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21.
Sample selection in radiocarbon dating   总被引:1,自引:0,他引:1  
Archaeologists working on the island of O'ahu, Hawai'i, use radiocarbon dating of samples of organic matter found trapped in fish-pond sediments to help them to learn about the chronology of the construction and use of the aquicultural systems created by the Polynesians. At one particular site, Loko Kuwili, 25 organic samples were obtained and funds were available to date an initial nine. However, on calibration to the calendar scale, the radiocarbon determinations provided date estimates that had very large variances. As a result, major issues of chronology remained unresolved and the archaeologists were faced with the prospect of another expensive programme of radiocarbon dating. This paper presents results of research that tackles the problems associated with selecting samples from those which are still available. Building on considerable recent research that utilizes Markov chain Monte Carlo methods to aid archaeologists in their radiocarbon calibration and interpretation, we adopt the standard Bayesian framework of risk functions, which allows us to assess the optimal samples to be sent for dating. Although rather computer intensive, our algorithms are simple to implement within the Bayesian radiocarbon framework that is already in place and produce results that are capable of direct interpretation by the archaeologists. By dating just three more samples from Loko Kuwili the expected variance on the date of greatest interest could be substantially reduced.  相似文献   
22.
The matching identification problem (MIP) is a combinatoric search problem related to the fields of learning from examples, boolean functions, and knowledge acquisition. The MIP involves identifying a single “goal” item from a large set of items. Because there is commonly a cost associated with evaluating each guess, the goal item should be identified in as few guesses as possible. As in most search problems, the items have a similar structure, which allows an evaluation of each guessed item. In other words, each guessed item elicits partial information about the goal item, i.e. how similar the guess is to the goal. With this information the goal is more quickly identified.The unordered MIP has been studied by Mehrez and Steinberg (ORSA J. Comput. 7 (1995) 211) in which they proposed two different types of algorithms. The purpose of the present paper is to suggest an improved Spanning Heuristic algorithm. Its improvement increases as the problem size increases. Further results and comparisons are derived for the unordered and ordered cases.This research shows that when the search space is very large, it is better to inquire from items that are known not to be the goal (they have been ruled out by previous guesses), for the purpose of acquiring more information about the goal. As the search space is narrowed, it is better to guess items that have not been ruled out.  相似文献   
23.
一、引言双关语是一种常见的修辞格,利用语言文字的同音或多义的关系,使一个词或一句话关涉到两件事,例如:“A Can-nonball took off h is legs,so he laid down h is arm s.”(“炮弹打断了他的腿,所以他放下了武器”)在这句话中,采用同词异义或一词多义以为诙谐之用,这里的“  相似文献   
24.
以疑问义为核心范畴的疑问代词是句子的天然焦点,它在英汉两种语言系统中都占据显赫位置。由于其地位显赫,所以常常扩张用途。为了满足人类交际需要,疑问代词从基本疑问义扩张到了遍指、不定指、感叹、否定等非疑问范畴。这一现象跨语言存在并非偶然,是与人类共同的认知规律密不可分的。此外,英汉疑问代词还分别扩张出引导从句功能和回指用法,之所以出现此种类型差异,与疑问代词作为疑问焦点时所处的句法位置息息相关。  相似文献   
25.
政党价值观的功能主要包括显功能和潜功能,显功能又包括正功能和反功能两个方面.政党价值观的正功能,是政党价值观对于政党成员、政党组织乃至整个社会所具有的积极功能,主要表现为合法性辩护、凝聚激励、价值导向和社会整合等功能.政党价值观的反功能,是指政党价值观对政党的生存和发展乃至整个社会产生的消极作用和不良影响,集中体现在错误或落后的价值观的不良影响之中.不为政党成员和广大民众所预期而又确实地对政党乃至社会产生直接或间接影响的一切社会作用或客观结果,便是政党价值观的潜功能.这种结果可能与政党及其成员的主观目的相一致,也可能出现不一致的情况.  相似文献   
26.
Emergency material allocation is an important part of postdisaster emergency logistics that is significant for improving rescue effectiveness and reducing disaster losses. However, the traditional single‐period allocation model often causes local surpluses or shortages and high cost, and prevents the system from achieving an equitable or optimal multiperiod allocation. To achieve equitable allocation of emergency materials in the case of serious shortages relative to the demand by victims, this article introduces a multiperiod model for allocation of emergency materials to multiple affected locations (using an exponential utility function to reflect the disutility loss due to material shortfalls), and illustrates the relationship between equity of allocations and the cost of emergency response. Finally, numerical examples are presented to demonstrate both the feasibility and the usefulness of the proposed model for achieving multiperiod equitable allocation of emergency material among multiple disaster locations. The results indicate that the introduction of a nonlinear utility function to reflect the disutility of large shortfalls can make the material allocation fairer, and minimize large losses due to shortfalls. We found that achieving equity has a significant but not unreasonable impact on emergency costs. We also illustrate that using differing utility functions for different types of materials adds an important dimension of flexibility.  相似文献   
27.
韦恩·布斯是二十世纪美国修辞学界的知名学者,尤以小说修辞学著称。但布斯对隐喻的论述也颇具前瞻性。由于其修辞学家身份,其在阐述隐喻定义、评价等方面时难免不涉及一些诸如修辞情境、修辞动机、劝说等修辞学概念,这些概念的运用极大地充实了他的隐喻观。研究对韦恩·布斯的隐喻观作了梳理与分析,主要阐析了布斯对隐喻的概念本质、评价等方面的理解,分析了布斯的隐喻观与西方修辞学之间的内在关联,在此基础上评价了其理论贡献和局限。研究发现,布斯的隐喻观较具前瞻性,有深厚的西方修辞学底蕴,为后来的隐喻研究作了重要的铺垫。  相似文献   
28.
哈贝马斯(Habermas)是当代西方具有影响力的批判理论家,其对修辞学的贡献在于将归属于批判理论的交往重要性进行理论化。他对各种形式的公共性的历史叙述,尤其是18世纪的公共领域的叙述,以及他对交往行为理论的阐述,构成了他对20世纪修辞学理论所作的贡献。本文拟从修辞学的角度探讨哈贝马斯的批判理论,以便从一个全新的视角对他的理论进行解读。  相似文献   
29.
A procedure is proposed for testing the equality of k dependent correlation coefficients. The procedure is simulated utilizing Monte Carlo techniques; and, a method for post hoc probing is also suggested.  相似文献   
30.
以长沙市T区为分析案例,通过对T区进行调查研究,寻找当前长沙市社区管理模式存在的一些问题:管理体制的行政化,政府职能的错位与缺位,居民与社区中介组织参与社区管理程度低,社区工作任务繁重,等等。要解决当前社区管理存在的一系列问题,必须重新考析政府、社区、社区中介组织以及居民之间的关系,理顺社区管理体制,明确政府职能,大力培育社区中介组织,培养居民的参与意识,构建长沙市功能型社区管理模式。  相似文献   
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