贪心算法求解最少资源问题的探讨

面对资源的日益紧缺,如何有效合理的利用资源一直是专家学者研究和探讨的热点问题。最少资源问题是对初步资源规划问题的探讨,可以为多个资源组合规划问题的基础研究提供有效的参考作用。传统的回溯法穷举虽然能找到最少资源问题的最优解但其时间复杂度会高于o(n!),往往耗时太多,不能满足问题的及时性。提出了一种以最早开始时间为贪心策略的求解最少资源问题的贪心算法,不仅能够找到最优解,而且其时间复杂度仅为o(n2),极大提高了算法的效率。     

Outdoor recreation participation and views on resource development and preservation

Abstract

Views on the preservation of resources versus their development for recreation are compared among participants in three types of outdoor recreation: “appreciative”; activities (cross‐country skiing, hiking, and canoeing); “consumptive”; activities (fishing and hunting); and “mechanized”; activities (motorboating, snowmo‐biling, and trail biking). The results from a 1984 questionnaire survey conducted in Edmonton and Calgary, Canada, indicate a stronger preservationist orientation among participants in appreciative activities, whereas (with the exception of hunters) participants in consumptive and mechanized activities hold stronger pro‐development views. These differences cannot be attributed to simultaneous variations in socioeco‐nomic characteristics or environmental attitudes among the recreational groups. The findings suggest that differences in outdoor recreational activity preferences represent an important source of variation in views about appropriate levels of preservation versus development of Alberta's natural and wildernesss resources.     

Time Changes for Lévy Processes

The goal of this paper is to consider pure jump Lévy processes of finite variation with an infinite arrival rate of jumps as models for the logarithm of asset prices. These processes may be written as time-changed Brownian motion. We exhibit the explicit time change for each of a wide class of Lévy processes and show that the time change is a weighted price move measure of time. Additionally, we present a number of Lévy processes that are analytically tractable, in their characteristic functions and Lévy densities, and hence are relevant for option pricing.     

Recreation and Leisure Research from an Active Living Perspective: Taking a Second Look at Urban Trail Use Data

This paper examines recreation and leisure research within the context of active living, and highlights an apparent gap between the current involvement of recreation and leisure researchers and the potential they could offer to this important and expanding area of inquiry. To illustrate this potential, I looked at two previous studies that focused on the recreational use of urban trails and reanalyzed the data from an active living perspective. In Study 1, individual, social and environmental factors helped distinguish between low, moderate, and high activity level trail uses. In Study 2, use patterns helped distinguish between health-motivated trail users and individuals using trails for recreation and other purposes, but perceptual and demographic data were similar among groups. Findings from similar studies can help inform active living research, and recreation and leisure studies can provide leadership and contributions to a transdisciplinary understanding of active living.     

Using CRM to Manage Marketing Productivity

Abstract

The appropriate tool for measuring and managing marketing productivity is the present value of the total dollar contribution produced, divided by the total dollar value of the marketing effort expended to produce it. This ratio is referred to as the contribution return on marketing effort or CRM ratio. CRM integrated with activity based costing (ABC) and activity based management (ABM) systems, value analysis and value engineering (VA-VE) techniques offer a viable and practical foundation for managing customer relationship efforts and linking them to customer- and share holder value. The article offers a systematic approach for integrating contribution return on marketing (CRM) with customer relationship management (CRM).     

创建活动代表着人民群众的根本利益

创建文明城市活动是满足群众需要,密切党群、干群关系的桥梁和纽带;是依靠群众,实现自我价值的实践活动;是提高市民素质和城市文明程度的有效载体,要精心实施灵魂工程、基础工程、网络工程和环境工程.     

农地非农化与人类活动的动力学演化分析

研究目的:建立农地非农化与人类经济活动、人口增长的非线性动力学模型。研究方法:数学建模与数值模拟。研究结果:(1)当农地承载力较大时,可持续利用的土地资源总量可维持在一个较低的水平,农地非农化水平较高。(2)过度的农地非农化、低效率土地资源利用等一些减小资源承载力的人类活动,都将导致人口—土地资源系统作较快的非周期运动,而剧烈的变化意味着灾变。(3)农地非农化水平一定时,提高经济发展水平,可促使土地资源持续利用。(4)当前,大量的农地被非农化,提高土地资源承载力尤为重要。研究结论:农地非农化—人口增长—经济发展是一个复杂非线性系统,不同的土地利用和人口发展方向,将形成不同的平衡态,进而导致系统演化趋势迥异。     

中国西北干旱地区湿地生态系统的形成、演变和保护对策

在我国西北干旱地区，一些内陆湖泊湿地生态系统滋养了西北地区的历史文明和繁荣，从多方面支持了当地人民生活、全球生态系统的稳定和生物多样性，对保护干旱地区生态环境和促进干旱区域可持续发展具有重要意义；分析了西北干旱地区湿地生态系统的类型、形成过程及人类活动的影响，从区域可持续发展、流域水资源的合理利用、生态用水的保证、湿地生态系统服务功能的维持等方面，提出了西北干旱地区湿地生态系统的管理目标和保护对策。     

物流作业成本核算模型研究

通过对物流中心作业流程的标准化设计,基于作业成本法的思想,运用表格工具进行各项作业的成本参数设置,从而建立起物流作业成本核算模型。     

俱乐部旅游:实施、意义与前景

本文根据实地调研，讨论国内新近出现的一种新的旅游方式——俱乐部旅游。文章首先分析这种旅游方式成功实施的三要素，即相关主体、旅游线路设计、物质准备及费用；其次，从旅游者、当地社区、旅游组织者以及旅游目的地生态环境和遗产保护等角度，对俱乐部旅游进行收益分析，并同时与其他旅游方式进行效益比较；第三，通过讨论俱乐部旅游与“大众旅游”、“自助旅游”、“另类旅游”以及“活动旅游”等旅游概念的关系，对其进行学术定位；最后，从俱乐部旅游的易行性、潜在的参加者群体、与户外健身运动的关联性、以及中国户外运动资源等4个方面，指出俱乐部旅游在中国的发展前景。