如何成就优秀的植物园科普展览

科普展览是现代人精神文化生活不可或缺的“书卷”。植物园以大量收集的活植物作为科普展览的素材向公众传播植物科学知识及开展相关的环境教育活动,帮助参观者理解人与自然的依存关系。本文详述了如何成就一个优秀的植物园科普展览的流程,希望能为成功举办植物园科普展览提供一些参考。     

CDMA无线传播模型校正探讨

传播模型是无线网络规划和优化的基础,每一个模型反映了特定地区的电波传播特性,由于各个地区,各个不同的城市,其地物地貌有着很大的不同,需要建立适合当地特点的模型来指导网络规划和优化工作,无线传播模型校正必须在通用传播模型的基础上根据合理的测试数据和物理数据,关注模型校正中可能出现的误差,合理设置参数,最终形成适合当地无线传播环境的传播模型。     

射线跟踪模型及应用实例

射线跟踪模型作为一种高精度的规划仿真传播模型,在大中型城市重点覆盖区域的规划方案仿真验证中得到广泛应用。首先对射线跟踪模型基本原理进行介绍,然后对影响射线跟踪模型准确性的因素进行分析,最后以广州天河区和东山区的部分区域为例,将射线跟踪模型预测结果与现场路测结果进行验证及对比分析,从而说明在微蜂窝环境下射线跟踪模型的应用优势。     

Simulated annealing and tabu search approaches for the Corridor Allocation Problem

In the Corridor Allocation Problem, we are given n facilities to be arranged along a corridor. The arrangements on either side of the corridor should start from a common point on the left end of the corridor. In addition, no space is allowed between two adjacent facilities. The problem is motivated by applications such as the arrangement of rooms in office buildings, hospitals, shopping centers or schools. Tabu search and simulated annealing algorithms are presented to minimize the sum of weighted distances between every pair of facilities. The algorithms are evaluated on several instances of different sizes either randomly generated or available in the literature. Both algorithms reached the optimal (when available) or best-known solutions of the instances with n ? 30. For larger instances with size 42 ? n ? 70, the simulated annealing implementation obtained smaller objective values, while requiring a smaller number of function evaluations.     

Stochastic models for strategic resource allocation in nonprofit foreclosed housing acquisitions

Increased rates of mortgage foreclosures in the U.S. have had devastating social and economic impacts during and after the 2008 financial crisis. As part of the response to this problem, nonprofit organizations such as community development corporations (CDCs) have been trying to mitigate the negative impacts of mortgage foreclosures by acquiring and redeveloping foreclosed properties. We consider the strategic resource allocation decisions for these organizations which involve budget allocations to different neighborhoods under cost and return uncertainty. Based on interactions with a CDC, we develop stochastic integer programming based frameworks for this decision problem, and assess the practical value of the models by using real-world data. Both policy-related and computational analyses are performed, and several insights such as the trade-offs between different objectives, and the efficiency of different solution approaches are presented.     

Strategic and operational decisions in restaurant revenue management

The paper addresses restaurant revenue management from both a strategic and an operational point of view. Strategic decisions in restaurants are mainly related to defining the most profitable combination of tables that will constitute the restaurant. We propose new formulations of the so-called “Tables Mix Problem” by taking into account several features of the real setting. We compare the proposed models in a computational study showing that restaurants, with the capacity of managing tables as renewable resources and of combining different-sized tables, can improve expected revenue performances. Operational decisions are mainly concerned with the more profitable assignment of tables to customers. Indeed, the “Parties Mix Problem” consists of deciding on accepting or denying a booking request from different groups of customers, with the aim of maximizing the total expected revenue. A dynamic formulation of the “Parties Mix Problem” is presented together with a linear programming approximation, whose solutions can be used to define capacity control policies based on booking limits and bid prices. Computational results compare the proposed policies and show that they lead to higher revenues than the traditional strategies used to support decision makers.     

Online stochastic UAV mission planning with time windows and time-sensitive targets

In this paper we simultaneously consider three extensions to the standard Orienteering Problem (OP) to model characteristics that are of practical relevance in planning reconnaissance missions of Unmanned Aerial Vehicles (UAVs). First, travel and recording times are uncertain. Secondly, the information about each target can only be obtained within a predefined time window. Due to the travel and recording time uncertainty, it is also uncertain whether a target can be reached before the end of its time window. Finally, we consider the appearance of new targets during the flight, so-called time-sensitive targets, which need to be visited immediately if possible. We tackle this online stochastic UAV mission planning problem with time windows and time-sensitive targets using a re-planning approach. To this end, we introduce the Maximum Coverage Stochastic Orienteering Problem with Time Windows (MCS-OPTW). It aims at constructing a tour with maximum expected profit of targets that were already known before the flight. Secondly, it directs the planned tour to predefined areas where time-sensitive targets are expected to appear. We have developed a fast heuristic that can be used to re-plan the tour, each time before leaving a target. In our computational experiments we illustrate the benefits of the MCS-OPTW planning approach with respect to balancing the two objectives: the expected profits of foreseen targets, and expected percentage of time-sensitive targets reached on time. We compare it to a deterministic planning approach and show how it deals with uncertainty in travel and recording times and the appearance of time-sensitive targets.     

Fuzzy Multi-fractional Programming for Land Use Planning in Agricultural Production System

In this paper, we present a multi-objective linear fractional programming (MOLFP) approach for multi-objective linear fuzzy goal programming (MOLFGP) problem. Here, we consider a problem in which a set of pair of goals are optimized in ratio rather than optimizing them individually. In particular, we consider the optimization of profit to cash expenditure and crop production in various seasons to land utilization as a fractional objectives and used remaining goals in its original form. Further, the goals set in agricultural production planning are conflicting in nature; thus we use the concept of conflict and nonconflict between goals for computation of appropriate aspiration level. The method is illustrated on a problem of agricultural production system for comparison with Biswas and Pal [1] method to show its suitability.     

居民生活碳排放抽样调查方案设计:以青海省为例

调查方案设计是居民生活碳排放调查及数据分析的基础和保证.以大量文献和作者在居民生活碳排放调查中的实践经验为基础,立足调查方案的科学性和实践操作的可行性,以青海省为例,从居民生活碳排放调查的统计量选取、抽样框的构建、抽样方法的选择和样本量的确定、调查方案实施的详细步骤4方面综述性归纳了一套居民生活碳排放调查方案设计的方法,以期为居民生活碳排放研究提供参考.     

中国信息产业的发展情况及1999年主要任务

１９９８年中国信息产业继续保持了较快的增长速度，投资力度加大，产业结构优化，市场开发了不断推进，运行质量和效益进一步提高，各项改革顺利进行。１９９９年任务更加艰巨，已制定出各项发展指标，并需积极开拓市场，改善服务和提高质量，实现有效益的快速增长。