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61.
62.
俄罗斯极北地区的水电工程解决了许多在严寒条件和永冻土上进行施工的难题;表明水电站的修建是可行的,投入是很低的。这些水电站建成后都能在一定程度上满足北方地区的用电需求。  相似文献   
63.
A Product and Process Model of the Technology-Sourcing Decision   总被引:1,自引:0,他引:1  
The technology‐sourcing decision traditionally has examined the choice either to innovate internally or to acquire technology from outside sources. The increasing complexity of this decision requires a move beyond the simple “make‐versus‐buy” dichotomy. We seek to test factors that influence the technology decision of subsidiaries for product and process technology across the continuum of options from internal development to outsourcing. We also explore concordance between the research streams of new product development and technology sourcing. Regression models are used to analyze data from 187 subsidiaries that suggest product and process technology development decisions sometimes are associated with similar factors and at other times they diverge. In particular, we find that external product and process technology acquisition decisions are associated negatively with differentiation goals and associated positively with product dynamism. While external product acquisition is associated negatively with a low cost goal and positively with increasing distance between primary marketing and R&D operations, external process technology acquisition is associated positively with high competitive intensity. Implications include the following: (1) While external product technology acquisition may provide quicker or even less expensive initial solutions, external reliance makes it difficult to maintain a long‐term positional advantage; (2) When greater distances separate key functional activities, external partners may provide solutions that are more responsive to local consumer needs, and the potential for improved communication may allow for quicker adaptation and increased flexibility; (3) In highly dynamic product situations, internal development, while providing greater control, can be expensive and can result in technologies that are not accepted by the marketplace; and (4) As competitive intensity increases, strategic imperatives may reduce the focus on product design and development and may require increasing concentration on manufacturing costs and efficiencies.  相似文献   
64.
Industrial solid-liquid separation processes, such as pressure filtration or membrane processes, involve the application of pressure to suspensions. In response, some water is extracted, the suspension volume is reduced, and the dispersed aggregates start to form a network. In recent works, we aimed to make a prediction for the response of aggregates to stress which occurs during a filtration. We chose model systems made of aggregated silica nanoparticles. Some of these systems offer a strong resistance to applied stresses, and retain their permeability; others yield and collapse. We used small angle neutron scattering by which we can locally quantify the particle distribution withi the network to determine the processes by which particles reorganise during collapse: we found that reordering processes at the scale of 1 to 10 particle diameters control the course of collapse and the loss of permeability. Finally we constructed a numerical model for describing the processes by which colloidal aggregates are compressed. This model predicts that the response of such networks to pressure follows some scaling laws, which depend only on the elastic vs. dissipative nature of interparticle bonds.  相似文献   
65.
We examine voting by a board designed to mitigate conflicts of interest between privately informed insiders and owners. Our model demonstrates that, as argued by researchers and the business press, boards with a majority of trustworthy but uninformed “watchdogs” can implement institutionally preferred policies. Our laboratory experiments strongly support this conclusion. Our model also highlights the necessity of penalties on insiders when there is dissension among board members. However, penalties for dissent appeared to have little impact on the experimental outcomes.  相似文献   
66.
The Amazon is the largest tropical forest area on Earth, and has been undergoing rapid deforestation for the last four decades. In the Brazilian Amazon, large‐scale pasture for cattle ranching and soybean production are the main land uses, leading to a yearly deforestation rate of 0.5%. These conversions are mostly located in frontier areas distributed along the so‐called “arc of deforestation”. Within this large zone, various land use change processes are interacting through several modes of land valuation and organisation. From several case studies in the State of Pará (Brazil), the current project aims at analysing how landscape dynamics are related to infrastructure development, ecological conditions, zoning policies and to the evolution and the organisation of the production, consumption and marketing chains of livestock products. This paper presents the results for one test site, the region of São Félix do Xingú, South of Pará This region is the focus of land speculation, cattle expansion, and deforestation. Road construction, investments in electrical energy, financial credit for cattle, and the land reform policies have all fuelled this process. All these factors make this region one of the most dynamic agricultural frontiers in the Brazilian Amazon. The main objective of the paper is to improve our understanding of deforestation processes by crossing spatial analyses and 1ivestock economics.studies, and to characterise the role and impact of various natural and anthropic factors in the location and development of the main types of farmers, and their policy implications.  相似文献   
67.
Equity Volatility and Corporate Bond Yields   总被引:8,自引:0,他引:8  
This paper explores the effect of equity volatility on corporate bond yields. Panel data for the late 1990s show that idiosyncratic firm‐level volatility can explain as much cross‐sectional variation in yields as can credit ratings. This finding, together with the upward trend in idiosyncratic equity volatility documented by Campbell, Lettau, Malkiel, and Xu (2001), helps to explain recent increases in corporate bond yields.  相似文献   
68.
69.
We introduce a new method for proving large-deviation principles (LDPs). This method amounts to "mixing" a collection of LDPs with a sequence of probability measures that obeys itself an LDP. As an illustration, we construct from empirical measures a sequence of capacity-valued maps that can be considered as an indexed collection of LDPs. The index 1 coincides with Sanov's theorem. By taking a Poisson mixture we establish a new connection with Cramér's theorem.  相似文献   
70.
An algorithm is described to compute equilibria of the general economic model with incomplete asset markets, that is, of GEI. The algorithm is based on the existence of a route of zeros of a homotopy whose domain includes the price simplex and a Grassmann Manifold. This route is followed, in effect, by localizing and following diffeomorphic pieces in Euclidean space, and by relocalizing as is necessary.  相似文献   
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