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1.
李刚俊 《电子科技大学学报(社会科学版)》2005,(6)
在考虑了操作机的关节极限、自碰撞和静态障碍物的情况下,从给定的初始位形出发,发现一条到末端效应器目标位置和姿态的相连可到达路径。方法给出了机器人操作机点到点逆运动学问题求解算法,利用碰撞算法实现了冗余度机器人运动规划,仿真验证了该方法的有效性,并表明了该方法具有较大的实用价值。 相似文献
2.
郑发科 《西华师范大学学报(自然科学版)》2002,23(2)
变点颊脊隐翅虫群目前已知10种,都生活在东亚和东南亚地区 ( Smetana, 1998 ),其中,来自越南北部 1种,尼泊尔1种,日本1种,中国7种.本文记述并图示中国四川一新种,卢氏颊脊隐翅虫,Quedius (Raphirus) luae,该种与Q. (R.) jindrai相似,但除雄性外生殖器的差异外,腹部第1背板两侧无金色毛簇,触角和足的颜色也与之有别. 相似文献
3.
组合预测误差信息矩阵研究 总被引:11,自引:0,他引:11
唐小我 《电子科技大学学报(社会科学版)》1992,(4)
研究组合预测误差信息矩阵的结构与组合预测方法性质之间的联系,首次提出冗余信息概念,对最优组合预测方法的组合结构进行了研究。 相似文献
4.
5.
Quantifying the Establishment Likelihood of Invasive Alien Species Introductions Through Ports with Application to Honeybees in Australia
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The cost of an uncontrolled incursion of invasive alien species (IAS) arising from undetected entry through ports can be substantial, and knowledge of port‐specific risks is needed to help allocate limited surveillance resources. Quantifying the establishment likelihood of such an incursion requires quantifying the ability of a species to enter, establish, and spread. Estimation of the approach rate of IAS into ports provides a measure of likelihood of entry. Data on the approach rate of IAS are typically sparse, and the combinations of risk factors relating to country of origin and port of arrival diverse. This presents challenges to making formal statistical inference on establishment likelihood. Here we demonstrate how these challenges can be overcome with judicious use of mixed‐effects models when estimating the incursion likelihood into Australia of the European (Apis mellifera) and Asian (A. cerana) honeybees, along with the invasive parasites of biosecurity concern they host (e.g., Varroa destructor). Our results demonstrate how skewed the establishment likelihood is, with one‐tenth of the ports accounting for 80% or more of the likelihood for both species. These results have been utilized by biosecurity agencies in the allocation of resources to the surveillance of maritime ports. 相似文献
6.
Communicating Conservation Status: How Different Statistical Assessment Criteria Affect Perceptions of Extinction Risk
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Although alternative forms of statistical and verbal information are routinely used to convey species’ extinction risk to policymakers and the public, little is known about their effects on audience information processing and risk perceptions. To address this gap in literature, we report on an experiment that was designed to explore how perceptions of extinction risk differ as a function of five different assessment benchmarks (Criteria A–E) used by scientists to classify species within IUCN Red List risk levels (e.g., Critically Endangered, Vulnerable), as well as the role of key individual differences in these effects (e.g., rational and experiential thinking styles, environmental concern). Despite their normative equivalence within the IUCN classification system, results revealed divergent effects of specific assessment criteria: on average, describing extinction risk in terms of proportional population decline over time (Criterion A) and number of remaining individuals (Criterion D) evoked the highest level of perceived risk, whereas the single‐event probability of a species becoming extinct (Criterion E) engendered the least perceived risk. Furthermore, participants scoring high in rationality (analytic thinking) were less prone to exhibit these biases compared to those low in rationality. Our findings suggest that despite their equivalence in the eyes of scientific experts, IUCN criteria are indeed capable of engendering different levels of risk perception among lay audiences, effects that carry direct and important implications for those tasked with communicating about conservation status to diverse publics. 相似文献
7.
唐婧 《西南石油大学学报(社会科学版)》2019,21(1):106-114
构式与其组构成分间的互动关系一直是构式语法关注的核心问题之一。Goldberg在构式语法理论框架中提出了动词与构式的双向互动观,但在实际论述中却过于强调构式对动词的单向压制,降低了动词义对构式生成的贡献,忽略了对构式组构成分的系统研究。以构式与其组构成分间的互动关系为视点,从构式压制与承继的辩证关系出发,进一步阐释图示构式生成是构式与组构成分在互动压制和多重承继合力作用下的结果。同时,基于封闭语料库穷尽分析汉语羡余否定构式"好不X"的特征,结果表明:构式压制与词汇压制是双向互动的;图示构式特征的形成取决于构式对其组构成分的多重动态承继;图示构式基于互动压制承继合力机制的形成。 相似文献
8.
Anthony Almudevar 《Revue canadienne de statistique》2000,28(1):81-95
Assignment of individuals to correct species or population of origin based on a comparison of allele profiles has in recent years become more accurate due to improvements in DNA marker technology. A method of assessing the error in such assignment problems is présentés. The method is based on the exact hypergeometric distributions of contingency tables conditioned on marginal totals. The result is a confidence region of fixed confidence level. This confidence level is calculable exactly in principle, and estimable very accurately by simulation, without knowledge of the true population allele frequencies. Various properties of these techniques are examined through application to several examples of actual DNA marker data and through simulation studies. Methods which may reduce computation time are discussed and illustrated. 相似文献
9.
气候变化科学对以人类为中心的人文主义史学具有重要影响。科学家关于气候变化的观点不仅挑战了人类支撑历史学这门学科的观念,而且挑战了后殖民与后帝国时代历史学家在过去20年来,回应战后非殖民地化与全球化势态时所运用的分析策略。现在的历史知识构建以人文主义史学关于人类历史与自然史古老区分的失效为历史学科的大前提,将人类视为一种地质力量的人类世观念严格限定了人文主义史学,要求资本主义历史与地球和人类进化的更大尺度的历史进行对话。有记载的历史与深层历史进行这种对话是一个探索历史理解界限的过程。 相似文献
10.
Teiji Sota 《Researches on Population Ecology》1998,40(2):173-174
I studied the effect of treehole (microhabitat) size distribution in local habitats on geographic difference in aquatic metazoan
community structure by comparing differences between two sites on Iriomote Island, and between Iriomote Island (subtropical)
and Tsushima Island (temperate), in southwestern Japan. In treeholes at each local site, the amount of litter, the species
richness and total biomass of metazoa were positively correlated with treehole capacity. Between the two sites on Iriomote
Island (Shirahama and Komi), the amount of litter, biomass and species number per treehole was greater at Komi where the mean
and variance of treehole size were greater, while the dependencies of these parameters on treehole capacity were common to
both sites. Total species number was larger at Komi (2 predators and 20 saprophages) than at Shirahama (1 predator and 19
saprophages). Most of the dominant taxa colonized larger treeholes with higher probabilities, although one taxa showed the
opposite trend. Treeholes on Tsushima were smaller than those on Iriomote. The metazoan fauna in treeholes consisted of 15
saprophages on Tsushima, being less richer than that on Iriomote Island which had 2 predators and 21 saprophages. However,
the dependencies of litter amount and biomass on treehole capacity did not differ significantly between the islands, although
treeholes on Iriomote harbored a greater number of species per treehole than those on Tsushima. This study indicated that
there are general correlates between community structure within individual treeholes (infracommunity structure) and treehole
capacity (microhabitat size). Therefore, microhabitat-size distribution is potentially a significant constraint of local community
structure, and its variation may contribute to the variation in local and regional species richness. 相似文献