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1.
Despite the abundant research on material flows and the growing recognition of the need to dematerialize the economy, business enterprises are still not making the best possible use of the many opportunities for material efficiency improvements. This article proposes one possible solution: material efficiency services provided by outside suppliers. It also introduces a conceptual framework for the analysis of different business models for eco-efficient services and applies the framework to material efficiency services. Four business models are outlined and their feasibility is studied from an empirical vantage point. In contrast to much of the previous research, special emphasis is laid on the financial aspects. It appears that the most promising business models are ‘material efficiency as additional service’ and ‘material flow management service’. Depending on the business model, prominent material efficiency service providers differ from large companies that offer multiple products and/or services to smaller, specialized providers. Potential clients (users) typically lack the resources (expertise, management's time or initial funds) to conduct material efficiency improvements themselves. Customers are more likely to use material efficiency services that relate to support materials or side-streams rather than those that are at the core of production. Potential client organizations with a strategy of outsourcing support activities and with experience of outsourcing are more keen to use material efficiency services.  相似文献   

2.
As part of a study investigating the naturally-occurring fractures in mafic rocks, two holes were drilled 450 m apart through the Palisades dolerite sill in New York. Well-2 is 229 m deep and Well-3 was drilled to 305 m, both penetrating through the sill and into the underlying Triassic sediments of the Newark Basin. Both holes were logged with downhole geophysical tools, including the BHTV, which acoustically images fractures intersecting the well. Understanding the fracture pattern, density, and porosity in the sill is essential for identifying possible zones of active fluid flow and high permeability. Using the BHTV logs, 96 and 203 fractures were digitally mapped within the sill in Well-2 and Well-3, respectively. Most fractures appear to dip steeply (76-78°). There is a shift in fracture orientation, however, and these fractures may or may not be continuous over the short lateral distance between Well-2 and Well-3. The lithology of the sill as identified by drill chips is nevertheless continuous between the holes. Both intersect a 7 m thick olivine-rich layer about 15 m above the bottom of the sill. Several fractures identified in Well-2 have large apparent aperture (>6cm) which correspond to high porosity zones (6-14%) observed in the logs. Resistivity logs were used to compute porosity using Archie's law and match well with the neutron porosity log in Well-2. We use the relationship between porosity and fracture aperture within the sill at Well-2 to infer the porosity in Well-3. High-porosity, large-aperture zones, including the target olivine layer, are identified in both holes. Changes in the temperature gradient log indicate active fluid flow in the sill, although flow appears to be most active in the sediments. Direct field measurements of bulk permeability, hydrologic modeling of fluid flow and calibration of fracture and log porosity will be undertaken in the future.  相似文献   

3.
"In this paper, an individual model of rural-urban migration is studied, emphasizing the effects of information flow and urban wage dispersion. Migration is viewed in the context of a lifetime program of job search. It is shown that migration can occur even when the mean urban wage is no larger than the rural income flow.... Both the shape and spread of the urban wage dispersion are shown to affect migration behavior significantly." The geographical focus is on developing countries.  相似文献   

4.
An empirical analysis is developed that quantifies the impact of different types of traffic incidents on the speed and maximum flow averages of vehicles on a controlled-access highway. The incident types considered include damage to highway infrastructure, vehicle rollover, crashes (into stationary objects), collisions (with moving vehicles), rain, fog, vehicle breakdowns, pedestrians on roadway, etc. Using real-world data from Chile’s most heavily used urban motorway/freeway, estimates of incident impacts on speed are generated using a multiple linear regression model incorporating instrumental variables to correct for endogeneity. Flow results are then generated using the fundamental traffic equation relating speed, flow and density. A ranking of the impacts on highway traffic of the different incident types based on incident frequency as well as impact size demonstrates that for the real case studied, the incidents with the greatest cumulative effect are (in order of magnitude) vehicle breakdown, collisions and rain.  相似文献   

5.
Tax portfolio literature has focused on deriving the optimal composition of the tax structure for a particular state. However, tax revenue flow is influenced by both tax structure and economic conditions which are unique for each state. Therefore, the literature has been unable to generalize the characteristics of optimal tax structures. This paper examines the contribution of a state's economic condition, as well as the tax structure, to the growth and variability of tax revenue flow. In addition, the optimal tax portfolio is studied for changes in revenue growth targets and economic conditions.  相似文献   

6.
Base on the framework of material flow analsis (MFA) proposed by Eurostat, this paper collected related data and conducted a regional MFA for the Chengyang Districgt in Qingdao. The indicators such as Direct Material Input(DMI), Direct Material Consumption (DMC) and Exports are calculated or estimated for the period of year 1995 through 2004. Several derivable iudicators defining direct material productivity and material intenstiy are also evaluated and some valuable conclusions were drawn. DMI in absolute number increased from about 1645.9 kilotons in 1995to about 8052.5 kilotons in 2004. Imports contribute to about 47 to 69% of DMI, and the biggest component of imports is fossil fuel that approximatley accounts far 50% of imnports. DMI per capita of Chengyang District increased rapidly and reached 17. 4 tons in 2004. Compared with other five economies studied by WRI, material consumption intensity of Chengyang District is significantly lower than developed countries, which indicates that Chengyang District is still in a development stage The direct material productivity (actual GDP per DMI) increased 59.1% from 1995 to 2004 and has been higher than either of stadies in China, which indicates efficiency of resources utilization has improved obviously in Chengyang District. But there was significant increase in material input in the last decade, which shows that rapid increase of economy is highly dependent on requirement and consumption of natural resources. Therefore, in order to promote the sustainahility, it is essential to develop circular economy and improve utilization efficiency of resources.  相似文献   

7.
This empirical study examines the extent of non–linearity in a multivariate model of monthly financial series. To capture the conditional heteroscedasticity in the series, both the GARCH(1,1) and GARCH(1,1)–in–mean models are employed. The conditional errors are assumed to follow the normal and Student– t distributions. The non–linearity in the residuals of a standard OLS regression are also assessed. It is found that the OLS residuals as well as conditional errors of the GARCH models exhibit strong non–linearity. Under the Student density, the extent of non–linearity in the GARCH conditional errors was generally similar to those of the standard OLS. The GARCH–in–mean regression generated the worse out–of–sample forecasts.  相似文献   

8.
The process of economic activities is on the basis of tremendous material inputs. China has been discharging an enormous amount of waste, giving rise to a wide range of environmental impacts. The method of economy-wide material flow analysis (EW-MFA) is one of the effective tools to examine the flow of materials entering physical economies, and recognize early environmental problems. Relevant researches are still at the early stage in China and most focus on material throughput but are rarely concerned about the utilization of recycling resource and environmental impact. Based on more than 3,000 items of data related, materials entering Chinese economy are classified into three types, and then the characteristics of material input and environmental impact are presented for the years 1990-2005 by using the indicators derived from EW-MFA. The Ratio of Recycled Material (RRM) is added as the new indicator in order to be in accordance with the need of circular economy being promoted in China. Results show that the great changes in the structure of material input cause the continuous increase of industrial solid waste emissions and the bogging down of material productivity. The RRM reveals that the utilization of recycling resources remains at a fairly low level in China. Finally, some weakness of EW-MFA is discussed according to the calculated results.  相似文献   

9.
本文运用投入产出理论与方法,对工业企业生态系统的投入产出进行了分析,界定了工业企业生态工程的投入产出,给出与投入产出有关概念的量化定义。工业企业生态工程作为一个投入产出系统,不仅仅是传统意义上的投入产出,它不仅包括经济投入与经济产出,还包括生态投入与生态产出。在工业企业生态系统中,各部门、各分厂及车间的生产过程不是孤立和封闭的,而是通过物质流、能量流、信息流和价值流相互联系的,并支撑其投入产出结构,根据这一原理,我们构建了工业企业生态系统基于物质流的投入产出表。在调查分析的基础上,我们结合RH制药企业构建了生态投入产出模型,填制了其投入产出表,测算了其消耗系数,为企业进一步推进生态工程提供依据。  相似文献   

10.
This study proposes a full Bayesian nonparametric procedure to investigate the predictive power of exchange rates in relation to commodity prices for three commodity-exporting countries: Canada, Australia, and New Zealand. We propose a new time-dependent infinite mixture of a normal linear regression model of the conditional distribution of the commodity price index. The mixing weights follow a set of Probit stick-breaking priors that are time-varying. We find that exchange rates have a positive predictive effect in general, but accounting for time variation does not improve forecasting performance. By contrast, the intercept in the regression and the lagged dependent variable show signs of parameter change over time in most cases, which is important in forecasting both the mean and the density of commodity prices one period ahead. The results also suggest that the variance is a large source of the time variation in the conditional distribution of commodity prices.  相似文献   

11.
In an earlier article we studied the Communities of Practice and their conditions of emergence using an Agent based model with a set of agents facing a continuous flow of problems. We now center our analysis on the performance of this organizational structure compared to a two-level hierarchical delegation structure. Our results show the crucial role played by the communication and the specialisation of agents; especially that community structures are efficient for competence building and learning in the long term. This paper backs the claim made by (Bowles, S., Gintis, H., 2002. Social capital and community governance. The Economic Journal 112, 419–437.) that hierarchy and communities are complementary modes of governance.  相似文献   

12.
《Ecological Economics》2011,70(12):2606-2613
A dynamic material flow analysis model is developed to quantify aluminum in-use stocks and old scrap recycling and recovery in the United States for the period of 1900 to 2007. The total in-use aluminum stock in 2007 is estimated as 93 million metric tons, which represents approximately 34% of the cumulative apparent consumption since 1900. Alternately, since 1900 nearly 40% of the cumulative discarded aluminum has not been recycled for domestic use in the U.S. or for export to foreign consumers. Statistical time series analysis is used to explore the relationship between model results of in-use stocks and gross domestic product (GDP). Unlike most previous studies of material consumption and economic activity, which ignore the statistical properties of time series data to the detriment of model estimation and inference, data stationarity is explicitly evaluated through unit root testing and model specification is adjusted accordingly. The annual percentage change in GDP is found to have a large and significant association with the annual percentage change in net additions to in-use stocks. Model sensitivity and uncertainty are quantified through the application of the Fourier Amplitude Sensitivity Test and alternate specifications of product lifetime probability density functions.  相似文献   

13.
Finite Prandtl number thermal convection is important to the dynamics of planetary bodies in the solar system. For example, the complex geology on the surface of the Jovian moon Europa is caused by a convecting, brine-rich global ocean that deforms the overlying icy “lithosphere”. We have conducted a systematic study on the variations of the convection style, as Prandtl numbers are varied from 7 to 100 at Rayleigh numbers 106 and 108. Numerical simulations show that changes in the Prandtl number could exert significant effects on the shear flow, the number of convection cells, the degree of layering in the convection, and the number and size of the plumes in the convecting fluid. We found that for a given Rayleigh number, the convection style can change from single cell to layered convection, for increasing Prandtl number from 7 to 100. These results are important for determining the surface deformation on the Jovian moon Europa. They also have important implications for surface heat flow on Europa, and for the interior heat transfer of the early Earth during its magma ocean phase. Electronic Supplementary Material is available if you access this article at http://dx.doi.org/10.1007/s10069-002-0004-4. On that page (frame on the left side), a link takes you directly to the supplementary material.  相似文献   

14.
The standard view is that value is added to raw material by labor and capital. The question here discussed is whether or not raw material must contain value previously added by nature, or whether it can be simply inert indestructible building blocks. Can humanly added value substitute for value added by nature? If the answer were yes, it should be possible, since matter-energy is not destroyed in consumption, to substitute the waste flow of matter-energy for the flow of fresh natural resources (raw materials). But this would contradict the second law of thermodynamics. The quality of low entropy is what differentiates raw material from waste, and we know of no process whose net effect is to lower the entropy of the total system on which we depend. We must focus more on “that to which value is added,” and not just on value added. This is especially true as the former more and more replaces the latter as the limiting factor in production. Further consequences of the two different views about value added for theory and policy are discussed.  相似文献   

15.
This article analyses whether international material input structures have converged or diverged over time. Pooled variances for 25 industries were obtained from OECD input–output tables in constant prices for nine countries over the period 1971–1990. It is found that high-tech industries were mainly characterized by divergence of material input structures, whereas convergence was found for many low-tech, more mature industries. In line with studies on (labour) productivity growth rates, convergence of material input structures was prevalent in the 1970s, while divergence dominated in the 1980s.  相似文献   

16.
王鑫 《经济与管理》2007,21(8):52-55
电子商务是一种新的商务模式,它以互联网为依托,物流、资金流、信息流融合,高效流动。它形成企业竞争的利器和战略转折点,增加竞争优势,为企业发展开辟新天地。  相似文献   

17.
Data envelopment analysis is used to establish comparisions of maximum profit without and with participation in government progarammes. A measure of a farm's ability to survive, returns on equity, is used to measure the benefit received from participation in government programmes. Density functions are estimated with kernel density estimation using bootstrap samples, and weighted regressions are used to test density estimation using bootstrap samples, and weighted regressions are used to test the equality of mean benefits between different size groups. The results indicate that almost all farms that could be considered of commercial size receive the same benefit from participation in government programmes.  相似文献   

18.
Noisy Directional Learning and the Logit Equilibrium   总被引:1,自引:0,他引:1  
We specify a dynamic model in which agents adjust their decisions toward higher payoffs, subject to normal error. This process generates a probability distribution of players’ decisions that evolves over time according to the Fokker–Planck equation. The dynamic process is stable for all potential games, a class of payoff structures that includes several widely studied games. In equilibrium, the distributions that determine expected payoffs correspond to the distributions that arise from the logit function applied to those expected payoffs. This “logit equilibrium” forms a stochastic generalization of the Nash equilibrium and provides a possible explanation of anomalous laboratory data.  相似文献   

19.
Most studies on housing price dynamics are only concerned with the conditional mean and variance, but overlook other higher-order conditional moments and the structural change characteristics inherent in housing prices. In order to take into account these two important issues, this study utilizes the generalized Markov switching GARCH model to explore house price dynamics and conditional distribution for US market over 1975Q1–2007Q4. The housing return follows two distinct dynamics: the bust regime and the boom regime. The volatility pattern is different in the bust and boom regimes. In addition, the conditional densities derived by the regime-switching model change dramatically over time and are significantly different from normal distribution. More importantly, the regime-switching model can detect in advance a weak US housing market such as the one that occurred in the middle of 2007. The in-sample fitting ability of regime-switching model, which incorporates higher-order moments, has significant improvements compared to the single-regime AR and AR-GARCH models. For the out-of-sample Value-at-Risk forecasting performance, the ability of regime-switching AR-GARCH model to forecast one-step-ahead density is better compared to the single-regime AR-GARCH model.  相似文献   

20.
We measure the mean and inequality in country material wellbeing based on households’ consumer durables, using household-level data from OECD’s PISA surveys for 40 countries over 2000–2012. Our consumption-based measures capture aspects of material wellbeing not captured fully by income-based measures. For 2012, tests show that the consumption-based metrics are more closely associated with objective mortality-related outcomes than are income-based measures; in 2000 (and over 2000–2012) each set of measures adds information relative to the other. The consumption-based measures may be particularly useful in revealing where income-based measures provide inaccurate indications of the mean and/or inequality in household living standards.  相似文献   

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