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保护性耕作适应性评价与模式选择方法研究 被引量:2
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作者 原君静 李洪文 《农机化研究》 北大核心 2009年第7期10-13,共4页
构建了保护性耕作适应性评价指标体系,利用该指标体系,可以快速评价免耕、浅松、深松、平作、垄作、碎秆覆盖、整秆(立秆)覆盖、整秆(倒秆)覆盖、留茬覆盖等关键技术的适应性等级与得分,根据适应性状况,区别独立方案和互斥方案两种不同... 构建了保护性耕作适应性评价指标体系,利用该指标体系,可以快速评价免耕、浅松、深松、平作、垄作、碎秆覆盖、整秆(立秆)覆盖、整秆(倒秆)覆盖、留茬覆盖等关键技术的适应性等级与得分,根据适应性状况,区别独立方案和互斥方案两种不同条件,确定适合的保护性耕作模式。 展开更多
关键词 保护性耕作 适应性评价 模式选择方法 互斥方案 独立方案
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考虑直流附加控制能力的近端地方电网与直流外送系统的接入模式选择 被引量:1
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作者 林俐 郭恒 +1 位作者 周正 戚庆茹 《现代电力》 北大核心 2018年第6期16-24,共9页
针对能源基地近端、规模小、网架结构弱的地方电网的并网需求,提出考虑直流附加控制能力的近端地方电网与直流外送系统的接入模式选择方法。首先,在总结联网和孤岛接入模式存在问题的基础上,分析直流紧急功率控制和直流附加频率控制对... 针对能源基地近端、规模小、网架结构弱的地方电网的并网需求,提出考虑直流附加控制能力的近端地方电网与直流外送系统的接入模式选择方法。首先,在总结联网和孤岛接入模式存在问题的基础上,分析直流紧急功率控制和直流附加频率控制对送端系统稳定的影响,明确了直流附加控制能力对小容量地方电网接入模式选择的显著作用。进一步地,给出了模式选择原则,借鉴电力系统安全稳定导则等的相关规定,计及潮流、短路电流的要求,综合考虑故障发生几率及其对送端系统稳定影响的严重程度,确定第一级、第二级暂态安全稳定校验顺序和标准,根据交、直流特征量反映系统稳定的敏感程度,给出暂稳校验判据。最后,以某实际直流工程为算例,验证了模式选择方法的有效性与适应性。 展开更多
关键词 直流外送系统 接入模式 直流附加控制 模式选择方法 校验顺序和标准
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A purely data driven method for European option valuation 被引量:1
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作者 黄光辉 《Journal of Chongqing University》 CAS 2006年第3期175-180,共6页
An alternative option pricing method is proposed based on a random walk market model. The minimal entropy martingale measure which adopts no arbitrage opportunity in the market, is deduced for this market model and is... An alternative option pricing method is proposed based on a random walk market model. The minimal entropy martingale measure which adopts no arbitrage opportunity in the market, is deduced for this market model and is used as the pricing measure to evaluate European call options by a Monte Carlo simulation method. The proposed method is a purely data driven valuation method without any distributional assumption about the price process of underlying asset. The performance of the proposed method is compared with the canonical valuation method and the historical volatility-based Black-Scholes method in an artificial Black-Scholes world. The simulation results show that the proposed method has merits, and is valuable to financial engineering. 展开更多
关键词 derivative security: minimal entropy martingale measure Monte Carlo simulation
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Tour Level Mode Choice Analysis of Madison Area in Wisconsin
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作者 Zhang Miao Cheng Yang 《Chinese Journal of Population,Resources and Environment》 北大核心 2008年第3期90-92,共3页
This study is to investigate what factors and how they affect tours (trip chains) behavior. The key issue is the understanding and definition of tour and tour level mode. Also, these definitions should fit for the dat... This study is to investigate what factors and how they affect tours (trip chains) behavior. The key issue is the understanding and definition of tour and tour level mode. Also, these definitions should fit for the data. A semi-home based tour definition is stated, and a competing mode based tour mode is defined. Based on the definition, this study used Madison Area Data from National Household Survey to estimate a MNL structured model. It is found that travel distance could be a positive factor for car mode. Meanwhile, the number of trips is also a positive factor for choosing car. 展开更多
关键词 trip chaining multi-nominal logit model mode choice travel behavior tour analysis
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Single Production of Charged Gauge Boson W_H^-from Left-Right Twin Higgs Model in Association with Top Quark at LHC
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作者 LIU Yao-Bei WANG Xue-Lei +1 位作者 HAN Hong-Mei CAO Yong-Hua 《Communications in Theoretical Physics》 SCIE CAS CSCD 2008年第4期977-980,共4页
The twin Higgs mechanism has recently been proposed to solve the little hierarchy problem. In the context of the left-right twin Higgs (LRTH) model, we discuss single production of the new charged gauge boson WH^- ,... The twin Higgs mechanism has recently been proposed to solve the little hierarchy problem. In the context of the left-right twin Higgs (LRTH) model, we discuss single production of the new charged gauge boson WH^- , which is predicted by the left-right twin Higgs model, in association with top quark at the CERN Large Hadron Collider (LHC). It is found that, for a typical nonzero value of mass mixing parameter M = 150 GeV in the LRTH model, the production cross section is in the range of 3 ×10^-2 - 6.07×10^3 fb at the LHC. As long as the WH^- is not too heavy, the possible signatures of the heavy charged gauge boson might be detected at the LHC experiments. 展开更多
关键词 left-right twin Higgs model cross section new charged gauge boson
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连锁超市O2O条件下物流服务模式探究
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作者 李清滢 张锦 闫妍 《综合运输》 2018年第4期92-95,共4页
本文分析了连锁超市O2O模式的运营现状,探究了连锁超市发展O2O过程中“最后一公里”物流服务存在的模式和适用背景,以及顾客选择送货上门、门店自提和自提柜自提三种“最后一公里”物流服务的影响因素;同时,综述现有的物流模式选择... 本文分析了连锁超市O2O模式的运营现状,探究了连锁超市发展O2O过程中“最后一公里”物流服务存在的模式和适用背景,以及顾客选择送货上门、门店自提和自提柜自提三种“最后一公里”物流服务的影响因素;同时,综述现有的物流模式选择方法,并提出后续研究可采用的新方法,为高效设计连锁超市O2O条件下的物流服务提供参考依据。 展开更多
关键词 连锁超市O2O模式 “最后一公里” 物流服务模式 模式选择方法 NL模型
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The evolution of multi-component visual signals in darters (genus Etheostoma) 被引量:1
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作者 Jennifer M. GUMM Tamra C. MENDELSON 《Current Zoology》 SCIE CAS CSCD 北大核心 2011年第2期125-139,共15页
As complex traits evolve, each component of the trait may be under different selection pressures and could respond independently to distinct evolutionary forces. We used comparative methods to examine patterns of evol... As complex traits evolve, each component of the trait may be under different selection pressures and could respond independently to distinct evolutionary forces. We used comparative methods to examine patterns of evolution in multiple components of a complex courtship signal in darters, specifically addressing the question of how nuptial coloration evolves across different areas of the body. Using spectral reflectance, we defined 4 broad color classes present on the body and fins of 17 species of freshwater fishes (genus Etheostoma) and quantified differences in hue within each color class. Ancestral state reconstruction suggests that most color traits were expressed in the most recent common ancestor of sampled species and that differences among species are mostly due to losses in coloration. The evolutionary lability of coloration varied across body regions; we found sig- nificant phylogenetic signal for orange color on the body but not for most colors on fins. Finally, patterns of color evolution and hue Of the colors were correlated among the two dorsal fins and between the anterior dorsal and anal fins, but not between any of the fins and the body. The observed patterns support the hypothesis that different components of complex signals may be subject to distinct evolutionary pressures, and suggests that the combination of behavioral displays and morphology in communication may have a strong influence on patterns of signal evolution . 展开更多
关键词 Comparative method ETHEOSTOMA Independent evolution Nuptial coloration
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