Performance Analysis of China Ethylene Plants by Measuring Malmquist Production Efficiency Based on an Improved Data Envelopment Analysis Cross-Model

Data envelopment analysis (DEA) has been widely used for efficiency evaluation of industrial plants. A conventional DEA model may easily lead to the situation where more than one-third of efficiency values are set to 1, so it is hard to analyze the pros and cons of the multi-decision-making units. The DEA cross-model can distinguish the pros and cons of the effective decision-making units, but it is unable to indicate the improvement direction of the ineffective decision-making units. This paper proposes an efficiency analysis method based on an improved DEA cross-model, which can get higher efficiency discrimination in identifying the efficiency state of the decision-making units compared with the conventional DEA model. The improved DEA cross-model avoids the impacts of unreasonable weight allocation of input and output indices. Meanwhile, self-evaluation of the improved DEA cross-model with the slack variables can find the improvement direction of the ineffective decision-making units. Also, the Malmquist productivity index (MPI) based on the improved DEA cross-model can comprehensively consider various input–output factors and obtain dynamic consistent analysis performance of industrial plants. To get relative effectiveness of ethylene plants under different technologies and different scales, the performance analysis of 19 ethylene plants in China were executed by proposed MPI. According to the results, various indices of MPI are evaluated over time by the improved DEA cross-model to obtain the root causes and direction of performance improvement of ethylene plants. As a result, the method proposed in this paper is effective and practical

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Mixing State of Black Carbon Aerosol in a Heavily Polluted Urban Area of China: Implications for Light Absorption Enhancement

<div><p>Black carbon (BC) is important for climate forcing, and its effects on the Earth's radiative balance remain a major uncertainty in climate models. In this study, we investigated the mixing state of refractory black carbon (rBC) and aerosol optical properties in a polluted atmosphere at Xi’an, western China. The average rBC mass concentration was 9.9 <b>μ</b>g m⁻³ during polluted periods, 7.6 times higher than that in clean periods. About 48.6% of the rBC was internally-mixed or coated with nonrefractory materials during polluted periods; this was 27% higher than in clean periods. Correlation analysis between the number fraction of thickly-coated rBC particles (<i>f</i>_BC) and the major particulate species indicate that organics may be the primary contributor to rBC coatings during polluted periods. The average mass absorption cross section of rBC (MAC_BC) particles at <b>λ =</b> 870 nm was 7.6 <b>±</b> 0.02 m² g⁻¹ for the entire campaign. The MAC_BC showed a positive correlation with <i>f</i>_BC, and the enhancement of MAC_BC due to internal mixing was 1.8 times. These observations suggest that an enhancement of BC absorption by a factor of ∼2 could be appropriate for climate models associated with high PM_2.5 levels.</p><p>Copyright 2014 American Association for Aerosol Research</p></div

Comparison of CTO-375 EC with A) IMPROVE-550 ECR, B) IMPROVE-550 ECT, C) STN60 ECR, and D) STN60 ECT.

<p>The relationship between CTO-375 EC and IMPROVE soot (EC2+EC3 by IMPROVE-550) for E) all dust and soil samples as well as F) those excluding two samples (red circles in E) with high EC1 are also presented. All concentrations are in mg g^-1. Robust linear regression was used for all the analyses.</p

Laser signal changes, i.e., ∆R_min and ∆T_min (the minimum R and T minus the corresponding initial R and T) among the four different protocols (IMPROVE-550 vs. IMPROVE-675 in (A)-(B) and STN60 vs. STN120 in (C)-(D)), which serve as indicators for the degree of pyrolysis.

<p>UD stands for urban dust and S stands for soil. See supplement <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0083462#pone.0083462.s001" target="_blank">Figure S1</a> and <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0083462#pone.0083462.s005" target="_blank">Table S1</a> for sample IDs.</p

Thermograms of A) the conventional IMPROVE (Interagency Monitoring of Protected Visual Environments) and B) the STN (Speciation Trends Network) protocols (for sample UD-2).

<p>Thermograms of A) the conventional IMPROVE (Interagency Monitoring of Protected Visual Environments) and B) the STN (Speciation Trends Network) protocols (for sample UD-2).</p

Comparison of ECT (EC with transmittance correction) between IMPROVE-550 and other three protocols using robust linear regression.

<p>(A)-(C): in urban dust samples with relatively high percentage of soot contents and (D)-(F) in soil samples with relatively low soot contents.</p

Palaeontological signatures of the Anthropocene are distinct from those of previous epochs

 The “Great Acceleration” of the mid-20th century provides the causal mechanism of the Anthropocene, which has been proposed as a new epoch of geological time beginning in 1952 CE. Here we identify key parameters and their diagnostic palaeontological signals of the Anthropocene, including the rapid breakdown of discrete biogeographical ranges for marine and terrestrial species, rapid changes to ecologies resulting from climate change and ecological degradation, the spread of exotic foodstuffs beyond their ecological range, and the accumulation of reconfigured forest materials such as medium density fibreboard (MDF) all being symptoms of the Great Acceleration. We show: 1) how Anthropocene successions in North America, South America, Africa, Oceania, Europe, and Asia can be correlated using palaeontological signatures of highly invasive species and changes to ecologies that demonstrate the growing interconnectivity of human systems; 2) how the unique depositional settings of landfills may concentrate the remains of organisms far beyond their geographical range of environmental tolerance; and 3) how a range of settings may preserve a long-lived, unique palaeontological record within post-mid-20th century deposits. Collectively these changes provide a global palaeontological signature that is distinct from all past records of deep-time biotic change, including those of the Holocene. </p