Discrepancies in solutions between traditional and net present value formulations of finite horizon,discrete-time economic lot size problems

Studies that compare the Economic Order Quantity formula and similar models against their more correct net preset value (NPV) counterpart formulations have shown that the difference in discounted cost is relatively small, even in extreme cases. In this paper, we perform a similar comparison between traditional and NPV formulations of finite horizon, discrete-time economic lot sizing problems. Surprisingly, and in sharp contrast to earlier studies, we find that the traditional and NPV models can yield substantially different discounted costs and inventory policies. The results are extended to the currently emerging, similar models with pricing decisions.     

Colonising the Red Planet: Humans to Mars in Our Time

Astronautical engineer and President of the Mars Society Robert Zubrin explains why a human exploration of Mars is preferable to the Moon and now within our grasp, despite being an average of 225 million miles away. He advocates how missions might be realised through a Mars Direct approach that employs relatively small spacecraft launched directly to the Red Planet via boosters.     

Dynamic multiple-frame bandwidth provisioning with fairness and revenue considerations for Broadband Wireless Access Systems

The increasing demand for wireless heterogeneous multimedia services presents a real challenge to mobile network operators. Even with the substantial increase in the supported bandwidth in emerging Broadband Wireless Access Systems (BWASs) such as 3.5G High Speed Downlink Packet Access (HSDPA) and the Worldwide Interoperability for Microwave Access (WiMAX), satisfying the bandwidth requirements of mobile users while increasing the revenues of network operators is still one of the major issues in these systems. Therefore, bandwidth provisioning will certainly play a decisive role in the success of such BWASs. In this paper, we propose a novel dynamic multiple-frame bandwidth provisioning scheme for BWASs. The proposed scheme spans multiple time frames and optimally allocates them to the different classes of traffic depending on their weights, the real-time bandwidth requirements of their users’ connections, their channel quality conditions and the expected obtained revenues. To maximize fairness and still maintain service differentiation between classes, we provide a unique formulation for dynamically computing the class weights. Simulation results are provided to show the potential and effectiveness of our scheme.     

Should firms invest in social commerce? An integrative perspective

Integrating resource-based view and opportunity–motivation–ability framework, we theorize that social commerce represents firms’ opportunity to access valuable social media resources and gain a competitive advantage. We further argue that product uncertainty and firm reputation indicate firms’ motivation and ability, respectively, to use the social media resources, affecting the extent to which the competitive advantage can be realized. An event study of 275 social commerce initiatives announced between 2006 and 2011 supports our arguments, showing that social commerce increases firms’ stock returns, but such increases are more significant for firms selling products with high uncertainty and having high reputation.     

大海之润,非一流之归大厦之成,非一木之材--高校建筑设计研究院的成长与展望

浙江大学建筑设计研究院始终秉承浙江大学“求是创新”的文化。在建筑设计与研究中,掌握古今中外是求是的基础,理解环境形势是创新的桥梁。在设计院成立五十周年之际,通过回顾和展望,既对今后的工作起到指导的作用,也向社会展示了一所高校设计研究院的执业追求。     

基于使用可用度的核岛外设备机会维修策略研究

针对核电站事故停机将导致较大经济损失且核岛外设备允许实施并行维修的特点,对核岛外设备机会维修策略进行了研究,提出了一种以设备自身最优维修间隔期为基准的机会维修控制策略.利用蒙特卡罗仿真方法,给出了该策略中以使用可用度最大为目标的最优维修问隔期和机会维修系数的仿真求解算法,并用算例证明了采取机会维修策略能有效提高系统的使用可用度.     

三网融合背景下信息服务业发展的机遇与挑战

三网融合与信息服务业联系紧密,已成为产业发展热点。本文介绍了三网融合的概念,阐述了三网融合的重要意义,重点分析了三网融合给信息服务业发展带来的机遇和挑战,并进行了展望,最后提出了相关对策建议。     

实施浙江农村水电站技改更新的科学性与可行性

本文分析研究了浙江省上世纪90年代以前农村水电建设的发展过程和主要工程特点,论述浙江省水电技改建设的社会发展要求和建设实施的技术、环境的科学性和可行性,提出开展农村水电站技改工程是社会主义新农村建设的重要组成部分,是科学发展观的实际应用,也是浙江省农村水电发展的必然。     

游憩机会谱（ROS）在城市森林公园中的运用研究 ——以重庆照母山森林公园为例

城市森林公园是森林公园的一种 特殊类型,它既是维护城市环境的重要生态 林地,同时还兼具城市公园的功能,因此在设 计中需借助合适的分析手段,平衡林地保护 和游憩活动安排之间的关系。在分析城市森 林公园特征及问题的基础上,以重庆照母山 森林公园为例,借助城市森林公园游憩机会 谱（ROS）的评分模型及指标体系,通过城 市森林公园游憩机会谱评价,以寻求城市森 林公园中自然环境、游憩活动和管理设施之 间相互制约的关系;根据游憩机会谱评价结 果,对城市森林公园活动场所进行系统性的 分类,针对不同的游憩机会等级,提出各类 型活动场地景观设计优化的对策。以此探索 游憩机会谱（ROS）在城市森林公园中的运 用途径及对景观设计的影响。     

我国能源投融资现状及面临的机遇与挑战

本文分析讨论了我国能源投资规模、融资渠道的变化;能源融资机制与体制的历史沿革;以及当前我国能源投融资所面临的机遇与挑战。研究最后指出,当前我国能源行业面临的挑战主要有以下几个方面,在投融资监管机制、法律法规体系完善、金融市场发育程度、能源市场化程度、投资渠道和资金结构等方面都存在很大的挑战。