更多
关键词 High-quality and high-yield Apple orchard Structure parameters Physio-logical index
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A new method to construct reservoir capillary pressure curves using NMR log data and its application 被引量:5
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作者 肖亮 张伟 《Applied Geophysics》 SCIE CSCD 2008年第2期92-98,共7页
By analyzing hundreds of capillary pressure curves, the controlling factors of shape and type of capillary pressure curves are found and a novel method is presented to construct capillary pressure curves by using rese... By analyzing hundreds of capillary pressure curves, the controlling factors of shape and type of capillary pressure curves are found and a novel method is presented to construct capillary pressure curves by using reservoir permeability and a synthesized index. The accuracy of this new method is verified by mercury-injection experiments. Considering the limited quantity of capillary pressure data, a new method is developed to extract the Swanson parameter from the NMR T2 distribution and estimate reservoir permeability. Integrating with NMR total porosity, reservoir capillary pressure curves can be constructed to evaluate reservoir pore structure in the intervals with NMR log data. An in-situ example of evaluating reservoir pore structure using the capillary pressure curves by this new method is presented. The result shows that it accurately detects the change in reservoir pore structure as a function of depth. 展开更多
关键词 NMR log pore structure Swanson parameter synthesized index capillary pressure curves
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Fingerprint analysis of different Panax herbal species by HPLC-UV method 被引量:4
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作者 曾凤 王晓明 +2 位作者 杨敏 卢志强 果德安 《Journal of Chinese Pharmaceutical Sciences》 CAS 2007年第4期277-281,共5页
Aim To establish a method for differentiating commercial samples of Panax species including notoginseng, cultivated ginseng (Chinese ginseng and Korean ginseng), wild ginseng, red ginseng, three types of American gi... Aim To establish a method for differentiating commercial samples of Panax species including notoginseng, cultivated ginseng (Chinese ginseng and Korean ginseng), wild ginseng, red ginseng, three types of American ginsengs, and one American ginseng preparation with their HPLC fingerprints for assnrning the quality of different commercial samples of Panax species. Methods HPLC-UV method was used to establish their fingerprints, Zorbax Extend C18 (250 mm×4.6 mm, 5 μm) was used as the analytical column, and acetonitrile/KH2PO4 aqueous solution was used as the mobile phase with gradient elution. Results The fingerprints of different commercial samples of Panax species varied in their holistic chromatograms and some specific constituents. Conclusion This method is reliable, reproducible and simple, It could be applied in the routine authentication of different commercial samples of Panax species 展开更多
关键词 GINSENG Panax species HPLC fingerprint
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Magnetic Resonance Imaging and Biological Markers in Pituitary Adenomas with Invasion of the Cavernous Sinus Space
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作者 潘力雄 刘运生 +1 位作者 赵继红 陈忠平 《The Chinese-German Journal of Clinical Oncology》 CAS 2005年第1期30-35,67,共7页
Objective: To investigate the predictability of MRI and the possiblebiological markers of cavernous sinus invasion of pituitary adenomas associated with fourphenomenas: angiogenesis, cell proliferation, apoptosis and ... Objective: To investigate the predictability of MRI and the possiblebiological markers of cavernous sinus invasion of pituitary adenomas associated with fourphenomenas: angiogenesis, cell proliferation, apoptosis and matrix metalloproteinase. Methods: Weevaluated 45 patients with pituitary adenoma according to the MRI, surgical findings and theimmunohistochemistry staining of tumor tissues. Results: The results have shown that the sensitivityof MRI for predicting cavernous sinus invasion in this prospective study was 60%, its specificity85%, its positive predictive value 83.33%, negative predictive value 62.96%. 45 specimens ofpituitary adenomas were analyzed for expression of F8, VEGF, Ki-67, c-myc, Bcl-2, nm23 and MMP-9immunoreactivity using immunoperoxidase staining. MVD was assessed using F8-related antigen. Theresults have shown that MVD of invasive pituitary adenomas was significantly higher than that ofnoninvasive (P 【 0.001). There was an association between the invasion of pituitary adenomas andKi-67 LI (P = 0.039) or the expression of VEGF (P 【 0.001) and MMP-9 (P 【 0.001). But c-myc LI andBcl-2 expression have no association with invasiveness of pituitary adenomas (P = 0.061 versus P =0.201). On the other hand, there is an inverse relationship between nm23 expression and tumorinvasion (P 【 0.001). Conclusion: Parasellar extension of pituitary adenomas through the medial wallof the cavernous sinus is diagnosed at surgery, and with sensitive gadolinium-enhanced MRI, itsextent can be partly determined by radiology. Although our study has shown that MVD and theexpression of VEGF, Ki-67, nm23 and MMP-9 have associations with invasiveness of pituitary adenomas,they are lack of specificity. These markers can only provide some useful information. 展开更多
关键词 MRI biological markers invasion of cavernous sinus pituitary adenoma
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Six—Parameter Exponential—Type Potential and the Identity for the Exponential—Type Potentials 被引量:1
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作者 JIAChun-Sheng ZENGXiang-Lin 《Communications in Theoretical Physics》 SCIE CAS CSCD 2002年第5期523-530,共8页
We propose a six-parameter exponential-type potential (SPEP), which has been shown to be a shape-invariant potential with a translation of parameters. For this reducible potential, the exact energy levels are obtained... We propose a six-parameter exponential-type potential (SPEP), which has been shown to be a shape-invariant potential with a translation of parameters. For this reducible potential, the exact energy levels are obtained byusing the supersymmetric shape invariance technique. Choosing appropriate parameters, four classes of exponential-typepotentials and their exact energy spectra are reduced from the SPEP and a general energy level formula, respectively.Each class shows the identity except for the different definitions of parameters. 展开更多
关键词 six-parameter exponential-type potential shape invariance energy eigenvalue
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Non-occupational lead exposure and hypertension in Pakistani adults 被引量:4
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作者 RAHMAN Sohaila KHALID Nasir +2 位作者 ZAIDI Jamshed Hussain AHMAD Shujaat IQBAL Mohammad Zafar 《Journal of Zhejiang University-Science B(Biomedicine & Biotechnology)》 SCIE CAS CSCD 2006年第9期732-737,共6页
Hypertension is one of the most prevalent diseases in the developed and developing countries. Based on the long historical association and the provocative findings of blood pressure effects at low level of lead exposu... Hypertension is one of the most prevalent diseases in the developed and developing countries. Based on the long historical association and the provocative findings of blood pressure effects at low level of lead exposure a study was carried out to determine if an association existed between low blood lead concentration and hypertension. In this study the effects of low-level exposure to lead on blood pressure were examined among 244 adults using atomic absorption spectrometer. For quality assurance purpose certified reference materials i.e., Animal blood A-13, Bovine liver 1577 and cotton cellulose V-9 from IAEA (International Atomic Energy Agency) and NIST (National Institute of Standard Technology) were analyzed under identical experimental conditions. The mean age of hypertensive adults was 52 years (range 43-66). The mean values of systolic and diastolic blood pressure were (209±11.7) (range 170-250) and (117±3.9) (range 105-140) mmHg respectively. Blood lead concentration ranged from 78-201 μg/L with a mean of 139 μg/L and 165-497 μg/L with a mean of 255 μg/k in normal and hypertensive adults respectively. Increase in systolic blood pressure was significantly predictive with increase in blood lead levels. Body mass index (BMI) and lipid profile including total cholesterol, low density lipoprotein cholesterol, high density lipoprotein cholesterol and triglyceride correlated with blood pressure. 展开更多
关键词 HYPERTENSION Lead exposure Biochemical parameters Body mass index
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Performance Analysis of Physical Layer Security over α-η-κ-μ Fading Channels 被引量:1
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作者 Shaobo Jia Jiayan Zhang +1 位作者 Honglin Zhao Yao Xu 《China Communications》 SCIE CSCD 2018年第11期138-148,共11页
In this paper, we consider the secure data transmission over α-η-κ-μ fading channels, which are recently proposed to encompass nearly all the well-known statistical models adopted in the literature. In particular,... In this paper, we consider the secure data transmission over α-η-κ-μ fading channels, which are recently proposed to encompass nearly all the well-known statistical models adopted in the literature. In particular, we address the secrecy performance in terms of the average secrecy capacity(ASC) and the secrecy outage probability(SOP), for which novel analytical expressions are derived. Simulation results verify the analysis and demonstrate the impact of the physical parameters on the secrecy performance of this new channel fading model. 展开更多
关键词 Physical layer security α-η-κ-μgeneralized fading channels average secrecycapacity secrecy outage probability
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Genetic Determination and Selection of Sugarcane Families
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作者 Shiyun TANG Rongzhong YANG +8 位作者 Lunwang WANG Baoqing ZHANG Yuchi DENG Cuifang YANG Shah ZHOU Wu XIAN Fang TAN Hongwei TAN Litao YANG 《Agricultural Science & Technology》 CAS 2017年第1期5-11,共7页
Sugarcane family evaluation on 108 hybridized combinations generated during 2013-2014 was conducted by measuring the main traits of plant and ratoon crops. Stalk height, stalk diameter, stalk number per stool and brix... Sugarcane family evaluation on 108 hybridized combinations generated during 2013-2014 was conducted by measuring the main traits of plant and ratoon crops. Stalk height, stalk diameter, stalk number per stool and brix were investigated in both plant cane and ratoon cane, while stalk weight per stool and brix weight per stool were measured only in plant cane. Genetic variation and genetic parameters of all traits were analyzed, and the families were evaluated based on comprehensive index method. The results showed that the stalk height of both plant and ratoon, stalk diameter of both plant and ratoon, stalk number per stool of plant, brix of both plant and ratoon, stalk weight per stool and brix weight per stool were sig- nificantly different among the families. Stalk height, stalk diameter, stalk number per stool of plant crop showed higher level of broad-sense heritability, genetic variation coefficient and relative genetic advance than those in ratoon crop. But there were no significant differences in broad-sense heritability, genetic variation coefficient and relative genetic advance of brix between plant and ratoon crops. Analysis of phenotypic and genotypic correlation showed that stalk weight per stool was significantly correlated with brix weight per stool, Fifteen elite families including Zhanzhe 74-141× CP72-1210, Guitang 05-3081×Yuetang 91-976, Yunzhe 02-588×ROC22, Funong 39× Guitang 03-1229, Guitang 02-901×Guitang 03-2357, Guitang 05-2743×Guitang 03- 1229, Guitang 92-66×ROC22, Dezhe 93-88×ROC22, Guitang 05-3445×Guitang 03- 2309, Yuetang 00-319×CP72-1210, Guitang 03-3089×ROC22, Yuetang 91-976×CP84- 1198, Yuefu 90-95 ×CP72-1210, Yunzhe 99-601×Guitang 00-122, Yuetang 00-236× ROC22 were selected based on comprehensive index method, and stalk weight per stool and brix weight per stool showed greater genetic gain. The families selected based on comprehensive index were not completely the same as the families selected by brix weight per stool, the rank correlation coefficient of the families selected based on comprehensive index and brix weight per stool was 0.748 (P〈0.01). 展开更多
关键词 Sugamane FAMILY Genetic parameter Index selection
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New Change of Technical Indicators System of Watt-Hour Meters
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作者 盛泉根 《China Standardization》 2012年第3期68-71,共4页
There is an imperfection in the accuracy indicators system and the technical parameters system in IEC standards 62053-21 implemented for watt-hour meters currently. This article quoted some parts of OIML MI-003 and R4... There is an imperfection in the accuracy indicators system and the technical parameters system in IEC standards 62053-21 implemented for watt-hour meters currently. This article quoted some parts of OIML MI-003 and R46 contents to provide a reference of the integrity comparison between the accuracy system and technical parameter system. The comparison result shows that the watt-hour meter accuracy technical indicators system of OIML R46 is more integrated. First reason is that it determines all the accuracy (basic error) defining rules just by using the technical parameter I efficiently; secondly, it can solve the contradiction that no error regulation of the range from starting current to minimum current in the process of providing, handing over and checking watt-hour meter products' qualities efficiently. Please pay close attention to the R46 official version which will be released soon, as it is still in the Committee Draft (CD6) stage currently. 展开更多
关键词 OIML R46 technical indicator ACCURACY watt-hour meter
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Watershed Prioritization of Palar Sub-watershed Based on the Morphometric and Land Use Analysis 被引量:2
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作者 Evangelin Ramani SUJATHA Radhakrishnan SELVAKUMAR Balasubramaniam RAJASIMMAN 《Journal of Mountain Science》 SCIE CSCD 2014年第4期906-916,共11页
Morphometric analysis is an indispensable tool for hydrological investigation that involves the development and management of drainage basin. This study characterizes the micro watersheds in the Palar sub-watershed us... Morphometric analysis is an indispensable tool for hydrological investigation that involves the development and management of drainage basin. This study characterizes the micro watersheds in the Palar sub-watershed using morphometric analysis and assesses its risk by land use and land cover features in a particular micro watershed. Palar sub-watershed is divided into 6 micro watersheds for prioritization based on morphometric and land use analysis. Several morphometric parameters (linear, shape and relief) are determined from the drainage map; ranks are assigned based on their capacity to induce erodability and degradation. Final ranking is based on the composite index calculated from the sum of the ranks of each morphometric parameter. Morphometric analysis reveals micro watersheds 5 and 6 as most susceptible and 2 and 3 as low susceptible. Land use is mapped using IRS ID LISS III satellite data. The risk in terms of watershed degradation involved to each micro watershed is based on the ranks of each land use feature, obtained from a similar composite index as that of morphometric analysis. Land use analysis shows that micro watersheds 2 and 4 fall under high priority category while 5 and 6 under low priority category. Integration of the morphometric and land use analysis shows that only microwatershed 1 falls under the same category in both analyses. Control measures are suggested to contain degradation depending on its specific land use pattern and morphometric features. This study ean be used to prepare a comprehensive watershed plan for the development or for planning resource conservation strategies, by integrating land use features with the drainage characteristics of the region, in particular for a hill ecosystem as the prioritization is at micro level. 展开更多
关键词 Morphometric analysis Watersheddeterioration risk Land use Palar sub-watershed Kodaikkkanal
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Resistivity response to the porosity and permeability of low rank coal 被引量:4
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作者 Wang Gang Qin Yong +3 位作者 Shen Jian Hu Yuanyuan Liu Donghai Zhao Long 《International Journal of Mining Science and Technology》 SCIE EI CSCD 2016年第2期339-344,共6页
Laojunmiao coal samples from the eastern Junggar basin were studied to understand the relationship between coal resistivity and the physical parameters of coal reservoirs under high temperatures and pressures.Specific... Laojunmiao coal samples from the eastern Junggar basin were studied to understand the relationship between coal resistivity and the physical parameters of coal reservoirs under high temperatures and pressures.Specifically,we analysed the relationship of coal resistivity to porosity and permeability via heating and pressurization experiments.The results indicated that coal resistivity decreases exponentially with increasing pressure.Increasing the temperature decreases the resistivity.The sensitivity of coal resistivity to the confining pressure is worse when the temperature is higher.The resistivity of dry coal samples was linearly related to φ~m.Increasing the temperature decreased the cementation exponent(m).Increasing the confining pressure exponentially decreases the porosity.Decreasing the pressure increases the resistivity and porosity for a constant temperature.Increasing the temperature yields a quadratic relationship between the resistivity and permeability for a constant confining pressure.Based on the Archie formula,we obtained the coupling relationship between coal resistivity and permeability for Laojunmiao coal samples at different temperatures and confining pressures. 展开更多
关键词 High temperature and high pressure Low rank coal Resistivity Porosity Permeability
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Microphysical Structure of a Nimbostratus over Jilin Province Provided by Airborne Observations
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作者 ZHAO Zhen LEI Heng-Chi 《Atmospheric and Oceanic Science Letters》 2009年第6期362-367,共6页
Airborne measurements were collected during a stepwise ascent within a nimbostratus cloud associated with a cold vortex depression over the Jilin Province on 21 June 2005 to study cloud structure and ice particle spec... Airborne measurements were collected during a stepwise ascent within a nimbostratus cloud associated with a cold vortex depression over the Jilin Province on 21 June 2005 to study cloud structure and ice particle spectra. The melting layer of the nimbostratus was clearly defined in the radar images. The microphysical structure of the nimbostratus was elucidated by a King liquid water probe and Particle Measuring Systems (PMS) probes aboard the research aircraft. The PMS 2-D images provided detailed information of ice crystal transformations. A thick layer of supercooled cloud was observed, and the high ice particle concentrations at temperatures ranging from -3℃ to -6℃ were consistent with Hallett-Mossop ice multiplication. The shape of ice crystals from near the cloud top to the melting layer were in the form of columns, needles, aggregations, and plates. In addition, significant horizontal variability was evident on the scale of few hundred meters. Particle spectra in this cloud were adequately described by exponential relationships. Relationship between the intercept (No) and slope (2) parameters of an exponential size distribution was well characterized by a power law. 展开更多
关键词 PMS cloud structure ice multiplication particle spectra
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Exponential stabilization of distributed parameter switched systems under dwell time constraints
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作者 鲍乐平 费树岷 翟军勇 《Journal of Southeast University(English Edition)》 EI CAS 2013年第4期389-394,共6页
The exponential stabilization problem for finite dimensional switched systems is extended to the infinite dimensional distributed parameter systems in the Hilbert space. Based on the semigroup theory, by applying the ... The exponential stabilization problem for finite dimensional switched systems is extended to the infinite dimensional distributed parameter systems in the Hilbert space. Based on the semigroup theory, by applying the multiple Lyapunov function method, the exponential stabilization conditions are derived. These conditions are given in the form of linear operator inequalities where the decision variables are operators in the Hilbert space; while the stabilization properties depend on the switching rule. Being applied to the two-dimensional heat switched propagation equations with the Dirichlet boundary conditions, these linear operator inequalities are transformed into standard linear matrix inequalities. Finally, two examples are given to illustrate the effectiveness of the proposed results. 展开更多
关键词 distributed parameter switched systems exponential stabilization multiple Lyapunov function linear operator inequalities dwell time
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Design Guide for Playgrounds 被引量:1
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作者 Gamze Sensoy Mehmet Inceoglu 《Journal of Civil Engineering and Architecture》 2015年第11期1390-1398,共9页
Children, who are the most weak people about sensibility and telling their desires clearly, act differently at every age phases. Because of this, child oriented designs must appeal to children about whole ages and fea... Children, who are the most weak people about sensibility and telling their desires clearly, act differently at every age phases. Because of this, child oriented designs must appeal to children about whole ages and features. Playgrounds are places where children of all ages and features spend their times commonly. But when these playgrounds were observed, that can be seen, playgrounds can not meet children's need and, because of this, they become quitted places. Within this article, child, play and playground concepts have been examined and the parameters of playground design have been classified. The aim of article is revealing the parameters for playgrounds design and offering a guide so that it can give an idea for the new- designs. 展开更多
关键词 Playground space playground design parameters spatial behaviour.
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A Two-parameter Exponential Recession Model for Simulating Cropland Soil Moisture Dynamics
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作者 SHANG Songhao MAO Xiaomin 《Chinese Geographical Science》 SCIE CSCD 2014年第5期575-586,共12页
To simulate the soil moisture variation in cropland, a two-parameter exponential recession model was derived to depict the recession process of soil moisture in the root zone. The model is based on the assumption that... To simulate the soil moisture variation in cropland, a two-parameter exponential recession model was derived to depict the recession process of soil moisture in the root zone. The model is based on the assumption that the recession rate of soil water is proportional to the potential evapotranspiration rate and the difference of soil water content and steady soil water content. Two parameters in this model are soil texture-dependent recession constant and steady soil water content. The model was calibrated and validated with measured soil water data at two experiment sites in North China with different soil textures and cropping systems. Coefficients of determination between measured and model simulated soil water content were all greater than 0.7, indicating that both models gave satisfactory simulation results. Results showed that values of two parameters mentioned above are both larger for finer soil than those for coarser soil. At the same potential evapotranspiration rate and soil water content, the recession rate of finer soil is usually lower than that of coarser soil. The proposed model can be used in irrigation management to predict approximate date for irrigation, as well as be embedded into watershed hydrological models to estimate the antecedent precipitation index. 展开更多
关键词 soil water content recession process recession coefficient potential evapotranspiration soil texture CROPLAND
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The Diversity of the Environmental Impact in Kurzeme
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作者 Imants Liepa Oskars Zalkalns 《Journal of Life Sciences》 2014年第7期570-581,共12页
The analysis of environmental impact effects on forest ecosystems has a theoretical and practical nature. Many methods have been developed to determine characteristics and intensity of this impact. Methodologically, t... The analysis of environmental impact effects on forest ecosystems has a theoretical and practical nature. Many methods have been developed to determine characteristics and intensity of this impact. Methodologically, they can be divided into three groups: environmental parameter, bioindicative and combined methods. To evaluate the environmental impact a combined method was used in this study, it was based on trees as the bioindicators and their response reactions, and environmental parameter analysis. In this study the bioindicator was Norway spruce (Picea abies (L.) Karst.), whose response reaction was used to explain total impact volumes of environmental factors in different places in the region of Kurzeme and try to interpret the causes of these differences. As the bioindicators criterion was used response reaction of Norway spruce during a period of 20 years, which was expressed with cumulative and annual additional volume increment, and was depending on the location of the stand and its morphometric characteristics. The empirical material was collected in Kurzeme region in 28 sample plots that are located on two transects and in one reference stand. For the evaluation the widths of the last 40 year growth rings were measured. To express the environmental impact in Kurzeme region a multiple regression model was developed, which explains the environmental impact in the volume of 68.2%, the rest part can be explained by the local conditions of each stand. It must be noted that methodology used in this study is very sensitive, thus, each of the nuances in the dynamics of volume's annual reduced additional increments has biological and ecological cause. 展开更多
关键词 Norway spruce additional volume increment BIOINDICATION environmental impact.
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