玩具中激光器和发光二极管辐射测试方法

玩具中激光器和发光二极管发出的过量辐射会导致人眼和皮肤的严重损伤,尤其容易对儿童造成伤害。本文论述了激光器和发光二极管辐射关键参数的测试方法和测试步骤,并对样品进行了具体测试。     

Optimal safety stock levels of subassemblies and manufacturing components

In order to control the time to market and manufacturing costs, companies produce and purchase many parts and components before receiving customer orders. Consequently, demand forecasting is a critical decision process. Using modular product design and super bills of materials are two effective strategies for developing a reliable demand forecasting process. They reduce the probability of stockouts in diversified production contexts. Furthermore, managing and controlling safety stocks for pre-assembled modules provide an effective solution to the problem of minimizing the effects of forecast errors. This paper develops, evaluates, and applies innovative cost-based analytical models so that the optimal safety stock of modular subassemblies and components in assembly to order and manufacturing to order systems, respectively, can be rapidly quantified. The implementation of the proposed models in two industrial case applications demonstrates that they significantly reduce the safety stock inventory levels and the global logistical cost.     

The business case of a network that serves both public safety and commercial subscribers

Deploying a single nationwide broadband wireless network to serve all public safety users would have great advantages over the existing fragmented public safety systems. A nationwide system could be created to serve both public safety and commercial subscribers, which would allow a provider to exploit important economies but force it to meet the more costly requirements of public safety. This paper analyzes the viability of a public-private partnership that serves public safety and commercial subscribers from a for-profit provider's perspective. A model is presented that estimates the net present value (NPV) of a wireless network by calculating costs based on the number of cell sites required and revenue based on the projected number of subscribers acquired. The model is applied to both a network that serves only commercial subscribers on 10 MHz of 700 MHz spectrum and a public-private partnership that serves commercial subscribers and public safety personnel on 20 MHz of 700 MHz spectrum. It is found that NPV is greater for the public-private partnership than for the commercial-only network for any population density, which shows that the value of 10 MHz of spectrum exceeds the cost of meeting public safety requirements. Furthermore, the paper demonstrates that NPV/cell increases with population density, so urban areas are profitable and rural areas are unprofitable. The paper demonstrates that a partnership covering 94% of the US population breaks even because the most urban 56% of population subsidizes coverage for the next 38%. If initial deployment is subsidized, a financially sustainable public-private partnership can serve much more than 94%. Additionally, it is shown that allowing urban municipalities to opt-out of the partnership can significantly increase the subsidies required.     

Net Neutrality in Europe: Desperately seeking a market failure

Net Neutrality has become the focus of attention in the regulatory debate on the Internet. This article attempts to strip down the debate to its bare essential. It identifies two main types of Net Neutrality obligations that have been put forward and assesses what type of potential concerns they may be designed to address. It concludes that while some of these concerns may be important it remains doubtful (at least in Europe) that an ex ante per se rule, such as those proposed under the Net Neutrality term, is the best way to address them.     

Multihoming, content delivery networks, and the market for Internet connectivity

Peering points between different Internet service providers (ISPs) are among the bottlenecks of the Internet. Multihoming (MH) and content delivery networks (CDNs) are two technical solutions to bypass peering points and to improve the quality of data delivery. So far, however, there is no research that analyzes the economic effects of MH and CDNs on the market for Internet connectivity. This paper develops a static market model with locked-in end users and paid content. It shows that MH and CDNs create the possibility for terminating ISPs to engage in monopolistic pricing towards content providers, leading to a shift of rents from end users and content providers to ISPs. Implications for future innovations are discussed.     

投资项目评价标准的比较与选择

净现值、内部收益率、获利指数等贴现指标在互斥项目选择的实际应用中,常导致不同的投资决策,其原因、解决方法是本文探讨的目的。文章首先对净现值和内部收益率进行比较分析,着重介绍了内部收益率的先天缺陷及替代方法MIRR;然后分析净现值和获利指数的主要差异,最后得出结论:净现值是确定条件下投资项目评价标准中最合理的方法,其他标准则需结合着净现值来运用,否则可能导致决策失误。     

参与和治理:中国社会安全网建设的战略选择

中国正处在社会经济转型时期，在此期间，社会安全网的建设完善与否不仅是保证经济持续增长的内在要求。更是保证社会稳定的关键。分析中国社会安全网的建设过程，评估社会安全网的状况，本文认为，中国社会安全网的未来走向或者战略选择应该以政府为主导力量，通过多元主体的互动逐步迈向善治，实现从政府管理到治理的转变，建立责任分担的社会风险防御机制，提升弱势群体的社会参与机会与能力，消除社会隔阂、实现社会整合。     

论安全食品供应链管理

本文提出安全食品供应链管理是保障食品安全的重要途径,并从以下几方面来讨论安全食品供应链管理:食品供应链管理的必要性;食品供应链设计的基本要求;目前我国食品供应链的特性分析;食品供应链的优化管理方法。     

用收敛类刻划第一可数公理

本文用收敛类诱导出满足第一可数公理的拓扑空间,并得到一个拓扑空间满足第一可数公理的充要条件。     

Anticipated foreign military threat, arms accumulation, and the current account in a small open economy

This paper examines the effects of an anticipated foreign military threat on consumption, the home weapons stock, and net foreign asset position in a small open economy. If the utility function is separable between butter and guns, the economy decreases both butter and guns when the news arrives, accumulates foreign assets prior to the foreign threat realization, and increases guns as the foreign threat realizes. If the utility function is nonseparable between butter and guns, the economy may have two dynamic responses. The first is similar to the separable case, except that consumption exhibits a discrete jump when the foreign threat realizes. The second is that the economy increases both butter and guns on impact, decumulates foreign assets prior to the foreign threat implementation, but either increases or decreases guns as the foreign threat realizes.