Based on an investigation of the meaning of development, the neo-classical economic approach to development, and the post-welfarist theory of development, this paper proposes a conceptual framework for understanding human development potentials, while undertaking empirical analysis using cross-sectional and time series data on human development. Human development is associated with basic necessities for subsistence, the quality of life, and political and civil rights, in addition to income indicators. Our analysis suggests that the concept of human development potentials has two dimensions: the rights of development and limits to human development. Both are largely ignored in the neoclassical theory of development. However, human development is not unbounded, which approaches to a relatively fixed constant at given economic, technological and institutional conditions. This conceptual understanding is supported by results from the empirical examination of the relationships between demands for carbon emis 相似文献
Current liquid flammability classification mainly relies on flash point and its risk is largely dependent on consequence and probability. However, combustions of liquefied marine fuels have their uniqueness, leading to a less consistent with the common classification. This work aims at classifying flammable liquids in compression ignition engines for further safety evaluation. Besides liquid flammability characteristics, flame propagation and aerosol formulation are considered. Two unsupervised machine learning clustering algorithms, k-means and spectral clustering, are applied to the collected liquid compounds database. To consider both cluster cohesion and separation, the global mean silhouette value is used to find the optimal number of clusters and to evaluate the clustering performance. The results show that the spectral clustering outperforms k-means on classifying the risk ratings for all proposed models, while the clustering accuracy of the optimal model has been doubled by employing spectral clustering algorithm. Moreover, principal component analysis and star coordinate diagrams are presented to visualize high dimensional data to 2-D graphs. Finally, the overall liquid safety performance is evaluated by a novel combustion risk index via the weight values determined by the information entropy approach. This index can be used to explore inherently safer fuels in the process industries. 相似文献
Scientists have aimed at exploring land use and land cover change (LUCC) and modeling future landscape pattern in order to
improve our understanding of the causes and consequences of these phenomena. This study addresses LUCC in the upper reaches
of Minjiang River, China, from 1974 to 2000. Based on remotely sensed images, LUCC and landscape pattern change were assessed
using cross-tabulation and landscape metrics. Then, using the CLUE-S model, changes in area of four types of land cover were
predicted for two scenarios considering forest polices over the next 20 years. Results showed that forestland decreased from
1974 to 2000 due to continuous deforestation, while grassland and shrubland increased correspondingly. At the same time, the
farmland and settlement land increased dramatically. Landscape fragmentation in the study area accompanied these changes.
Forestland, grassland, and farmland take opposite trajectories in the two scenarios, as does landscape fragmentation. LUCC
has led to ecological consequences, such as biodiversity loss and lowering of ecological carrying capacity. 相似文献
We present an approach for predicting the lower flammability limits of combustible gas in air. The influence of initial pressure and temperature on lower flammability limit has been examined in this study. The lower flammability limits of methane, ethylene and propane in air are estimated numerically at the pressure from one to 100 bar and the temperature from ambient to 1200 K. It was found that the predicted LFLs of methane, ethylene and propane decrease slightly with the elevated pressure at the high temperature. The LFLs variation for methane-air mixture is 0.17, 0.18, 0.18 volume% with the initial pressure from one to 100 bar at the initial temperature of 800 K, 1000 K and 1200 K respectively, which is significantly higher than that at lower temperature. And the LFL of methane-air mixture at 1200 K and 100 bar reaches 1.03 volume% which is much lower than that at 1 bar and ambient temperature. On the other hand, the LFLs variation is 0.11–0.12 volume% for ethylene-air mixture and 0.06–0.07 volume% for propane-air mixture with the initial temperature from 800 K to 1200 K at the same range of pressure. The LFL values at high temperatures and pressures represent higher risk of explosion. 相似文献
Objective: Although a considerable amount of prior research has investigated the impacts of speed limits on traffic safety and operations, much of this research, and nearly all of the research related to differential speed limits, has been specific to limited access freeways. The unique safety and operational issues on highways without access control create difficulty relating the conclusions from prior freeway-related speed limit research to 2-lane highways, particularly research on differential limits due to passing limitations and subsequent queuing. Therefore, the objective of this study was to assess differences in driver speed selection with respect to the posted speed limit on rural 2-lane highways, with a particular emphasis on the differences between uniform and differential speed limits.
Methods: Data were collected from nearly 59,000 vehicles across 320 sites in Montana and 4 neighboring states. Differences in mean speeds, 85th percentile speeds, and the standard deviation in speeds for free-flowing vehicles were examined across these sites using ordinary least squares regression models.
Results: Ultimately, the results of the analysis show that the mean speed, 85th percentile speed, and variability in travel speeds for free-flowing vehicles on 2-lane highways are generally lower at locations with uniform 65 mph speed limits, compared to locations with differential limits of 70 mph for cars and 60 mph for trucks.
Conclusions: In addition to posted speed limits, several site characteristics were shown to influence speed selection including shoulder widths, frequency of horizontal curves, percentage of the segment that included no passing zones, and hourly volumes. Differences in vehicle speed characteristics were also observed between states, indicating that speed selection may also be influenced by local factors, such as driver population or enforcement. 相似文献