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Making architectural decisions in long lifecycle systems is challenging because the time between system definition and end of operations can span multiple decades, resulting in shifts in stakeholder needs and major advances in technologies. Space-based communications using relay satellite constellations is one such example, requiring substantial up-front planning to define capabilities and size capacity due to the large investment of time and resources. Additionally, there are numerous viable system architectures. In this paper, we build on existing methods to develop a graph-based decision method to assess and explore architectural flexibility in the future evolution of long lifecycle systems. The tradespace graph defines edges between similar architectures, quantifies the switching cost between architectures, using graphs to analyse the potential system evolution pathways. In a test case on NASA communication satellites, we find that hosting government communications payloads, in particular optical payloads, on commercial satellites could reduce cost and increase flexibility of the NASA network.  相似文献   
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A familiar theory of how the volume of lending depends on the rate of interest is deficient in at least two respects. First, it treats household income as independent of the rate of interest; second, it supposes the relative prices of consumption commodities to be independent of that rate.  相似文献   
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We examine differences in price delay for a sample of real estate investment trust (REIT) and non-REIT matched pairs. Results suggest an economically and statistically higher level of price delay for REIT securities, which implies heightened frictions that increase the time needed for new information to be impounded into the prices of REIT shares. The primary drivers for the observed delay differential include differences in idiosyncratic volatility, market risk, and the number of days traded. Within-REIT determinants of delay confirm findings for the pooled sample of matched pairs. Importantly, we infer find that REIT investors are not compensated for restricted information flow, as excess returns are unrelated to the price delay.  相似文献   
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Property rights and information flows: a simulation approach   总被引:1,自引:0,他引:1  
With the growth of the information economy, the proportion of knowledge-intensive goods to total goods is constantly increasing. Lessig (The future of ideas: the fate of the commons in a connected world. Vintage, New York 2001) has argued that IPRs have now become too favourable to existing producers and that their ‘winner-take-all’ characteristics are constraining the creators of tomorrow. In this paper we look at how variations in IPRs regimes might affect the creation and social cost of new knowledge in economic systems. Drawing on a conceptual framework, the Information Space or I-Space to explore how the uncontrollable diffusibility of knowledge relates to its degree of structure, we deploy an agent-based modelling approach to explore the issue of IPRs. We take the ability to control the diffusibility of knowledge as a proxy measure for an ability to establish property rights in such knowledge. Second, we take the rate of obsolescence of knowledge as a proxy measure for the degree of turbulence induced by different regimes of technical change. Then we simulate the quantity and cost to society of new knowledge under different property right regimes.
Kyeong Seok HanEmail:
  相似文献   
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This paper explores the issue of a simultaneous reduction in tariffs at different stages of a vertically related market where each stage is oligopolistic. When vertically related markets are characterized as a successive oligopoly, reducing tariffs by an equivalent amount on upstream and downstream imports will have a differential effect on market access and hence profits at each stage as a result of a combination of horizontal and vertical effects. These differential effects have implications for the tariff structure post‐trade reform.  相似文献   
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Traditionally, consumers used the Internet to simply expend content: they read it, they watched it, and they used it to buy products and services. Increasingly, however, consumers are utilizing platforms—such as content sharing sites, blogs, social networking, and wikis—to create, modify, share, and discuss Internet content. This represents the social media phenomenon, which can now significantly impact a firm's reputation, sales, and even survival. Yet, many executives eschew or ignore this form of media because they don’t understand what it is, the various forms it can take, and how to engage with it and learn. In response, we present a framework that defines social media by using seven functional building blocks: identity, conversations, sharing, presence, relationships, reputation, and groups. As different social media activities are defined by the extent to which they focus on some or all of these blocks, we explain the implications that each block can have for how firms should engage with social media. To conclude, we present a number of recommendations regarding how firms should develop strategies for monitoring, understanding, and responding to different social media activities.  相似文献   
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This article introduces a newly discovered household budget data set for 1904. We use these data to estimate urban poverty among working families in the British Isles. Applying Bowley's poverty line, we estimate that at least 23 per cent of people in urban working households and 18 per cent of working households had income insufficient to meet minimum needs. This is well above Rowntree's estimate of primary poverty for York in 1899 and high in the range that Bowley found in northern towns in 1912–13. The skill gradient of poverty is steep; for instance, among labourers' households, the poverty rates are close to 50 per cent. Measures of the depth of poverty are relatively low in the data, suggesting that most poor male-headed working households were close to meeting Bowley's new standard.  相似文献   
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