1,766,607 research outputs found
下料问题的研究与应用
No full textThis thesis develops and investigates heuristic approaches to the classical and practical Cutting Stock problems. In particular, we concentrate on hill climbing and dynamic programming techniques, incompletely enumerative and sequential heuristic procedures.There are in total four cutting problems to be solved in this thesis. They are 1D and 2D Knapsack Problems, 1D and 1.5D Cutting Stock Problems. In 1DKP, we develop a hill climbing method, with high approximation ratio and relatively low computational complexity in solving the 1DKP of special data structure as we have described. In 2DKP, a heuristic dynamic-programming method is proposed for solving efficiently an unconstrained non-staged 2D knapsack problem. Compared with the traditional dynamic programming, the algorithm gives a high percentage of optimal solutions (93%) with a much lower computational complexity. The worst-case performance of the algorithm is evaluated. Some theoretical analyses for the algorithm are performed. Computational results are given for small and medium-sized problems. After solving the 1D and 2D Knapsack Problems, we focus our attention on a kind of 1DCSP proposed by a factory in Macao. Although this is a classical 1DCSP, the problem has so large a size that tradition Column Generation technique is no longer applicable. Thus we developed an incompletely enumerative algorithm to solve the problem. Theoretical analyses and numerical experiments show that this incompletely enumerative algorithm is an approximate implicitly enumerative solution.Finally, an iterative sequential heuristic procedure is developed to solve the general real-life 1.5DCSP. An SHP algorithm is used firstly to generate a feasible solution to the general problem. Then the SHP is improved into an iterative SHP, in which different strucures for a single cutting pattern are found by adjusting four adjustable parameters given in the SHP. With this method, the search space is enlarged and the probability that an optimal solution is found is highly improved
下料问题的研究与应用
No full textThis thesis develops and investigates heuristic approaches to the classical and practical Cutting Stock problems. In particular, we concentrate on hill climbing and dynamic programming techniques, incompletely enumerative and sequential heuristic procedures.There are in total four cutting problems to be solved in this thesis. They are 1D and 2D Knapsack Problems, 1D and 1.5D Cutting Stock Problems. In 1DKP, we develop a hill climbing method, with high approximation ratio and relatively low computational complexity in solving the 1DKP of special data structure as we have described. In 2DKP, a heuristic dynamic-programming method is proposed for solving efficiently an unconstrained non-staged 2D knapsack problem. Compared with the traditional dynamic programming, the algorithm gives a high percentage of optimal solutions (93%) with a much lower computational complexity. The worst-case performance of the algorithm is evaluated. Some theoretical analyses for the algorithm are performed. Computational results are given for small and medium-sized problems. After solving the 1D and 2D Knapsack Problems, we focus our attention on a kind of 1DCSP proposed by a factory in Macao. Although this is a classical 1DCSP, the problem has so large a size that tradition Column Generation technique is no longer applicable. Thus we developed an incompletely enumerative algorithm to solve the problem. Theoretical analyses and numerical experiments show that this incompletely enumerative algorithm is an approximate implicitly enumerative solution.Finally, an iterative sequential heuristic procedure is developed to solve the general real-life 1.5DCSP. An SHP algorithm is used firstly to generate a feasible solution to the general problem. Then the SHP is improved into an iterative SHP, in which different strucures for a single cutting pattern are found by adjusting four adjustable parameters given in the SHP. With this method, the search space is enlarged and the probability that an optimal solution is found is highly improved
Incompletely enumerative solution for 1D cutting-stock problem II
No full textIn this note, several implicitly enumerative properties of the incompletely enumerative solution for 1D cutting-stock problem given by [Far East J. Math. Sci. (FJMS) 5(1) (2002), 25-46] are proved
Song post exposure, song features, and predation risk
Full text linkMale birds use song to attract mates and deter other males, but in doing so, they also attract the attention of predators and parasites. Such viability costs are inherent in reliable signals, potentially causing females to prefer mates that display from the most exposed sites. However, viability costs of sexual signals may be ameliorated by affecting the choice of microhabitat, which in turn may affect the design of song features that are most efficiently transmitted in this microhabitat. We estimated the exposure of song posts (microsites used by males when singing) used by passerine birds in relation to prey selection by the sparrowhawk Accipiter nisus, by calculating the proportion of males that sang from song posts that were at the maximum level of the vegetation, in an attempt to quantify the costs of sexual selection. We quantified prey susceptibility to predation as the difference between the log-transformed observed number of prey minus the log-transformed expected number of prey in the environment. This prey susceptibility index increased with increasing song post exposure similarly in sexually dichromatic and monochromatic species, although the prey susceptibility index was related to sexual dichromatism. Song post exposure was dependent on habitat, but comparative models controlling for the potentially confounding effects of habitat, sexual dichromatism, hole nesting, coloniality, body mass, cognitive capacities, and flying abilities indicated that the relationship between the prey susceptibility index and song post exposure is strong. Path analyses of the relationship between song post exposure, sexual dichromatism, and prey susceptibility index revealed that selection acting on sexual dichromatism and song post exposure has secondary impact on prey susceptibility index. The opposite causal mechanisms by which predation affects sexual traits are less likely. These models suggest that female preference for high song posts or dichromatic plumage increases predation risk on an evolutionary time scale. Copyright 2006.birds; costs of sexual selection; prey selection; sound transmission
以「春秋」通「論語」--宋翔鳳「論語說義」探析
Full text link晚清公羊學的興起是近代學術史上的一件大事，影響極其深遠，與晚清學風的流變，乃至於政治、社會的變遷，均有相當密切的關係。
在常州學派?堙A宋翔鳳是繼莊存與之後，地位僅次於劉逢祿的關鍵人物之一。簡言之，莊存與是開山始祖，劉逢祿是建立理論的大宗師，龔自珍則首先以公羊議政，開晚清變法先聲，而宋翔鳳的貢獻則在於以《春秋》通《論語》，進而以《春秋》之義貫於群經，使今文經學得以進一步發展，導引了晚清今文經學家試圖以《春秋》微言大義貫於群書的治學傾向；茲以《易》、〈禮運篇〉等研究為例，後來的龔自珍、康有為都受到他的影響。
本文限於篇幅，實無法對宋翔鳳的學術思想作全面而深入的研究，而係以宋氏的《論語說義》為主要文獻依據，以《春秋》通《論語》為主題，盼能透過具體文獻的分析與詮釋，來說明他是如何以《春秋》之義通《論語》，進而揭示以《春秋》通《論語》有何重要的歷史意義與影響。為達到此一目的，筆者係透過為什麼要以《春秋》通《論語》、《論語說義》內容之分析以及綜合學者專家的相關評價等程序，逐層展開本文的析論，最後則在上述析論的基礎上，對宋氏的《論語說義》的意義、價值、影響，嘗試作一總的、適切地開發。國際紙本TW
Sexually size dimorphic brains and song complexity in passerine birds
No full textNeural correlates of bird song involve the volume of particular song nuclei in the brain that govern song development, production, and perception. Intra- and interspecific variation in the volume of these song nuclei are associated with overall brain size, suggesting that the integration of complex songs into the brain requires general neural augmentation. In a comparative study of passerine birds based on generalized least square models, we tested this hypothesis by exploring the interspecific relationship between overall brain size and repertoire size. We found no significant association between song complexity of males and brain size adjusted for body size. However, species in which males produced complex songs tended to have sex differences in overall brain size. This pattern became stronger when we controlled statistically for female song complexity by using sex differences in song complexity. In species with large differences in song complexity, females evolved smaller brains than did males. Our results suggest no role for the evolution of extended neural space, as reflected by total brain size, owing to song complexity. However, factors associated with sexual selection mirrored by sex differences in song complexity were related to sexual dimorphism in overall brain size
The evolution of song in female birds in Europe
No full textBird song is usually regarded as an attribute of males. However, in some species, females may also produce songs even with comparable complexity to that of males. It has been suggested that female song may evolve due to similar selection pressures acting on males, but no study has yet investigated the evolution of female vocalization in a phylogenetic context, a gap that we intended to fill with this study. Based on standard descriptions in The Birds of Western Palearctic, we classified 233 European passerine species with respect to whether females are known to produce songs or not. We were more likely to find information on female song for species whose song is more studied than for less intensively studied species. When we traced information on female song on a phylogeny, we found that at least in 2 avian families, female song appeared to be the ancestral state, but such an ancestral state may be expected to be even deeper in the phylogenetic tree with increasing information on female song. In fact, we cannot exclude the possibility that the ancestor of European passerines had females capable of singing. In a preliminary comparative study based on the available data, we found some evidence that female song may have evolved under the influence of sexual selection as carotenoid-based dichromatism was positively related to female song among species. Our findings imply that due to publication bias, the evolutionary importance of female song is generally underestimated. Copyright 2007.bird song; calls; comparative study; female vocalization; repertoire size; sexual selection
Age-dependent health status and song characteristics in the barn swallow
No full textBird song has been hypothesized to evolve, partly, to signal health status of males, and song features should therefore correlate with parasite load. Immune function, parasitism, and secondary sexual characters can, however, differ between age classes, and any apparent relationship between song and parasite loads can be the result of systematic age effects. We tested for an age-dependent relationship between sexually selected characters and measures of parasitism in a Spanish population of the barn swallow Hirundo rustica. A comparison across age classes revealed that chewing lice load, song duration, mean peak amplitude frequency of songs, and tail length differed significantly between yearlings and adults. In a longitudinal analysis, we found significant evidence for mean peak amplitude frequency of songs, tail length and chewing louse parasitism, and a nonsignificant tendency for song duration to change with age of an individual. We found a significant association between song duration and chewing louse load and between hematocrit and peak amplitude frequency of the rattle, the typical harsh terminal syllable. In tests for associations between song traits and health status, while controlling for age, age and chewing louse load were independently related to song duration. We found a significant relationship between pairing success and song duration, implying that females may use this song trait in their choice of parasite-free males. Although the song of the barn swallow may provide information about both male age and parasite resistance, signaling of health status appears to be independent of age effects, in accordance with the theory of parasite-mediated sexual selection, suggesting that male signals can be used as reliable indicators of parasitism. Copyright 2005.age; barn swallow; bird song; chewing louse; hematocrit; sedimentation rate
Cutting Stock Problems: Research and Application
No full text本文中共求解了四类下料问题。它们为1维，2维背包问题，1维和1.5维下料问题。在1维背包问题中，本文给出了一个爬山算法来解决这类问题。实验结果和理论分析表明，该算法在解决这类特殊数据结构的背包问题时具有很高的近优率，较低的计算复杂度。在2维背包（下料）问题中，本文提出一个启发式动态规划方法来解决这一2维背包问题。与传统的动态规划方法相比，该方法大大降低了计算复杂度，同时以较高的比率(93%)得到最优解。在理论上，本文对该算法的最坏情形进行了分析，并给出了相关理论结果。通过对中小型下料问题的数值实验对该算法的优越性进行了验证。本文给出不完全枚举方法对经典的1维下料问题进行求解。对问题的算法进行了理论上的论证，论证结果表明，采用该算法可以得到某些特殊情形下原问题的最优解。理论分析和数值实验均表明该不完全枚举解法是一种近隐式枚举方法。文中所研究的1.5维下料问题具有多目标，多约束的特性，在所获得的文献中尚没有现成的算法可以遵循。本文根据问题特点首先采用顺序启发式解法(SHP)得到问题的较好的可行解。然后通过改变SHP方法中引入的四个可调整参数的取值，将SHP方法改进为迭代启发式解法，使问题的搜索空间扩大，提高了得到问题最优解的概率
Humpback whale song on the southern ocean feeding grounds: implications for cultural transmission
No full textMale humpback whales produce a long, complex, and stereotyped song on low-latitude breeding grounds; they also sing while migrating to and from these locations, and occasionally in high-latitude summer feeding areas. All males in a population sing the current version of the constantly evolving display and, within an ocean basin, populations sing similar songs; however, this sharing can be complex. In the western and central South Pacific region there is repeated cultural transmission of song types from eastern Australia to other populations eastward. Song sharing is hypothesized to occur through several possible mechanisms. Here, we present the first example of feeding ground song from the Southern Ocean Antarctic Area V and compare it to song from the two closest breeding populations. The early 2010 song contained at least four distinct themes; these matched four themes from the eastern Australian 2009 song, and the same four themes from the New Caledonian 2010 song recorded later in the year. This provides evidence for at least one of the hypothesized mechanisms of song transmission between these two populations, singing while on shared summer feeding grounds. In addition, the feeding grounds may provide a point of acoustic contact to allow the rapid horizontal cultural transmission of song within the western and central South Pacific region and the wider Southern Ocean
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