软土地面中机械化双叠隧道的三维数值模拟

研究目的：通过三维数值模拟,研究隧道施工过程对双叠隧道的影响。创新要点：使用全三维数值模拟方法研究软土中双叠隧道施工对先挖隧道或地面的影响。研究方法：1.运用FLAC软件创建双叠隧道的三维数值模型（图1）;2.分情况模拟机械化双叠隧道的挖掘过程;3.研究不同情况下的地面沉降,水平地面位移,以及隧道衬砌的法向位移、法向力、纵向力和弯曲力矩等。重要结论：1.新隧道施工对现有的隧道有很大的影响,最大影响出现在先挖上层隧道的情况下;2.一般来说,上层隧道的挖掘会比下层隧道产生更大的地面沉降;3.下层隧道产生的法向力总是比上层隧道大;4.在多数情况下,下层隧道产生的法向位移和弯曲力矩要比上层隧道小。     

Tribal art market: signs and signals

In this paper, we present a model for the marketability of a Tribal artwork, and we test this model empirically using a unique hand-collected dataset, which comprises the worldwide Tribal art market auctions between 1999 and 2008. Our results show a significant relationship between the probability of an artwork to be sold and several signs and signals. The effect of the auction estimated prices on the probability of sales is nonlinear and allows us to divide the Tribal art market into two price regimes. In the low-price regime, the effect of the auction estimated price on the probability of sales is negative. In the high-price regime, the effect of the auction estimated price on the probability of sales is positive.     

Modular exaptation: A missing link in the synthesis of artificial form

Exaptation, the cooption of existing technologies for emergent functions, is an important but neglected mechanism for innovation. Exaptation may enable an existing technology to (a) construct a new technological niche, (b) enter into a preexisting niche, or (c) transform the internal architecture of an artifact without changing its function.     

Systematic lossy error protection based on H.264/AVC redundant slices and flexible macroblock ordering

INTRODUCTION In typical video transmission systems, a video signal is compressed, and the resulting bit stream is transmitted over an error-prone channel. The errors may consist of symbol errors caused by fading, as observed for wireless channels, or packet erasures caused by congestion, as observed in the Internet. If a received video packet contains errors, then the portion of the video signal contained in the packet is lost and must be concealed. Error concealment schemes alone cannot …     

Electricity (de)regulation and innovation

In this paper we study the effect of deregulation on innovation in the electricity sector using a sample of 31 OECD countries. Exploiting sharp reductions in the level of product market regulation, explicitly linked to changes in the legal framework, we perform a difference-in-difference analysis by matching data retrieved from the OECD International Regulation, OECD Patent Grants, and UN World Development Indicators databases. Our main findings suggest that a decrease in regulation intensity, following a significant reform, has a negative impact on patents (granted by the European Patent Office). This impact appears to be mainly due to the degree of market contestability. Finally, we find evidence of an inverted U-shaped relationship between regulation and innovation. This may imply that the effect of deregulation on innovation depends on the strength of the deregulatory process.     

On the relationship between reserve prices and low estimates in art auctions

Using a unique hand-collected dataset comprising all auctions held by a major Italian auction house in Italy from 1994 to 1997 and including confidential information on reserve prices, we find empirical evidence in support of several studies in cultural economics literature that reserve prices are set in a range of approximately 75 % of low presale estimates.     

Exploring the dynamics of novelty production through exaptation: a historical analysis of coal tar-based innovations

Theories of technological change fail to account for innovation stemming from affordances of previously developed artefacts.  The literature has highlighted that novelty can originate from market needs, from inferences made from scientific theories or be the object of deliberate technology projects in technology-push models. More recently, scholars have suggested that exaptation, defined as the co-option of artefacts for new functions, may constitute a different path to novelty production. However, the link between the existing artefact and the genesis of new functions driving exaptation is underexplored. Through a longitudinal case study of instances of emergence of new technologies stemming from a single compound, coal tar, we show that exaptation plays a role in all novelty production and, in some cases, it is its main determinant. We build a model of exaptive novelty production that captures the interactions between secondary effects of existing technology, affordances, functionalities, and the emergence of new functions. Our model enriches the theory of innovation by integrating both serendipitous and planned processes as well as both artefactual characteristics and human intentionality.