共查询到20条相似文献,搜索用时 761 毫秒
1.
基于最优停时理论、实物期权方法、平滑粘贴条件和道格拉斯生产函数转换,通过时机模型构建与求解,比较分析了无泊松跳跃和有泊松跳跃两种情形下的最佳并购时机。研究结果显示,驱动企业并购的主要是协同效应;企业并购存在仅与并购双方相对股价有关的最佳并购时机及其对应的并购区域;泊松跳跃使并购阈值下界和并购阈值上界右移,并购区域变宽,选择最佳并购时机需要更多信息;在相对股价进入并购区域时,即可实施并购,否则,主并方的最佳策略为持有等待期权,即继续等待。研究结论可为企业选择最佳并购时机,尤其是国有企业选择产权转让的最佳时机提供直接理论指导和实践借鉴。 相似文献
2.
灰色关联分析在最佳承包商选择中的应用 总被引:2,自引:0,他引:2
陈群 《数学的实践与认识》2009,39(14)
承包商选择方法是否科学合理直接关系到工程项目的成败.由于承包商选择方的主观性和承包商信息获取的不完备性,若采用传统选择方法,难以取得良好的效果,并最终影响到业主的利益.针对承包商信息的灰色特征,建立了承包商选择的灰色关联度决策模型,选用投标报价、施工方案、施工工期、质量水平和企业信誉作为5个主要评价指标,运用该模型并结合工程实例进行了灰色关联分析,获得了较为可靠的承包商排序,选出了最佳承包商,证明了该方法在最佳承包商选择中的可行性和有效性.旨在为承包商选择方提供一种简单、快捷而有效的评价方法,帮助承包商选择方做出综合和相对客观的评价. 相似文献
3.
本文主要借助期权理论,讨论项目投资分多阶段进行时选择最佳投资的问题.首先通过在单阶段投资下建立项目投资的最佳选择框架,然后展开到项目投资分两个阶段进行的情形上进行讨论分析,得出此情形下的投资选择结论,最后把这一结论扩展到项目投资分多阶段进行的项目上. 相似文献
4.
5.
6.
7.
8.
提高成本相关性的关键是提高成本动因的相关性.传统方法在成本动因选择方面依靠的是规范分析方法。样本匮乏是难以采用实证方法检验成本动因相关性的根本原因.本文通过引入部门ABC获取足够样本,采用实证检验方法研究成本动因的选择问题:首先,在实地获取第一手资料的基础上,通过规范分析,确定备选成本动因;其次,引入部门ABC获取足够的样本;最后,采用统计检验方法研究成本动因的相关性选择.研究发现,原有成本动因不是最佳成本动因;ABC方法确定的成本动因是最佳成本动因. 相似文献
9.
本文介绍如何用正交试验法选择提取医用黄腐酸的最优方案 ,使提取出的医用黄腐酸达到最佳提取率 ,并符合国家药典标准 相似文献
10.
在计量经济学的研究中,计量经济模型的选择问题是一个很重要的课题。本文把一般的计量经济模型化为线性统计模型,用模型参数的最佳线性无偏估计量作为模型选择的标准,从线性统计模型的角度讨论计量经济模型的选择问题。推断结果表明:计量经济模型的选择问题转化为已知矩阵的计算。 相似文献
11.
12.
李铭 《数学的实践与认识》2008,38(7)
城市公交枢纽由于用地规模有限、公交线路集中,其内部始发站的设置不同于一般的公交首末站.本文提出了公交枢纽内始发站的布置方法,建立了公交线路和站台间优化配置模型,并提出运用模拟退火算法对模型进行求解.最后通过实例分析了提出的优化模型及解法的有效性. 相似文献
13.
In this paper, a mathematical programming model and a heuristically derived solution is described to assist with the efficient planning of services for a set of auxiliary bus lines (a bus-bridging system) during disruptions of metro and rapid transit lines. The model can be considered static and takes into account the average flows of passengers over a given period of time (i.e., the peak morning traffic hour). Auxiliary bus services must accommodate very high demand levels, and the model presented is able to take into account the operation of a bus-bridging system under congested conditions. A general analysis of the congestion in public transportation lines is presented, and the results are applied to the design of a bus-bridging system. A nonlinear integer mathematical programming model and a suitable approximation of this model are then formulated. This approximated model can be solved by a heuristic procedure that has been shown to be computationally viable. The output of the model is as follows: (a) the number of bus units to assign to each of the candidate lines of the bus-bridging system; (b) the routes to be followed by users passengers of each of the origin–destination pairs; (c) the operational conditions of the components of the bus-bridging system, including the passenger load of each of the line segments, the degree of saturation of the bus stops relative to their bus input flows, the bus service times at bus stops and the passenger waiting times at bus stops. The model is able to take into account bounds with regard to the maximum number of passengers waiting at bus stops and the space available at bus stops for the queueing of bus units. This paper demonstrates the applicability of the model with two realistic test cases: a railway corridor in Madrid and a metro line in Barcelona. 相似文献
14.
15.
发展电动公交能减少燃油消耗和城市污染物排放,对改善城市环境具有十分重要的意义.提出一种能显著减少电动公交运营成本的直流快速充电方式及相应的充电设施的建设模式.对公交枢纽直流快速充电模式下电动公交充电服务排队模型、高峰和平峰期充电设施最优配置模型进行了研究,并通过算例验证了这些模型的有效性.研究成果对我国电动公交的充电设施建设具有借鉴意义. 相似文献
16.
校车站点及线路的优化设计 总被引:1,自引:0,他引:1
以高校新校区教师校车站点及线路安排为对象,首先针对乘车站点建立了双目标非线性规划模型,其中目标函数包括乘客到达站点的距离偏差最小与所有乘客到达站点的总的距离最小两个方面;站点确定后针对车辆数最少、车辆行驶的总距离最短、各辆车的运行距离均衡及各辆车的负荷均衡这4个目标建立针对线路优化的多目标非线性规划模型,并给出了解决这类问题的启发式优化算法.与目前国内外研究相比较,该模型与算法更实际,更具体的给出了问题的解答. 相似文献
17.
In small towns, or in those peripherical metropolitan areas in which the demand for public transportation is relatively low, the objectives of the bus route planner are different from those faced in highly congested networks. Some towns, also in Italy, are experimenting with urban public transportation systems where regular bus routes are designed which allow users located at specific points outside the main line to signal their presence to the bus driver, who then deviates from the main route to satisfy this demand. This way the bus line is a mixture between a regular line and a dial-a-ride system. The bus deviation route problem is concerned with the design problem which arises in planning the location of the demand points outside the line. A model is presented which takes into account both the advantage of passengers served by this deviation device and the disadvantage suffered by passengers on the bus, whose travel time increases during deviations, and by passengers downstream of the deviation whose waiting time also increases. Through some modeling assumption we are able to represent this problem as a mixed integer linear programming problem, whose relatively low dimension allows for exact solution through standard simplex-based branch and bound code. The proposed model has been applied to a real case and some results of this are presented and discussed. 相似文献
18.
The crew rostering problem in public bus transit aims at constructing personalized monthly schedules for all drivers. This problem is often formulated as a multi-objective optimization problem, since it considers the interests of both the management of bus companies and the drivers. Therefore, this paper attempts to solve the multi-objective crew rostering problem with the weighted sum of all objectives using ant colony optimization, simulated annealing, and tabu search methods. To the best of our knowledge, this is the first paper that attempts to solve the personalized crew rostering problem in public transit using different metaheuristics, especially the ant colony optimization. The developed algorithms are tested on numerical real-world instances, and the results are compared with ones solved by commercial solvers. 相似文献
19.
20.
We model the problem of dispatching time control in rolling horizons following a periodic optimization approach reactionary to travel time and passenger demand disturbances. This model provides more flexibility to transport planners allowing them to adjust the bus schedules during the daily operations. We prove that our periodic optimization model is a convex quadratic program, guaranteeing the global optimality of its solution. To reduce the computational burden, we introduce an iterative algorithm that uses gradient approximations to obtain an approximate dispatching solution. The proposed solution method is found to be significantly faster than exact optimization approaches for quadratic programming and maintains an (almost) negligible optimality gap in realistic bus operation scenarios. Finally, we show that our periodic optimization method outperforms myopic methods that adjust the dispatching time of each bus trip in isolation using operational data from bus line 302 in Singapore. 相似文献