Traffic engineering and congestion control for open shortest path first networks

Open shortest path first (OSPF) is the most widely used intra-domain Internet routing protocol. The OSPF protocol directs the Internet traffic along the shortest paths that are defined by the links weight. Traffic engineering is responsible for improving the network performance, for instance, the objective function that minimizes the maximal link utilization which is usually adopted to avoid the network congestion. This paper formulates the model of OSPF routing, and further evaluates the performance of different approaches. We also propose a heuristic algorithm to solve the routing problems by optimizing OSPF weights. Computational results indicated that the proposed algorithm could lead to good load balancing, and make efficient utilization of network resources.     

Two-dimensional density estimation using smooth invertible transformations

We investigate the problem of estimating a smooth invertible transformation f when observing independent samples X₁,…,X_n∼P°f where P is a known measure. We focus on the two-dimensional case where P and f are defined on R². We present a flexible class of smooth invertible transformations in two dimensions with variational equations for optimizing over the classes, then study the problem of estimating the transformation f by penalized maximum likelihood estimation. We apply our methodology to the case when P°f has a density with respect to Lebesgue measure on R² and demonstrate improvements over kernel density estimation on three examples.     

Variable Royalty Rates for Improving Franchise Channel Coordination*

A business format franchisor obtains a major part of its revenues from franchise royalties, which are typically a fixed percentage of franchisee gross sales. When a fixed royalty rate is used and the marginal costs of operating the franchise are increasing, the franchisee does not have an incentive to increase sales beyond a certain “optimal” volume. We present a model that recommends the use of a variable franchise royalty rate for extending this optimal sales volume. For a general convex cost function, we show that a new lower rate can be applied to incremental sales beyond the original optimal level. We show that this new rate should be less than half of the original rate when a quadratic cost function is applicable. Adopting a variable royalty rate increases franchisor royalty revenues and franchisee profits.     

地方政府竞争与区域对外开放——基于我国省级面板数据的实证研究

本文将政府与空间两重维度进行结合,从地方政府竞争的视角来分析区域对外开放问题.对地方政府进行适当的分类,分为独立型、合谋型与互助型的地方政府,尝试性地将地方政府竞争行为从纵向竞争和横向竞争扩展到时期竞争,同时以省级面板数据为基础进行实证分析,解释地方政府竞争对区域对外开放进程产生的不同效应.实证结果表明,税收优惠对区域对外开放的整体效果已经减弱.多数经济发达的地区已经不再把税收优惠作为主要的经济竞争手段,而转向改善地方公共物品的供给竞争.但在硬件和软件公共物品之间,地方政府更倾向于硬件基础设施投资,这也引发了政府对软件供给物品的供给不足.此外,制度优化竞争涉及到的产权保护、法律制度和中介组织发育等一系列制度环境因素,也会对区域的对外开放产生重要的影响意义.     

A simulation-based multi-objective optimization framework: A case study on inventory management

We propose a simulation-based solution framework for tackling the multi-objective inventory optimization problem. The goal is to find appropriate settings of reorder point and order quantity to minimize three objective functions simultaneously, which are the expected values of the total inventory cost, the average inventory level, and the frequency of inventory shortage. We develop new algorithms that can exploit statistically valid ranking and selection (R&S) procedures and the desirable mechanics of conventional multi-objective optimization techniques. Two simulation algorithms are proposed to be applied in different scenarios depending on the preference information that is revealed either during or after the actual optimization process. Experimental results are provided to evaluate the efficiency of the developed algorithms and other existing solution frameworks.     

京津冀城市群人口空间结构演变及优化路径研究

人口的流动和分布直接影响着城市群城镇体系的质量,进而影响着城市群经济社会的可持续协调发展。文章从人口分布的空间差异、动态变化以及空间格局三个层面探讨了京津冀城市群人口分布演化特征;基于中心地理论和新经济地理理论,从行政、经济、交通三个角度构建了城市人口规模分布演化影响因素分析框架,利用Zipf法则对2003～2013年京津冀城市群人口演化规律进行研究。结果表明,城市行政级别、人力资源水平、经济结构、交通建设等因素对京津冀城市群人口规模分布影响显著。基于此,提出应当通过公共服务均等化、城市技能互补、产业布局优化、交通网络建设完善等对策引导京津冀地区人口合理布局的建议,助推京津冀协同发展重大战略的实施。     

农业工程类专业本科人才培养模式的研究与实践

针对面向21世纪人才培养的要求,从如何转变教育思想观念、构建和优化农业工程人才培养目标和培养方案、优化课程体系、更新教学内容、改进教学方法和教学手段等方面出发,介绍了在教学管理实践中所取得的经验和效果。     

土地资源管理专业课程体系优化的理论与实践研究——以广西师范学院土地资源管理专业为例

土地资源管理专业课程体系在设置上存在着专业设置的标准不够规范,主干学科和主要课程设置差异较大;课程体系不够成熟,没有体现出培养不同人才的特点,主干课程的教学大纲没有统一;在人才培养上重理论、轻技术和能力等问题。研究从土地资源管理专业课程体系设置的外部环境和内部结构入手,结合新的教育理论、专业特点和社会需要等,对本专业的课程体系进行优化,分为资源、经济、管理、技术、应用和选修等六个模块,并已在广西师范学院土地资源管理专业课程设置中实践。     

On the use of local optimizations within Metropolis–Hastings updates

Summary.  We propose new Metropolis–Hastings algorithms for sampling from multimodal dis- tributions on ℜ ⁿ . Tjelmeland and Hegstad have obtained direct mode jumping proposals by optimization within Metropolis–Hastings updates and different proposals for 'forward' and 'backward' steps. We generalize their scheme by allowing the probability distribution for forward and backward kernels to depend on the current state. We use the new setting to combine mode jumping proposals and proposals from a prior approximation. We obtain that the frequency of proposals from the different proposal kernels is automatically adjusted to their quality. Mode jumping proposals include local optimizations. When combining this with a prior approximation it is tempting to use local optimization results not only for mode jumping proposals but also to improve the prior approximation. We show how this idea can be implemented. The resulting algorithm is adaptive but has a Markov structure. We evaluate the effectiveness of the proposed algorithms in two simulation examples.